Narcissistic personality disorder is characterized by extreme vanity, arrogance and self-absorpotion, according to the American Psychiatric Association. (Image credit: <a href="http://www.shutterstock.com/gallery-304216p1.html">holbox</a>, <a href="http://www.shutterstock.com/index-in.mhtml">Shutterstock</a>)
People who suffer from narcissistic personality disorder, which is characterized by extreme arrogance and self-absorption, have structural abnormalities in a region of the brain that has been linked to empathy, a new study finds.
Researchers used magnetic resonance imaging to scan the brains of 34 people, including 17 individuals who suffer from narcissistic personality disorder, and found that pathological narcissists have less gray matter in a part of the cerebral cortex called the left anterior insula. Gray matter is primarily composed of neuron cell bodies and non-neuron brain cells that provide nutrients and energy to neurons, rather than sending and receiving information.
Individuals with narcissistic personality disorder suffer from low self-esteem and feelings of inferiority, while also projecting displays of arrogance and vanity, according to the American Psychiatric Association.
One of the key traits of pathological narcissists is their clear lack of empathy, said Stefan Röpke, a professor in the department of psychiatry at the Charité - Universitätsmedizin Berlin in Germany. Generally, these patients are able to recognize what others feel and think, but outwardly exhibit little compassion. [The 10 Most Controversial Psychiatric Disorders]
The left anterior insula region of the brain, which is thought to be involved with cognitive functioning and the regulation of emotion, has also been tied to the generation of compassion and empathy.
"This was already a region of interest for empathy, but for the first time, we were able to show that it is structurally correlated in the brain," Röpke told LiveScience.
The researchers found that the degree to which a person was able to exhibit empathy was tied to the volume of gray matter in the brain, both in the group of healthy individuals and among those with narcissistic personality disorder. The finding suggests that regardless of personality disorders, the left anterior insula plays an important role in feeling and expressing compassion, Röpke said.
"These results are important because they stick very well with our theories of narcissistic personality disorder," Röpke said.
Next, the researchers intend to investigate how the volume of gray matter in the cerebral cortex affects the interplay between various regions of the brain. Röpke and his colleagues will use functional magnetic resonance imaging, which is a technique to measure brain activity based on cerebral blood flow, to study the functions of the left anterior insula, and how the brain's various networks differ in patients with narcissistic personality disorder.
"It's not just one region or brain location that is responsible for empathy," Röpke said. "We want to understand how this region works, and what happens when it doesn't function well."
The detailed results of the study were published online June 17 in the Journal of Psychiatric Research.
Follow Denise Chow on Twitter @denisechow. Follow LiveScience @livescience, Facebook & Google+. Original article on LiveScience.com.
