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Understanding the female brain

Your Life

Understanding the female brain

Why women are more at risk is one of the many unsolved mysteries of Alzheimer’s Disease. KAILAS ROBERTS explains the various factors that come into play.

There is a not inconsiderable discrepancy between men and women when it comes to Alzheimer’s Disease – the fairer sex have roughly double the odds.

Research into the phenomenon may shed some light on the causes of Alzheimer’s more generally, and so it is relevant to us all, regardless of our biological gender.

So, let’s examine what might be driving the difference.

One of the most straightforward explanations lies in longevity.

Statistically, women live longer than men, and age is the most significant risk factor for Alzheimer’s.

In Australia in 2021, the median age of death was 79 for men and a whopping 85 for women.

Acknowledging that the rates of dementia double every five years, the age factor is quite relevant, but I’m not sure it explains it all, as at most ages over 65, more women than men seem to have the condition.

There are also likely to be genetic factors. The best example of this is the apoe4 gene type, which I have written about previously. Having this increases the risk of developing Alzheimer’s Disease in both sexes, but its influence is more pronounced in women.

Hormones are another consideration. There is a lot of debate about menopause and how this influences dementia risk, though there is strong data that the two are linked.

It is known, for instance, that having an early menopause is associated with a higher risk of dementia. The link is likely explained by the loss of oestrogen in particular.

This hormone is neuroprotective in several ways, including by enhancing connectivity in brain circuits crucial for learning and memory, supporting the growth of nerve cells, and dampening inflammation.

It also helps maintain blood flow to the brain and may reduce the deposition of beta-amyloid, a protein implicated in Alzheimer’s Disease. The precipitous drop in oestrogen with menopause is therefore a potential problem.

In men, testosterone is converted to oestrogen, and although there is still a decline of this hormone with age, it is much more gradual.

And then there is evidence that certain areas of the brain shrink more readily in women than men – including the hippocampus, which is critical for memory and is an early site of damage in Alzheimer’s Disease.

Additionally, in women with Alzheimer’s Disease, other parts of the brain – including the frontal and parietal lobes – seem to attract more amyloid than in men.

Perhaps though, the difference lies in something more indirect. We know that psychological conditions such as depression and anxiety occur more frequently in women, and these conditions – if severe and protracted – are themselves associated with a higher risk of Alzheimer’s Disease.

Much of this might be related to the immune and inflammatory effects of these mental health problems. And maybe this relates to something even more fundamental – the different societal roles and expectations of men and women.

If, as many experts believe, life is in general harder for females, this might go some way to accounting for the late life consequences of dementia.

Despite the negative findings above, after almost three years of penning these columns, I would hope that it’s apparent that I am an optimist when it comes to dementia risk reduction, and it’s important to realise that all is not doom and gloom.

Regardless of your biological sex, you still have considerable agency when it comes to brain health. Stay active, socialise, eat healthily, get good sleep, don’t overindulge, and manage stress. It will go a long way to maintaining a healthy brain.

Kailas Roberts is a psychogeriatrician and author of Mind your brain The Essential Australian Guide to Dementia now available at all good bookstores and online. Visit yourbraininmind.com or
uqp.com.au

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