LONGITUDINAL ASSESSMENT OF DEPRESSION AND COGNITIVE IMPAIRMENT FOLLOWING STROKE

Previous studies have demonstrated that patients with major depression following stroke have a greater degree of cognitive impairment than n ondepressed patients with comparable lesions. The present study examin ed the longitudinal course of cognitive impairment related to depressi on. Patients were prospectively evaluated following an acute stroke (N = 309), using a structured psychiatric interview and the Mini-Mental State Examination. Longitudinal evaluations were obtained at 3, 6, 12, and 24 months follow-up in a subset of these patients. During the ini tial in-hospital evaluation, the frequency and severity of cognitive i mpairment was significantly greater in patients with major depression compared with nondepressed patients. This effect occurred predominantl y in patients with major depression following left hemisphere stroke. The association of depression and cognitive function was strongest dur ing the initial evaluation, but was present for up to 1 year. The year -long effect, however, was evident only in patients with left hemisphe re stroke. Patients with both depression and cognitive impairment had a greater duration of depression than depressed patients without cogni tive impairment. Depression with cognitive impairment appears to be a phenomenon produced by left hemisphere lesions. This suggests that lef t hemisphere stroke may produce depression through a different mechani sm than lesions in other locations. In addition, the fact that the str ongest influence of depression on cognitive function was seen during t he initial evaluation suggests that this phenomenon may be mediated by acute or subacute physiological effects of the lesion.