Objectives. Even though many studies demonstrate cognitive impairment in the acute phase of depression and several studies indicate that this impairment might be long lasting despite symptom reduction and recovery, there is a lack of longitudinal studies on this field with considerable follow-up length. The aim of this study was to investigate whether the impairment observed in cognitive inhibition in the acute phase of depression is reversible or irreversible in a 10-year follow-up assessment.
Design. A longitudinal study of 38 individuals, 19 with recurrent unipolar depression and 19 healthy controls matched for gender, age, and education were included in the study.
Method. Cognitive inhibition was investigated using the Stroop test at three different occasions: acute phase, short-term (6 months), and long-term (10 years) follow-up.
Results. The results show that recurrent major depressive disorder patients have a long-lasting impairment in inhibition as measured by the Stroop test in 10-year follow-up. Further there is high consistency in inner group performance suggesting that severe impairment in the acute phase of illness is associated with severe impairment 10 years later despite recovery in the patient group.
Conclusions. The results show that impairment in cognitive inhibition is long lasting when present in the acute phase of recurrent depression. Impaired cognitive inhibition might be an irreversible vulnerability marker for recurrent depression.