Summary: A long-term study found that women who developed high blood pressure in their 40s had a substantially higher risk of dementia later in life compared with women whose blood pressure remained normal. The increased risk was not observed for men in this cohort.
Source: AAN
New research reported in the October 4, 2017, online issue of Neurology indicates that women who develop high blood pressure in their 40s face a significantly higher risk of dementia as they age.
High blood pressure (hypertension) in midlife has long been associated with later-life cognitive decline and dementia. This study, led by Rachel A. Whitmer, PhD, of the Kaiser Permanente Division of Research in Oakland, California, examined when blood pressure-related risk begins, how changes across early and mid-adulthood relate to dementia, and whether men and women are affected differently.
The investigators analyzed data from 7,238 people who were members of the Kaiser Permanente Northern California health system and who had recorded blood pressure and health examinations in the period from 1964 to 1973. Participants had examinations in early adulthood, when their average age was about 33, and again in mid-adulthood, when their average age was about 44. At the 30s assessment, roughly 22 percent of the group had high blood pressure overall (31 percent of men and 14 percent of women). By the 40s assessment, high blood pressure was present in 22 percent overall, with a distribution of 25 percent of men and 18 percent of women.
From the original sample, the researchers identified 5,646 participants who were still alive and enrolled in the health system by 1996 and followed them for an average of 15 years to detect incident dementia. During this follow-up period, 532 of those participants were diagnosed with dementia.
The analysis found that elevated blood pressure in one’s 30s—early adulthood—was not associated with an increased risk of later dementia for either sex. However, developing high blood pressure in the 40s—mid-adulthood—was associated with a markedly higher dementia risk for women. Compared with women whose blood pressure remained normal across their 30s and 40s, women who developed high blood pressure in their 40s had a 73 percent higher likelihood of developing dementia. More broadly, high blood pressure in mid-adulthood corresponded to a 65 percent increased dementia risk for women after accounting for other risk factors.
Researchers adjusted their models for potential confounding factors including smoking, diabetes, and body mass index; the associations for women remained robust after these adjustments. In contrast, although high blood pressure was more common in men in this cohort, the study found no evidence that elevated blood pressure in the 30s or 40s increased dementia risk in men within this sample.
To illustrate absolute risk patterns, among women who reached age 60 without dementia, the study reported a cumulative 25-year dementia risk of 21 percent for those who had high blood pressure in their 30s, compared with an 18 percent risk for women who had normal blood pressure in their 30s. These figures highlight the complex relationship between blood pressure at different life stages and long-term cognitive outcomes.
The authors emphasize that the observed sex differences warrant further investigation to identify possible biological or social mechanisms that could explain why midlife hypertension appears to accelerate brain aging more in women than in men. Potential pathways might include differences in vascular biology, hormonal changes, or interactions with other health conditions, but the study does not establish causal mechanisms.
The study has important clinical and public health implications. It suggests that monitoring and managing blood pressure in midlife—especially for women—may be an important strategy for reducing the risk of dementia decades later. Early detection and effective treatment of high blood pressure remain key priorities in cardiovascular and brain health.
At the same time, the researchers note limitations that affect how broadly the findings can be generalized. The baseline data were collected in the 1960s and early 1970s, and both screening practices and antihypertensive treatments have changed substantially since then. These advances in detection and therapy could influence dementia risk in more recent cohorts. In addition, observational studies like this cannot prove causation, and unmeasured factors may have influenced the outcomes.
Source: Michelle Uher – AAN
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Original Research: Study published in Neurology