Assessment and screening
Narcissistic Personality Inventory
Risk factors for NPD and grandiose/overt and vulnerable/covert subtypes are measured using the narcissistic personality inventory, an assessment tool originally developed in 1979, has undergone multiple iterations with new versions in 1984, 2006 and 2014. The subtype is also assessed with the pathological narcissism inventory (PNI). The PNI is a screening tool for antisocial, borderline, narcissistic personality disorders. The PNI scales exhibited significant associations with parasuicidal behavior, suicide attempts, homicidal ideation, and several aspects of psychotherapy utilization. Pathological narcissism a term for concurrent grandiose and vulnerable narcissism, which is linked to poor self-esteem, lack of empathy, feelings of shame, interpersonal distress, aggression, and significant impairments in personality functioning across both clinical and non-clinical samples. Despite the phenomenological and empirical distinction between vulnerable and grandiose narcissism, some theories suggest that grandiose narcissists also have fragile personality traits. There are a number of other assessment tools for narcissism and NPD subtypes. Millon Clinical Multiaxial Inventory
The Millon Clinical Multiaxial Inventory (MCMI) is another diagnostic test developed by Theodore Millon. The MCMI includes a scale for narcissism. The NPI and MCMI have been found to be well correlated. Whereas the MCMI measures narcissistic personality disorder (NPD), the NPI measures narcissism as it occurs in the general population; the MCMI is a screening tool. In other words, the NPI measures "normal" narcissism; i.e., most people who score very high on the NPI do not have NPD.
Narcissistic personalities are more likely to respond with anger or aggressiveness when presented with rejection. Because they are sensitive to perceived criticism or defeat, people with NPD are prone to feelings of shame, humiliation, and worthlessness over minor incidents of daily life and imagined, personal slights, and usually mask such feelings from people, by feigning humility, responding with outbursts of rage and defiance, or seeking revenge.The DSM-5 indicates that: "Many highly successful individuals display personality traits that might be considered narcissistic. Only when these traits are inflexible, maladaptive, and persisting, and cause significant functional impairment or subjective distress, do they constitute narcissistic personality disorder." Given the high-function sociability associated with narcissism, some people with NPD might not view such a diagnosis as a functional impairment to their lives. Although overconfidence tends to make people with NPD very ambitious, such a mindset does not necessarily lead to professional high achievement and success, because they refuse to take risks, in order to avoid failure or the appearance of failure. Moreover, the psychological inability to tolerate disagreement, contradiction, and criticism, makes it difficult for persons with NPD to work cooperatively or to maintain long-term, professional relationships with superiors and colleagues. Differential diagnosis
The occurrence of narcissistic personality disorder presents a high rate of comorbidity with other mental disorders. People with NPD are prone to bouts of psychological depression, often to the degree that meets the clinical criteria for a co-occurring depressive disorder. NPD is associated with the occurrence of bipolar disorder and substance use disorders, especially cocaine use disorder.