Psychopathology and cognition in schizophrenia spectrum disorders: the role of depressive symptoms

The cognitive correlates of five symptom dimensions based on PANSS ratings were examined in a group of 50 recent onset psychotic patients, using both objective and subjective cognitive measures. We were particularly interested in the depression dimension, since it has not been studied extensively thus far. The depression dimension showed a high number of correlations with both objective and subjective cognitive measures, such as problems with simple and divided attention, psychomotor slowing and subjectively experienced distractibility, overload and diminished attentional control. The other dimensions, including negative symptoms, have less cognitive correlates. It is possible that previous studies based on a three-dimensional model confounded correlates of negative symptoms with correlates of depressive symptoms. The results of this study suggest the need for more research into the mechanisms underlying the relationship between depressive symptoms and cognitive functioning in schizophrenia, and that patients with depressive symptoms are less efficient in information processing, but can compensate by investing more mental effort. Because subjective cognitive measures were related to mental effort in previous research, they can be a useful tool in future research.