Neuroscientist: Most Women Are Raising Their Dementia Risk (Without Knowing It)

1. RCDr. Rangan Chatterjee0:01

   Let's talk about women's brain health.

2. TWDr. Tommy Wood0:04

   Mm-hmm.

3. RCDr. Rangan Chatterjee0:05

   It's getting a lot more attention these days, very rightly so.

4. TWDr. Tommy Wood0:09

   Absolutely.

5. RCDr. Rangan Chatterjee0:09

   Um, but I know you've got some, some really quite thought-provoking ideas relating to women's brain health through the lens of your three S model in terms of stimulation.

6. TWDr. Tommy Wood0:19

   Mm.

7. RCDr. Rangan Chatterjee0:19

   So can you speak to that as a topic?

8. TWDr. Tommy Wood0:21

   Yeah, ab- absolutely. So one of the... Another reason why I think we have this hopeful message for dementia prevention and decreasing population dementia burden in the future is because over the past hundred years, we've seen a decrease in the age-specific incidence of dementia, and that, that's measured in a very specific way. But what we hear all the time is dementia cases are gonna triple in the next 10 or 20 years. Um, you know, the, the, the risk of dementia is constantly increasing, and those things are technically true because the, the, the world is, you know, the population is living longer. And if you live longer without dying of something else, then you're more likely to get dementia. We know that. But you are less likely to be diagnosed with dementia at the age of 70 n- like today than you ever have been in, in, in, in previous history. And people don't, people don't realize that. So what that means is, over time, age-specific incidence of, of dementia has decreased.

9. RCDr. Rangan Chatterjee1:30

   What does that mean, age-specific incidence?

10. TWDr. Tommy Wood1:32

    So that's exactly... So that's ex- exactly what I was saying is, so, like, if you pick up a specific age, 60 years old, 70 years old, you're now less likely to have dementia at 70 years old than you were 20 or 30 years ago.

11. RCDr. Rangan Chatterjee1:42

    So w- just... And I just wanna make sure everyone's got this. So why is there this apparent discrepancy then between, you know, rates going up-

12. TWDr. Tommy Wood1:49

    Yeah

13. RCDr. Rangan Chatterjee1:49

    ... but our individual risk at any given age going down?

14. TWDr. Tommy Wood1:52

    It's because we're living longer. So it is true that, um, because now we're more likely to live to be 80 or 90, that, yes, the, the, the risk of having dementia at 80 is lower than it was previously. But because more of us will live to 80, more of us will have d- will have dementia at some point in our lives, but it will just happen later in life, if that makes sense. So both of those th- both of those things are happening at the same time, which is complicated. Like, I, I understand it. But what's then interesting is, is you see that it is possible to move the needle on the incidence of dementia at any, any given age, which then means that it's probably also possible to move the needle on dementia overall, right?

15. RCDr. Rangan Chatterjee2:35

    Mm.

