Reducing the risk of dementia: efficacy of long-term treatment of hypertension.

BACKGROUND AND PURPOSE The efficacy of treating older persons for hypertension remains controversial. Although clinical trials suggest no short-term harm, or some benefits, there are little data on the effect on cognitive function of long-term antihypertensive treatment. We evaluated the risk of dementia and cognitive decline associated with duration of antihypertensive treatment. METHODS Data are from the Honolulu Asia Aging Study on Japanese American men followed since 1965. The subjects included in this analysis were hypertensive from midlife and dementia-free in 1991 (mean age 76.7 years). In 1991, 1994 and 1997, global cognitive function was assessed with the Cognitive Abilities Screening Instrument (CASI) and dementia by a standardized examination using international criteria. The sample was grouped by treatment duration (never-treated hypertensives (NTH), <5 years, 5 to 12 years, >12 years). Normotensive subjects up to 1991 were included in the analysis as a control group. RESULTS For each additional year of treatment there was a reduction in the risk of incident dementia (hazard ratio [HR]=0.94, 95% CI, 0.89 to 0.99). The risk for dementia in subjects with >12 years of treatment was lower compared to NTH (HR for dementia=0.40; 95% CI, 0.22 to 0.75 and for Alzheimer disease HR=0.35; 95% CI, 0.16 to 0.78) and was similar to the normotensives. Nondemented subjects with 5 to 12 years of treatment had lower yearly CASI decline compared to NTH. CONCLUSIONS Results suggest that in hypertensive men, the duration of the antihypertensive treatment is associated with a reduced risk for dementia and cognitive decline.