Alzheimer’s disease greater in females, researchers speculate

By Dr. Ananya Mandal, MDJul 23 2018

This week, at the Alzheimer's Association International Conference in Chicago, a group of researchers presented reserch findings on the gender differences in Alzheimer’s causation. They speculated that women might be getting Alzheimer’s and dementia more commonly than men and the reason behind this has not been clearly understood. Estrogen or the female hormone could be the key, the researchers state.

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The authors state that there are 50 million people worldwide who are living with dementia and Alzheimer’s disease and most of these are women. In the United States, of the 5.7 million people with Alzheimer’s, two thirds are females. Alzheimer’s is a twice common diagnosis among women over 60 years rather than breast cancer, they add. Alzheimer’s is the sixth leading cause of death in the US and in the UK and Australia too, Alzheimer’s kill more women compared to heart disease.

One of the studies presented at the conference has noted that more number of births in a woman is associated with a lower risk of dementia. Women who have given birth thrice or more times have been found to have a 12 percent lower risk of cognitive decline compared to women who have given birth only once. The study looked at nearly 15,000 women before coming to this conclusion. The study from Kaiser Permanente however adds that women who have had failed pregnancies have a greater risk of cognitive decline with women who have had three or more miscarriages being at a 47 percent greater risk of dementia. The study looked at age of menarche, menopause, female hormones and their associations with dementias.

They accessed the women’s medical records between 1964 and 1973 and then again from 1996 to 2017. Not only births, miscarriages, menarche and menopause, they also obtained other data such as stroke, diabetes, high blood pressure, heart disease etc. explained Paola Gilsanz, a staff scientist at Kaiser Permanente who co-led the study. This fortified the study results she added. The results also showed that women who were fertile between ages of 21 and 30 years had a 33 percent higher risk of dementia compared to women who were fertile for a longer period. Late menarche beyond age of 16 years was tied to a 31 percent greater risk of cognitive problems compared to girls who started at 13 years, the study found. Authors caution that this was an observational study and it really does not tell one how the female hormones might be affecting the brain yet.

University of Illinois psychology and psychiatry professor Pauline Maki is presenting the latest study at the conference. She said that age has been the biggest Alzheimer’s predictors till date and it has been thought that women are more at risk of dementias because they tend to live longer. She added, “No one was paying attention to what was going on in the female brain throughout a woman's life.” Presenter Carey Gleason of the Wisconsin Alzheimer's Disease Research Center added that they found it difficult to obtain research grants to look at effects of estrogen on Alzheimer’s. This has changed over the years they note.

Another study presented by Gleason explored the recent studies that looked at cognitive functions in women who were getting a hormone replacement therapy (HRT) after menopause. Earlier studies conducted in large number of women has shown that HRT containing estrogen and progesterone can raise the risk of stroke, blood clots, breast cancer and dementia among the women. The Women's Health Initiative after their initial discouraging results on HRT came up with new interpretations after a decade saying that they had initially included only elderly women. According to Gleason, younger women taking HRT may not be at risk of dementia but the elderly women on the drugs definitely are. Diabetics of any age however are at a greater risk. She explains that concrete conclusions are still awaited with HRT and dementia risk.

According to numbers from the Alzheimer’s Association, in 2018, Alzheimer’s along with other forms of dementia could cost the United States $277 billion in direct costs and this includes $186 billion in Medicare and Medicaid payments. The organization says that by 2015 the cost would rise to $1.1 trillion with one in every three Medicare dollar being spent on this condition.