Comparison of cognitive impairment associated with major depression following stroke versus traumatic brain injury.

Several studies have reported an association between cognitive impairment and major depression following stroke but failed to find a similar association among patients with traumatic brain injury (TBI). This study examined the hypothesis that age differences between stroke and TBI patients would account for the differences in the effect of major depression on cognitive function. We examined subjects' cognitive function using the Mini-Mental State Examination and compared findings among patients with stroke or TBI. Results indicated that stroke patients with major depression (N = 73) were significantly older and more cognitively impaired than similar TBI patients (N = 35), even after matching patients for lesion volume and years of education. After matching for age, however, there was no association of major depression with cognitive impairment in this relatively young stroke population. These findings support the hypothesis that age, presumably related to physiological response to brain injury, accounts for differences in the effect of major depression on cognitive function between stroke and TBI patients.