Symptom recovery and relationship to structure of corpus callosum in individuals with an ‘at risk mental state’

Previous studies have revealed that changes in sub-threshold psychotic symptoms observed in individuals with an ‘at risk mental state’ (ARMS) are associated with biological changes in the corpus callosum (CC). To elucidate the biological background for resilience against transition to psychosis, we investigated the relationship between CC structural changes and recovery of sub-threshold psychotic symptom in subjects with ARMS who did not develop psychosis (ARMS-N). Sixteen healthy controls and 42 ARMS (37 ARMS-N) subjects participated this study. The volumes of five sub-regions of the CC were analyzed using MRI. The sub-threshold psychotic symptoms of the ARMS were measured using the Scale of Prodromal Symptoms (SOPS). Imaging and symptoms were re-administered in the ARMS group 52 weeks later. Significant baseline volume differences in the mid-posterior CC, central CC and mid-anterior CC were found between the controls and the ARMS-N subjects. These findings suggest that biological abnormalities are present in a so-called “false-positive” group of individuals. For the ARMS-N subjects, improvement in negative symptoms significantly correlated with an increase in the volume of the central CC at follow-up. This finding may suggest that a neurobiological ‘resilience’ is associated with symptom recovery. •Corpus callosum (CC) has been implicated in at risk mental state (ARMS).•CC volume reduction was found in ARMS who did not develop psychosis (ARMS-N) group.•Changes in negative symptoms and the volume of CC was correlated in ARMS-N group.