Abstract
Background: Axis I and II disorders are not independent. Understanding the relationship between these groups of disorders requires further exploration. This thesis will explore whether personality disorders, assessed by clinical interview using DSM criteria, or personality traits, assessed by the self-report Temperament and Character Inventory (TCI), impact on the presentation of bulimia nervosa (BN) and binge eating disorder (BED) and on outcome of BN. Examining personality comorbidity in BN and BED using both categorical and dimensional models may help to clarify relationships between personality functioning and these eating disorders. Identifying personality predictors of outcome may have implications for treatments of these eating disorders.
Objectives: 1. To determine the impact of personality functioning on clinical characteristics at pre-treatment and long-term outcome in women with BN
2. To determine the impact of personality functioning on clinical characteristics in women with BED at pre-treatment
3. To compare personality profiles between women with BN and BED at pre-treatment, in comparison to psychiatric control and healthy control groups
Methods: Participants for this study were drawn from two randomised controlled trials: the Bulimia Treatment Study (BTS) and the Binge Eating Psychotherapy study (BEP). In the BTS study (n=134), separate analyses were used to examine the specific impact of borderline, avoidant and complex personality disorders on clinical characteristics, global functioning and outcome on women with BN. Personality traits and symptoms were examined to determine the ability of these measures to predict long-term outcome of BN.
In the Binge Eating Psychotherapy (BEP) study, 38 women with BN and 41 women with BED participated at pre-treatment. To establish the specificity and the significance of any findings regarding personality profiles, two comparison samples of 39 women with depression and 44 healthy control women were used. The impact of personality disorders on clinical characteristics, general psychiatric functioning and global functioning were compared between BN and BED groups.
Results: The presence of borderline, avoidant or complex personality disorders had a negative impact on depression severity and global functioning in women with BN however the presence of a personality disorder did not impact on long-term BN outcome. The only personality variable to predict outcome at five-years was self-directedness.
Women with BN and BED had similar personality profiles to depressive controls but were distinguishable from healthy controls. Personality disorders were associated with increased binge eating in the BED group but not the BN group. Self-directedness and cooperativeness were significantly lower in the BED group than the BN group.
Conclusions: Although personality disorders are associated with a more severe clinical picture at pre-treatment, they have little predictive validity as they do not influence eating disorder outcome and broader outcomes. Specific dimensional measures of personality had more predictive validity, however the most important of these was self-directedness. Self-directedness may be capturing the essence of personality dysfunction and it appears to be as important in eating disorders as it is in other Axis I disorders. Developing interventions to increase this characteristic may enhance treatment for these eating disorders.