[Dr Tommy Wood] (0:00 - 0:17)
We are essentially treating our brains as the overtraining amateur athlete treats their bodies. We are constantly exposing them to a wide variety of different stresses, but never allowing ourselves time to really rest and recover and adapt, so that we can come back and deal with more of those stresses the next day.

[Angela Foster] (0:17 - 0:29)
The lack of control seems to play a big part from what you're saying. If you have stress in your life, but you feel in control of it, you feel resilient enough and you can meet that stress, but if you are out of control with it, that is more damaging to the brain.

[Dr Tommy Wood] (0:29 - 0:46)
Those who have high demand, high stress jobs, but have a high feeling of control over those stresses, actually have a lower risk of dementia and a lower risk of depression. Whereas those who have high stress, high demand jobs, but don't feel like they have adequate control over those, have an increased risk of depression and dementia.

[Angela Foster] (0:49 - 1:25)
What if nine blood markers could predict how fast you're ageing and you could change it? Research shows for every extra year of biological age, mortality risk increases nine percent. Stride tests the exact biomarkers that predict longevity, plus your DNA and microbiome.

So you know what to change through diet, movement and sleep. I'm testing myself and my family. Get 10% off at getstride.com forward slash Angela, or check the link in the description below. Tommy, what is a healthy brain?

[Dr Tommy Wood] (1:26 - 3:04)
What a great question to start with. A healthy brain is one that does what you want it to do when you want it to do it. I think it's important to think about a healthy brain in that way because it allows us a lot of freedom to shape our brains in ways that are important to us personally.

The reason why I say that is because, yes, there are some core functions of the brain that all of us want. We want to be able to remember. We want to be able to control our emotions.

We want to be able to perform complex skills or use knowledge that we've acquired. But those skills and knowledge in particular are very personal to us, and they may be very different from person to person. Could be languages, could be skills as a surgeon, could be a sport that we play.

And these experiences and the way we use our brains are really what drives how our brains work. So the core ideal goal is that our brains do exactly what we want them to do when we want them to do that. Of course, within some reason, I'm never going to be a fabulous dancer, if you ask my wife, no matter how hard I try.

But I might be able to expect that my brain does the science-related things that I tend to do in my job. So I think that's where we should start. And then we can think about how we can build up an environment that then supports our brains to be healthy in the ways that we want them to.

[Angela Foster] (3:04 - 4:14)
Yeah, I love it. I love that definition. So it's basically a brain that does what we want when we want it to do it.

Do you know what comes immediately to mind straight away? And I think as a midlife woman myself, and for so many of my audience listening, is that the midlife brain in particular, at least the midlife female brain, seems to have so many demands on it at multiple points during the day. And I think that that can feel difficult for many women.

There's another kind of flexion point, if you like, where a woman is going through pregnancy. We talk about pregnancy brain and then afterwards, postpartum. I think for us women, we struggle because there seem to be ups and downs.

But certainly in midlife, there are a lot of demands at any one time. And I think that we have to switch focus frequently as well, because we may, as you say, you were talking there about being a scientist. We may have a job that we want to be really good at and have a high performing brain.

But then we immediately want to be able to turn to empathy, for example, and listen to our kids and what they're talking about. How can we... Well, I suppose before we talk about how to support it, what effect is constant demands having on the brain?

[Dr Tommy Wood] (4:15 - 7:58)
When I think about how demands affect brain function, actually, a lot of how I think about how we build and support brain function, there are direct parallels to how our bodies function in relation to how we use them. I have been an athlete my entire life. And, you know, I'd like to go to the gym and do a few bicep curls.

So I'd kind of think in bicep curls. And I think that this can sort of give us a similar framework to think about the brain. So when you are training for some kind of athletic endeavour, whatever it is, triathlon, marathon, powerlifting competition, CrossFit, we know that you need to apply some kind of stress to the body, a physical stress.

That's what drives adaptation, right? We know that these stresses are important because that's what actually allows our body to respond and adapt and create the function that we want. But we also know that we need to have some period of recovery afterwards.

So any good athlete knows that you don't get stronger in the gym, you get stronger when you rest and recover afterwards. However, a lot of amateur athletes, and I spent a lot of time in my career working with amateur athletes, they focus mainly on the stressor. They spend more time training.

They think that the more they do, the better they're going to get. And they never attend to the recovery piece. Whereas professional athletes spend probably more time thinking about recovery often than they do about training because they know how important recovery is for adaptation.

So what happens more frequently in amateur athletes is they get stress fractures, they get overtraining, they don't eat enough to support all the exercise that they're doing. And this then translates perfectly over to what we're doing with our brains on a day-to-day basis in the modern environment, which is we are essentially treating our brains as the sort of overtraining amateur athlete treats their bodies. We are constantly expecting more.

We are constantly exposing them to a wide variety of different stresses, but never allowing ourselves time to really rest and recover and adapt so that we can come back and deal with more of those stresses the next day, which is always going to happen. So what this looks like, what overtraining looks like in the brain, you might call burnout. Or in the literature, it's been called many things like high allostatic load or vital exhaustion.

But all of them essentially show the same thing, which is that having a high burden of stresses, psychological, cognitive, could be physical as well. That we don't have full control over. And it's that loss of control that's really a big part of the problem.

That lack of control then results in changes in physiology, in cognitive function, in our psychological and mental health and well-being that sort of compounds over time. So it's those two main things. One is just the continuous barrage of all these different stresses.

Plus, and especially because we then don't give ourselves time to really recover in between, either because these things are put upon us and we can't find the time, or for whatever reason, we haven't yet structured our days so that we can find the time. But then we get these sort of knock-on effects in terms of our cognitive function and our mental well-being.

[Angela Foster] (7:59 - 8:33)
And this, I want to pick up on an important point there, right? The lack of control seems to play a big part from what you're saying. If you have stress in your life, but you feel in control of it, you feel resilient enough and you can meet that stress or whatever those obligations are.

