Dissociation of functional and anatomical brain abnormalities in unaffected siblings of schizophrenia patients

• A dissociation phenomenon suggested that brain functional and anatomical abnormalities might be present independently in unaffected siblings of schizophrenia patients.
• The recruitment of unaffected siblings offers insight into the pathophysiology of schizophrenia independently of the clinical and treatment issues that complicate studies of the patients themselves.
• Several possible factors were given to the increase of gray matter volume in the left putamen in the sibling group.

ObjectiveSchizophrenia patients and their unaffected siblings share similar brain functional and structural abnormalities. However, no study is engaged to investigate whether and how functional abnormalities are related to structural abnormalities in unaffected siblings. This study was undertaken to examine the association between functional and anatomical abnormalities in unaffected siblings.MethodsForty-six unaffected siblings of schizophrenia patients and 46 age-, sex-, and education-matched healthy controls underwent structural and resting-state functional magnetic resonance imaging scanning. Voxel-based morphometry (VBM), amplitude of low-frequency fluctuation (ALFF) and fractional ALFF (fALFF) were utilized to analyze imaging data.ResultsThe VBM analysis showed gray matter volume decreases in the fronto-temporal regions (the left middle temporal gyrus and right inferior frontal gyrus, orbital part) and increases in basal ganglia system (the left putamen). Functional abnormalities measured by ALFF and fALFF mainly involved in the fronto-limbic-sensorimotor circuit (decreased ALFF in bilateral middle frontal gyrus and the right middle cingulate gyrus, and decreased fALFF in the right inferior frontal gyrus, orbital part; and increased ALFF in the left fusiform gyrus and left lingual gyrus, and increased fALFF in bilateral calcarine cortex). No significant correlation was found between functional and anatomical abnormalities in the sibling group.ConclusionsA dissociation pattern of brain regions with functional and anatomical abnormalities is observed in unaffected siblings.SignificanceOur findings suggest that brain functional and anatomical abnormalities might be present independently in unaffected siblings of schizophrenia patients.