Behavioral adjustment moderates the effect of neuroticism on brain volume relative to intracranial volume.

OBJECTIVE: The present study examined whether the effect of neuroticism on brain structure is moderated by behavioral adjustment. BACKGROUND: Neuroticism is widely thought to be harmful to health. However, recent work using proinflammatory biomarkers showed that this effect depends on behavioral adjustment, the willingness and ability to adjust and cope with environmental contingencies, such as different opinions of others or unpredictable life situations. Here, we sought to extend this observation to "brain health" by testing total brain volume (TBV). METHOD: Using a community sample of 125 Americans, we examined structural magnetic resonance imaging of the brain and quantified TBV. We tested whether the effect of neuroticism on TBV was moderated by behavioral adjustment, net of intracranial volume, age, sex, educational achievement, and race. RESULTS: Behavioral adjustment significantly moderated the effect of neuroticism on TBV, such that neuroticism was associated with lower TBV only when behavioral adjustment was low. There was no such effect when behavioral adjustment was high. CONCLUSION: The present findings suggest that neuroticism is not debilitating to those who constructively cope with stress. Implications are further discussed.