Frequency of cognitive impairment without dementia in patients with stroke: a two-year follow-up study

Abstract

Background and purpose: Studies on cognitive impairment without dementia (CIND) after stroke are scarce and there are no widely accepted diagnostic criteria for this condition. The purpose of this study was to determine the frequency of CIND in a hospital cohort before and after stroke during a 2-year follow up according to two alternative operational criteria.

Methods: Three hundred twenty-seven consecutive stroke inpatients were prospectively evaluated with an extensive neuropsychological battery and the Informant Questionnaire of Cognitive Decline in the Elderly (IQCODE) on admission and then at 3, 12, and 24 months after discharge. CIND was established according to two alternative operational criteria: proxy information (a cutoff score of 3.35 in the IQCODE: IQ-c) or to neuropsychologic examination (a score below the sixth percentile in >/=50% of the tests exploring one cognitive domain: NPE-c).

Results: A total of 12.6% patients had CIND (IQ-c) before stroke. After 3 months, the CIND frequency was 26.9% (IQ-c) or 19.6% (NPE-c); after 12 months, 39.5% or 26.8%; and after 24 months, 36.6% or 21%. The risk for developing delayed dementia was significantly higher for poststroke patients with CIND diagnosed by IQ-c (OR 8.8), NPE-c (OR 10.3), or both criteria (OR 20.8).

Conclusions: Patients with CIND are frequent before and after stroke and prone to delayed dementia. Both criteria are valid for identifying CIND cases and predicting long-term conversion to dementia, but NPE-c may be more adequate for the long-term follow up and IQ-c for detecting changes from prestroke status.