16. TWDr. Tommy Wood2:35

    Which just goes back to our, the fact that, uh, dementias are preventable or some provot- proportion of dementias are preventable. But when you think about, well, why might this be? 'Cause it, 'cause it kind of goes against some of the narrative, and one is an improvement in cardiovascular health, and this seems to be partic- have particularly been beneficial for men, decreasing the, um, age-specific incidence of dementia for men because, uh, uh, heart disease risk factors overlap, um, very tightly with dementia risk factors. We've already talked about, um, blood pressure, blood sugar, but, um, smoking, um, blood lipids play a role here too. We've become much better at treating and preventing heart disease, and that seems to have translated to a, a lower age-specific incidence of de- of dementia. Maybe more so in men because men tend to have higher heart, you know, heart disease risks, uh, than, than women. But we do also see some of this shift happening in women as well, and there were these big meta-analyses that have been done in studies using data from the US, from the UK, uh, from multiple European countries. And I wonder if some of what we're seeing, particularly in women, is ch- uh, the changing role of women in society, which has been, uh, you know, overwhelmingly beneficial. So if you think back to, uh, I mentioned, uh, Warner Shaw's, uh, Seattle Longitudinal Study. Um, and one of the things that they looked at in the, in the Seattle Longitudinal Study was, um, environmental enrichment or an enriched environment, which basically meant how complex and cognitively stimulating is the world that you exist in, largely related to your work and your hobbies. And the more enriched or complex your environment, the lower your risk of dementia or cognitive decline in the Seattle Longitudinal Study. But there were a group of, um, individuals who had low environmental complexity and a higher risk of cognitive decline dementia, um, and they were all overwhelmingly women, which was the housewife. Um, and this in the 1950s was a very traditional thing, right? Um, and the way that they measured these things and the way they wrote about them, you know, is part- partly of their time, right? Now, 60, 70 years ago. But something that they saw in that study was that that environment was not necessarily as, um, stimulating or complex as, you know, the work environment or the, that other people might have access to. But we've seen both within, you know, Westernized, um, societies but also globally, as education has become more accessible and equitable, um, to women in particular, dementia rates and dementia risks have decreased, right?

17. RCDr. Rangan Chatterjee5:23

    Mm.

18. TWDr. Tommy Wood5:23

    That's one of the reasons why education is actually the m- the, the risk factor in the Lancet, uh, Commission report. That is the biggest number, 7% of dementia is related to, to education. And then we think about the work environment. So, um, wom- like women's presence in the workplace only really started to expand in the 1970s, and this is based on like US labor and statistics data. Um, and so there's been this big shift from, you know, what was maybe, um, the potential for a, a less cognitively stimulating environment and, and, and I realize that that doesn't have to be the case, right? People can, um-You know, be primarily at home and, you know, the, the most of their work and commitments are at home with their children or family or family members, right? And that's, that's, that's what they do, and that can be incredibly stimulating and incredibly enriching and in- incredibly, um, like satisfying, of course. Right? So we're, we're talking like averages and maybe how things looked 60 to 70 years ago.

19. RCDr. Rangan Chatterjee6:29

    Yeah.

20. TWDr. Tommy Wood6:29

    Um, but as those things have shifted, right, um, women have been allowed access to more complex, um, higher, higher powered jobs and, you know, more education, again, both within Westernized countries and globally. Um, we've seen age-specific instances of dementia decrease. So I think as society becomes more equitable across the sexes, we may start to see some of those benefits pay off in terms of dementia rates. 'Cause right now, right, about 2/3 of d- of Alzheimer's disease burden is in women, right? We know that. But the, those statistics come from women who are, who are largely of that period, and so I th-

21. RCDr. Rangan Chatterjee7:10

    Mm.

22. TWDr. Tommy Wood7:11

    So, uh, my hope is that, yes, we should do a, a, a whole, um, bunch of additional research where, you know, women have been left out of neuroscience and neurology research for decades, and I'm so happy that that's changing. But I also wonder if, like, this shift in, in society will pay off in a beneficial way, uh, because of the, the stimulus that you can get from, from work and education that now more people have access to.

23. RCDr. Rangan Chatterjee7:41

    It's so fascinating to, to think about that, and it all feeds back to this idea that the stimulus to the brain is the most important thing.

24. TWDr. Tommy Wood7:50

    Mm-hmm.

25. RCDr. Rangan Chatterjee7:52

    Going back to women's health again, and specifically women's brain health, how do you think about the menopause-

26. TWDr. Tommy Wood8:00

    Mm

27. RCDr. Rangan Chatterjee8:00

    ... and the hormonal changes that occur in the menopause and risk of cognitive decline?

28. TWDr. Tommy Wood8:08

    This is an area that still right now is, is hotly debated.

29. RCDr. Rangan Chatterjee8:13

    Yeah.

30. TWDr. Tommy Wood8:13

    Um, and this is probably the most challenging part of the book for me to write, um, mainly because I want it to be very evidence-based, but equally, like, women should feel supported by men.

Episode duration: 50:55