ABSTRACT
In this chapter the research on developmental factors associated with personality disorders is reviewed. While earlier theories, primarily based on clinical observations, stressed the psychosocial origins of personality disorders, more recent research has suggested that genetic, biological, and environmental factors may all play important contributory roles in the development of personality disorder, with each variable on its own accounting for small to moderate outcome variance. Most research has been limited to Cluster B disorders, but even here we still do not have the final answer to the question of which factors “cause” the personality disorder. A genetically based temperament is probably a key factor in the development of most personality disorders, particularly for Clusters A and B. Such temperamental predispositions may increase the likelihood that negative life events will occur. Negative psychosocial events, in turn, may result in persisting biological alterations in the brain. Biological differences may result from interactions between individual temperamental factors and social and family processes. The findings of recent studies into gene–environment interaction suggest that purely environmental aetiological theories of personality disorders are incomplete, as are purely genetic accounts. Presumably, both pathogenic environmental influences (e.g. attachment, child maltreatment) and genetic risk factors are involved in the aetiology of personality disorders.
