A research team at Seoul National University Bundang Hospital has found that women who have given five or more births have a higher risk of developing dementia than those who gave only one birth.

Women have a higher prevalence of dementia and Alzheimer's disease than men, accounting for two-thirds of all dementia patients worldwide. While various factors, such as lifestyle habits, can play a role in these gender differences, it is known that childbirth, an experience only for women, can increase the risk of dementia by causing changes in hormones and health.

Few studies have analyzed the effect of childbirth on dementia, and existing studies have shown different results leading to confusion.

The team, led by Professors Bae Jong-bin and Kim Ki-woong at the hospital, analyzed the data of 14,792 women aged 60 and over from 11 countries in three continents, including Korea, Germany, France, China, Japan, and Brazil, to investigate the effect of childbirth on the risk of dementia.

It found that women who experienced five or more births had a 47 percent higher risk of developing dementia than women who gave birth only once. The research also considered other factors, such as age, education level, high blood pressure, and diabetes, which may affect the onset of dementia in analyzing the data.

The researchers did not find any significant difference in the risk of dementia in women who had no birth experience or who gave two to three births compared to women who gave birth only once.

Analyzing the groups by continent, they also discovered that women in Asia are more likely to develop Alzheimer's disease than Europe and South America, even without any birth experience.

"Considering the social background, this seems to be because if women over 60 in Asia have not experienced childbirth, it is likely due to infertility or recurrent miscarriage rather than a personal decision not to give birth," the team said.

Professor Bae said, "Women who have given birth five or more times are more likely to have diseases that increase the risk of dementia, such as heart disease, stroke, and diabetes, which acts as a risk-raising factor."

As these women are at high risk for dementia, they require proper management by having regular checkups, Bae added.

BMC Medicine published the results of the research.