Co-morbid depressive disorder is associated with better neurocognitive performance in first episode schizophrenia spectrum.

Background: Both major depressive disorder (MDD) and first episode schizophrenia spectrum (FES) are associated with significant neurocognitive deficits. However, it remains unclear whether the neurocognitive deficits in individuals with FES are more severe if there is comorbid depressive disorder. The aim of this study was to compare the neurocognitive profiles between those with and without full-threshold depressive disorder in FES.

Method: This study involved secondary analysis of baseline data from a randomized controlled trial of vocational intervention for young people with first-episode psychosis (N = 82; age range: 15-25 years).

Results: Those with full-threshold depressive disorder (n = 24) had significantly better information processing speed than those without full-threshold depressive disorder. Severity of depressive symptoms was also associated with better information processing speed.

Limitations: In additional to the cross-sectional design, limitations of this study include the absence of assessing insight as a potential mediator.

Conclusions: After the first psychotic episode, it could be speculated that those with better information processing speed may be more likely to develop full-threshold depressive disorder, as their ability to efficiently process information may allow them to be more aware of their situations and environments, and consequently to have greater insight into the devastating consequences of FES. Such novel findings support the examination of full-threshold depressive disorder in relation to neurocognitive performance across illness phases in future work.