Brain abnormalities linked to pathological lying

Pathological liars may have structural abnormalities in their brains, a new study suggests.

Dr. Adrian Raine and Yaling Yang of the University of Southern California, Los Angeles, and colleagues found that individuals who habitually lied and cheated had less gray matter and more white matter in their prefrontal cortex than normal people. They report their findings in the British Journal of Psychiatry.

Past studies have found that the prefrontal cortex shows heightened activity when normal people lie, and it is believed to be involved in both learning moral behavior and feeling remorse.

Because gray matter consists of brain cells, while white matter forms the “wiring” or connections between these cells, pathological liars may have more capacity to lie and fewer moral restraints, the authors suggest. “They’ve got the equipment to lie, and they don’t have the disinhibition that the rest of us have in telling the big whoppers,” Raine said in a press release accompanying the study.

The researchers used a series of psychological tests and interviews in a group of volunteers to identify 12 pathological liars, 16 people with antisocial personality disorder but no history of lying, and 21 normal people. They then examined the brains of all study participants using magnetic resonance imaging.

Liars had 26 percent more white matter in their prefrontal cortex than people with antisocial personality disorder, and 22 percent more than normal people. But they had 14 percent less gray matter than normal individuals.

Interestingly, the researchers note, autistic people—who are known to have difficulty lying—show a shift in gray-to-white matter ratio opposite to that seen among liars in the current study. “Although autism is a complex condition and cannot be taken as a model for lying, these results on autistic children, combined with the prior fMRI findings on lying in normal controls, converge with current findings on adult liars suggesting that the prefrontal cortex is centrally involved in the capacity to lie,” the authors write.

Also, they note, while small children aren’t good liars, by the age of 10—by which time a burst in white matter volume has occurred—they become much more proficient in telling falsehoods.

While the findings have no practical implications at present, if confirmed they could be useful in clinical diagnoses of whether a person is pretending to be sick; in criminal justice settings, by helping police determine if a suspect is lying; and in pre-employment screening, the authors suggest.

SOURCE: British Journal of Psychiatry, October 2005.

Print Version
Tell-a-Friend