Background  Midlife hypertension has long been established as a risk factor for dementia, but the role of late-life hypertension remains unclear.

Objective  To investigate the role of hypertension in cognitive deterioration among older subjects with cognitive impairment, no dementia.

Design  The Canadian Study of Health and Aging was conducted in 3 waves (1991, 1995-1996, and 2001-2002).

Setting  Community-based cohort study.

Patients  We studied 990 subjects with a mean (SD) age of 83.06 (6.97) years having cognitive impairment, no dementia who were followed up for 5 years in the Canadian Study of Health and Aging.

Main Outcome Measures  Determination of cognitive dysfunction and association between hypertension and cognitive deterioration.

Results  No difference in the rate of progression to dementia based on the presence of hypertension was found between subjects with memory dysfunction alone or in combination with executive dysfunction. However, among subjects with executive dysfunction alone, 57.7% having hypertension progressed to dementia compared with 28.0% having normotension (P = .02).

Conclusions  Hypertension predicts progression to dementia in older subjects with executive dysfunction but not memory dysfunction. Control of hypertension could prevent progression to dementia in one-third of the subjects with cognitive impairment, no dementia.