Dimensional models of BPD

Selasa, 12 Januari 2010

Alternative to categorical descriptions of BPD are approaches that assume that PD is an amplification of normal personality traits (Paris 1998b). The best established is Cloninger et al.’s eight-factor model incorporated in the Temperament and Character Inventory (Cloninger et al. 1993). The dimensions suggested are: (1) novelty seeking, (2) harm avoidance, (3) reward dependence, (4) persistence, (5) self-directedness (autonomy), (6) co-operativeness, (7) compassion, and (8) self-transcendence (identity). More recently, Shedler and Westen proposed a clinician-oriented dimensional assessment procedure that asks the clinician to sort 200 personality characteristics into stacks of increasing applicability to an individual patient (Westen 1998; Westen and Shedler 1999a,b; Shedler 2002). The sort yields similarity scores to prototypes (profiles of characteristics) well-recognized by clinicians: (1) psychological health, (2) psychopathy, (3) hostility, (4) narcissism, (5) emotional dysregulation, (6) dysphoria, (7) schizoid orientation, (8) obsessionality, (9) thought disorder, (10) oedipal conflict, (11) dissociated, and (12) sexual conflict.

A range of studies reported BPD to be associated with temperament characterized by a high degree of neuroticism (i.e. emotional pain) and a low degree of agreeableness (i.e. strong individuality) (Clarkin et al. 1993a; Soldz et al. 1993; Trull 1993; Zweig-Frank and Paris 1995). BPD has also been shown to be associated with a high degree of harm avoidance (i.e. compulsivity) and novelty-seeking (i.e. impulsivity) (Svrakic et al. 1993). For BPD the key dimensions are likely to involve impulsive aggression and affective instability.

In a factor analysis of 18 personality traits assessed in the general population (n = 939), in patients with PD (n = 656), and in twins (n = 686 pairs) a four-factor solution was found (Livesley et al. 1992). The four factors were emotional dysregulation, dissocial behaviour, inhibitedness, and compulsivity.

There seems to be a general consensus that impulsivity and negative affectivity/ emotional dysregulation characterize BPD and possibly mediate the influence of psychosocial factors on BPD (Gurvits et al. 2000; Paris 2000; Silk 2000; Trull et al. 2000). It is the combination of impulsivity and negative affectivity that appears uniquely characteristic of BPD. Negative affectivity can be found in
Narcissistic personality disorder (NPD) while impulsivity is evidently marked in
ASPD.

Naturally, personality traits like affective instability or impulsive aggression are not unrelated to the putative intrapsychic disturbances such as identity disturbance or defense mechanisms such as passive aggression. In one study of 140 PD patients, degree of affective instability was found to be correlated with identity disturbance, chronic emptiness and boredom, defensive splitting, projection, acting out, and somatization (Koenigsberg et al. 2001). This kind of association is to be expected given that the phenomena upon which these apparently alternative modes of observation are made are the same.

However, the question of causality is moot. While dimensions such as affective instability and impulsiveness are known to be in part biologically-determined, the association with intrapsychic defenses may not be accounted for by the biological components of these traits. Nevertheless, the associations of trait and psychodynamic descriptions of BPD indicate the desirability of a multimodal approach to the aetiology of BPD.