Is Late Menopause Associated With a Lower Risk of Dementia And Diabetes?

Pregnancy, a long reproductive period and an older age at menopause are associated with a lower risk of dementia in women. This is the result of a study published in the open access journal PLOS Medicine. Conversely, hysterectomy, younger age at first birth and younger or older age at first period were associated with a higher risk of dementia. The study suggests that reproductive and hormonal factors may play a role in dementia risk. However, a similar association was found between the number of children and dementia risk in women and men, suggesting that the physical experience of having children is not responsible for the variations in risk.

Longer Reproductive Life And Older Menopause Age Lower Dementia Risk

Dementia rates are increasing worldwide, with some studies finding a higher incidence in women than men, but there is little evidence on reproductive factors and dementia risk. Jessica Gong of Australia’s George Institute for Global Health and colleagues used data from the UK Biobank to examine the risk of dementia from all causes and reproductive factors in 273,240 women, as well as the number of children these women had and in 228,965 men.

After controlling for age, socioeconomic status, smoking, body mass index (BMI) and other factors, certain events associated with shorter cumulative exposure to internally produced oestrogen – such as older than average age at first period, younger than average age at menopause and hysterectomy – were associated with a higher risk of dementia.

Pregnancy, even an aborted pregnancy, longer reproductive duration, older age at menopause and use of birth control pills were associated with a lower risk of dementia overall. For both men and women, the risk of dementia appeared to be higher if they had no children or four or more children than if they had two children. The study has some limitations, including the retrospective reporting of reproductive factors, which may introduce bias, and the fact that the UK Biobank is a relatively healthy cohort of affluent people of white British descent, which may not be representative of a wider population.

According to Gong, reproductive events related to shorter exposure to endogenous estrogen in women were associated with a higher risk of dementia, and these findings underscore the vulnerability of dementia risk in women. However, the similar association between the number of children and dementia risk observed in women and men suggests that the variation in risk in women is related to social and behavioral factors in parenting rather than biological factors related to childbearing.

Late Menopause And a Lower Risk of Diabetes

Other research shows that birth control pill use and longer menstrual cycles are associated with a higher risk of developing type 2 diabetes (T2D), while later puberty and later menopause are associated with a lower risk. The study by Dr. Sopio Tatulashvili, Avicenne Hospital, Bobigny, France, and colleagues suggests that, in general, longer exposure to sex hormones but later in life could reduce diabetes risk and that women at high risk of T2D who take the birth control pill may need individualized counseling. Early screening to detect poor glycemic control (which can lead to T2D) could reduce the risk of further complications. For this reason, it is important to identify the risk factors for T2D. The aim of this study was to determine the association between various hormonal factors and the risk of developing T2D in the large prospective women’s cohort study E3N.

The study included 83,799 French women from the prospective E3N cohort who were followed between 1992 and 2014. Computational models adjusted for the main T2D risk factors were used to estimate the risk and statistical significance between different hormonal factors and T2D risk. Adjusted risk factors included body mass index, smoking, age, physical activity, socioeconomic status, education level, family history of T2D, and blood pressure.

The authors found that older age at puberty (over 14 years compared to under 12 years) reduced the risk of T2D by 12% and older age at menopause (52 years and older compared to under 47 years) reduced the risk by 30%. Breastfeeding (ever breastfed compared to never breastfed) was also associated with a 10% reduced risk of T2D. In addition, a higher total number of menstrual cycles (more than 470 in a woman’s lifetime compared to less than 390) was associated with a 25% reduced risk of developing T2D, and a longer duration of exposure to sex hormones (i.e. the time between puberty and menopause) (more than 38 years compared to less than 31 years) was associated with a 34% reduced risk of developing T2D.

In contrast, taking birth control pills (at least once in a woman’s lifetime versus not taking them at all) was associated with a 33% increased risk of developing T2D, and a longer time between periods (length of menstrual cycle) (32 days or more versus 24 days or less) was associated with a 23% increased risk. The authors explain that longer but later exposure to sex hormones could reduce the risk of developing type 2 diabetes later in life, independent of known risk factors. The risk induced by oral contraceptives could lead to personalized counseling for young women at increased risk of T2D, such as those with a family history of diabetes, those who are overweight or obese, or those with polycystic ovary syndrome.