But if you are out of control with it, so an example might be, you're in a relationship, right? Where you may be being psychologically or emotionally abused by someone, right? That would make you feel out of control.

It sounds like that is more damaging to the brain than a stressful situation. For example, a stressful job, but you can meet those demands and you feel in control of.

[Dr Tommy Wood] (8:33 - 10:17)
Exactly. So there are two very related studies or types of study that show this. So, and actually, stresses can be beneficial.

And this is something I talk about a lot because often we think about stress as a bad thing. But stress that we can respond and adapt to because we have time to recover is actually what makes us cognitively and physically stronger. It's the lack of recovery and the lack of control that allows for recovery that's really important.

So when you look at studies and you ask people about the demands of their job, and this, you look at work stress, because there's something that's quite consistent, whereas other things in our lifestyle environment could change a lot. If you try and look at a long-term exposure, you know, our jobs for most of us are relatively similar over long periods of time. You ask people about the demands of the job and how much control they feel that they have.

Those who have high demand, high stress jobs, but have a high feeling of control over those stresses, actually have a lower risk of dementia and a lower risk of depression. Whereas those who have high stress, high demand jobs, but don't feel like they have adequate control over those stresses have an increased risk of depression and dementia. So I think this is where a lot of the discussion comes up around, people have said, you only get burnout because you're not passionate about what you're doing.

And I don't think that's quite right. I think what it is, is like, regardless of your passion, if you don't have control over your schedule because of the nature of your job, or because of the nature of your other commitments, then that's where these stresses start to cause problems over time.

[Angela Foster] (10:18 - 10:52)
Very interesting, because I mean, you know, I'd also, I don't know how true this is. For example, I think I'd read somewhere that a university education is protective, right? So the higher, that's true, you're nodding, right?

The higher level you take education to, and I guess if we continue learning throughout our lives. So someone in, for example, a professional job may be thinking, well, I'm quite well protected against dementia, because I'm continuing to use my brain and continuing to learn. But actually, if they feel out of control, and then they're maybe out of control in their home environment a little bit, then actually, the risk is increasing.

[Dr Tommy Wood] (10:52 - 13:57)
Yeah, so all of those things can be true at the same time. And that's why it's important to figure out what is sort of relevant to each of us individually. So you're right that educational attainment, the longer you spend in education and early life, and the greater your level of attainment.

So, you know, finishing secondary school versus finishing a bachelor's degree versus a graduate degree of some kind, the more time you spend in education, on average, the higher and the later the peak in your cognitive function. So you basically spend more time as a professional learner, challenging your brain, and the brain responds accordingly. So, yes, the average cognitive function is higher in those who have higher educational attainment.

And then that peak happens about the time you leave formal education, whenever that is. So sometime in your sort of teens to maybe late 20s, or even early 30s, if you spend all your time as a student, like I did. And from then on, on average, again, cognitive function starts to decline.

But what you see is that, yes, people who have higher levels of education early in life are protected, relatively protected against dementia and significant cognitive decline. Or if they do experience cognitive decline or dementia, it happens later in life, because they started from a higher peak. So if you're going to then decline, you sort of like you've shifted the curve, you know, along a few years.

But if you want to change the angle of that decline, what you do later in life really matters. So that's where, yes, our jobs are important. So if we have cognitively stimulating jobs that require complex problem solving, a lot of social interaction, they're not particularly repetitive, we're constantly having to learn new skills, then that's, again, associated with an increased or with a decreased risk of dementia.

And you see the lowest risk in those who have a high level of education and complex and stimulating jobs. But you also see that, say, those who didn't have high levels of early life education, they then experience protection again, if they have, they end up in jobs that are cognitively stimulating. So I think that's important, because not everybody gets a chance to, you know, go to university and get a medical degree or whatever, right.

But if you can find significant cognitive stimulation later in life through whatever it is that you want to do, you can then still see those benefits. So all of these things are important. But you're right that that later period of work, yes, if it's cognitively stimulating, that's great.

But if it is, that comes with stresses that you don't feel you have control over, then that may negate some of those benefits. So that allow, hopefully that allows people to figure out, okay, where am I, where am I on that curve and in those different areas? And therefore, where do I need to focus?

[Angela Foster] (13:58 - 14:14)
Yeah, very much so. And I guess, like, if you pick up education, again, later in life, right, some people are doing a PhD in their 40s or 50s. But what that's doing is extending protection, it's not actually creating, like a new upgrade, if you like, in the same way that earlier education is, or is it?

[Dr Tommy Wood] (14:15 - 16:14)
Oh, so I would say that it is. And I think that we assume and this is, I think this is part of the problem is that we assume that as we get older, we assume two things. One is that we are no longer capable of learning in the same way that we were when we were younger.

And two is that once we get into our 30s and beyond, it's just this like unstoppable decline of cognitive function, there's nothing that we can do about it. And we know that neither of those things are true. So the adult brain, say, compared to the developing or younger brain, yes, it requires a little more work to kind of direct the forces of neuroplasticity, we might call it, to kind of like direct improvements in brain function.

And that's because the brain has already adapted to the environment and the person that you are. And you want that to be relatively stable, right, that the brain is an adaptation machine, it's literally created itself such that you can perform as well as it thinks you need to in the environment that you're in. So yeah, it requires a little more effort to kind of change things, but it's still perfectly capable of change.

Most of the reason why we think we can't learn stuff as we get older is because we just we don't have the time to dedicate to learning that we did when we were kids. Those are two very different things. The brain is capable of learning if we can find the time.

And then the other thing is that we assume that it's just like a one way street downwards. But that again, doesn't seem to be the case, we can significantly improve multiple aspects of cognitive function through skill development and learning in adults. So if you think about like a curve over time, right, your sort of cognitive function may be decreasing with age, you can create a bump upwards, and you can move it upwards.

Certainly, with many aspects of cognitive function, there are some things that will decline with age, and we can't prevent ageing entirely. But we can certainly improve function and then slow decline significantly by sort of attending to our brain health overall.

