Midlife hypertension is associated with an increased risk of dementia in women
Female sex, early-onset hypertension, and risk of dementia
Hypertension is more common among men compared with women in early adulthood, however, the risk of target organ damage and the CVD burden attributable to hypertension is higher in women . Dementia is one of the consequences of hypertension in midlife, but gender differences in this context have not been evaluated [2,3].
In this study, the associations of BP in early (mean: 32.7 years, SD: 1.8; range: 30.0–36.0) and mid-adulthood (mean: 44.3 years, SD: 3.0; range: 40.0–55.9) with the risk of dementia later in life were evaluated, and possible gender differences were investigated.
For this purpose 5,646 members of the Kaiser Permanente Northern California (KPNC) integrated health care delivery system, who participated in the Multiphasic Health Check-ups and had their BP measured at early- and mid-adulthood were included in the analysis . KPNC members were classified according to their BP at each time point as follows:
- hypotensive: SBP <80 mm Hg or DBP <60 mm Hg
- normotensive: SBP 81–120 mm Hg and DBP 61–80 mm Hg
- pre-hypertensive: SBP 120–139mmHg or DBP 80–89 mmHg
- hypertensive: SBP ≥140 mm Hg or DBP ≥90 mm Hg
Furthermore, individuals were classified into the following 4 categories based on the changes between the 2 time points: stable normotensive, onset hypertension, remitted hypertension, persistent hypertension. The mean follow-up time for dementia was 15.3 years (SD: 6.1; range: 0.1–19.7 years).
- After adjusting for demographics, early-adulthood hypotension (HR: 1.30; 95% CI: 0.42–4.04), pre-hypertension (HR: 1.04; 95% CI: 0.86–1.26), and hypertension (HR: 1.06; 95% CI: 0.85–1.32) were not associated with the risk of dementia.
- In similar models, midlife hypertension was associated with the risk of dementia (HR: 1.36; 95% CI: 1.10–1.67), but pre-hypertension (HR: 1.07; 95% CI: 0.88–1.30) or hypotension (HR: 0.61; 95% CI: 0.08–4.48) were not.
- In mid-adulthood, hypertension among women was associated with a 65% increased dementia risk (95% CI: 1.25–2.18) compared to normotensive women, which was not the case among men. The estimated effects remained similar when further adjusting for late-life conditions.
- The cumulative 25-year dementia risk at the age of 60 was 21% (95% CI: 12%–27%) for women with early-adulthood hypertension and 18% (95% CI: 14%–21%) for those without hypertension.
- Compared to women who remained normotensive during early- and mid-adulthood, onset of hypertension and persistent hypertension were associated with a 73% (95% CI: 1.24–2.40) and a 63% (95% CI: 1.11–2.40) increased risk of dementia.
- The association between mid-adulthood hypertension and dementia risk among women remained significant after further adjusting for mid-adulthood BMI and early or mid-adulthood smoking (HR: 1.59; 95% CI: 1.19–2.13).
Although midlife hypertension is more common in men, it was only associated with the risk of dementia in women. These findings may have important implications for hypertension management for women in their early 40s and brain health in later life.