Selective impairment in effortful information processing in major depression

Automatic and effortful information processing in depressed patients was investigated by a visual search paradigm, in order to examine dysfunctional effortful processing in depressed patients. Twenty-one patients with major depression, according to the DSM-IV, and with a moderate depression measured by the Hamilton Rating Scale score at > 18 participated in the study. The healthy control group was matched for age, gender, and level of education. Half of the trials involved only one type of distractor, and the other half of the trials involved two types of distractors being presented. The results show that the performance of the depressed patients was equal to the control group when the target was easily recognized with only one type of distractor present. However, when target detection required a more difficult and complex attentive search strategy, effortful information processing, the depressed patients needed longer visual search time compared to the controls. Depressed patients seem to have impaired performance on effortful but not automatic information processing.