[Angela Foster] (16:14 - 17:15)
And I want to dive into some of those in a moment. But just on a related point to this, one thing that strikes me is we talked about stress beyond our control. And we've talked about kind of extending learning and things like that, right?

And our capacity, if you like, I guess would be one way to refer to it. It strikes me what effect does decision making happen? So we hear a lot about entrepreneurs like Elon Musk, will wear the same t-shirt every day to reduce decision fatigue so that they have the attention to make the decisions that really matter.

As a female, I have, as a woman, I've tried to develop a capsule wardrobe to reduce the number of decisions. But I feel like us women have many more decisions that we make, including how am I going to wear my hair? What am I going to do?

Will this blazer look right with this? Like, you know, makeup, jewellery, earrings, like so many decisions that I think, and then looking after children, I think about just the average morning routine of a woman, maybe compared to a man, there's so many decisions that are being made. Is that having an effect on the brain?

[Dr Tommy Wood] (17:15 - 17:56)
I think you could, you could sort of lump all these things together, even though they're not quite the same. In reality, yes, anytime you're having to make a decision, anytime you're having to use willpower to overcome the environment to do something that requires, it would create some amount of cognitive load, and it diminishes overall cognitive resources for the day. And we do know, right, and again, we have to talk averages here.

But we do know that on average, you're right, all those decisions that you have to make as you get ready in the morning, I don't make those, I throw on a hoodie, and I'm ready.

[Angela Foster] (17:57 - 17:59)
And you put a different lipstick on for this interview today.

[Dr Tommy Wood] (18:01 - 20:08)
Next time, I'll make sure I'm wearing different lipstick. And then we know that child care and family care, there's a greater burden on women than there is on men, again, still on average. And this is something that I think has improved over time, but it's still highly inequitable.

And we know that. So you're right, that there is a greater burden of many of these things on women than there is on men. And I actually think that a lot of these things have resulted in part of the imbalance in dementia prevalence in women versus men.

So about two thirds of individuals with Alzheimer's are women compared to a third of men. The other types of dementia are a little more sort of evenly balanced. But Alzheimer's disease in particular seems to affect women more than men.

And there's a whole bunch of reasons for that. You know, there's hormones, there's other aspects of the biology of sex that could play a role here. But if we think about the more recent cohorts of women who've been diagnosed with Alzheimer's disease, they grew up in a world where women didn't get as much education as men did.

And women didn't get cognitively stimulating jobs as much as men did. But they had high burdens of family and child care, as well as, unfortunately, potentially less cognitive stimulation because of the home environment where they're sort of just like doing the jobs of keeping a house. And there are, again, studies that suggest that this is the case.

So I think that, luckily, a lot of this is changing. And that may then translate into decreased dementia burdens as care distribution becomes as education and access to those types of jobs become more equitable. But I think those things that you're thinking about may have actually contributed to the imbalance in dementia prevalence in women versus men.

[Angela Foster] (20:08 - 21:10)
Yeah, it's very interesting what you say there, right? Because as you say, time is going to tell. When I look, I mean, my mum, sadly, has ended up with Alzheimer's.

And when I look at her generation and the things they did, they weren't in as many of them in professional jobs. They did have a lot of stress as well going on, as you say. And I think some of the things that we're going to go on to talk about, they weren't real things either.

Do you know what I mean? Like high-intensity training wasn't a thing when my mum, I remember her going to the pool and she was very endurance fit. Do you know what I mean?

She might swim 40, 50 lengths of a 50-metre pool, but she wasn't sprinting or doing things that produce a lot of lactate or OBDNF, which we're going to talk about in a moment. So it is really interesting. You did mention their hormones.

I think this is a really important question. What's happening in that perimenopausal transition? Because a lot of women experience brain fog, that can feel quite scary for them at first.

And they're wondering, will this continue? How much of an impact does menopause and menopause hormone therapy have on the female brain?

[Dr Tommy Wood] (21:11 - 27:12)
You're right that the perimenopausal period and the menopausal transition, there's a lot that changes with respect to both hormones and the brain. And it's very common for women to experience brain fog or at least subjective, if not objective changes in cognitive function. And some of that does seem to be related to hormones, although imperfectly, like the studies that have looked at this, there's not as much correlation as we might think.

And this, I think, is a product of the studies that have and have not been done. And there is some really important, there's been some really important recent investment in this area that I think is going to give us some better answers going forward, like CARE, which has been run by Lisa Moscone. She's got a massive amount of money from the Wellcome Foundation to sort of better look at hormones and menopause and cognitive function.

So I think that we'll get some better answers, although there's probably a lot that we can know right now. So oestrogen, which declines significantly during that period, is critical to several aspects of brain metabolism and brain function. But not every woman who goes through menopause experiences brain fog or any other cognitive symptoms, and not all women get dementia.

So there are certainly other things that are going on at the same time. What actually seems to better predict cognitive changes in that period is vasomotor symptoms rather than absolute hormone changes. So night sweats, hot flushes, that may be because sleep is often affected.

And there are even interventions that improve vasomotor symptoms without affecting hormones that significantly improve cognitive function. There was a study where they gave a nerve injection to women with significant vasomotor symptoms during perimenopause and saw significant improvements in cognitive function without changing hormone levels. So there are a lot of things that are happening.

I think a lot of it then, if you're affecting sleep, or these big swings in temperature might be having separate effects on the brain. But MHT, or menopausal hormone therapy, is very good at treating those symptoms if women have them. And so that's one very good reason to use MHT, is to address those symptoms.

Because then you see improvements across a lot of things. You might see improvements in sleep, you might see improvements in overall well-being, social interaction, sexual function, and sexual relationships. All of those things we know are important for the brain.

So even if these changes aren't purely driven by hormones, MHT is an important tool in that toolbox, which many women feel they benefit from cognitively. When you look at the studies that kind of look at the effect of MHT on cognitive functional dementia, they're much less clear-cut. And this is probably because of the different types of hormones, right?

