Background: Systolic hypertension increases the risk of dementia in elderly people. The vascular dementia project, set up in the framework of the double-blind placebo-controlled Systolic Hypertension in Europe (Syst-Eur) trial, investigated whether antihypertensive drug treatment could reduce the incidence of dementia.
Methods: Eligible patients had no dementia, were at least 60 years old, and had a blood pressure when seated of 160-219 mm Hg systolic and below 95 mm Hg diastolic. Active treatment consisted of nitrendipine (10-40 mg/day) with the possible addition of enalapril (5-20 mg/day), hydrochlorothiazide (12.5-25 mg/day), or both drugs, titrated or combined to reduce the systolic blood pressure by at least 20 mm Hg to reach a value below 150 mm Hg. Cognitive function was assessed by the mini mental state examination (MMSE). If the MMSE score was 23 or less, diagnostic tests for dementia were done (DSM-III-R criteria). The cause of dementia was established by the modified ischaemic score with brain imaging or the Hachinski score.
Findings: Median follow-up by intention to treat was 2.0 years. Compared with placebo (n=1180), active treatment (n=1238) reduced the incidence of dementia by 50% from 7.7 to 3.8 cases per 1000 patient-years (21 vs 11 patients, p=0.05). The median MMSE score at randomisation was 29 in both treatment groups. At the last available assessment, systolic and diastolic blood pressure were, respectively, 8.3 mm Hg and 3.8 mm Hg lower (p<0.001) in the active-treatment group, but on average the MMSE scores did not change in either group. In the control patients, however, the MMSE decreased (p=0.04) with decreasing diastolic blood pressure, whereas in the active-treatment group MMSE scores improved slightly (p=0.01) with greater reduction in diastolic blood pressure (p=0.002 for between-group difference).
Interpretation: In elderly people with isolated systolic hypertension, antihypertensive treatment was associated with a lower incidence of dementia. If 1000 hypertensive patients were treated with antihypertensive drugs for 5 years 19 cases of dementia might be prevented.