Narcissistic personality disorder is often equated with the selfie-loving, shallow, boaster that wears on your patience. However, there is significantly more to the condition. Their behavior and mood are often dependent and driven by feedback from their environment; they typically need the message from others to be a positive one. The impression they wish to make and the intense guarding of their fragile self esteem is a strong determinant of their actions and thoughts.
Some narcissists can become stricken with anger, anxiety, depression, shame and so forth if the information they receive does not match their inflated, protected, inner self. From a neuropsychological standpoint, narcissistic personality disorder reflects problems with self and emotion regulation.