If you're giving synthetic, bioidentical, you're giving premarin from oestrogen, or estrogens that are kind of conjugated equine estrogens from horse urine, which is a historical version of MHT. So I think the research is quite muddy because of all these differences, like when you're giving it, who you're giving it to, what are you giving? How long are you following these things up?

And I think that's, again, going to improve over time. So I can't show up with a big meta-analysis that says MHT decreases the risk of dementia, because we don't have that. Recent studies that show actually for cognition, on average, based on the studies that exist currently, there's no benefit, but also no risk.

However, I think that's partly the nature of the studies. But if we focus on individual symptoms and individual quality of life, then I think MHT can have a big impact. The final part, or maybe two final parts that are worth thinking about there.

One is that the menopausal transition seems to be a period of risk amplification. So if you have other risk factors, sedentary, metabolic disease, poor quality diet, then those, we know there's a risk factors for cognitive decline dementia. And that period seems to be when some of those risks are amplified.

And there are studies that show that, so say, if you have metabolic disease during that period, you're more likely to experience certain decreases in certain cognitive functions. So we also know that we see improvements in function and decreases in certain symptoms, like motor symptoms, by improving diet quality, by increasing exercise, by addressing sleep. So there are multiple ways that you can address those symptoms and improve cognitive function, even during that period, if that's something that you're experiencing.

The final point that I think is important is that it is very much a transition period. So there are studies like the SWAN study in the US that showed that for women who did experience some cognitive changes during the perimenopausal period, and then the transition after that, they actually rebounded back to where they were before. So just because you experience changes during that period doesn't mean that you're destined to have that long term.

Although absolutely addressing symptoms, either with lifestyle or with MHT or multiple other options is important during that period, absolutely. But there's some hope that later on, things will come back. And it's important to just think about it as a transition period rather than some destiny is being set based on the symptoms that you experienced during that period.

[Angela Foster] (27:12 - 27:52)
Which I think will give comfort to a lot of people listening to this. And I think treating the symptoms, as you say, may then have beneficial impact, right? If you know that things like menopause hot flushes are impacting the brain potentially, but also it's impacting women's confidence.

And I think from that perspective, it's just really hard, isn't it? To live with your brain not working properly for five years or so is tough. One thing that I noticed is, and I think this again is very common for women in perimenopause, is an iron deficiency will also cause your brain to have a very kind of cotton wool feeling where actually you'd find it hard to hold on to words and things like that.

And sometimes correcting micronutrient deficiencies, right, can help.

[Dr Tommy Wood] (27:52 - 28:37)
Yeah, absolutely. And that's another part of that. We know that nutrient deficiencies are risk factors for cognitive decline and dementia.

And like you say, their presence during that period, as it's like, if we think of it as a risk amplifying period without making it sort of like hyperbolic or scary, you're absolutely right. If we can address some of these other risk factors, I think you'll see an improvement in many people. Having some idea of iron status, vitamin D status, omega-3 status, B vitamin status, I think can be really helpful so that you know you're addressing these risk factors that may be contributing to any cognitive changes you're experiencing.

[Angela Foster] (28:38 - 29:17)
Yeah, and in your book, The Stimulated Mind, you go through, I think, all of the different nutrients, right, that impact the brain. So if you're listening to this, you can go and get The Stimulated Mind and actually go and see. And then you can, as you say, you can do some lab work to test, am I deficient in any of these?

And where to find these important nutrients in your diet? One thing that's getting a lot of attention that you talk about is creatine. And this has massively helped me with brain energetics.

I'm a huge fan of it. And I think I read that women make and store about 20 to 30% less creatine than men. So kind of, we need it more.

It's not just for bodybuilders. Explain how creatine is affecting the brain.

[Dr Tommy Wood] (29:17 - 32:23)
Sure. So as somebody who's existed in the sort of same world as you for a long period of time, right, I could have written about dozens of supplements for the brain, each with their specific use cases and their specific evidence. But outside of the nutrients that I just mentioned, which you might need to take as a supplement, right, you might need to take a omega-3 supplement or a vitamin D supplement, or a B vitamin supplement.

Outside of those, the only supplement that I'd mentioned in the book is creatine. And there has been some, I think, people have sort of like oversold the evidence of creatine. But you're absolutely right that there are multiple strands of evidence that suggest that creatine is beneficial for brain function.

So it's been used as an adjunct in treatment for depression in randomised controlled trials. There are multiple studies that show that it overcomes some of the cognitive changes we might experience after a night of poor sleep, which is going to be very common if you're a busy woman or any busy individual, you've got kids and all these other things that are going on. And it seems to be largely due to energetics, like you said.

So in the case of sleep deprivation, we have this ongoing suppression of certain metabolic activity in the brain because we haven't managed to clear out some things that we would normally clear out during sleep that then affect brain energetics like adenosine being one. And creatine seems to overcome some of that and help maintain cognitive function and the execution of complex skills. So there was a study, actually one of the original studies was in rugby players, and then they had them sleep deprived or not, and they gave them creatine and they saw that they had better maintenance of their rugby skills the next day when they were sleep deprived if they took creatine.

So it seems to be helping to overcome some of these energetic changes that we experience and that may be associated with certain clinical conditions. So like I mentioned, depression, they've done a small study on creatine supplementation in postmenopausal women and saw some changes in cognitive function. Although it was a very small study, they've done another small study in individuals with early Alzheimer's disease and saw some potential benefits.

So we're very early on in some of this evidence, but big meta-analyses show that particularly as you get older, creatine seems to benefit cognitive function, particularly memory. And it's also the most studied supplement in the world. I mean, hundreds of studies at this point and overall no significant side effects compared to placebo, even at very high doses.

So one reason why I talk about creatine a lot is because there's a lot of benefit both for brain and body, but it also has what I call positive asymmetry. High potential for benefit with very low risk. So if people are thinking about trying something to kind of support cognitive function, it seems like a good place to start.

[Angela Foster] (32:24 - 33:18)
And when I spoke to Dr. Darren Kanda about this, he was talking about higher dosages, particularly when you were speaking there around lack of sleep. He was using a jet lag protocol, for example, of I think 10 grammes a day. What's the best way to get it into the brain, right?

