Bulimia nervosa with co-morbid avoidant personality disorder: behavioural characteristics and serotonergic function
Background. Separate lines of research link lowered serotonin tone to interpersonal submissiveness and bulimia nervosa (BN). We explored the impact of co-morbid avoidant personality disorder (APD), as a proxy for submissiveness, on behavioural inhibition and serotonin function in women with BN.
Method. Participants included women with BN with co-morbid APD (BNA+, N=13); women with BN but without APD (BNA−, N=23), and control women with neither BN nor APD (N=23). The women were assessed for psychopathological tendencies and eating disorder symptoms, and participated in a computerized laboratory task that measured behavioural inhibition and disinhibition. Participants also provided blood samples for measurement of serial prolactin responses following oral administration of the partial 5-HT agonist meta-chlorophenylpiperazine (m-CPP).
Results. The BNA+ group had higher scores than the other groups on self-report measures of submissiveness, social avoidance, restricted emotional expression, affective instability and self-harming behaviours. Compared with the other groups, the BNA+ group tended to be more inhibited under cues for punishment on the computerized task and to have blunted prolactin response following m-CPP. The bulimic groups did not differ from each other on current eating symptoms or on frequencies of other mental disorders.
Conclusions. Findings indicate that women with BN and co-morbid APD may be characterized by interpersonal submissiveness and avoidance, affective instability, self-harm, behavioural inhibition in response to threat and lower sensitivity to serotonergic activation. These findings may indicate common, serotonergic factors, associated with social submissiveness, behavioural inhibition to threat and BN.(Published Online January 14 2004)
c1 Dr Kenneth Bruce, Eating Disorders Program, Douglas Hospital, 6875 LaSalle Boulevard, Montreal, Quebec, Canada H4H 1R3.