October 17, 2005

Brain abnormalities linked to pathological lying

NEW YORK (Reuters Health) - 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

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

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

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

SOURCE: British Journal of Psychiatry, October 2005.