Women's dementia risk increased by midlife hypertension

Researchers have uncovered a possible sex difference in how blood pressure affects dementia risk, after finding that women who get hypertension in their 40s are likelier to develop the condition. But for men, hypertension in midlife appears to have no impact on dementia risk.

The study - conducted by researchers from Kaiser Permanente in Oakland, CA - was recently published in the journal Neurology.

Around 75 million adults in the United States have high blood pressure, or hypertension, putting them at increased risk of heart disease and stroke.

An array of studies have also suggested a link between high blood pressure and increased risk of dementia.

For the new research, study co-author Rachel A. Whitmer, Ph.D., of the Kaiser Permanente Division of Research, and colleagues sought to determine whether the link between hypertension and dementia risk varies by age and sex.

The team reached their findings by assessing the data of 7,238 adults enrolled in the Kaiser Permanente Northern California healthcare system.

Between 1964 and 1973, when subjects were an average age of 33 years, all participants had their blood pressure measured. Blood pressure was assessed again between 1978 and 1985, when they were aged 44, on average.

Around 31 percent of men and 14 percent of women had high blood pressure in their 30s, and around 25 percent of men and 18 percent of women had high blood pressure in their 40s.

Hypertension and dementia: Women vs. men

The researchers tracked down 5,646 of the subjects who were still a part of the Kaiser Permanente Northern California healthcare system between 1996 and 2015. During this period, a total of 532 subjects received a dementia diagnosis.

The study results revealed that women who had high blood pressure in their 30s showed no greater risk of dementia than those whose blood pressure remained normal.

However, women who had high blood pressure during their 40s were found to have a 65 percent increased risk of dementia.

For women who experienced onset of hypertension in their 40s, dementia risk was increased by 73 percent, compared with women whose blood pressure remained normal during their 30s and 40s.

Among men, the researchers found no evidence to suggest that high blood pressure during their 30s or 40s was associated with an increased risk of dementia.

These results remained after accounting for a number of possible confounding factors, including body mass index (BMI), diabetes, and smoking status.

Overall, the researchers say that their findings suggest that high blood pressure becomes a dementia risk factor for women from their 40s, but this is not the case for men.

Commenting on what their findings may mean, the authors write:

"Sex differences in the timing of dementia risk factors have important implications for brain health and hypertension management."

However, Dr. Whitmer notes that further research is required to pinpoint the "sex-specific pathways through which the elevated blood pressure accelerates brain aging."