Longitudinal assessment of neuropsychological function in major depression.

Neuropsychological impairment is a core component of major depression, yet its relationship to clinical state is unclear. The aims of the present review were to determine which neuropsychological domains and tasks were most sensitive to improvement in clinical state in major depression and to highlight the methodological issues in such research. Studies that included a baseline and at least one follow-up neuropsychological testing session in adults with major depression were identified using MEDLINE, Web of Science and ScienceDirect databases. Thirty studies were included in the review. Findings in younger adult populations suggested that improvement in mood was most strongly related to improved verbal memory and verbal fluency, while measures of executive functioning and attention tended to remain impaired across treatment. In late-life major depression, improved psychomotor speed was most closely related to treatment response, but there was much inconsistency between study findings, which may be due to methodological issues. In major depression, particular neuropsychological domains are more strongly related to clinical state than others. The findings from the present review suggest that the domains most sensitive to clinical state are verbal learning and memory, verbal fluency and psychomotor speed. In contrast, measures of attention and executive functioning perhaps represent more trait-like markers of major depression. With further methodologically sound research, the changes in neuropsychological function associated with treatment response may provide a means of evaluating different treatment strategies in major depression.