Schizophrenia and the frontal brain: a quantitative review

Area of Science:

• Neuroscience
• Psychiatry
• Medical Imaging

Background:

• Schizophrenia is often associated with frontal brain system dysfunction.
• Previous research has yielded mixed results regarding frontal lobe abnormalities in schizophrenia.

Purpose of the Study:

• To quantitatively review structural and physiological frontal brain system deficits in schizophrenia patients.
• To assess the magnitude of differences between patients and controls using neuroimaging data.

Main Methods:

• Systematic review of structural (CT, MRI) and functional (PET) neuroimaging studies published since 1980.
• Calculation and analysis of effect sizes for frontal brain measures.

Main Results:

• Significant heterogeneity observed; most patients exhibit normative frontal function and structure.
• Average effect sizes for frontal brain volume and resting metabolism/blood flow are modest (e.g., M = -.36, M = -.64).
• Patient and control distributions overlap considerably (60-88%) on most frontal brain measures, decreasing to <50% only during activation tasks.

Conclusions:

• Current neuroimaging resolution makes it difficult to support single disease models proposing major frontal system involvement in schizophrenia.
• Frontal brain dysfunction is not a consistently necessary component across all schizophrenia patients.
• Findings highlight the complexity and heterogeneity of brain alterations in schizophrenia.