Psychiatrists at University of Montreal and Sainte-Justine University Hospital Research Center have identified an early brain marker of vulnerability for psychosis. The research team followed more than a thousand European teenagers from age 14 to 16 who were part of the IMAGEN (Imaging Genetics for Mental Disorders) cohort. They measured the teens’ brain activity during completion of various cognitive tasks to evaluate reward sensitivity, inhibitory control and the processing of emotional and non-emotional content. Moreover, the teenagers completed self-reported questionnaires on various psychiatric symptoms at ages 14 and 16. The team first selected a group of youth at 14 years of age who were already reporting occasional psychotic-like experiences and showed that they responded to non-emotional stimuli as though they had strong emotional salience. Then, using a machine learning approach, the researchers tested whether these functional brain characteristics predicted emergence of future psychotic symptoms in a larger group of adolescents at 16 years of age. At the age of 16, 6% of the youths reported having had auditory or visual hallucinations and delusional ideas, and these experiences were significantly predicted by psychotic-like tendencies and brain reactivity to neutral stimuli at 14 years of age, and cannabis use prior to 16 years of age.