A controlled family study of anorexia nervosa and bulimia nervosa: psychiatric disorders in first-degree relatives and effects of proband comorbidity.

BACKGROUND: We used contemporary family-epidemiological methods to examine patterns of comorbidity and familial aggregation of psychiatric disorders for anorexia and bulimia nervosa.
METHODS: Direct interviews and blind best-estimate diagnostic procedures were used with diagnostically "pure" groups of probands with eating disorders and a matched control group. Lifetime prevalence rates of eating disorders, mood disorders, substance use disorders, anxiety disorders, and selected personality disorders were determined in female probands with restricting anorexia nervosa (n=26) or bulimia nervosa (n=47), control women (n=44), and first-degree biological relatives (n=460).
RESULTS: Relatives of anorexic and bulimic probands had increased risk of clinically subthreshold forms of an eating disorder, major depressive disorder, and obsessive-compulsive disorder. Familial aggregation of major depressive disorder and obsessive-compulsive disorder was independent of that of anorexia nervosa and bulimia nervosa. These relatives also had increased risk of other anxiety disorders, but the mode of familial transmission was not clear-cut. The risk of substance dependence was elevated among relatives of bulimic probands compared with relatives of anorexic probands, and familial aggregation was independent of that of bulimia nervosa. The risk of obsessive-compulsive personality disorder was elevated only among relatives of anorexic probands, and there was evidence that these 2 disorders may have shared familial risk factors.
CONCLUSIONS: There may be a common familial vulnerability for anorexia nervosa and bulimia nervosa. Major depressive disorder, obsessive-compulsive disorder, and substance dependence are not likely to share a common cause with eating disorders. However, obsessional personality traits may be a specific familial risk factor for anorexia nervosa.