Intelligence quotient changes over 10 years: Diversity of cognitive profiles in first episode of psychosis and healthy controls

Abstract

Objective: This study aimed to analyse whether intelligence quotient (IQ) improves, declines, or remains stable over 10 years among FEP patients and healthy subjects. Methods: A group of FEP patients enrolled in a Program of First Episode Psychosis in Spain called PAFIP, and a sample of Healthy Controls (HC) completed the same neuropsychological battery at baseline and approximately 10 years later, which included the WAIS vocabulary subtest to estimate premorbid IQ and 10-year IQ. Cluster analysis was performed separately in the patient group and the HC group to determine their profiles of intellectual change. Results: One hundred and thirty-seven FEP patients were grouped into five clusters: "Improved low IQ" (9.49 % of patients), "Improved average IQ" (14.6 %), "Preserved low IQ" (17.52 %), "Preserved average IQ" (43.06 %), and "Preserved high IQ" (15.33 %). Ninety HC were grouped into three clusters: "Preserved low IQ" (32.22 % of the HC), "Preserved average IQ" (44.44 %), and "Preserved high IQ" (23.33 %). The first two clusters of FEP patients, characterized by a low IQ, earlier age at illness onset, and lower educational attainment, showed a substantial cognitive improvement. The remaining clusters demonstrated cognitive stability. Conclusions: The FEP patients showed intellectual improvement or stability, but no decline post-onset of psychosis. However, their profiles of intellectual change are more heterogeneous than that of HC over 10 years. Particularly, there is a subgroup of FEP patients with a significant potential for long-term cognitive enhancement