Does cognitive impairment cause post-stroke depression?

Studies have demonstrated that poststroke depression is associated with cognitive impairment, but have failed to show improvement in cognitive function when mood improves. A consecutive series of patients with (n=41) or without (n=135) major depression were evaluated for cognitive functioning during acute hospitalization and either 3 or 6 months later. Patients with poststroke major depression whose mood improved at follow-up had significantly greater recovery in cognitive functioning than patients whose mood did not improve. Furthermore, patients whose cognitive functioning improved at follow-up had significantly greater improvement in mood than comparable patients whose cognitive function did not improve, suggesting that poststroke major depression leads to cognitive impairment and not vice versa. The failure of previous treatment studies to show cognitive improvement in poststroke patients with depression was probably due to the inclusion of patients with minor depression (not associated with cognitive impairment) or the failure of patients with major depression to respond to treatment.