Abstract
The neural correlates of human personality have been of longstanding interest; however, most studies in the field have relied on modest sample sizes and few replicable results have been reported to date. We investigated relationships between personality and brain gray matter in a sample of generally healthy, older (mean age 73 years) adults from Scotland drawn from the Lothian Birth Cohort 1936. Participants (N = 578) completed a brain MRI scan and self-reported Big Five personality trait measures. Conscientiousness trait scores were positively related to brain cortical thickness in a range of regions, including bilateral parahippocampal gyrus, bilateral fusiform gyrus, left cingulate gyrus, right medial orbitofrontal cortex, and left dorsomedial prefrontal cortex. These associations – most notably in frontal regions – were modestly-to-moderately attenuated by the inclusion of biomarker variables assessing allostatic load and smoking status. None of the other personality traits showed robust associations with brain cortical thickness, nor did we observe any personality trait associations with cortical surface area and gray matter volume. These findings indicate that brain cortical thickness is associated with conscientiousness, perhaps partly accounted for by allostatic load and smoking status.
Highlights
Longstanding interest has been directed towards the neural correlates of human personality trait differences (Eysenck, 1967; Gray and McNaughton, 2000; Zuckerman, 2005)
The most prominent of these associations were noted with bilateral parahippocampal gyrus, bilateral fusiform gyrus, left dorsal cingulate gyrus, right ventral anterior cingulate, right medial orbitofrontal cortex, and left dorsomedial prefrontal cortex
We observed no evidence for associations between cortical surface area and gray matter for any of the personality traits
Summary
Longstanding interest has been directed towards the neural correlates of human personality trait differences (Eysenck, 1967; Gray and McNaughton, 2000; Zuckerman, 2005). Nostro et al (2017), using a large sample (N 1⁄4 364: 182 males), reported no neuroanatomical associations with personality when the sexes were aggregated; a range of gray matter associations were noted for a males-only sub-set With these observations in mind we sought to examine the relationship between cortical thickness, cortical surface area, and gray matter volume and personality using a relatively large sample (N 1⁄4 578) of generally healthy, older adults who completed an MRI session and a selfreport Big Five personality measure. These data allowed us to test for neuroanatomical associations with the Big Five traits and the two metatraits (stability and plasticity). Our analyses were exploratory in nature (see Statistical analyses for more details)
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