Impulsivity in disordered eating, affective disorder and substance use disorder

Background. Failure to control impulsive behaviour has been postulated as an underlying mechanism common to substance use disorder, sociopathy and to a substantial subgroup of women with bulimia nervosa. Method. Three hundred and one women recruited to a general population study were selected either at random or because they had lifetime substance use disorder, affective disorder or symptoms of bulimia. A subsequent interview determined the existence of problems with impulsivity. Behaviour that is an integral part of a DSM-III axis 1 disorder was excluded from the impulsivity measure. Results. Similar rates of impulsivity were found in all three of these types of disorder, and this was little different from the rate found in the women selected randomly from the general population. However, among those with comorbid disorder there was more impulsivity, and the more comorbid disorders found, the higher the proportion with problems of impulsivity. Conclusions. Because those in treatment facilities are more likely to have other comorbid disorders (Berkson's bias), findings derived from observations of women with bulimia who are in treatment may be compromised by selection bias and may have limited applicability to those with the disorder who are not in treatment.