Most studies aiming to predict transition to psychosis for individuals at ultra-high risk (UHR) have focused on either neurocognitive or clinical variables and have made little effort to combine the two. We aimed to investigate the relative value of neurocognitive and clinical variables for predicting transition to psychosis as well as long-term functional outcome.

Sixty-seven adolescents at UHR and 72 controls completed an extensive clinical and neurocognitive assessment. Forty-three UHR individuals and 47 controls participated in long-term follow-up approximately six years later. UHR adolescents who had converted to psychosis (UHR-P) were compared to individuals who had not (UHR-NP) and controls on clinical and neurocognitive variables. Regression analyses were performed to determine which baseline measures best predicted transition to psychosis and long-term functional outcome for UHR individuals.

Low IQ was the single neurocognitive parameter that discriminated UHR-P individuals from UHR-NP individuals and controls. The severity of attenuated positive symptoms was the only significant predictor of a transition to psychosis and disorganized symptoms were highly predictive of functional outcome.

IQ was lowest for those individuals at ultra high risk for psychosis who later went on to have a psychotic episode. However, IQ was not a good predictor of either transition or functional outcome. Rather, clinical measures proved to be the most important vulnerability markers for long-term outcome.