Peila R et al. (2006) Reducing the risk of dementia: efficacy of long-term treatment of hypertension. Stroke 37: 1165–1170

Studies have indicated that midlife hypertension might increase the risk of late-life cognitive impairment. Although some studies have reported that antihypertensive treatment reduces dementia risk in elderly patients, there is controversy over the long-term effects. Data from the prospective, population-based Honolulu-Heart Program/Honolulu-Asia Aging Study, which started in 1965, have been used to investigate the risk of dementia and cognitive decline associated with various durations of antihypertensive treatment.

The analysis was based on 1,294 elderly men (born from 1900 to 1919) who had been hypertensive since middle age; 108 of these patients were diagnosed with dementia during follow-up. Treated hypertensives (n = 848) had received an average of 12.8 years of antihypertensive treatment and, compared with nontreated hypertensives, the risk of dementia was reduced by about 5% for each year of antihypertensive treatment. Hypertensive men who had received ≤5 years of antihypertensive treatment, however, were at similar risk of dementia to hypertensives who had never received treatment. Treatment duration affected the risk of dementia, with hypertensive patients who had been treated for ≥12 years showing a similar risk of dementia to normotensives; this 'treatment duration effect' occurred mainly among patients with controlled blood pressure. Cognitive function declined with age in patients without dementia; hypertensive patients without dementia who had been treated with antihypertensives for 5–12 years, however, showed a lower rate of decline than hypertensives who had never received treatment.

The authors recommend that the finding that increased duration of antihypertensive treatment reduces the risk of dementia and cognitive decline is tested in further trials.