Inferring pathobiology from structural MRI in schizophrenia and bipolar disorder: Modeling head motion and...

Area of Science:

• Neuroimaging
• Psychiatric Disorders
• Brain Anatomy

Background:

• Over 400 studies document neuroanatomic abnormalities in bipolar disorder and schizophrenia using structural MRI.
• Confounding effects of head motion and regional specificity of brain defects remain unclear.

Purpose of the Study:

• To investigate neuroanatomic differences in bipolar disorder and schizophrenia, considering head motion and regional specificity.
• To clarify the impact of head motion on structural MRI findings in these illnesses.

Main Methods:

• Utilized a large cohort of individuals (schizophrenia n=226, bipolar disorder n=227, healthy controls n=370) scanned with research-dedicated MRI.
• Assessed cortical thickness and surface area, controlling for head motion estimated from time-series data.
• Performed vertex-level analyses, covarying global indices to assess regional specificity.

Main Results:

• Both schizophrenia and bipolar disorder exhibited reduced cortical thickness, more pronounced in schizophrenia.
• Schizophrenia showed widespread surface area reductions; bipolar disorder did not differ from controls.
• Head motion influenced surface area and cortical thickness measurements, affecting some, but not all, between-group differences.
• Covarying global indices rendered between-group effects nonsignificant in vertex-level analyses.

Conclusions:

• Findings raise doubts about the regional specificity of current structural brain imaging findings in affective and psychotic disorders.
• Observed differences in cortical thickness and surface area changes suggest potential biological specificity between bipolar disorder and schizophrenia.
• Further research is needed to elucidate the precise nature and specificity of structural brain alterations in these conditions.