When we think of the blood brain barrier, like would you be better off splitting this? Because I know the other thing that comes up for a lot of people is bloating. And certainly what I found is say, for example, you're making up a protein shake in the morning and you think, right, I'll put a scoop of creatine in.

If you don't have enough liquid and you put quite a lot of creatine in, it almost is like drawing water into the gut and then you get a little bit of bloating. Whereas I found that's alleviated by really good hydration with minerals and also maybe like splitting the dose. You're not having quite as much in one go.

I'm curious from the research things you've done when you're working with athletes and individuals yourself, what you advise in terms of dosing that creatine?

[Dr Tommy Wood] (33:18 - 36:34)
Yeah, so I think for most people, a standard dose, which is five grammes is a great place to start. That's been, you know, even in that rugby player study, they were using like doses down at that end and saw benefit. In some of the depression trials, they used doses of five grammes and saw benefit.

So I think that's like a really good place to start. You're right that some of the studies that looked at increasing brain creatine, they used a loading protocol. So something close to 20 grammes a day for a week significantly increases brain creatine.

And that's one of the more recent sleep deprivation studies. They use something close to 30 grammes after a night of sleep deprivation to sort of overcome some of those energetic deficits. I don't think most people need to be up there, but certainly we know it's safe.

There are studies in older populations where they've given 20 grammes for long periods of time, years, and, you know, not seen any negative side effects. But like five to 10 grammes is probably a great place for most people to start. In terms of some of the side effects, like I said, when you look across all the studies, there doesn't seem to be an increase in side effects compared to placebo.

There's a big meta-analysis looking at creatine side effects that just came out and showed that. And some of the bloating and, you know, other symptoms may be related to creatine quality. So if you're not taking creopure, which is the best known form of creatine monohydrate, then other forms of creatine seem to have a higher level of impurities that may be driving certain side effects if you experience this.

So make sure that you're getting high quality creatine. Creopure is made by a company in Germany. Most good supplement companies just buy creopure and then they white label it, right?

They put their own sticker on it. That's what I would recommend people take. So that may be some of it.

Yes, we also know that when you start taking creatine, creatine starts to go into the muscles in particular. It draws in a little bit of extra fluid. So particularly as you start creatine, extra hydration does seem to be important.

And that's not a bad thing. That's just creatine doing its job. And that doesn't seem to be associated with any side effects.

But I do recommend that athletes, if they're starting it for the first time, they just make sure to stay well hydrated. A dose of five grammes for most people should be absorbed pretty easily without any issue. Once you start getting close to the 10 plus grammes, there's some evidence that you might start saturating creatine transporters.

So then more does stay in the gut. And that then, well, first of all, you're not absorbing everything that you're taking. And then perhaps you get some of those sort of gut side effects that you mentioned.

And that's probably very different from person to person. And actually the experience of creatine does seem to be quite different from person to person overall. And so then if you're gonna take more than 10 grammes, I would split it up probably into multiple doses of five grammes split throughout the day, just to make sure that you're getting the most out of what you're taking.

[Angela Foster] (36:34 - 36:37)
So even 10, you could do five in the morning, five in the afternoon, for example.

[Dr Tommy Wood] (36:38 - 36:56)
Yeah, but I'll admit that I take 10 grammes every day. And just to make sure that I take it, I take it all at one time. And I don't feel like I have any issues with it.

But if I got myself a pillbox or I built a routine where I was taking supplements multiple times a day, then I could do that too.

[Angela Foster] (36:57 - 37:00)
Yeah, consistency is always gonna be perfection, right?

[Dr Tommy Wood] (37:00 - 37:00)
Yeah.

[Angela Foster] (37:01 - 37:36)
You've mentioned a few times depression. This is a common thing. I think big percentages of people that are taking antidepressants, something I've used myself in the past.

I'm keen to understand the link that you talk about between depression and dementia risk. So is having untreated depression increasing your risk of dementia? You also mentioned that creatine can help with mood stability as well, but is it untreated depression or is it depression per se?

It seems to be associated with increased dementia risk.

[Dr Tommy Wood] (37:37 - 39:32)
Yeah, that's a great question. And I think the answer is probably a bit of both, depending on the underlying causes or drivers of depression, of which there are many. But one specific example, say, could be inflammation.

So we know that inflammatory diseases or inflammatory processes are associated with something like a third of cases of depression. We also know that chronic inflammation increases the risk of dementia. So some of the link between the two could just be that they have a common underlying cause.

Whether the depression is treated or not probably matters a bit less for that connection because we know that people who have depression have a higher risk of dementia. People who have dementia have a higher risk of depression. That goes in both directions.

The other side is that if somebody has depression, then that changes their behaviour in ways that may influence their dementia risk. So we've already mentioned physical activity is critical. Social interaction is critical.

Those are maybe two big ones. Individuals who are experiencing significant depression may do less physical activity and have less social interaction. Seeing friends less, family less.

They're not engaging in some of these cognitively challenging, stimulating activities that we mentioned earlier that we know are beneficial for the brain. In that setting, treating depression however you treat it, including with antidepressant medications, if that improves symptoms so that that individual then goes out and continues to do those activities again, then I think you'll decrease the risk. So it's probably a bit of both.

And ideally, we'd sort of attend to all of that to make sure that we're treating the individual right now and then also making sure that we're minimising their risk long term.

[Angela Foster] (39:32 - 39:58)
That makes a lot of sense. Thank you. So let's look at how we can protect the brain.

There's a few questions I have here. Maybe we can get through these reasonably quickly. So first one, we talked about exercise, really important.

And specifically, in your book, you talk about leg power. I've seen research that I put out on my Instagram on this. Really interesting, right?

The more powerful you are in your legs, the better protected your brain is. Why is that? What's the link between the legs and the brain?

