Why Alzheimer’s hits women harder than men

Sex differences in dementia are only just being recognised – but the consequences could change the way we fight the disease.

Diagnosed with Alzheimer’s in 2015, 75-year-old Brenda Whittle still enjoys jigsaws, sewing and dancing. New activities are less appealing, but participating in Alzheimer’s research and drug trials is an exception. She’s so at ease with loud brain scans, she even falls asleep during them.Brenda is one of more than 50 million people worldwide living with dementia – a catch-all category of diseases affecting memory and brain processing, including Alzheimer’s. That number is rising quickly. Globally, experts estimate that 75 million people will live with dementia by 2030 and 131.5 million by 2050.

In Australia, nearly two-thirds of all dementia-related deaths were women; in the US, two-thirds of those living with the disease are women, too. In some cases, dementia even outstrips more famously ‘female’ diseases: US women over 60 are twice as likely to develop Alzheimer’s disease as breast cancer. (Breast cancer remains the leading cause of death for UK women aged 35 to 49).And in England and Wales as well as in Australia, dementia has become the leading cause of death for women, knocking heart disease off the top spot.

“This can’t be sustained by any medical health system – it is too much in terms of numbers, says Antonella Santuccione-Chadha, a physician and Alzheimer’s specialist based in Switzerland. “And as women are more confronted by the disease, we need to investigate the differences between the male and female specifics of it.”

Much of the gender gap comes down to one of dementia’s biggest risk factors: age. The older you are, the more likely you are to develop late-onset Alzheimer’s. Women typically live longer than men, so more have dementia.But recent research hints that we would be wrong to assume that ageing means Alzheimer’s is inevitable. Results from two major Cognitive Function and Ageing Studies (CFAS) suggest that over the last 20 years, new dementia cases in the UK have dropped by 20% – driven mostly by a fall in incidence among men over 65 years old.

Experts say this may be because of public health campaigns targeting heart disease and smoking. Both are risk factors for Alzheimer’s. But because men tend to get heart disease younger and smoke more than women, these campaigns also may have helped stave off these risk factors more for men than women.

Meanwhile, other risk factors for the disease affect women more than men. For example, more women develop depression – and depressed mood has been linked to the onset of Alzheimer’s. Other risk factors affect only women, such as surgical menopause and pregnancy complications like pre-eclampsia, both of which have been linked to cognitive decline in later life.

Social roles, such as caregiving, also may increase the chance of developing dementia. Some research has shown that being a caregiver is, in itself, a risk factor for Alzheimer’s disease, says Annemarie Schumacher, a health psychologist. In the UK, some 60-70% of all unpaid caregivers looking after someone with dementia in particular are women.

“Sex-specific prevention might start from having more of this information about female-specific risk factors,” says Maria Teresa Ferretti, a biomedical researcher in the field of Alzheimer’s disease at the University of Zurich.

This idea is gaining momentum. Advocacy group the Women’s Brain Project (WBP), co-founded by Santuccione-Chadha, Ferretti and Schumacher as well as chemist Gautam Maitra, has just published a major review analysing a decade’s worth of scientific literature on Alzheimer’s, revising existing data and asking scientists to stratify it by sex for the first time.–BBC

“The most obvious differences that come out of the literature are in the display and progression of cognitive and psychiatric symptoms between men and women with Alzheimer’s disease. Based on these new studies we can design new hypotheses and figure out new ways to improve treatment of patients,” says Ferretti.Currently, for example, Alzheimer’s is detected by looking for two toxic proteins that have accumulated in the brain. Evidence suggests no difference in the levels of these proteins, or ‘biomarkers’, in men and women with Alzheimer’s disease. But the women show greater cognitive decline. – BBC