Development and predictive effects of eating disorder risk factors during adolescence: Implications for prevention efforts

Eating disorders show a chronic course and result in significant functional impairment, emotional distress, and medical problems.1, 2, 3 A cross-sectional retrospective epidemiological study suggested that approximately 7.5% of young women meet criteria for a DSM-IV-TR4 eating disorder of anorexia nervosa, bulimia nervosa, or binge eating disorder (BED).1 A recent examination of the natural history of DSM-5 eating disorders5 in a community sample of 496 female adolescents who completed annual diagnostic interviews over an 8-year period found that 13% of participants experienced some form of threshold or subthreshold eating disorder by age 20, with the peak age of onset for bulimia nervosa and BED being 17-18 years of age, and 18-20 for purging disorder.6 Retrospective data suggest a median age of onset (with interquartile range) of 18 years (16-22) for anorexia nervosa, 18 years (14-22) for bulimia nervosa, and 21 years (17-32) for BED among community-recruited adults.1 Although the incidence of eating disorders in early adolescence (ages 10-14) is very low,3, 7 extant data suggest that risk factors for symptoms of eating disorders8 and eating disorder syndromes7,9 escalate in early adolescence. Accordingly, the focus of the present report is on the development and predictive power of potential eating disorder risk factors during early adolescence. The first aim of this study was to describe the developmental changes in potential risk factors from age 13 to 21, using data from a 8-year longitudinal study of community female adolescents.6 We focused on young women because they are at much higher risk for onset of eating pathology than young men.1 We examine whether the course of each variable is increasing, decreasing, or stable over this developmental period and, if change is present, whether it is linear or quadratic, as non-linear change might capture critical periods of increases in risk factors. These data should provide direction regarding when to target populations at elevated risk for eating disorders by virtue of possessing these risk factors. Further, if there are qualitatively distinct periods during which different risk factors emerge prior to eating disorder onset, it may be possible to improve the yield of prevention efforts by targeting different risk factors during these distinct developmental periods. It is possible that decreasing these risk factors may reduce future eating disorder onset, though predictive effects cannot establish a causal relation because it is always possible that some third variable explains both the emergence of the risk factor and eating pathology. Very few studies have examined the course of potential risk factors prior to mid-adolescence. One exception is Bucchianeri, Arikian, Hannan, Eisenberg, and Neumark-Sztainer,10 who followed a cohort of girls recruited during middle school (M age at first assessment = 12.8 years, SD = 0.7) over a 10-year period; data revealed a significant upward linear increase in body dissatisfaction from middle school to high school and to young adulthood. However, body mass index (BMI = kg/m2) scores also increased across all three time points for both male and female participants, and after adjusting for BMI, the linear trend in body dissatisfaction was nonsignificant. No studies, to our knowledge, have investigated the temporal development of several risk factors prior to and during peak period of eating disorder onset (i.e., from early adolescence to young adulthood). Guided by the dual-pathway model of eating pathology11 and prior research with female adolescents,9,12-15 we focused on six potential risk factors: (1) perceived pressure to be thin, (2) thin-ideal internalization, (3) body dissatisfaction, (4) dieting, (5) temperamental negative affectivity (i.e., the tendency to experience negative emotional states), and (6) body mass. The dual-pathway model posits that perceived pressure to be thin from significant others and the media and internalization of the thin beauty ideal produces body dissatisfaction, which in turn promotes unhealthy dieting behaviors that may progress to an eating disorder. Body dissatisfaction may also contribute to negative affect given the importance of appearance in Western culture, which in turn might lead people to binge eat to provide comfort and distraction from negative emotions. According to the affect regulation model,11 people binge eat in an effort to achieve comfort and distraction from their negative emotions. Previous research with adolescents has found that female adolescents in 6-9th grade reporting social pressure to be thin and body image preoccupation showed a higher risk for onset of threshold or subthreshold bulimia nervosa or binge eating disorder over 3-year follow-up,14 high school women reporting weight and shape concerns and negative affectivity showed a higher risk for onset of threshold or subthreshold bulimia nervosa over 4-year follow-up,8 and female adolescents (11-15 years of age) reporting elevated dietary restraint showed elevated risk for onset of threshold or subthreshold bulimia nervosa over 5-year follow-up.16 It is arguably more important to identify youth at elevated risk for any eating disorder because prevention programs should ideally target all eating disorders, rather than just one type of eating disorder, and elevated dietary restraint has been found to increase risk for onset of any eating disorder among young women (16-23 years of age) over 2-year follow-up,12 young women (14-15 years of age) over 3-year follow-up,14 and 16-year-old women over 1-year follow-up.15 In an earlier report examining data used in the present study using classification tree analysis to predict onset of threshold and subthreshold eating disorders over 8-year follow-up,17 a three-way interaction emerged suggesting a body dissatisfaction pathway to eating disorder onset that was amplified by depressive symptoms, as well as a pathway characterized by self-reported dieting among young women who are more satisfied with their bodies. Further, increased adiposity has been theorized to result in both increased social pressure to be thin and body dissatisfaction, which putatively lead to dieting, negative affect, and elevated risk for eating pathology.18 BMI is known to increase during the adolescent developmental period.19 For example, one study found that self-reported BMI among female adolescents in their younger cohort increased from an average of 21.7 at the first assessment (M age = 12.8) to an average of 26.4 at the third assessment (M age = 23.2).10 To identify variables that predict pathological eating behavior in children and early adolescents, Gardner, Stark, Friedman, and Jackson examined the degree to which six variables (weight, teasing, body esteem, body dissatisfaction, depression, perceived body size, ideal body size) predicted elevated scores on an eating disorder survey in 216 female and male children ages 6-14 who were assessed annually for 3 years.20 They examined each predictor at various ages to identify when the factors tended to became significant predictors of elevated eating disorder scores, finding that low body esteem became a significant factor at age 9, depression at age 10, body dissatisfaction and larger perceived body size judgments at age 11, and thinner ideal body sizes at age 12. Using a similar analytic approach, our second aim was to examine whether each of the Aim 1 potential risk factors examined during early adolescence predicted subsequent onset of DSM-5 eating disorders, and whether the predictive effects of these risk factors varied as a function of age. We sought to extend the findings of Gardner and colleagues20 by (a) following a larger cohort of youth, (b) examining a longer period of time, and (c) by predicting onset of DSM-5 eating disorders as determined by diagnostic interview. To address this aim, we examined the degree to which each of the six potential risk factors at ages 13, 14, 15, and 16 significantly predicted the onset of eating disorders in the four year period following each assessment. These data may also advance etiologic models for eating disorders by illuminating the earliest risk factors that predict eating disorder onset.