- A new study investigated the risk factors of dementia.
- Reproductive history was taken into account when assessing women's risk.
- The number of children people have can also be a contributing factor to the development of dementia.
Women’s reproductive factors have been associated with dementia. Women who had their first live birth at a young age and underwent a hysterectomy were especially linked with greater dementia risk.
The study published in PLOS Medicine examined the incidence of all-cause dementia associated with reproductive factors in women, the number of children (in both sexes), and whether the associations vary by age, socioeconomic status, smoking status, and body mass index (BMI).
The research enrolled 273 240 women and 228 957 men without prevalent dementia from the United Kingdom, aged 40 to 69 years. The participants underwent assessments soliciting information on lifestyle, medical history, and reproductive history. Their body measurements were recorded, and blood samples were taken.
The women reported their pregnancy history, number of live births, age at first live birth, number of stillbirths, number of miscarriages, number of abortions, reproductive life span, the age of natural menopause, and age of hysterectomy. They also reported on hormone exposures such as oral contraceptive pill use, age when they started using oral contraceptive pills, and hormone replacement therapy.
Hormones may be the culprit
The study found that exposure to the hormone oestrogen may increase dementia risk. The findings show that pregnancy, long reproductive span, and older age at menopause are associated with a lower risk of dementia in women. While a hysterectomy, younger age of first birth, and younger or older than the average age at first period were associated with greater dementia risk. The study results show that oral contraceptive pills were linked with lower dementia risk.
The researchers also found that elevated dementia risk associated with early natural or artificial menopause was more strongly associated with dementia in women of lower socioeconomic status. For both men and women, having two children, having no children or four or more were connected with a greater risk of dementia.
The study authors say that the findings show a need to focus on women’s reproductive health as a risk factor for dementia.
“Reproductive events related to shorter exposure to endogenous oestrogen in women were associated with higher dementia risk, and these findings highlight the vulnerability in dementia risk pertaining to women. However, the similar association between the number of children and dementia risk observed for women and men indicates that the risk variation in women may be more related to social and behavioural factors in parenthood, rather than biological factors involved in childbearing,” said study co-author Jessica Gong in a press statement.