[Brain imaging and transition to psychosis]

First episode psychosis is usually preceded by a prodromal period of about 5 years during which the manifestation of the disease is not yet clear. This prodromal phase is called 'At Risk Mental State' (ARMS) as all subjects with prodromal symptoms will not develop a psychotic disorder. Several brain imaging studies have been conducted over the past decade in these ARMS subjects and found structural, functional and neurochemical deviations. These deviations are similar to those observed when the psychosis is established but with less severity. These deviations have important translational perspective as they might help to distinguish the development of a psychotic disorder from occasional psychotic symptoms.