[Angela Foster] (0:00 - 0:16)
The biggest thing that concerns so many of the women I speak to is the brain fog that can show up in midlife. What's driving that? And whether it is something to be concerned about long-term.

Can you describe what's happening during that peritopostmenopause transition?

[Dr. Sarah McKay] (0:17 - 2:10)
This is one of these questions where there's a number of different answers or kind of puzzle pieces. Brain fog, as we would describe it colloquially, doesn't really have a very good clear, firm definition clinically or neuroscientifically, so to speak. Because lots of people might use different words to describe a similar feeling or sensation, like you're forgetting words or you look into a room, you don't know why you walked in there, or you find it hard to pay attention or concentrate.

Lots of people might have those experiences and at different points of time in their lives or ages or stages use different language to describe that. So right now, women in midlife have been taught that the word we're using to describe the feelings that our brain isn't functioning like it used to is brain fog. I think it is worth pointing out that there was a study done here or a survey done here recently of Australian women by Jean Hales for Women's Health, who found that the greatest proportion or the age group that was most worried about feeling foggy in their brain or their brains not working were actually women in their early 20s.

So there was more of them concerned about what women in midlife might call brain fog than actual women in midlife. So we've got, you know, and that's probably just a hint that we're going to be using different words to describe these different experiences depending on who we are and where we're at and what we're ascribing it to. Similarly, we've got baby brain and pregnancy and motherhood.

So I think if we just focus on what we do know about what could potentially be causing women to feel like their brain isn't working properly at midlife, and do I need to get into the physiology of perimenopause and menopause and the ovarian brain conversation in much detail for your audience?

[Angela Foster] (2:11 - 2:12)
No, not too much detail.

[Dr. Sarah McKay] (2:12 - 11:58)
I think they're pretty well versed in that. Yeah, they're pretty well versed in that. It kind of gets a bit tiring to hear that trotted out over and over and over again.

But it's safe to say that there are a whole host of changes that could possibly be taking place in our bodies and our brains and our minds that could be contributing to this experience of brain fog. So the first is probably the one that we have the clearest neurobiological story about, and that is the idea of temperature control in the brain. The hypothalamic neurones, the hypothalamus is this like kind of key hub in the centre of our brain which maintains kind of our physiological, you know, biochemical homeostatic basis.

And it's receiving signals from our ovaries when that conversation starts to fluctuate, the ovarian hormone levels start to fluctuate, the neurones in the hypothalamus become very, very hyperreactive. And that means they become very, very hyperreactive, particularly to temperature. The reason that these neurones and ovarian hormones and temperature like are even related at all, it's like, why do they even care?

Because reproduction and temperature is very, very intimately entwined and controlled. So we can see these very clear variations of temperature across the course of a natural menstrual cycle. And lots of women chart their body temperature to know when they ovulate and then to find out when they're pregnant.

So body temperature, thermoregulation intimately entwined with reproduction. When you're not reproducing anymore, you don't need to have that same tight thermoregulatory control. So what happens?

We get the hot sweats, we get the night sweats, we get the hot flashes, la, la, la, la. Everyone's familiar more or less with that kind of scenario. Long story short, that disrupts sleep.

Now it may disrupt you enough to wake you up at night, or, and you are aware that you're awake at night and then you kind of lay there awake, or it may be that you don't necessarily wake up, but it disrupts your sleep architecture. So that nice, those kind of like patterns that we want to ideally go through down into the deep, the deep stages of sleep and back up into REM and up and down nicely through the night. Temperature regulation and sleep architecture are also intimately entwined.

So you may not necessarily have to be waking up to have healthy sleep disrupted. For those women who are waking up at night, we kind of know, if you're familiar with that, you're familiar with that. I don't need to explain what that feels like.

One interesting nervous system pathway that is potentially involved here with brain fog is the idea that our hypothalamus and our sympathetic nervous system, which is the kind of the activation branch of our autonomic nervous system. It's that branch, which is involved with the sweating and the flushing and the heat dissipation. And so every time you get a little bit of an increase in body temperature, your sympathetic nervous system has to kind of fire off to dissipate that heat.

And when you get repeated sympathetic nervous system activation, particularly when you are asleep, you end up feeling kind of wired, you kind of become hyped up and hypervigilant, but you're also tired because you've had your sleep disrupted. So we've got this relationship there between your autonomic nervous system responses and the sleep disruption. And we can kind of track that back to the hormones.

What is a really interesting thing to think about here is when you feel tired and wired. So when you feel kind of hypervigilant, the sympathetic nervous system's kind of dialled up and you're not bringing it back down as easily as you used to be able to. What does that hypervigilance feel like?

Well, it feels like kind of anxiety in your body. And if you wake up at 3am, I guarantee it'll take you like less than a minute, probably five seconds to find something to worry about because your brain is a prediction machine. So your brain's going, I feel nervous in my body.

There must be something that I need to be thinking about that explains this. And you just glom on to the most clearest and obvious thing in your life that is concerning you. That's kind of what anxiety is.

It's like your brain filling in the gap when your body is hypervigilant. So again, what happens when you're feeling anxious, you're sleep-deprived, you might find something to worry about, we can start to see the emergence of mood disorders. And what we might call brain fog goes hand-in-hand with the sleep disruption, with the anxiety, and perhaps even with the low mood if that's kind of a downstream kind of consequence of that.

