Narcissistic personality disorder (NPD) is one of 10 personality-based conditions defined by the American Psychiatric Association as mental health disorders. People with NPD have a noted lack of ability to feel compassion or empathy, combined with a noted excess of self-regard. Current research indicates that these outward signs of a narcissistic personality are reflections of actual abnormalities within the brain. For instance, according to a study published in 2013 the Journal of Psychiatric Research, NPD-affected individuals apparently have unusual thinness in the part of the brain responsible for producing empathy. They also have unusually high levels of activity in other key brain areas. Narcissistic Personality Disorder Basics The American Psychiatric Association categorizes narcissistic personality disorder with a group of conditions called Cluster B personality disorders. All of these disorders produce behaviors or thought processes that rely to a dysfunctional degree on emotional excess or drama. People affected by NPD do such things as focus their lives around self-centered pursuits, greet criticism with outsized or excessive emotional displays, manipulate others for their own purposes, redirect other people\u2019s attention toward themselves, make unsupported boasts or exaggerations, expect others to treat them as superiors or \u201cbetters,\u201d and develop heavily involved fantasies centered on unfounded notions of their own abilities or achievements. While almost anyone can display narcissistic traits in certain circumstances, people with narcissistic personality disorder have at least five narcissistic traits that appear regularly and produce a pattern of behavior that either causes them substantial personal distress or reduces their ability to function well in school-related, work-related or social situations. This pattern of behavior must occur repeatedly in a broad range of circumstances. In order to qualify for an official diagnosis, affected individuals must also have strong indications of narcissistic behavior dating back to their late teenage or early adult years. In addition, they must not have other issues that account for their behavior, including other mental health problems, drug or medication use\/abuse, or physical health concerns. Unusual Brain Thinness In the study published in the Journal of Psychiatric Research, a team of German researchers used modern brain scanning technology to examine the brain structure of 34 volunteers. Half of these volunteers had diagnosed cases of narcissistic personality disorder, while the other half did not. The part of the brain examined during the study was the cerebral cortex, the outer brain layer that regulates most of the functions that we associate with core human characteristics such as self-awareness, self-determination and self-control. One particular part of the cerebral cortex acts as the seat for empathy, the common term for the human ability to identify with others on both emotional and logical levels. After reviewing the results of their examination, the authors of the study concluded that, when compared to people unaffected by NPD, people with the disorder have unusual cerebral cortex thinness in the region responsible for empathy production. They also concluded that the degree of lost empathy in NPD patients matches up with the degree of thinness present in the abnormal cerebral cortex area. Unusual Brain Activity Levels In a study published in 2010 in the journal PLOS ONE, a team of researchers from the University of Southern California used modern brain scanning technology to examine the levels of brain activity in a group of volunteers during the performance of specific tasks, as well as during periods of rest between these tasks. All of the volunteer participants were generally healthy and had no diagnosis for narcissistic personality disorder or any other mental health condition. However, when assessed with standard psychological tests, they exhibited varying degrees of narcissistic personality traits. After reviewing the results of their brain activity scans, the authors of the study concluded that the presence of narcissistic traits is linked with an unusual level of activity during periods of rest in a part of the cerebral cortex responsible for self-directed or self-absorbed thinking. They also concluded that people who have more narcissistic traits show a greater level of activity in this brain region than people with fewer narcissistic traits. In addition, the authors of the study linked the presence of narcissism to increased activity in another part of the cerebral cortex that helps control impulsive behavior. This activity increase diminishes impulse control, and thereby increases the likelihood of poor decision-making in affected individuals.