An international team of researchers investigated whether brain anatomy plays a role in the emergence and/or expression of personality traits. This was the first research effort ever to study this hypothetical relationship, and scientists have found notable associations that could provide valuable clues about behavior and the risks of developing mental disorders. To some extent, personality may be related to the anatomy of the brain.
In this study, researchers used a prevalent theoretical personality construct in academic psychology – the Big Five: Neuroticism, Extraversion, Openness to Experience, Agreeableness and Conscientiousness. Brain imaging of 500 people between the ages of 22 and 36 were scrutinized to examine differences in the cortex. Focusing on metrics like thickness, area and folding, some interesting observations were made. Neuroticism and conscientiousness were correlated with thicker prefrontal cortex regions over smaller and less folded areas. Conversely, the brains of people who were more open to new experiences displayed thinner cortices over larger and more folded parietal areas. The most agreeable also had thinner cortices in addition to smaller fusiform gyrus areas.
Co-author Antonio Terracciano noted that the findings fit into what has been documented about brain development as people get older: cortex areas grow larger and thinner while neuroticism goes down.
Researchers also hypothesize that the findings may fit into a postulate that they refer to as ‘cortical stretching hypothesis’ – the theory that the gradual increase in cortex area and folding at the expense of thickness has been a defining characteristic of human brain evolution.
The authors cautioned, though, that this study — published in the journal Social Cognitive and Affective Neuroscience — did not conclusively show a causal relationship between brain shape and personality types. In other words, the study could not determine whether the anatomical particularities of the brain cause personality differences or vice versa.
It is believed that the anatomy of the brain is largely determined by the interplay between genetics and environmental factors. But the degree to which this is distributed, and/or whether one aspect is a more determining factor than the other, remains a topic of heated debate.
Nevertheless, this study was the first to relate the five-factor model of personality to brain anatomy. Researchers highlighted that their findings could help understand why people with particular personality profiles are at greater risk of developing certain mental disorders. Neuroticism, for example, predisposes people to anxiety and depression disorders. By proactively screening patients in clinical settings, doctors and mental health institutions could also envisage new ways to curb the psychological impact of life-threatening or limiting diseases/injuries in patients.