Cases of dementia are higher in women than men and the fertility period in women may be the reason behind it. A recent study showed that women who have longer fertility periods have a higher risk of developing the disease.
A study published in the Alzheimer's & Dementia journal entitled, "Reproductive period and dementia: A 44‐year longitudinal population study of Swedish women," found that estrogen plays a role in the risk of dementia in women. Researchers from the University of Gothenberg looked into 1,364 women, particularly their reproductive period, which starts from the time that they have their first period up to menopause, or the time when their menstruation ceases.
The researchers noted that in the group of women who had a shorter reproductive period, spanning 32.6 years or lesser, 16 percent of them developed dementia. However, in the group who had longer reproductive periods, spanning 38 years or more, there was 24 percent of them who later developed dementia. Researchers find the eight point difference very much significant.
Dr Jenna Najar, a medical doctor at AgeCap, Centre for Ageing and Health at the University of Gothenburg said that their findings may explain why women have a higher risk of developing Alzheimer's disease and dementia after they reach the age of 85. She said that it further strengthens the hypothesis that a woman's estrogen levels also affect her risk of developing the disease later. For every year added that a woman remains fertile, her risk for dementia also increases.
The researchers found that even after adjusting other factors that are identified to have an influence on the onset of dementia, such as physical activity, educational attainment, BMI, cardiovascular disease, and smoking, the results of the study still persisted. They also ascertained that the age of the onset of menstruation, duration of breastfeeding, how many pregnancies a woman had or taking hormonal replacement therapy (HRT) or the use of oral contraceptives have no association with the risk.
Najar said that what's novel about their study is that they were able to access information about the various events that transpire in a woman's life. She pinpointed three events - pregnancy, giving birth, and breastfeeding. She explained that estrogen levels are boosted during pregnancy, declines when the baby is born and falls again when women breastfeed their babies. Najar said that the more indicators that they capture, the more reliable their results will be.