Perceived weight, not obesity, increases risk for major depression among adolescents

Abstract

This study examined the association between major depression, obesity and body image among adolescents. Methods: Participants were 4175 youths 11–17 years of age sampled from the community who were interviewed using the Diagnostic Interview Schedule for Children and Adolescents, Version IV, completed a self-report questionnaire, and had their weight and height measured. There were 2 measures of body image: perceived weight and body satisfaction. Obesity was associated with increased risk of depression, with no controls for covariates. However, when the association was examined in models which included weight, major depression, and body image measures and covariates, there was no association between major depression and body weight, nor between body satisfaction and major depression. Perceived overweight was strongly and independently associated with body weight (O.R. = 2.62). We found no independent association between major depression and body weight. If there is an etiologic link between major depression and body weight among adolescents, it most likely operates through processes involving components of body image. Future research should focus on the role of depression and body image in the etiology of obesity.

Introduction

Obesity is a significant public health problem because of the high prevalence of the condition (Odgen et al., 2008), as well as the morbidity and mortality attributed to it (Must et al., 1999; Barlow & Dietz, 1998) and the medical expenditures resulting from obesity-related conditions (Finkelstein et al., 2004; Finkelstein et al., 2009) The increasing prevalence of obesity has been noted in children as well (Ogden et al., 2006; 2008). In terms of the etiology of adolescent obesity, we now have considerable evidence for the role of behavioral determinants such as physical activity, sedentary lifestyles, and a high calorie diet. We have considerable less data on the role of social and psychological factors in obesity. For example, the relation between obesity and depression is unclear, with mixed evidence thus far. For example, a review by Atlantis and Baker (2008) found that among adults, obesity modestly increased risk for depression among women but not men, and that studies from outside the United States found no association between obesity and depression. Most studies have been cross-sectional, both for adults and adolescents.

Historically, obesity has been a stigmatized condition with reports documenting social exclusion, occupational and educational discrimination, and prejudice attributed to negative attitudes (Puhl and Brownell, 2001). This is true for adults (Puhl & Heuer, 2009) as well as children and adolescents (Puhl & Latner, 2007). The multiple, adverse social and interpersonal consequences of obesity have resulted in the widespread assumption that the obese suffer psychologically both as a direct consequence of social adversities and indirectly through negative “reflected appraisal”(Wardle et al., 2006). However, epidemiologic studies of adolescents have yielded mixed results for an association between obesity and the most common mental health outcome examined – depression (see Wardle et al., 2006; Zametkin, 2004).

In their recent meta-analytic study, Luppino et al. (2010) identified only 6 papers that met their criteria for prospective studies of the relation between obesity and depression involving adolescents, that is, subjects were under the age of 18 at baseline. They found that the pooled data from the studies of adolescents which examined obesity as a risk factor for subsequent depression found little increased risk. Herva et al. (2006) and Anderson et al. (2007) found that obesity at baseline was not related to depression at follow-up for adolescents. Bardone et al. (1998) found obesity at baseline predicted subsequent depression only marginally. Other studies also have found mixed or no support for increased risk of depression associated with obesity (Wardle et al., 2006). Frisco et al. (2009) found no association between weight and depressive symptoms among girls, but did for boys. In their recent paper, Merikangas et al. (2012) found obesity was not associated with obesity among adolescents overall, but there was elevated risk for boys.

Merikangas et al. (2012) note that evidence thus far on obesity and depression among adolescents has been confounded by diverse sample characteristics and methodologic differences in measuring both depression and weight. Many studies have relied on self-reports of weight, which appears to contribute to confirmation bias (Ge et al., 2001). Many studies also have focused on symptoms of depressed mood, rather than diagnosed depression, thus ignoring more severe manifestations and more rigorously measured depression status.

While there are limited coherent epidemiologic data linking obesity to clinical depression among adolescents, there is evidence from the literature suggesting that the primary effect of obesity is indirect rather than direct. That is, the association between obesity and depression may be mediated by other factors. One of these factors is body image, in particular perceived weight and body satisfaction.

Longitudinal studies indicate that poor body image is associated with greater psychological distress, more disordered eating, binge eating and fewer health-promoting behaviors such as physical activity and consumption of fruits and vegetables (Holsen et al., 2001; Stice, 2001; Stice and Bearman, 2001; Neumark-Sztainer et al., 2006). ter Bogt et al. (2006) report that body image is a better predictor of internalizing problems (but not externalizing problems) than weight. Daniels (2005) finds no relationship between obesity and depressive symptoms, but poor body image was related to depressive symptoms. Neumark- Sztainer et al. (2007) report that poor body image was one of the strongest prospective predictors of obesity, binge eating, and extreme weight control behaviors. None of these papers focused on clinical depression.

Thus far, to our knowledge, no paper has examined the association between weight, body image, and diagnosed depression among adolescents. The purpose of this paper is to reexamine the association between obesity and DSM-IV major depression, taking into account the effects of body image. To this end, we use data from Teen Health 2000 (TH2K), a large community-based sample of adolescents 11–17 years of age which assessed DSM-IV major depression (among other psychiatric disorders) and also measured height and weight and included two measures of body image: perceived weight and satisfaction with one's body.

Our hypothesis is that there is an association between obesity and major depression and this relationship is mediated by body image, e.g., negative body image better accounts for risk of major depression than body weight per se.