First-episode schizophrenia patients show frontal white matter deficits

By Mark Cowen

Results from a Brazilian study suggest that patients with a first episode of schizophrenia or schizophreniform disorder show significant white matter deficits in the middle frontal gyrus region of the brain.

"Our results… reinforce the notion that abnormalities of the frontal portion of the superior longitudinal fasciculus are already present at an early course of the illness," comment Marcus Vinicius Zanetti (University of São Paulo) and team.

The findings come from a study of 122 individuals, aged 18-50 years, with a first episode of psychosis (FEP) and 94 age- and gender-matched mentally healthy controls. Of the FEP patients, 62 had schizophrenia or schizophreniform disorder, 26 had psychotic bipolar I disorder, 20 had psychotic major depressive disorder, and 14 had "other" types of psychosis.

All of the participants underwent magnetic resonance imaging of the brain, and voxel-based morphometry was used to compare white matter volumes among the groups.

Initial analysis revealed no significant differences between FEP patients and controls or between FEP subgroups regarding white matter volume.

However, after excluding participants with comorbid substance abuse or dependence, the team found that patients with schizophrenia or schizophreniform disorder (n=40) had significant deficits in middle frontal gyral white matter volume compared with controls (n=89).

This region, also known as the third subcomponent of the superior longitudinal fasciculus, "provides the ventral premotor region and pars opercularis with higher-order somatosensory input and may be engaged in phonemic and articulatory aspects of language," notes the team.

No significant white matter differences were observed in other group or subgroup comparisons after exclusion of participants with substance use disorders.

Zanetti and team conclude in Psychiatry Research: Neuroimaging: "The FEP schizophrenia/schizophreniform disorder subgroup exhibited a focus of volume reduction in the middle frontal gyrus white matter."

They add that "replication of the present findings by studies recruiting larger samples, preferably free of substance use disorders, is warranted."

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