Structural brain correlates of externalizing traits and symptoms in the IMAGEN sample

Area of Science:

• Neuroscience
• Psychiatry
• Genetics

Background:

• Evidence for brain structure correlates of the externalizing spectrum (EXT) is limited and inconsistent.
• Previous large-sample studies focused narrowly on either personality traits or disorders, yielding null to small effects.
• Investigating integrated personality-psychopathology EXT factors is crucial for understanding its neurobiological underpinnings.

Purpose of the Study:

• To examine the structural brain correlates of the externalizing spectrum (EXT) by integrating personality and psychopathology constructs.
• To explore these relationships across different levels of morphometric specificity, from global measures to regional brain volumes.
• To identify potential neurobiological markers associated with the multifaceted nature of the externalizing spectrum.

Main Methods:

• Utilized data from the IMAGEN study (N = 1,370) including structural magnetic resonance imaging metrics.
• Employed exploratory factor analysis to define integrated EXT factors encompassing personality and psychopathology.
• Assessed brain morphometry using omnibus measures, subcortical volumes, and Desikan atlas regions (161 metrics).

Main Results:

• The majority of investigated brain-EXT relations were null, with all effect sizes being very small (largest marginal R² < .02).
• Preregistered supplementary analyses revealed that significant findings were driven by total intracranial volume and participant sex.
• These significant associations became non-significant after controlling for covariates like total intracranial volume and sex.

Conclusions:

• Findings align with previous large-sample studies, indicating minimal structural brain associations with the externalizing spectrum.
• Emphasizes the critical role of relevant covariates (e.g., total intracranial volume, sex) in clinical neuroscientific research.
• Highlights the necessity of large sample sizes for robust and reliable investigations into brain-behavior relationships.