Research article
Posttraumatic Stress Disorder and Obesity: Evidence for a Risk Association

https://doi.org/10.1016/j.amepre.2008.09.026Get rights and content

Background

There is evidence from cross-sectional studies that posttraumatic stress disorder (PTSD) may be associated with obesity. The aim of this study was to examine prospective longitudinal associations between PTSD and obesity in a community sample.

Methods

A prospective, longitudinal, epidemiologic study with a representative community sample of adolescents and young adults (N=3021, aged 14–24 years at baseline) was conducted in Munich, Germany. Participants were assessed four times between 1995 and 2005 with the Munich-Composite International Diagnostic Interview. Associations between obesity (BMI ≥30) and DSM-IV PTSD were evaluated in 2007, using cross-sectional and prospective data during young adulthood.

Results

The cumulative lifetime incidence of obesity in the sample at 10-year follow-up during young adulthood was 4.3% (women, 4.6%; men, 4.0%). Among women but not among men, obesity was associated with a lifetime history of PTSD (OR=3.8; 95% CI=1.4, 10.7) in the cross-sectional analyses. Prospective longitudinal analyses from 4-year follow-up to 10-year follow-up confirmed that obesity was predicted by antecedent subthreshold and full PTSD (OR=3.0; 95% CI=1.3, 7.0) among women but not among men. There were no associations between other mental disorders and obesity in the prospective analyses.

Conclusions

The findings indicate a possible causal pathway for the onset of obesity in females with PTSD symptoms. These findings need replication with regard to the pathophysiologic and behavioral mechanisms underlying this relationship.

Introduction

Obesity, as defined by a BMI of ≥30.0 (or other cut-offs and measures),1, 2 is a serious public health problem associated with elevated morbidity3, 4, 5 and mortality.6 Several population-based studies7, 8, 9 have reported that mental disorders are associated with obesity, but most such studies have failed to incorporate exposure to traumatic events and posttraumatic stress disorder (PTSD) into their models.8, 9 In the context of an increasing number of findings on associations between PTSD and adverse health (including metabolic) outcomes,10, 11 a better understanding of the nature of the relationship among traumatic events, PTSD, and obesity becomes particularly important.

Several clinical observational studies12, 13, 14 have reported higher rates of obesity in military veterans with PTSD. David et al.12 found, in a sample from a rehabilitation unit, that male military veterans with PTSD were more frequently obese compared to veterans with alcohol dependence. Dobie and colleagues13 reported an association between current PTSD and obesity among female military veterans who received care at a U.S. Department of Veterans Affairs hospital. Vieweg et al.14 found a higher percentage (45.7%) of obesity among male military veterans with PTSD compared to prevalence estimates in the U.S. general population (30.5%), but there was no association with PTSD severity.

Thus, although the limited literature that has addressed the topic has found associations between PTSD and obesity in military veterans, these studies have tended to be small and of potentially limited generalizability. In particular, the role of trauma exposure itself and that of PTSD symptoms is unclear, and it is questionable whether obesity is related to PTSD in other traumatized populations such as, for example, the victims of natural catastrophes, severe accidents, or violence. Further, it is unclear whether associations between PTSD and obesity can be confirmed in general population samples. For example, Britz et al.15 found high lifetime prevalence estimates of PTSD among female adolescents and young adults in treatment for extreme obesity (mean BMI=42.4) but no association between PTSD and obesity among 1655 population-based controls with a mean BMI of 29.8. Another question that remains open is that of causality. It is not clear whether traumatic events, PTSD, or both are predictors of obesity, or whether obesity precedes traumatic events and PTSD. Britz et al.15 reported that in most patients the mental disorders, including PTSD, had their onset after obesity, while recent biological findings16 suggested a plausible causal pathway from severe stress exposure to obesity through the release of a specific neuropeptide from the sympathetic nervous system.

Because to our knowledge no prospective longitudinal studies have been conducted that focus on traumatic events and PTSD as risk factors for obesity, the present study aimed first to estimate the prevalence of obesity among young adults in the community. Second, it examined the associations of obesity with traumatic events, PTSD, or both, with other mental disorders. Third, it prospectively investigated the predictive power of traumatic events, PTSD, or both, on the occurrence of secondary obesity with and without controlling for other mental disorders.

Section snippets

Sample and Overall Design

Data were collected as part of the Early Developmental Stages of Psychopathology (EDSP) Study.17, 18 The EDSP is a 10-year prospective longitudinal study on the prevalence, incidence, and course of mental disorders and risk factors in a representative community sample of adolescents and young adults. The baseline investigation was conducted in 1995, with the total sample (N=3021) aged 14–24 years and a response rate of 71%. Conditional response rates at subsequent waves were Wave 2 (1996–1997),

Prevalence of Obesity

The point prevalence of obesity (BMI ≥30) in the EDSP sample at the 10-year follow-up was 4.0% among men, 4.6% among women, and 4.3% in the total sample. A high percentage of respondents also qualified as overweight (17.7%). Overweight was much more likely among men (23.8%) than women (11.7%). The prevalence of underweight was lower (4.3%), and a clear majority of women (7.5%; men, 1.0%) were so classified. To avoid confounding associations between underweight and PTSD, the underweight

Discussion

To our knowledge, this is the first community-based study to report potentially causal associations between PTSD and obesity using a prospective longitudinal study design. While the role of traumatic events remains unclear when PTSD symptoms are disregarded, threshold PTSD and subthreshold PTSD were associated in both cross-sectional and prospective longitudinal analyses with obesity among women but not men. Cross-sectional analyses also suggest that, in women, associations between other mental

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