[11] "Individuals with narcissistic personality disorder may be grandiose or self-loathing, extraverted or socially isolated, captains of industry or unable to maintain steady employment, model citizens or prone to antisocial activities.

[12] Grandiose, thick-skinned NPD patients show a sense of uniqueness or superiority, attitudes of entitlement, a belief that others envy their abilities or status, low empathy, social dominance, superficial charm, disdainfulness or snobbery, and an exploitative interpersonal style characterised by manipulation and selfishness.

[46] However, work on lower levels of narcissism suggests such individuals are not only aware of their traits but see them in a positive light, and strive to maintain them over time.

Only when these traits are inflexible, maladaptive, and persisting, and cause significant functional impairment or subjective distress, do they constitute narcissistic personality disorder.

[2][29] 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 relationships.

Severe symptoms of NPD can significantly impair the person's mental capabilities to develop meaningful human relationships, such as friendship, kinship, and marriage.

Generally, the symptoms of NPD also impair the person's psychological abilities to function socially, either at work or at school, or within important societal settings.

[50] NPD, as it currently conceptualised, would correspond more or less entirely to the ICD-11 trait of Dissociality, which includes self-centredness (grandiosity, attention-seeking, entitlement and egocentricity) and lack of empathy (callousness, ruthlessness, manipulativeness, interpersonal exploitativeness, and hostility).

These are as follows: Grandiose/overt: the group exhibits grandiosity, entitlement, interpersonal exploitativeness and manipulation, pursuit of power and control, lack of empathy and remorse, and marked irritability and hostility.

[59] This group was noted for high levels of comorbid antisocial and paranoid personality disorders, substance abuse, externalizing, unemployment and greater likelihood of violence.

[60] Vulnerable/covert: this variant is defined by feelings of shame, envy, resentment, and inferiority (which is occasionally "masked" by arrogance), entitlement, a belief that one is misunderstood or unappreciated, and excessive reactivity to slights or criticism.

[58][60] High-functioning/exhibitionistic: A third subtype for classifying people with NPD, initially theorized by psychiatrist Glen Gabbard, is termed high functioning or exhibitionistic.

"[56] This group has been found to have relatively few psychological issues and high rates of obsessive-compulsive personality disorder, with excessive perfectionism posited as a potential cause for their impairment.

This group was described as being grandiose, arrogant and thick-skinned, while also exhibiting personality traits of helplessness and emotional emptiness, low self-esteem and shame.

[68] Malignant narcissism, a term first coined in Erich Fromm's 1964 book The Heart of Man: Its Genius for Good and Evil,[69] is a syndrome consisting of a combination of NPD, antisocial personality disorder, and paranoid traits.

A person with malignant narcissism was described as deriving higher levels of psychological gratification from accomplishments over time, suspected to worsen the disorder.

Some examples include:[71] 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, which has undergone multiple iterations with new versions in 1984, 2006 and 2014.

[72] The Pathological Narcissism Inventory (PNI) was designed to measure fluctuations in grandiose and vulnerable narcissistic states, similar to what is ostensibly observed by some clinicians (though empirical demonstration of this phenomenon is lacking).

[72][73] The PNI scales show significant associations with parasuicidal behavior, suicide attempts, homicidal ideation, and several aspects of psychotherapy utilization.

[90] A 2021 review concluded the most consistent finding among NPD patients is lowered gray matter volume in the medial prefrontal cortex, previously associated with self-enhancement tendencies.

[90] Studies of the occurrence of narcissistic personality disorder identified structural abnormalities in the brains of people with NPD, specifically, a lesser volume of gray matter in the left, anterior insular cortex.

[92] It has been suggested that empathic dysfunction and selfish behaviour in NPD may result from dysfunction in the brain's salience network (SN; consisting of the anterior insula and cingulate cortices), which switches between internally- and externally-focused cognition, to inhibit the default mode network (DMN), involved in self-related information-processing, during social interactions resulting in continued self-focus even when interacting with distressed others.

[93] Consonantly, excessive selfishness in NPD appears to be related to decreased ability of the cingulate cortex to track motivational conflict between self-gain and other-pain.

[121] In The Psychoanalytic Theory of Neurosis (1946), Otto Fenichel said that people who, in their later lives, respond with denial to their own narcissistic injury usually undergo a similar regression to the megalomania of childhood.

[122] Narcissistic supply was a concept introduced by Otto Fenichel in 1938, to describe a type of admiration, interpersonal support, or sustenance drawn by an individual from his or her environment and essential to their self-esteem.

[123] The term is typically used in a negative sense, describing a pathological or excessive need for attention or admiration that does not take into account the feelings, opinions, or preferences of other people.

Narcissistic rage occurs on a continuum from aloofness, to expressions of mild irritation or annoyance, to serious outbursts, including violent attacks.

[129] The merging of the terms "inflated self-concept" and "actual self" is evident in later research on the grandiosity component of narcissistic personality disorder, along with incorporating the defence mechanisms of idealization and devaluation and of denial.

A contentious three-year debate unfolded in the clinical community with one of the sharpest critics being John Gunderson, who led the DSM personality disorders committee for the 4th edition of the manual.

[137][138] Clinicians critical of the DSM-5 revision characterized the new diagnostic system as an "unwieldy conglomeration of disparate models that cannot happily coexist", which is of limited usefulness in clinical practice.