of Eating Disorders
CYNTHIA M. BULIK
It has long been known that eating disorders tend to run in families. This chapter and Chapter 43 consider the possible genetic basis for this familiality. In this chapter, we consider genetic–epidemiological studies, the focus being on family and twin studies: There have been no adoption studies of eating disorders to date. Chapter 43 focuses on molecular–genetic studies of eating disorders.
The tendency for a particular illness to cluster among relatives is the hallmark of intergenerational family transmission. This phenomenon has been demonstrated, with remarkable consistency, for all major categories of psychiatric disorder. With regard to eating disorders, interest in the possible role of hereditary predisposition is not without historical precedent. As early as 1860, Louis Victor Marce noted that inherited psychopathologies were prominent in families of young women with anorexia nervosa, and that the rearing environment was often disturbed as well. Other, more contemporary, reports hint at the clustering of eating disorders or peculiar feeding habits in families. However, as these reports were derived without the benefit of specified diagnostic criteria, blind examination of relatives, and the use of appropriate control subjects, their validity is questionable.
Recently, a handful of studies has been published in which the researchers have attempted a more rigorous appraisal of family diagnostic patterns associated with anorexia nervosa and bulimia nervosa. The majority have found evidence for familial aggregation. Those studies that obtained negative findings were disadvantaged by small sample sizes and reliance on indirect, and therefore less precise, family diagnostic information. Over-