Prolonged impairment in inhibition and semantic fluency in a follow-up study of recurrent major depression

Several studies have demonstrated impaired performance in inhibition and semantic fluency in the acute phase of illness in patients with recurrent major depression. However, few studies have investigated these functions longitudinally, focusing on how these impairments relate to symptoms over time. The present longitudinal study investigated whether the specific impairment in inhibition and semantic fluency seen in the acute phase of Major Depressive Disorder (MDD) was prolonged or normalized with symptom reduction in a 9-month follow-up. Twenty recurrent major depressive patients and 19 control subjects were included in the study. Inhibition and semantic fluency were investigated using tests from the Delis-Kaplan Executive Function System. The results show that the patient group still had significantly lower scores in inhibition and semantic fluency compared with the control group despite significant symptom reduction. Further, the results show that impaired inhibition in the acute phase was strongly correlated with impaired inhibition in the follow-up, suggesting that the inability to inhibit may represent a trait marker in recurrent MDD.