Nearly one tenth of previously cognitively intact patients develop dementia in the year after stroke. The relative contributions of vascular injury and neurodegeneration to this cognitive decline remain unclear. Therefore, investigators conducted a longitudinal study of 355 older patients (aged 
75) who were free of dementia 3 months after stroke. Participants underwent neuropsychological testing annually; the investigators identified incident cases of dementia according to standard DSM-IV criteria. The researchers performed brain autopsies in 50 of the 176 participants who died.
Over time, 142 patients (40%) withdrew from neuropsychological follow-up, but their baseline characteristics were similar to those of patients who continued follow-up. During an average follow-up period of nearly 4 years, dementia occurred in 85 patients (24%). The risk for dementia correlated with vascular risk factors but not APOE allele status. Of the 50 patients who came to brain autopsy, 23 had incident dementia, and vascular dementia was the neuropathological diagnosis in 18 (78%) of these cases.
Comment: Although this study was limited by a high rate of loss to follow-up, the reporting of autopsy results provides novel and important information about the causes of poststroke dementia. The findings suggest that poststroke dementia more often results from vascular than from neurodegenerative pathology. Whether treatment of vascular risk factors reduces the risk for poststroke dementia remains unknown, but the possibility of such a benefit adds to the value of secondary stroke prevention strategies — such as antihypertensive, antithrombotic, and statin drugs — that have already been proven to reduce morbidity and mortality from other forms of vascular disease.
— Hooman Kamel, MD
Published in Journal Watch Neurology February 7, 2012