The kind of the fourth, I don't know whether up to three or four pieces of the puzzle here now, is around the idea, and it's kind of less related to the thermoregulation and the sleep, etc. It's the idea of how our brain is using energy and metabolising glucose for energy. So we know oestrogen helps neurones in the brain to generate, to turn glucose into ATP, which is kind of like the energy currency of the cell.

And you might remember back to like high school science, and you're looking at mitochondria, etc. When we're going through perimenopause, the shift in oestrogen can cause a bit of a shift in how efficiently neurones can metabolise and kind of produce energy. And perhaps while the brain is going through this shift, and it comes out the other side because it's very adaptable, it could be that thinking feels harder, or slower, or feels effortful.

And it doesn't feel great when something feels hard. It's like you're learning calculus at high school, and it was really difficult. It didn't feel great.

The struggle doesn't feel good. And so we might then kind of notice that struggle and the discomfort that comes from that and go, oh, well, that's brain fog. And that could be like kind of a brain energy metabolic shift.

So that's kind of another piece in the puzzle. We know structurally the brain is possibly reorganising slightly, but it's very much debatable. Any structural changes we see from, say, pre to peri to postmenopause are due to the hormonal changes, or whether they're due to ageing.

Because you could start perimenopause at 45 and be comparing a brain who's 45 to the brain of someone who's 60. You've got 15 years of ageing there. The brain's going to change over the course of 15 years, no matter what happens.

So it's quite hard to shift out chronological ageing from hormonal ageing. But we do know that there are changes taking place in the structure. Whether that's underpinning the feelings of brain fog, I'm not really sure on that.

We also know that how different parts of the brain networks interact with each other and work together change across the course of our lifespan. So when we go through puberty, they become very kind of specialised. So we've got specialised circuits for different roles.

As we get older, perhaps underpinned by the shifts in brain energy, more kind of networks are recruited and become more integrated together to support the same cognitive task. So the brain's still getting to the same end result, but it just might be going around in a bit of a different way. And perhaps that network reshuffling around perimenopause might slow down your processing speed.

So we've got a whole host of these different kinds of changes here. And then we've also got just simply our attention. And if the 18 to 25-year-olds are more concerned about their attention and their memory than anyone else, you've got to wonder how much this device, a mobile phone, plays in this whole thing.

Because I've started to think we carry our phones around like little newborn babies. And what we remember and how we pay attention depends on where our attention goes. And if we have lost the ability to thoughtfully monotask and focus on the job at hand, instead of constantly being distracted by a device, even if it's in the room with us, this competing demand of a phone constantly pulls attention.

We've got some really good data showing that even just having a phone in a room with you decreases your cognitive performance. So I think I've named eight different things there. Brain fog is a systems puzzle.

It's a complex web. It's hormones, it's sleep, it's metabolism, it's mood, it's brain networks, it's structures, it's attention. And there's also a little bit of, dare I say, perhaps ageism in there as well.

Because right now, everyone's being flopped with this menopause story, which is all about we're all catastrophising this phase of life as if we're about to commence the slide to the end with dementia being inevitable. And so the tiniest little blip, you forget where you put your keys or your glasses, or you can't remember someone's name. We're going, oh my God, it's menopause, it's brain fog.

Do I need HRT or not? Oh, it's a dementia. My brain's eating itself.

We're catastrophising. And so we're honing in and focussing on what we're missing. And we've paid zero attention to the wealth of research out there, which is emerging around the idea that cognition isn't in this inevitable decline at midlife.

Not all women experience brain fog. Lots of women sail through the menopause. Lots of women's cognition improves.

My teenage boys forget their shoes and whatever all the time. They're not like, oh my God, am I getting dementia? Have I got menopause?

No, they just forgot something. So we're also paying attention to the deficits because I feel like right now we've been primed to look at them and worry about them a bit.

If you've been told that perimenopause and menopause inevitably lead to permanent cognitive decline and "brain fog," the neuroscience says otherwise.

In this episode, neurologist and Neuroscience Academy founder Dr. Sarah McKay explains what actually drives cognitive changes during midlife and why temperature regulation, sleep disruption, and constant smartphone distractions matter far more than the catastrophized media narratives.

- Why "brain fog" isn't a true clinical term and how different life stages use it to describe general cognitive fatigue

- What a recent survey revealed about the surprising age group that actually worries the most about cognitive decline

- Why the hypothalamus and fluctuating estrogen levels trigger hot flashes and disrupt your critical sleep architecture

- How the sympathetic nervous system's response to body heat causes you to wake up feeling anxious, wired, and hypervigilant at 3 AM

- What really happens to your brain's ability to metabolize glucose for energy during perimenopause and why thinking can suddenly feel incredibly effortful

- Whether structural network changes in the midlife brain are a sign of decline or just a natural reorganization similar to puberty

- How constant smartphone usage and divided attention are destroying your ability to focus and remember basic tasks

- Why catastrophizing menopause and societal ageism are causing women to wrongly attribute simple, everyday forgetfulness to severe cognitive decline