Hypertensive Disorders of Pregnancy and Incident Dementia.

IMPORTANCE: Hypertensive disorders of pregnancy (HDPs) are established markers of later-life cardiovascular disease, but their association with dementia remains uncertain. OBJECTIVE: To investigate whether HDPs are associated with incident dementia in a nationwide population-based cohort with more than 2 decades of follow-up. DESIGN, SETTING, AND PARTICIPANTS: This retrospective cohort study used the Korean National Health Insurance Service database to identify females aged 16 years or older who delivered between January 1, 2002, and December 31, 2005, and followed up through December 31, 2024. Statistical analyses were conducted between October 2025 and May 2026. EXPOSURES: HDPs were defined as gestational hypertension, preeclampsia, HELLP (hemolysis, elevated liver enzymes, low platelet count) syndrome, or eclampsia. MAIN OUTCOMES AND MEASURES: The primary outcome was incident dementia, including Alzheimer disease and vascular dementia. Cox proportional hazards regression models estimated hazard ratios (HRs) and 95% CIs. RESULTS: Among 1 370 485 females (mean [SD] age, 29.2 [3.9] years), 28 747 (2.1%) experienced HDPs. The cumulative incidence of dementia was higher among females with HDPs than among those without HDPs (7.2 vs 2.8 per 10 000 females; P < .001), as was the incidence density of dementia (3.00 vs 1.05 per 100 000 person-years; P < .001). In model 1, HDPs were associated with an increased risk of incident dementia after adjustment for baseline maternal, socioeconomic, and obstetric factors (adjusted HR, 1.96; 95% CI, 1.19-3.23). In model 2, after additional adjustment for postdelivery hypertension, diabetes, myocardial infarction, and stroke, the association was attenuated and was no longer statistically significant (adjusted HR, 1.15; 95% CI, 0.70-1.91). CONCLUSIONS AND RELEVANCE: In this cohort study, HDPs were associated with an increased risk of incident dementia after adjustment for baseline maternal, socioeconomic, and obstetric factors. However, this association was no longer statistically significant after additional adjustment for postdelivery vascular and metabolic conditions. Given the small number of dementia events among females with HDPs, these findings should be interpreted cautiously. These findings suggest that HDPs may serve as an early-life marker of long-term neurovascular vulnerability.