Thalamic shape abnormalities in individuals with schizophrenia and their nonpsychotic siblings.

Deficits in the volume of the thalamus have been observed in both individuals with schizophrenia and their nonpsychotic relatives. However, no studies to date have examined the underlying pattern of thalamic shape change in relatives of individuals with schizophrenia. This study examined the volume and shape of the thalamus in schizophrenia subjects, their siblings, and healthy control individuals. T1-weighted magnetic resonance scans were collected in a group of young subjects with schizophrenia (mean age, 23 years) and their nonpsychotic siblings (n = 25 pairs), and control subjects and their siblings (n = 40 pairs). Thalamic surfaces were generated using high-dimensional brain mapping. A canonical weighting function was derived from the contrast between schizophrenia and control subjects and then used to generate a canonical shape score for all subjects. Maps of the estimated surface displacement between groups were also created to visualize the thalamic shape differences between groups. The thalamic canonical scores of the siblings of the schizophrenia probands were intermediate between the probands and healthy control subjects. These siblings also displayed an intermediate degree of the inward surface deformation of the anterior and posterior thalamus that was present between schizophrenia probands and controls. There was no main effect of group status on thalamic volume and no significant correlations of the structural measures with measures of psychopathology or cognitive function. Our results indicate that thalamic shape abnormalities are present in relatively young individuals with schizophrenia and their siblings. Inward deformation of the anterior and posterior regions of the thalamus represents a potential neuroanatomical endophenotype of schizophrenia.