Research reported at the Alzheimer’s Association International Conference (AAIC) 2018 in Chicago highlighted sex differences associated with dementia and Alzheimer’s disease across the life course, including the first ever large-scale study of reproductive history and dementia risk in women.
New results reported at AAIC 2018 suggest:
- Associations between dementia risk and number of children, number of miscarriages, age at first menstrual period, and reproductive period (years between first menstrual period and menopause).
- In a separate study, a correlation between cumulative months of pregnancy and Alzheimer’s risk.
- Re-thinking the long held thought that hormone therapy negatively affects cognition.
- A need for sex-based standards for cognitive assessments, to improve early detection in women.
“More women than men have Alzheimer’s disease or other dementias; almost two-thirds of Americans with Alzheimer’s are women,” said Maria Carrillo, Alzheimer’s Association Chief Science Officer. According to Alzheimer’s Association 2018 Alzheimer’s Disease Facts and Figures, of the 5.5 million people age 65 or older with Alzheimer’s in the United States, 3.4 million are women and 2.0 million are men.
There are a number of potential biological and social reasons why more women than men have Alzheimer’s or other dementias. The prevailing view has been that women live longer than men on average, and older age is the greatest risk factor for Alzheimer’s. However, some research suggests that the risk for developing Alzheimer’s could be greater for women due to biological or genetic variations, or even different life experiences, such as education, occupation or rates of heart disease.
“More research is needed in this area, because having a better understanding of sex-specific risk factors across the lifespan may help us discover – and eventually apply – specific prevention strategies for different populations of people with Alzheimer’s and other dementias,” Carrillo added.
Link between reproductive history and dementia risk in women
As reported at AAIC 2018, in the first-ever large-scale epidemiological investigation in the US of various aspects of reproductive history and dementia risk, Paola Gilsanz, ScD, staff scientist, Kaiser Permanente Northern California Division of Research in Oakland, Calif.; Rachel Whitmer PhD, Professor at UC Davis; and colleagues found a correlation between risk of dementia and the number of children, number of miscarriages, age at the time of first menstrual period, age at natural menopause, and reproductive period (the number of years between first menstrual period and menopause). Self-reported data from 14,595 women between the ages of 40-55 in 1964-1973 were evaluated.
“Possible causes of dementia in women, in particular reproductive factors, are not well understood,” said Gilsanz. “In our study, we aimed to identify female-specific risks and protective factors impacting brain health, which is critical to diminishing the disproportionate burden of dementia experienced by women.”
The researchers found that women in the study with three or more children had a 12 per cent lower risk of dementia compared to women with one child. These women continued to be at lower risk of dementia after adjusting for additional mid- and late-life risk factors, such as body mass index and stroke history.
The researchers also asked about miscarriage and menstrual history. They found that each additional report of a miscarriage was associated with a 9 per cent increased risk of dementia, compared to those women who reported no miscarriages. On average, women were 13 when they had their first menstrual period and were 47 at natural menopause. Additionally, women who indicated having their first menstrual period at age 16 or older were at 31 per cent gre