[Dr Tommy Wood] (39:59 - 42:22)
There's a study that we did that looked at leg power and processing speed in older adults. This was using a database called NHANES here in the US. And what we looked at, which I think is important, is relative leg power.

So how strong are your legs relative to your body size? Which is important, right? Because we shouldn't compare my leg strength to your leg strength, right?

We're different people with different body sizes, different histories of training. And that was actually the best predictor of processing speed in the brain, which does tend to decrease on average over time. So how powerful your legs were relative to you, right?

So how strong you are for you was a very important predictor of processing speed. There's probably a couple of reasons for this. One is that, again, having more powerful legs is an indication that you are doing things and going out in the world that are beneficial for the brain, including exercise.

And another one is that when we work our legs, the more muscles we work and the more we work them, we release a whole host of, they're called exokines, which people may have heard of, that then have a number of benefits, including for the brain. So with resistance training or strength training or power training, this includes things like IGF-1. So IGF-1 is really critical for the structure and function of the white matter in the brain, which is the part of the brain that has lots of fat surrounding it, which insulates it and lets the neurones sort of do very fast processing and have fast connections.

White matter and the changes in white matter with age are one of the best predictors actually of cognitive decline and dementia. And in randomised controlled trials, if individuals are put on a resistance training programme, we see improvements in strength. We then also see improvements in white matter structure, white matter function and cognitive function that comes along with that.

So I think it's both the process of actually doing the work, right? We will call it a neuromuscular stimulus, right? You're stimulating the connection between the brain and the body.

And then the things that get released while you're doing that, probably both of those are gonna be really important for brain function.

[Angela Foster] (42:22 - 43:03)
Interesting. So this is something that I've been playing around with just as a bit of fun. I don't know if this is the way to measure it to see, but I'm playing around on my carol bike to see how much power can I produce, right?

And so when you do these sort of intense 20 second sprints in terms of re-hit, then it will register your peak power. Is that what we're looking at? The peak power in Watts compared to my body weight.

So I think I got up to like, I don't know, I'm about 53 kilos, I got up to 700 Watts. And I was really happy to cross the threshold because I've been in the 600s, do you know what I mean, for some time. So that strikes me like, is that the ratio we're looking at?

How much really Watts can I produce in relation to my body weight or how do we assess power?

[Dr Tommy Wood] (43:03 - 44:22)
Yeah, the data that we had for our study was what we call isokinetic leg strength. So it's this weird, is it like a leg extension or a knee extension machine that you do in the gym? It's a weird version of that, which I have done when I was a part of a couple of studies when I was an undergrad.

But basically you push against, so as you're doing your leg extension, you push against it as hard as you can, but the speed is kept constant. So no matter how hard you push, it moves at the same speed. And so that was how they measured leg power was how hard you could push against this thing.

So that then means you could probably do something similar. Yes, I think maximum power output on a car or bike or a bike in the gym is a great way to do it. Yeah, or what bike?

Yeah, a Peloton bike. They'll all give you that. It could also be like, what can you push on a leg press in the gym?

Or what can you do with a leg extension? Something like that. All of those would give you a rough idea.

And so I think in the book, I say, if you do like a regular leg press in the gym and you can press double your body weight, right, that's a really good indicator for most people. Great.

[Angela Foster] (44:23 - 44:28)
Yeah, okay. So we want to look to double our body weight on the leg extension machine.

[Dr Tommy Wood] (44:28 - 44:30)
Or leg press, leg extension, double body weight would be hard.

[Angela Foster] (44:30 - 44:35)
Oh, I did it on a leg extension. Okay, where you go up like that. Yeah, the quadriceps.

Yeah. Okay. Oh, on a leg extension.

[Dr Tommy Wood] (44:36 - 44:38)
On a leg, yeah. So I'm thinking about a leg press.

[Angela Foster] (44:38 - 44:44)
On a leg press now you're thinking about. Oh, okay. Okay.

Yeah, I can get some multiples on that. Yeah.

[Dr Tommy Wood] (44:44 - 44:44)
Great.

[Angela Foster] (44:44 - 44:48)
Oh, so this is fun. This is quite fun then. So these things are actually.

[Dr Tommy Wood] (44:49 - 46:31)
And this is important because often when people think about, oh, I'm going to go to the gym, that's gonna be really hard. I'm gonna have to do a lot of hard work. And yes, right, you should go to the gym and do hard work.

That is very important for a number of reasons. But the amount of strength you have to achieve is probably less than you think. Almost all the studies that look at strength and dementia risk, disease risk, mortality risk, essentially say that once you're in like the top third to 25% of the average population, right?

That's it. More isn't necessarily better. Now, some people want to have more.

Like I enjoy lifting weights. My strength is higher up than that. But I also know that I have more than enough to protect me from dementia and death.

I do it because I enjoy it. I'm like, it's my hobby. So just think, the way I think about this is that, and this is not for legs, but because we know grip strength and upper arm strength is really important as well.

Think about a room full of people like you, similar age, similar sex, right? Sort of similar demographics. If you could beat most of them in an arm wrestle, that's more than enough.

You're in good shape, right? You don't need to like destroy all of them or be the best. You just need to be in that top sort of like 25% compared to like an average population.

And that's less, that requires less work than you think. One or two sessions in the gym per week, 30 to 45 minutes, five or six different exercises that cover your whole body, three sets of eight to 12 reps. That's what's been used in these studies that show significant benefits for the brain.

And I think that's something that achievable, even in a busy schedule for most of us.

[Angela Foster] (46:31 - 47:08)
100%. I'll tell you what, it's really interesting. So for reasons I won't explain, I did not sleep well last night.

And so I was reduced sleep. So when I went to the gym this morning, I actually did the leg press and did a whole leg workout because I have worked out that doing leg day when I'm under slept helps me concentrate better. So does high intensity as long as I don't leave everything on the gym floor.

Like if I go at it so hard, then obviously I'm fatigued. So maybe this is a hack if it's not just a me thing that people can use. Why would that be improving my cognitive focus?

And it feels like I'm taking creatine, right? It's making up for sleep deficits. Why would that be?

