S159. SUBCORTICAL GRAY MATTER VOLUME IS ASSOCIATED WITH SCHIZOPHRENIA AND WITH BOTH ITS FAMILIAL AND CLINICAL RISK

BACKGROUND: Patients with schizophrenia (SCZ) show lower volumetric estimates of gray matter (GM) than healthy controls (HC). Similar results have been reported in healthy siblings of patients (SIB). However, it is unclear whether this phenotype is also present in individuals at clinical high-risk (CHR), characterized by sub-threshold symptoms and loss of functioning. We hypothesized that GM volumetric differences are associated with both familial and clinical risk for schizophrenia METHODS: We processed the T1-weighted MRI scans acquired at 3 Tesla of 544 HC, 63 SIB, 20 CHR and 120 SCZ using CAT12. We used ANCOVA to assess group differences (HC vs. CHR vs. SIB vs. SCZ), with linear and quadratic age, gender and total intracranial volume as nuisance covariates. We assessed the reproducibility of our case/control findings in an independent sample of 127 HC and 36 SCZ. Group differences were tested post hoc through Fisher’s test. RESULTS: We found significant group effects in the bilateral thalamus, bilateral hippocampus and anterior cingulate (FWE<0.05). Specifically, SCZ presented the lowest GM volume in these regions compared to the other three groups, with SIB and CHR’s GM estimates intermediate between HC and SCZ (p<0.05). The associations with schizophrenia were replicated in the independent validation sample. DISCUSSION: Individuals with familial or clinical risk for schizophrenia have lower GM estimates in the same brain regions. These findings, suggest that these structural features are not only associated with familial risk for schizophrenia but that they are also associated with its sub-threshold symptoms.