Attentional disturbances in patients with unipolar psychotic depression: a selective and sustained attention study

Psychotic depression is a clinical subtype of major depressive disorder in the recent editions of the psychiatric diagnostic systems ICD-10 (1992) and DSM-IV (1994). Recent evidence suggests that psychotic depressed patients are more impaired on neuropsychologic tests measuring attention as compared to nonpsychotic depressed patients. However, information on this issue between psychotic and nonpsychotic depression is limited. It has become clear that attention is not a single concept; thus we studied both selective and sustained attention using the theoretic model of automatic and controlled information processing. Thirty-two patients with major depressive disorder, 16 psychotics and 16 nonpsychotics, were investigated and compared with 20 patients with schizophrenic disorder and 20 healthy volunteers who comprised the control groups, using Ruff's 2 and 7 selective attention tests. Compared to the healthy controls, both depressed groups were impaired; however, the psychotic depressed group was more severely impaired on both measures. Attentional performance speed and accuracy scores, on both effortless and effortful conditions, were significantly lower in the psychotic depressed group than in the nonpsychotic depressed group. No significant differences were found on attentional performance between the psychotic depressed patients and those with schizophrenic disorder. Attention deficits are thus more prominent in psychotic than in nonpsychotic depression. Furthermore, taking attention as a criterion, psychotic depression, although of mood congruent subtype, lies closer to schizophrenia than to nonpsychotic depression.