[Dr Tommy Wood] (47:09 - 50:02)
Yeah, that's great. I think it is a bit of a hack. And there are studies that actually show that in the setting of sleep deprivation, say high intensity interval training seems to help to overcome some of the sort of acute deficits that you might experience.

But equally, I would say that any movement you can do when you're sleep deprived is great for a number of reasons. One, and this is one of the things you experience is that arousal is really important for performance and cognition, right? So when you're sleep deprived, you are under aroused, right?

Because of all those things still kicking around that sort of like suppressing some metabolic activity in the brain. And so we can increase arousal by doing intense activity. And actually the type of activity that seems to best support cognitive function overall, just because these are the studies that have been done is like going for a 20 minute jog is like in all the studies seems to have the best evidence.

But you're right that more intense work may be more beneficial for some people, as long as like you said, you don't become exhausted because then cognitive function actually declined as a result. So some of it is that, right, you're doing a leg workout, you're doing a HIIT workout, you have to like really get amped up to do that, right? And doing that increases the release of dopamine, acetylcholine, noradrenaline, all these other things that are really important for focus.

And you can then feel that, you know, in the hours after you did your workout. So some of it is just like the nature of those workouts that gets you more aroused that then improves focus and attention for some period afterwards. Then the other part is probably again, what the things that you're releasing during those types of workouts.

So earlier you mentioned lactate very briefly. And lactate is actually really beneficial for the brain. Again, as long as it's not massive doses for very long periods of time, when you then may see some decreases in function.

But in the short term, increasing lactate through HIIT for example, that's where it's been best studied, seems to significantly improve cognitive function. So one of the reasons for that is one, lactate can act as a substrate for the brain. So the brain uses it like it would glucose as an energy substrate.

But probably what's more interesting is that lactate increases the production of brain-derived neurotrophic factor or BDNF in the brain, which supports the function of recently activated neuronal networks. Producing lactate seems to be an important part of this, partly through BDNF. And leg workouts and HIIT workouts are the best way to increase lactate production.

So it could be, whereas both of those things is probably you're getting more amped up because it's a more significant workout. Plus some of those things that get released during those types of workouts, then have a beneficial effect on cognitive function.

[Angela Foster] (50:03 - 50:04)
Yeah, and long-term brain health, right?

[Dr Tommy Wood] (50:04 - 50:05)
And long-term brain health, absolutely.

[Angela Foster] (50:07 - 50:53)
Now when we sleep, I know, I think it goes without saying, right, social connections you talk about and people can read about, I think it's very important to see your friends, right? Social connections and loneliness, really important. Also sleep, very, very important.

But part of sleep is the glymphatic system that you speak of that kind of washes the brain and cleans it overnight. So if we're thinking about how we might optimise for this, when we wake up in the morning, I've seen videos now on social saying, go and move or get a gua sha and stimulate the neck and that things, once you wake up, everything's kind of here and you need to detoxify around the limbs when you wake up from these toxins that are coming out of the brain, seeing different things. What's true, what isn't, what can we do to improve this and protect our brains?

[Dr Tommy Wood] (50:54 - 54:04)
Probably one of the most important functions of sleep is expansion of the glymphatic system. So the fluid around all the cells in the brain that acts to essentially like, it's like a overnight street sweeper, right? That comes through and just like washes everything out, including, right?

It helps to deal with metabolites like adenosine. I mentioned earlier, adenosine actually during the night, there's the up-regulation of enzymes that break adenosine down. But then there's also like the bulk, just like washing of things out.

So one that's focused on a lot, I don't think it's the only thing that we should think about, but something that's an important part of cognitive decline dementia is say amyloid protein. So the protein that we know accumulates is associated with Alzheimer's disease. That gets cleared out partly during sleep through the glymphatic system.

And so, yes, this is important. This is one reason why we need to make sure we're getting adequate deep sleep when most of this happens. But I don't think we need to, then like the next morning, think about ways to augment this.

It's happening anyway, right? Ensuring you get good quality sleep is the most important thing. You don't then need the next morning to think, well, I have all these toxins that I need to help clear out.

That's already being done. The system is already pretty good, as long as you're sleeping well. And right, there are many ways that you can improve sleep.

Cognitive stimulation, older adults improve sleep, physical activity improves sleep. Right, just sort of like your routine as you get into bed, all of that affects sleep. The timing of sleep, as long as it's regular, seems to be beneficial because the different stages of sleep and their relative balance happens as part of your circadian rhythm.

So having your deep sleep times to a similar time every night seems to make sure that it does its best job of doing what it needs to do during the night. So if you can get a regular sleep time, that helps as well. There is some interesting evidence that suggests that moving your body in certain ways can help promote fluid flow throughout the central nervous system, right?

Including the brain. And there's been some studies on, say like yoga poses and yoga movements. And there's related things in Pilates and Tai Chi where you're sort of like manipulating your body because then the fluid in the central nervous system, so the brain connects it down to the spine, it sort of acts almost like a pump, like the muscle pump in your legs where when you move your calves, that sort of helps to move blood flow up.

So there's probably some additional benefit from making sure that we're moving our bodies in multiple planes of motion because that's gonna help fluid flow through. But I don't think you need a complex routine. I think that the most important thing is gonna be ensuring, doing everything you can to ensure you get high quality sleep.

And then, you know, often we're just like letting the body do what it does best. It's already got that sorted out pretty well.

[Angela Foster] (54:05 - 54:05)
It's gonna do it itself.

[Dr Tommy Wood] (54:06 - 54:06)
Yeah. Okay.

[Angela Foster] (54:07 - 54:37)
Yeah. Amazing. I know like there's so much more I could ask you.

I would encourage people to go and read the simulated mind because you talk about creating headroom, right? Giving yourself like space and giving yourself the ability to kind of create more capacity in the brain and avoid ageing. There's all the nutrients that we spoke of.

Is there anything, before we link to where people can find more about you and also get the book, is there anything that we haven't covered that you think we should mention?

