A person who is excessively high in narcissism is said to have a narcissistic personality disorder (NPD), which is a diagnosable mental illness. A person with narcissistic traits may be mildly self-centered at times, but NPD, on the other hand, is a deeply ingrained, pervasive pattern. In this episode, I will attempt to explain the difference as the term narcissism is constantly (over-)used to describe people's behavior.