Cognitive impairment and dementia 20 months after stroke

Dementia is common after stroke, but the dementia syndrome does not cover the whole spectrum of cognitive impairment. Our aim was to quantify and compare dementia and cognitive impairments in elderly patients 1.5 years after stroke and a matched normal population.

We examined dementia and cognitive impairments in 149 out of an initial total of 243 acute stroke patients after a mean 20 months. Inclusion criteria were age > or =70 years, not living in an institution and no previous cerebral lesion. The patients' mean age was 81 years. Five controls matched by age and gender and fulfilling the same exclusion criteria were selected for each patient (n = 745) from a population-based survey in the same area. Dementia was diagnosed according to the DSM-III-R criteria, and impairments in different dimensions of cognitive function were assessed.

The prevalence of dementia was 28% in the stroke patients and 7.4% in the controls (OR 4.7; 95% CI 3.0-7.5). Seventy-two percent of the patients had cognitive impairments compared to 36% in the controls. Cognitive impairments were more common in nondemented stroke patients than in nondemented controls: 61 vs. 31% (OR 3.5; 95% CI 2.3-5.3). The risk increase attributable to stroke was highest for patients below 80 years of age.

Stroke confers an increased risk of dementia and cognitive impairments in the elderly, especially in the younger ones. Apraxia is the most frequent neuropsychiatric impairment after stroke. The concept of dementia does not describe cognitive impairments well, since it underestimates their extent not only after stroke but also in normal ageing.