Relationships between cognition and symptoms across mood and psychotic disorders

Cognitive impairments are common across mood and psychotic disorders; however, it is unclear whether different diagnoses show the same level of impairment. Further, it is unclear whether cognition is related to similar symptom domains across diagnostic groups. Differences in working memory, processing speed, vocabulary, and cognitive control were examined in schizophrenia/schizoaffective disorder (SCZ), bipolar disorder (BD), major depressive disorder (MDD), and healthy controls (HC). We examined relationships between these cognitive domains and the symptom domains of psychosis, negative symptoms, disorganization, and depression. In regards to group differences in cognition, people with SCZ showed reductions across all cognitive domains examined relative to HC, BD, and MDD. MDD showed no group differences in any domain relative to HC. BD showed reductions in cognitive control relative to HC. In SCZ, processing speed and vocabulary were significantly related to negative symptoms and working memory showed a strong trend in relation to negative symptoms as well. However, in BD, negative symptoms were only related to cognitive control. There were no correlations between other major symptom domains and cognition in any patient group. While different diagnostic groups may share some cognitive deficits, cognitive functioning does not have the same relationships to symptoms across diagnoses.