Narcissistic personality disorder (NPD) manifests as extreme self-glorification, grandiose thinking, need for admiration and lack of empathy. It begins in early adulthood and persists throughout life, according to the American Psychiatric Association. NPD is closely related to three other personality disorders that share similar features: borderline, histrionic and antisocial.
Scientists remain unclear about the precise causes of personality disorders, including narcissism. Areas of study include genetics, childhood abuse and the social environment during childhood.
Genetics
Scientists can study the genetics of personality through two different means: identical twin studies and examination of the human genome. Twin studies frequently examine identical twins who were separated at birth and raised in different households. Identical twins share identical genes, and therefore, any similarities in personality traits may be attributed to genetics. Research has suggested that identical twins raised separately share more personality traits than fraternal twins, who do not have identical genes, according to a 2004 article in the "Monitor on Psychology."
Geneticists have begun to correlate the existence of certain gene variations with personality disorders. According to a study in a 2007 issue of the "International Journal of Neuropsychopharmacology", a specific gene called tryptophan hydroxylase-2 may be implicated in the development of certain personality disorders, including narcissistic personality disorder. Tryptophan hydroxylase-2 helps regulate the production of serotonin, an important brain chemical involved in mood regulation.
Childhood Abuse
Research has suggested that childhood abuse can lead to many different forms of personality disorders, including narcissistic personality disorder. According to a 2004 article in the "Monitor on Psychology," individuals with documented experience of child abuse are four times more likely to be diagnosed with a personality disorder, including NPD, in early adulthood. Similar findings have been documented regarding a mother's verbal abuse of her children. However, researchers remain cautious because such retrospective studies cannot determine whether the abuse actually caused the personality disorder or whether the two are related in a different way.
Environment During Childhood
The environment in which a child grows up can impact the development of personality disorders. Even in the absence of full-fledged abuse, treatment by the parents or caregivers can influence the development of personality disorder through neglect, lack of affection, unpredictable caregiving and the parental demonstration and teaching of manipulative behaviors, according to the Mayo Clinic. If a child learns from his parents that vulnerability is unacceptable, he may lose his sense of empathy for other people, a classic symptom of NPD. Peer groups may also influence the development of full-fledged personality disorders like narcissism, according to a 2004 article in the "Monitor on Psychology."
References
- "Monitor on Psychology"; Where Personality Goes Awry; C. Huff; March 2004
- Mayo Clinic: Narcissistic Personality Disorder -- Basics -- Risk Factors
- "International Journal of Neuropsychopharmacology"; Tryptophan hydroxylase-2 gene variation influences personality traits and disorders related to emotional dysregulation; L. Gutknecht and colleagues; vol 10 issue 3, 2007
- "Diagnostic and Statistical Manual of Mental Disorders"; American Psychiatric Association; 2000
