Statistics tell us that 2/3 of the people with Alzheimer’s are women. The basic answer as to why this might be so is that women live longer than men so there are more older women to develop the disease. Researchers have always known this may be partly correct, but there definitely is more to this statistic.

Recent studies are coming closer to a more accurate explanation. Estrogen levels and hormone replacement are likely to play significant roles. According to recent research, the more estrogen a woman receives from pregnancy, the less risk of developing dementia. In addition, hormone replacement therapy may affect cognition in some subgroups of women.

Paola Gilsanz, a scientist with Kaiser Permanente Northern California, and Rachel Whitmer, professor of epidemiology at the University of California, Davis, conducted an extensive study on correlations between reproductive history and dementia in nearly 15,000 women between the ages of 40 to 55 for more than a decade. Findings showed women with three or more children had a 12% lower risk of dementia compared with women who had only one child. There was a small benefit for having two children.

Researches have yet to determine if estrogen alone is responsible, or something that works with it, such as immune cells called T cells, that increase during pregnancy. People with Alzheimer’s are believed to have fewer T cells. It may be that the increase in T cells in women who have had three of more children helps prevent the development of Alzheimer’s.

Other studies have been conducted on hormone replacement therapy and cognition. Cognitive affects differ depending on the age and health factors of the candidate, such as cardiovascular disease and diabetes.

Carey E. Gleason, of the Wisconsin Alzheimer’s Disease Research Center at the University of Wisconsin School of Medicine and Public Health, led two separate studies on estrogen and menopausal women. No negative effect was shown on cognition in women who began hormone therapy between the ages of 50 and 54. The results are very different if women start therapy between 65 and 79. This age group showed a clear reduction in cognition, memory and executive function.

Here are some of the findings of recent studies:

• Women who gave birth to three or more children had a 12% lower risk for dementia than women with one child.
• Women had a 9% greater risk of dementia for each miscarriage.
• Women who experienced their first menstrual period at 16 or older had a 31% greater risk of developing dementia than those who began menstruating at a younger age.
• Entering menopause at age 45 or younger increased a woman’s dementia risk by 28%.
• No negative effect on cognition was found in women who initiated hormone therapy between the ages of 50 and 54.
• Hormonal therapy increased the risk of dementia in postmenopausal women 65 years and older.
• Women on hormone therapy with type 2 diabetes showed a higher risk of cognitive impairment compared to women without diabetes on hormone.

Recognizing risk factors such as these that are beyond our control can motivate us to control the things we can such as with our diet and exercise and striving for moderate blood pressure. Today is the best day to begin striving for a healthier you.

(My book, Navigating Alzheimer’s, is available from Amazon.com, ACTA Publications, and my website.)