OVERVIEW OF BIOLOGIC FACTORS

What is currently known about the biology of personality disorders seems to be remarkable given the fact that a mere 10 to 15 years ago, most explorations into the cause of personality disorders were relegated to the area of psychologic theories. Those theoretic propositions were almost uniformly based on considering the impact childhood experiences had on the developing individual and the reaction of the interpersonal and familial environment to those experiences (including parental action, reaction, and behavior). 12 Thus, while it was believed that the Axis I disorders would eventually be found to have significant etiologic roots in biologic predispositions and mechanisms, for example, nature, personality disorders were viewed as resulting primarily as a response to external events and the interpersonal behaviors and reactions related to those events, for example, "nurture." Trying to understand the cause of personality disorders through a better appreciation of the developmental and familial milieu and environment in which the individual was raised made sense. This is because many believed that the disorders relegated to the Axis II Personality Disorders category had been placed there because there was no real biologic theory that could explain its origins. There were many who believed that personality disorders, especially when they were not too severe, were clearly disorders that could be modified and ameliorated (though certainly not cured), through psychodynamic and psychoanalytically oriented therapies. 4 In addition, some remain of the opinion that a separate axis for personality disorders was created as a way for the analytic community to agree on DSM-III. The Third Edition of the DSM 3 was allegedly an atheoretical document whereas the versions preceding it still gave homage to the great psychodynamic and psychoanalytic movements in psychiatry in the United States. Thus, Axis II belonged to the nonbiologic, dynamic segment of psychiatry. Furthermore, the amount of biologic research conducted and found to be positive in the arena of personality disorders was meager when compared with what had been uncovered with respect to the purported biologic underpinnings of the Axis I disorders, especially in areas of anxiety, depression, and schizophrenia. Currently clinicians stand on what might be considered an explosion in biologic research and theory in the area of personality disorders. 59 Currently, the amount and degree of information available with respect to results, not methodology, remains pale when compared with what has been uncovered for the Axis I disorders. Nonetheless, the idea that personality disorders, their cause, and treatment belong only within the realm of the psychodynamic or nonbiologic therapist seems to be fading fast. Papers published in the late 1980s and early 1990s proposed biologic theories for explaining some of the underlying pathologic processes found in personality disorders. 10,51 Empiric research has been found to support at least some of those biologic theories. It has certainly made credible the position that like many other psychiatric diseases, biology, constitutional predispositions, and perhaps even electrophysiologic kindling mechanisms 66 (similar to those proposed by Post et al 46 with regard to mood disorders), play as powerful a role in the development or maintenance of the Axis II disorders as they do with the Axis I disorders. 55,59 Fifteen years ago there began to emerge several biologic studies and biologic theories with respect to the personality disorders. These biologic studies and biologic theories came after a series of empiric studies that tried to compare or contrast a specific personality disorder with a near-neighbor Axis I disorder. 56 For example, the argument was made that many personality disorders, especially borderline personality disorder (BPD), are atypical manifestations of Axis I disorders such as Cyclothymic Disorder or Bipolar II Disorder. Similar arguments might be made with respect to schizotypal personality disorder (SPD) and schizophrenia, avoidant personality disorder and social phobia, histrionic personality disorder and somatization disorder, paranoid personality disorder, and delusional disorder or schizophrenia, paranoid type. These initial, first generation studies sought to understand how biologic processes in specific personality disorders were similar or dissimilar to biologic processes in what was thought to be the near-neighbor Axis I disorders. Thus, many of the early biologic studies into BPD sought to appreciate better whether biologic indices such as the Dexamethasone Suppression Test (DST) or time of onset of REM sleep distinguished these patients from patients with mood disorders, primarily major depressive disorder. 2,5,7,9,33,49 The results of these studies, while interesting, did not lead to clear conclusions with respect to whether the personality disorder was some atypical form of an Axis I disorder or with respect to what might be the underlying disturbed biologic mechanisms in a specific personality disorder. 56 Biologic researchers and theoreticians then turned their attention in a slightly different direction to pursue an understanding of some of the biologic mechanisms that might underlie dimensions of personality disorder psychopathology. These second generation biologic studies sought to appreciate better what might be the biologic underpinnings of dimensions of psychopathology frequently found to be disrupted in patients with personality disorders. These dimensions of psychopathology can be disturbed in different degrees of severity across most, if not all, of the personality disorders. Thus, studying these dimensions across many personality disorders differed conceptually and methodologically from studying what specific biologic mechanism might be the underlying disturbance in which specific personality disorder. Led by the theoretic proposals of Cloninger et al 10,11 and Siever and Davis, 51 researchers set out to look at what might be the underlying biologic disturbances in cognition, impulsivity and aggression, affective lability, and chronic anxiety among patients with personality disorders. This differing approach to trying to understand the biology of personality disorders has had a promising yield, and such yield is reviewed in other articles in this issue, particularly those by Gurvits et al and Oquendo and Mann. The purpose of this article is not to review, reiterate or compile in some comprehensive way, those previous studies. Rather, the aim is to examine and present for further discussion where these recent forays into the biology of personality disorders may lead, where there might be other, perhaps more fruitful avenues of biologic research into the personality disorders, how these biologic findings or avenues of biologic research can be predicted to come together, and how they might inform some of the older psychosocial and psychodynamic theories. A mutually supportive interplay between predispositions given by way of biologic mechanisms and experiences conveyed through environmental and interpersonal interactions may ultimately be discovered.