Reduced prepulse inhibition as an early vulnerability marker of the psychosis prodrome in adolescence.

Background: The onset of psychosis is thought to be preceded by neurodevelopmental changes in the brain. However, the timing and nature of these changes have not been established. The aim of the present study was to determine whether three "classic" neurophysiological markers of schizophrenia are also characteristic of young adolescents (12-18 years) at ultra-high risk for psychosis (UHR). Methods: 63 young UHR individuals and 68 typically developing, age-, sex- and IQ-matched controls were recruited for neurophysiological assessment. Data for P50 suppression, prepulse inhibition (PPI) and smooth pursuit eye movements (SPEM) were gathered and compared. Results: UHR individuals showed reduced PPI compared to controls, which became more pronounced when controls were directly compared to medication-naive UHR individuals (N=39). There were no group differences in P50 or SPEM measures. Conclusions: These results suggest that PPI is a relatively early vulnerability marker, while changes in other neurophysiological measures may only be detected or affected later during the illness course. Antipsychotic and antidepressant medication may aid in elevating PPI levels and potentially have a neuroprotective effect. (C) 2011 Elsevier B.V. All rights reserved.