Brain structure in schizophrenia: what do we know and what next?

Area of Science:

• Neuroimaging
• Psychiatry
• Neuroscience

Background:

• Extensive meta-analyses of structural MRI and diffusion MRI studies involving thousands of individuals with schizophrenia reveal significant reductions in brain volumes and structural connectivity compared to healthy controls.
• Evidence suggests that some of these observed structural brain differences may be present prior to the onset of schizophrenia symptoms (pre-morbidly).

Purpose of the Study:

• To synthesize findings from large-scale neuroimaging studies on schizophrenia.
• To investigate the relationship between structural brain changes, symptom severity, and cognitive impairment.
• To explore the temporal dynamics of brain volume changes in the schizophrenia spectrum.

Main Methods:

• Meta-analyses and mega-analyses of structural magnetic resonance imaging (MRI) and diffusion MRI data.
• Correlational analyses examining the relationship between brain structure, symptom severity, and cognitive function.
• Integration of findings with post-mortem studies to elucidate underlying pathophysiology.

Main Results:

• Consistent correlations observed between the severity of schizophrenia symptoms and the degree of cognitive impairment.
• Convergent evidence across different analytical methods confirms the non-artefactual nature of the observed structural differences.
• Post-mortem studies support a pathophysiology characterized by reduced neuronal size and dendritic arborization, suggesting a multifactorial basis.

Conclusions:

• Structural MRI changes in schizophrenia likely emerge between the at-risk state and the first psychotic episode, with ongoing reductions potentially linked to poorer outcomes.
• While some findings are highly suggestive, many require further investigation with adequately powered studies and standardized methodologies.
• Future progress necessitates clear hypotheses, robust study designs, and standardized reporting to advance scientific understanding and clinical applications.