[Dr Tommy Wood] (54:38 - 57:19)
I think the, I hope that the book is useful for all the things you mentioned, right? There are multiple chapters on, like you said, sleep, stress, nutrition, movement. Then there's a section that includes cardiovascular disease risks, smoking, alcohol.

Everybody always wants to talk about alcohol, hormones, right? Gut health. All of these things are important.

And there are like tactics that people can use if that's an area that they want to work on for themselves. I think, and I hope it's meant to be very practical. But one of the most important things for me is that later on in the book, I provide a model for how I think the brain works and how all these different areas interact.

Because it can be quite overwhelming for somebody to think, oh my God, he's listed like 15 different things. And inside those 15 different things, there's like eight different habits I need to build in order to do these things to affect the brain. Right.

This is what we see on social media, right? Here's a list of the seven things that you need to do for your brain health in 2026. And that means that's just hugely overwhelming.

And when you think about two things you need to do, usually you'll do none. However, when you think about how all these things fit together and how they influence one another. So I already mentioned how physical activity improves sleep.

And then sleep has multiple knock-on effects in terms of our cognitive function, but also our overall physical health. So when you look at all the data, what you really see is that when you change one thing, you actually change lots of things. And this is really important to me because I think it means that it's sort of like empowering for us to say, here's one area where I think I can make a difference, I can make a change.

And again, most of the evidence suggests that the benefits are kind of linear, right? Anything you do more than what you're doing right now will have some benefit. So it doesn't mean that you need to attend to a list of dozens of things that are just gonna be overwhelming.

It just means that find one area and it could be sleep, it could be physical activity, it could be elements of the diet, just like knowing what you are in terms of your nutrient status and addressing that. Then you fix one thing and you fix many things, right? If your sleep improves, or so say you change physical activity, sleep improves, blood pressure improves, inflammation decreases, right?

You've hit multiple things at the same time. So that's why I would like people to focus on is think about like one area where you feel like you have some capacity and space to make some change. And then when you do that, actually a whole bunch of stuff starts to shift in your favour.

And it's not nearly as overwhelming or as difficult as sometimes it might seem.

[Angela Foster] (57:19 - 58:07)
100%, I love that. It's like thinking about, isn't it? That you're saying, what is the one thing for me?

I call it the domino because it's the one that knocks all the other ones down. So it's like some people say, I know when I'm exercising, I just automatically eat better, I automatically sleep better. Whereas another person might say, if I get a really good night's sleep, I'm so much more likely to exercise.

I'm fat, I'll get up early, I'll go do it. And then if I've exercised now, I'm eating better. And it is just finding that one domino, isn't it?

It's gonna knock the other ones down instead of, as you say, having this massive list. But it is a really interesting read. And I think that so well-researched and also it's the type of book, as you say, that you can just pick something and go, right, I'm gonna dive into that and master that before even moving on.

It's not a book where you have to start at the beginning and go to the end necessarily. And also remember, Tommy, that when you read a book, you're upgrading your brain.

[Dr Tommy Wood] (58:08 - 58:26)
Absolutely, yeah. Book reading seems to be really important for cognitive function as well. And actually, the benefit comes from, there are some studies that look at this, the benefit comes from really thinking about the material.

So the best way would be to read the book and then have a book club and talk to your friends about it.

[Angela Foster] (58:27 - 58:28)
And share it.

[Dr Tommy Wood] (58:28 - 58:30)
And then you get social interaction and all that other kind of magic stuff.

[Angela Foster] (58:30 - 58:50)
Yeah, there we go. And then you're knocking multiple things off there. I'm sure this will be the topic of many book clubs.

Thank you so much for coming on this second time. We'll also link to our previous episode with you, which was really, really popular as well. How can people connect with you, the book?

You've got a Substack, I think. You're active on social. You've got a podcast.

Please share.

[Dr Tommy Wood] (58:50 - 59:59)
Yeah, thanks. So the book is The Stimulated Mind. It comes out March 26th in the UK.

It's available for order anywhere you would buy a book. You can go to thestimulatedmind.com and it will have all the links for buying the book in various places. You could also go to Dr. Tommy Wood on Instagram. Dr. Tommy Wood. There I have links to all that kind of stuff, as well as podcast appearances and papers that I've published and stuff like that. And then I have a Substack and podcast with my very good friend, Dr. Josh Turkner, who's a neurologist. The URL for that is betterbrain.fitness. Or if you go to Substack and look up Better Brain Fitness, you'll find us there. And we have a Q&A type podcast. So if you have any kind of question, you can just submit it to us and then we answer one question each week.

So anything that you wanna hear more about, wanna hear research about, please let us know and we'll address that in an upcoming episode.

[Angela Foster] (1:00:00 - 1:00:14)
Amazing. So you can read the book and then kind of test yourself and ask any questions and have them answered by Tommy and his co-host. Awesome.

We will link to all of that in the show notes. Thank you so much, so much. I've really enjoyed it.

Really, really great to have you back.

[Dr Tommy Wood] (1:00:14 - 1:00:18)
Likewise. Thanks so much for having me. It was great as ever.

Really appreciate it.

If you’re in midlife and feeling mentally stretched with brain fog, poor sleep or constant stress, this episode will help you understand what’s really happening.

In this episode, I’m joined by neuroscientist Dr. Tommy Wood to explore how stress, hormones, recovery and lifestyle shape your brain after 40 and what actually makes a difference.

This is a clear, practical conversation for women who want to protect their focus, memory and long-term brain health.

WHAT YOU WILL LEARN
• What a “healthy brain” actually means in real life
• Why lack of control drives burnout
• How high-demand jobs affect dementia risk differently depending on control
• Why education and cognitive stimulation protect against decline
• What really happens to the brain during perimenopause
• The link between vasomotor symptoms, sleep and brain fog
• How creatine supports brain energetics (and dosing guidelines)
• Why leg strength predicts processing speed and dementia risk
• How sleep clears metabolic waste from the brain
• Why improving one habit can improve multiple brain pathways