Abstract
Objective: Few studies have been reported on the characteristics of Japanese siblings with eating disorders. We investigated the similarities of the lifetime diagnoses, compensation behaviors such as binge eating and purging, obesity, and clinical and demographic characteristics of siblings with eating disorders. Method: Participant data were collected from institutions that participated in a study by the Japanese Genetic Research Group for Eating Disorders, all of whom had been diagnosed as having Anorexia Nervosa-restricting type (AN-R), Anorexia Nervosa-binging/purging type (AN-BP), Bulimia Nervosa-non purging type (BN-NP), Bulimia Nervosa-purging type (BN-P), Binge-Eating Disorders (BED), or Eating Disorder Not Otherwise Specified (EDNOS) based on the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV). AN-BP without binge eating was further sub-classified into AN-purging type (AN-P), and partially diagnosed AN and BN were classified into sub-clinical AN and sub-clinical BN. The subjects were 36 siblings with eating disorders (18 pairs, all females). The items surveyed included lifetime diagnosis, clinical information, and demographic data: 'Present age', 'age at onset', 'age at investigation', 'duration of illness', 'current BMI', 'maximum and minimum BMI in the past', 'duration before onset of binge eating or purging', 'history of the low body weight period (±17.5kg/m^2)' and 'diagnostic crossover'. Statistical analysis was done by x^2 analysis. Results: The lifetime diagnoses were AN (n=15,41.7%), BN (n=10,27.8%), AN & BN (n=10,27.8%), and EDNOS (n=1,2.8%). Ten of the 18 pairs had the same diagnosis (AN/AN, n=4, BN/BN, n=4, AN & BN/AN & BN, n=2). Irrespective of whether the diagnosis was lifetime or temporary, there was a tendency (p=0.001) toward having a similar history of the duration of the low body weight period (≦17.5kg/m^2). However, there was no similarity regarding complications such as binge-eating and self-reduced purging behavior. Conclusions: Although this study is preliminary, a possible association between siblings with eating disorders was found as to whether or not they were able to maintain the minimum normal body weight during their illness. Regardless of the presence or absence of binge eating or self-induced purging or a lifetime or temporary diagnosis, a similarity in body weight predisposition affects siblings with eating disorders.
