Summarize this article in one sentence.
Narcissistic personality disorder affects approximately 6% of the population. Anyone can be affected, but symptoms of the disorder are more common in certain individuals.  Males are more likely to have narcissistic personality disorder than females. Because the symptoms of personality disorders tend to decrease as a person ages, narcissistic personality disorder is typically more noticeable in younger people. If you suspect that you might have a personality disorder, it's a good idea to see your doctor for a complete physical exam. This can help rule out the possibility of any physical illnesses that may be contributing to your symptoms. Your doctor will probably want to do blood tests as well. In order to confirm a diagnosis of narcissistic personality disorder, the individual must be seen by a mental health professional, such as a psychiatrist or psychologist. A general practitioner can refer you to a mental health specialist, but will not be able to make the diagnosis.  The diagnosis process will involve a complete psychological evaluation. Questionnaires are sometimes used to understand the person's state-of-mind.  As with many mental health disorders, there is no laboratory test that can be used to diagnose narcissistic personality disorder. A trained mental health professional must analyze the person's symptoms and history in order to make a diagnosis. Once a person has been officially diagnosed with narcissistic personality disorder, they can receive treatment. Most often, this is psychotherapy, which helps to teach the person how to interact with people in a healthy way and how to manage their expectations.  Treatment for narcissistic personality disorder is a lengthy process. The person may require years of therapy. In some cases, medications may also be prescribed to help the person combat symptoms such as anxiety or depression.

Summary:
Understand who is affected. Get a physical examination. See a mental health professional. Get treatment.