Prefrontal dysfunction and treatment response in geriatric depression

Background: This study investigated the relationship of clinical, neuropsychological, and electrophysiological measures of prefrontal dysfunction with treatment response in elderly patients with major depression. Methods: Forty-nine depressed elderly subjects were studied before and after 6 weeks of adequate antidepressant treatment and compared with 22 psychiatrically normal controls. The psychomotor retardation item of the Hamilton Depression Rating Scale, the initiation/ perseveration subscore of the Mattis Dementia Rating Scale, and the latency of the P300 auditory evoked potential were used as indices of prefrontal dysfunction. The intensity of antidepressant drug treatment was classified and monitored for a 6-week period. Results: Abnormal initiation/perseveration score, psychomotor retardation, and long P300 latency predicted 58% of the variance in change of depression scores from baseline to 6 weeks (F-3 = 20.1, P<.001). Depressed patients who remained symptomatic (n = 25) had more abnormal initiation/perseveration scores and longer P300 latency compared with depressed patients who achieved remission (n = 24) and control subjects. There were no differences between the last 2 groups. The association between psychomotor retardation, initiation/perseveration scores, P300 latency, and response to antidepressant treatment could not be explained by differences in demographic and clinical characteristics or treatment intensity between remitted and nonremitted depressed patients. Conclusions: Prefrontal dysfunction was associated with poor or delayed antidepressant response in depressed elderly patients. This observation, if confirmed, may aid clinicians in identifying candidates for aggressive somatic therapies and for interventions offering structure of daily activities.