RECOVERY OF COGNITIVE FUNCTION AFTER STROKE

Background and Purpose Previous studies have suggested that recovery o f cognitive function after stroke is maximal within the first 3 months after onset. We performed the present study to investigate the long-t erm course and clinical correlates of improvement in generalized cogni tive function after ischemic stroke. Methods We administered a battery of neuropsychological tests to 151 patients (age, 70.4+/-7.7 years; e ducation, 10.4+/-4.6 years) at 3 months and then annually after stroke . We transformed their test results into z scores based on the perform ance of a stroke-free normative group, averaged those scores to create a summary score, and defined improvement in annual examinations as an increase in that summary score greater than two standard deviations a bove the mean first annual change of the normative group. We then used logistic regression to determine whether stroke location, syndrome, o r recurrence; vascular risk factors; dementia status; depression; or d emographic variables were associated with improvement. Results We foun d that 19 of the 151 patients exhibited improvement, which was evident only at the first annual examination in most cases. Logistic regressi on determined that improvement was significantly related to left hemis phere infarction relative to brain stem/cerebellar infarction (odds ra tio [OR], 5.57), while the presence of a major hemispheral stroke synd rome showed a trend toward significance (OR, 3.32). Diabetes mellitus was significantly associated with a failure to exhibit improvement (OR , 0.12). Based on the logistic model, the probability of long-term imp rovement would be 54.0% for a patient with a left hemisphere infarct a nd a major hemispheral syndrome but only 11.9% if diabetes was also pr esent. Conclusions Long-term improvement in generalized cognitive func tion may be evident after stroke in association with left hemisphere i nfarction and severe hemispheral syndromes, while it may be compromise d by diabetes, possibly because of an in creased burden of cerebrovasc ular disease.