Protein tau may spread more rapidly in female brains than males’, adding to range of factors
The reason women appear to be at greater risk of developing Alzheimer’s disease than men might be due to a number of genetic, anatomical and even social influences, researchers have suggested.
Recent figures show about 65% of those with living with dementia in the UK are women, with a similar statistic seen in the US for Alzheimer’s disease, while dementia is the leading cause of death for women in England. Alzheimer’s disease is only one of the types of dementia, but the most common form.
While one explanation is that dementia risk increases with age, and women have longer life expectancies than men, new research suggests there might be more to the matter, including that protein tangles found within neurons and linked to Alzheimer’s disease might spread differently in women’s brains than men’s.
The study, presented at the Alzheimer’s Association International Conference in Los Angeles by researchers from Vanderbilt University and which has not yet been peer-reviewed, used scans from a method called positron emission tomography. That allowed them to look at the way clumps of a protein called tau were spread in the brains of 123 men and 178 women without cognitive problems, as well as 101 men and 60 women with mild cognitive problems – although not yet diagnosed with Alzheimer’s disease. Cognitively normal older people often have small amounts of tau in certain areas of their brain.
From the data the team could build maps showing which areas of the brain show similar signals relating to tau in the scans, suggesting they are somehow connected. “Based on that we kind of try to reconstruct the pattern of spread,” Dr Sepideh Shokouhi, who is presenting the research, told the Guardian. “It is kind of like reconstructing a crime scene.”
The team says the results suggest these maps look different in women and men, suggesting tau might be able to spread more rapidly across the female brain..
Other research presented at the conference – and also not yet peer reviewed – added weight to the idea that there might be differences between men and women that affect dementia risk.
Research by scientists at the University of Miami has revealed a handful of genes and genetic variants appear to be linked to Alzheimer’s disease in just one biological sex or the other. While the actual importance of these factors has yet to be unpicked, and the study only looked at white participants, the team says it underscores that there could be a genetic reason for differences in the risk of dementia in men and women, and the way it develops.
Dr Jana Voigt, head of research at Alzheimer’s Research UK, welcomed the study.“Understanding which genes are associated with Alzheimer’s risk just in men and just in women may help us to develop methods to more accurately identify who is at risk of developing the disease,” she said.
Social factors might also play a role in why more women develop the disease, with researchers at the University of California Los Angeles reporting that their work with more than 6,300 women born between 1935 and 1956 shows that memory decline in older age was faster among those who had not worked. Looking at memory in the women as they aged from 60 to 70, the decline in performance was 61% faster among married mothers who had never worked, compared with married mothers who had worked until middle age.
However, the study does not prove that employment offers protection against cognitive problems, looks only at women and does not look at the development of actual dementia.
“While future studies need to explore links between employment and brain health, these initial findings support ongoing efforts to increase the number of women entering or staying in the workforce,” said Voigt.