Genetic risk for schizophrenia linked to brain volume alterations

By Mark Cowen

Patients with schizophrenia and their unaffected first-degree relatives show altered gray and white matter volumes in specific brain regions compared with mentally healthy individuals, researchers report.

The observed volumetric alterations were greater in schizophrenia patients than in their first-degree relatives.

"These results suggest that brain morphological changes associated with schizophrenia are in part determined by genetic risk factors and are not entirely explained by effects of medication or changes secondary to illness," say Viola Oertel-Knöchel (Johann Wolfgang Goethe-University, Germany) and colleagues.

The researchers used magnetic resonance imaging and voxel-based morphometry to compare regional gray and white matter volumes in 31 schizophrenia patients, 29 of their first-degree relatives, and 38 age-, gender-, verbal intelligence-, and education-matched mentally healthy controls.

They found schizophrenia patients and their first-degree relatives had increased gray matter volume in the striatum, globus pallidus internus, and thalamus compared with controls.

By contrast, schizophrenia patients and their first-degree relatives had decreased gray matter volume in the parahippocampal and cingulate gyri.

They also found that schizophrenia patients had reduced gray and white volume in temporal, frontal, and limbic areas compared with relatives and controls.

First-degree relatives showed intermediate volumetric values in many of these brain regions, the researchers note.

"Our results provide support for the hypothesis that non-psychotic first-degree relatives of patients with schizophrenia show structural brain abnormalities that are similar but less pronounced than those seen in patients with schizophrenia," conclude Oertel-Knöchel and team.

They add: "Increased volumes of basal ganglia structures in the schizophrenia spectrum may reflect heightened striatal dopaminergic tone and lead to the thalamic hyperstimulation… whereas the loss of cortical volume and connecting fibres may result in reduced ability for cognitive coordination and top-down control of sensory processes."

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