Women with high blood pressure in their 40s are more likely to develop dementia years later, warns a new study.

The study, published online in the journal Neurology, showed that women who developed high blood pressure in their 40s were 73 per cent more likely to develop dementia than women who had stable, normal blood pressure throughout their 30s and 40s."High blood pressure in midlife is a known risk factor for dementia, but these results may help us better understand when this association starts, how changes in blood pressure affect the risk of dementia and what the differences are between men and women," said Rachel Whitmer, PhD scholar at Kaiser Permanente Division of Research in Oakland, California.The study involved 7,238 people who were part of the Kaiser Permanente Northern California health care system. 

They all had blood pressure checks and other tests from 1964 to 1973 when they were an average age of 33, then again when they were an average age of 44. About 22 per cent of the participants had high blood pressure in their 30s (31 per cent of men and 14 per cent of women). In their 40s, 22 per cent overall had high blood pressure, but the makeup was 25 per cent of men and 18 per cent of women.Next the researchers identified the 5,646 participants who were still alive and part of the Kaiser Permanente system in 1996 and followed them for an average of 15 years to see who developed dementia.

During that time, 532 people were diagnosed with dementia.Women who developed high blood pressure in their 40s were 73 percent more likely to develop dementia than women who had stable, normal blood pressure throughout their 30s and 40s."Even though high blood pressure was more common in men, there was no evidence that having high blood pressure in one's 30s or 40s increased the risk of dementia for men," Whitmer said."More research is needed to identify the possible sex-specific pathways through which the elevated blood pressure accelerates brain aging," Whitmer added.