Substance dependence and eating disorders: impact of sequence on comorbidity.

There is a high comorbidity between eating disorders and substance dependence. The sequence of illness may indicate differences in the underlying pathology and could reflect different etiologies and treatment. The present study subjects were 218 inpatients and outpatients with diagnoses of anorexia nervosa binge-purge type (AN-BP), bulimia nervosa (BN), and eating disorder NOS (ED-NOS). Of these 218 patients, 38 had substance dependence predating the eating disorder (SDED), 71 had an eating disorder predating the substance dependence (EDSD), and 109 had only an eating disorder (ED-only). All subjects were administered the Structured Clinical Interview for DSM-III-R, Patient Edition With Psychotic Screen (SCID-P). EDSD patients had an earlier onset of the eating disorder than SDED patients and had the greatest prevalence of comorbid pathology. SDED patients were dependent on more substances. We conclude that the sequence of development of the eating disorder and substance dependence in eating disorder patients influences the amount of comorbid psychopathology. Clinical implications and future research are discussed.