Affective and psychotic symptoms relate to different types of P300 alteration in depressive disorder

Previous findings of P300 alterations in depressive disorder have been controversial. We therefore used multivariate methods to study the relationship between P300 and affective and psychotic symptoms in depressive disorder.

The P300 of 22 psychotropic drug-free depressed out-patients was registered within an auditory oddball paradigm. Affective and psychotic symptoms were evaluated using the depression and psychoticism subscales of SCL-90. The relationship of P300 amplitude and latency with affective and psychotic symptoms was assessed with multiple linear regression analysis and ANOVA. P300 values of the depressed patients were also compared with those of 22 healthy controls.

Psychotic symptoms were associated with an overall reduction in P300 amplitude, which was pronounced in the left temporocentral electrode chain (T3, C3, Cz). Psychotic symptoms were also associated with a prolonged P300 latency. Affective symptoms were associated with a relational amplitude reduction at the right temporal scalp sites. There were no statistically significant differences in P300 amplitude or latency between depressed and control-subjects.

Rather small number of study subjects. The psychotic scores were low in all subjects. Multiple statistical analyses were used, and no specific a priori hypothesis was tested.

In depressive disorder, affective and psychotic symptoms are associated with different types of P300 alteration, which may indicate different underlying neurobiological processes.