Political Orientations Are Correlated with Brain Structure in Young Adults

Substantial differences exist in the cognitive styles of
liberals and conservatives on psychological measures [1].
Variability in political attitudes reflects genetic influences
and their interaction with environmental factors [2, 3].
Recent work has shown a correlation between liberalism
and conflict-related activity measured by event-related
potentials originating in the anterior cingulate cortex [4].
Here we show that this functional correlate of political atti-
tudes has a counterpart in brain structure. In a large sample
of young adults, we related self-reported political attitudes
to gray matter volume using structural MRI. We found that
greater liberalism was associated with increased gray matter
volume in the anterior cingulate cortex, whereas greater
conservatism was associated with increased volume of the
right amygdala. These results were replicated in an indepen-
dent sample of additional participants. Our findings extend
previous observations that political attitudes reflect differ-
ences in self-regulatory conflict monitoring [4] and recogni-
tion of emotional faces [5] by showing that such attitudes are
reflected in human brain structure. Although our data do not
determine whether these regions play a causal role in the
formation of political attitudes, they converge with previous
work [4, 6] to suggest a possible link between brain structure
and psychological mechanisms that mediate political
attitudes.