Cognitive dysfunction in stroke survivors: a community-based prospective study from Kolkata, India.

The frequency of cognitive dysfunction among community stroke survivors (SS) is not known in India. This prospective study investigated the prevalence of poststroke mild cognitive impairment (psMCI) and poststroke dementia (psDem), the annual progression rate to dementia, and pertinent risk factors in a sample population of SS in Kolkata, India between September 2006 and July 2010. From a community-based stroke registry, 281 SS were assessed at baseline year after excluding attrition due to various causes. Validated cognitive tools were applied by trained field workers under supervision of a neuropsychologist. The assessment was repeated annually for consecutive three years. The mean follow-up period was 1.89 years (range, 1-3 years). The period prevalence rate of psDem was 13.88% (95% confidence interval [CI], 9.91%-18.90%) at baseline, and the average annual progression rate to dementia was 3.53% (95% CI, 2.09%-5.58%). Compared with subjects without dementia, those with psDem were significantly older at first-ever stroke and more likely to have cortical atrophy. The period prevalence rate of psMCI was 6.05% (95% CI, 1.45%-13.64%) at baseline, and 10.6% (95% CI, 4.57%-20.88%) of these subjects converted to psDem annually. Survival analysis of psDem patients showed a greater risk of death in psDem SS as compared to nondemented SS (hazard ratio, 2.65; 95% CI, 1.72-6.15). Our data suggest that the overall prevalence of psDem is higher than that of psMCI, possibly related to nonexclusion of prestroke dementia, but that the average annual progression rate of SS to psDem and that of psMCI to psDem are comparable. Older age at first-ever stroke and cortical atrophy are associated with increased risk for dementia among SS.