Indeed, the NPI does not capture any sort of narcissism taxon as would be expected if it measured NPD.A 2020 study found that females scored significantly higher on vulnerable narcissism than males, but no gender differences were found for grandiose narcissism. Causes
Although there are no specific causes for NPD, it is described using the biopsychosocial model which describes a combination of risk factors from biological, psychological and socio-environmental factors. This includes but is not limited to genetics, neurobiology, trauma, abuse and parenting. Genetic
Evidence suggests there is a high heritability of NPD, with a number of genetic influences indicating varying rates of heritability based on subtype. A number of twin studies historically suggested for the heritability of NPD, including personality disorders in general. Environment
Environmental and social factors also influence development of NPD. In some people, pathological narcissism may develop from an impaired emotional attachment to primary caregivers (usually parents). That lack of psychological and emotional attachment to a parental figure can result in the childs perception of themselves as unimportant and unconnected to other people, usually, family, community and society.
The neurologic findings of the studies suggest that NPD may be related to a compromised (damaged) capacity for emotional empathy and emotional regulation. Management
Treatment for NPD is primarily psychotherapeutic; there is no clear evidence that psychopharmacological treatment is effective for NPD, although it can prove useful for treating comorbid disorders. Psychotherapeutic treatment falls into two general categories: psychoanalytic/psychodynamic and cognitive behavioral. Psychoanalytic therapies include schema therapy, transference focused psychotherapy, mentalization-based treatment and metacognitive psychotherapy. Cognitive behavioral therapies include cognitive behavioral therapy and dialectical behavior therapy. Formats also include group therapy and couples therapy. The specific choice of treatment varies based on individual presentations.Management of narcissistic personality disorder has not been well studied, however many treatments tailored to NPD exist. Therapy is complicated by the lack of treatment-seeking behavior in people with NPD, despite mental distress. Additionally, people with narcissistic personality disorders have decreased life satisfaction and lower qualities of life, irrespective of diagnosis. People with NPD often present with comorbid mental disorders, complicating diagnosis and treatment. NPD is rarely the primary reason for which people seek mental health treatment. When people with NPD enter treatment (psychologic or psychiatric), they often express seeking relief from a comorbid mental disorder,  including major depressive disorder, a substance use disorder (drug addiction), or bipolar disorder.