Oestrogen may be linked to woman's risk of developing dementia

Washington, April 6: A new study led by the George Institute for Global Health has found that life events that influence levels of the female hormone oestrogen may be linked to a woman's risk of developing dementia in later life.

The findings of the research were published in the journal, 'PLoS Medicine'. The analysis also found that some reproductive events - like an early or late start to menstruation, early menopause and hysterectomy - were linked to higher risk of dementia while ever having been pregnant or having had an abortion and later menopause were linked to lower risk. Also read | India stands firm when world divided into rival factions, says PM Modi on BJP's 42nd foundation day But childbearing was not one of them, with a similar relationship observed between the number of children and dementia risk in men and women. Lead author Jessica Gong from the George Institute for Global Health said that although it appeared reproductive events related to changes in hormone levels in women may be involved in dementia risk, the exact relationship was still unknown. "While the risk of developing dementia increases with age, we don't yet know whether the higher rates seen in women are simply because they live longer," explained Gong. "But it's possible that female-specific reproductive factors like oestrogen may be able to explain some of the sex differences," she added. Dementia is fast becoming a global epidemic, currently affecting an estimated 50 million people worldwide. This is projected to triple by 2050 - mainly driven by aging populations. Rates of dementia and associated deaths are both known to be higher in women than men. Estradiol is the most predominant form of estrogen during reproductive life (from the start of menstruation to menopause) and estriol is the primary estrogen during pregnancy. Use of hormones that originate from outside the body, such as oral contraceptives during reproductive years, and hormone replacement therapy (HRT) in later life can also influence estrogen levels. Also read | Ahead of 'Runway 34' release, Amitabh Bachchan recalls working with Ajay Devgn's father To examine these relationships in more detail, George Institute researchers analysed data on a total of 273,240 women without dementia who were registered with the UK Biobank, a large-scale biomedical database. After adjusting for other factors that could have influenced the results, they found the following were associated with an increased risk of dementia. Early and late first occurrence of menstruation, younger age at first birth, and hysterectomy - specifically hysterectomy without surgical removal of one or both ovaries, or if the hysterectomy took place after ovary removal. Conversely, the factors associated with a decreased risk were ever having been pregnant, ever having had an abortion, longer reproductive lifespan and later menopause. "With regard to external hormones, the use oral contraceptive pills was associated with a lower risk of dementia, but our study findings did not support an association between HRT and dementia risk," Gong said. The authors proposed that risk variation in women may not be associated with childbearing because a similar pattern was observed between number of children fathered and dementia risk among a similar number men in the same study. "We found that the higher dementia risk linked to early (natural and artificial) menopause was more pronounced in women of lower socioeconomic status," she added. "Social deprivation is likely to be an important determinant of dementia risk as well as other aspects of women's health," she concluded. -PTC News