Cognitive Clusters in First-Episode Psychosis: Overlap With Healthy Controls and Relationship to Concurrent and Prospective Symptoms and Functioning

Objective: To identify cognitive subgroups (comprising neurocognition and social cognition domains) within first-episode psychosis (FEP) patients including a healthy control group for comparison. Predictive validity of cognitive clusters in relation to symptoms and functioning was also investigated. Method: A comprehensive cognitive battery was administered to 133 FEP participants and 46 healthy controls. Ward's method hierarchical agglomerative cluster analysis with k-means verification was used to determine clusters. Clusters were externally validated and 6-month predictive validity was also examined. Results: Three distinct clusters were identified and were defined by degree of impairment rather than specific deficit profiles. Social-cognitive performance mirrored neurocognitive performance in each cluster. Cluster 1 was characterized by significant widespread cognitive impairments (1-2 SD below the mean) and solely comprised FEP participants (n = 24). Cluster 2 suggested moderately impaired cognitive functioning (within 0.5 SD below the mean), and comprised mostly FEP participants and 2 healthy controls (n = 73). Cluster 3 showed a pattern of cognitively intact performance across domains and comprised 37 FEP participants and 44 healthy controls (n = 81). Premorbid IQ, negative symptom severity, and functioning were significantly associated with cluster membership at baseline. At 6-month follow-up, cluster membership remained significantly associated with negative symptoms and functioning. Conclusions: The heterogeneity of cognition in FEP may be based on degree of impairment across both neurocognitive and social-cognitive domains. Cognitive clusters were associated with symptom and functional outcome, suggesting that measurement of cognition at entry to treatment may be useful for prognosis and treatment.