Externalizing psychopathology has been linked to prefrontal
abnormalities. While clinically diagnosed subjects show altered frontal gray
matter, it is unknown if similar deficits relate to externalizing traits in
non-clinical populations. We used voxel-based morphometry (VBM) to
retrospectively analyze the cerebral gray matter volume of 176 young adult
social to heavy drinkers (mean age= 24.0 ± 2.9, male= 83.5%)
from studies of alcoholism risk. We hypothesized that prefrontal gray matter
volume and externalizing traits would be correlated. Externalizing personality
trait components— Boredom Susceptibility-Impulsivity (BS/IMP) and
Empathy/Low Antisocial Behaviors (EMP/LASB)— were tested for
correlations with gray matter partial volume estimates (gmPVE). Significantly
large clusters (pFWE < 0.05, family-wise
whole-brain corrected) of gmPVE correlated with EMP/LASB in dorsolateral and
medial prefrontal regions, and in occipital cortex. BS/IMP did not correlate
with gmPVE, but one scale of impulsivity (Eysenck I7) correlated
positively with bilateral inferior frontal/orbitofrontal, and anterior insula
gmPVE. In this large sample of community-dwelling young adults, antisocial
behavior/low empathy corresponded with reduced prefrontal and occipital gray
matter, while impulsivity correlated with increased inferior frontal and
anterior insula cortical volume. These findings add to a literature indicating
that externalizing personality features involve altered frontal
architecture.