Overlapping and Segregating Structural Brain Abnormalities in Twins With Schizophrenia or Bipolar Disorder

Pol HEH et al. – Brain structures reflect overlapping and segregating genetic liabilities for schizophrenia and bipolar disorder. The overlapping smaller white matter volume and common areas of thinner cortex suggest that both disorders share genetic roots.

Methods

• Magnetic resonance imaging findings of monozygotic (MZ) and dizygotic (DZ) twin pairs discordant for schizophrenia, twin pairs concordant and discordant for BD, and healthy twin pairs were compared using structural equation modeling.
• The Netherlands Twin Register and University Medical Center Utrecht.
• A total of 310 individuals from 158 (152 complete and 6 incomplete) twin pairs were included: 26 pairs discordant for schizophrenia (13 MZ and 13 DZ), 49 pairs with BD (9 MZ and 4 DZ concordant; 14 MZ and 22 DZ discordant), and 83 healthy twin pairs (44 MZ and 39 DZ).

Results

• Higher genetic liabilities for schizophrenia and BD were associated with smaller white matter volume, thinner right (and left) parahippocampus, thinner right orbitofrontal cortex, and thicker temporoparietal and left superior motor cortices; higher environmental liabilities were associated with thinner right medial occipital cortex.
• Genetic liability for schizophrenia was associated with thicker right parietal cortex; for BD, with larger intracranial volume.

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