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Pathological Liars Are Different

Liars had significantly more prefrontal white matter than either healthy controls or nonliars with symptoms of antisocial personality disorder.

On functional MRI, people who lie, cheat, and manipulate others exhibit an increased bilateral activation of the prefrontal cortex while telling lies. To see whether liars and nonliars have structural differences in prefrontal areas, researchers performed a structural MRI study. Participants were selected from a group of 108 people identified from temporary employment agencies (age range, 21–45).

All subjects underwent extensive evaluation to corroborate lying and antisocial personality disorder (ASPD), including examination of criminal records. There were three groups: 12 pathological liars (25% with ASPD, 67% with substance-use disorders); 16 control subjects who scored high on ASPD tests but who did not meet criteria for pathological lying (25% with ASPD); and 21 normal controls. The liar group was older, on average, and had significantly higher mean verbal-to-performance IQ ratios than the two control groups.

The liar group had significantly higher white-matter volumes than the control groups (22% higher than normal controls, and 26% higher than antisocial controls) and significantly lower ratios of gray-to-white matter (42% and 36% lower, respectively). The findings remained significant after adjustment for numerous factors including whole brain volume, age, ASPD, conduct disorder, the verbal-performance IQ discrepancy, and full-scale IQ.

Comment: These findings are consistent with the previously identified functional differences between pathological liars and others, and with the expectation that manipulators would have better verbal skills. The authors note that autistic children with the reverse structural differences on MRI are poor liars. These findings on pathological deception need to be translated into nosological classifications and intervention paradigms.

— Barbara Geller, MD

Published in Journal Watch Psychiatry November 16, 2005

Citation(s):

Yang Y et al. Prefrontal white matter in pathological liars. Br J Psychiatry 2005 Oct; 187:320-5.

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