Executive functioning correctly classified diagnoses in patients with first-episode psychosis: evidence from a 2-year longitudinal study.

Few studies have analysed factors that predict the ultimate clinical diagnosis in first-episode psychosis (FEP), and none has included cognitive factors. Eighty-six FEP patients and 34 healthy controls were recruited and followed up for two years. Positive and negative symptoms, depression, mania, duration of untreated psychosis (DUP), premorbid functioning, functional outcome and neurocognition were assessed over 2 years. Logistic regression models revealed that Wisconsin Card Sorting Test correctly distinguished the patients ultimately diagnosed with schizophrenia (87%) from those with bipolar disorder (80%) and those with other psychoses (85%), for an overall correct-diagnosis rate of 84.4%. The prediction was stable despite the inclusion of clinical and affective symptoms, DUP, clinical impression, and functional outcome scores. Results highlight the importance of reconsidering neurocognition as a diagnostic criterion for psychosis and schizophrenia.