Obesity and mental disorders in the adult general population

The aim of this study was to investigate (i) the associations between mental disorders (in particular the anxiety disorders) and obesity in the general population and (ii) potential moderators of those associations (ethnicity, age, sex, and education).

A nationally representative face-to-face household survey was conducted in New Zealand with 12,992 participants 16 years and older, achieving a response rate of 73.3%. Ethnic subgroups (Maori and Pacific peoples) were oversampled. Mental disorders were measured with the Composite International Diagnostic Interview (CIDI 3.0). Height and weight were self-reported. Obesity was defined as a body mass index (BMI) of 30 kg/m(2) or greater.

Obesity was significantly associated with any mood disorder (OR 1.23), major depressive disorder (OR 1.27), any anxiety disorder (OR 1.46), and most strongly with some individual anxiety disorders such as post-traumatic stress disorder (PTSD) (OR 2.64). Sociodemographic correlates moderated the association between obesity and mood disorders but were less influential in obesity-anxiety disorder associations. Adjustment for the comorbidity between anxiety and mood disorders made little difference to the relationship between obesity and anxiety disorders (OR 1.36) but rendered the association between obesity and mood disorders insignificant (OR 1.05).

Stronger associations were observed between anxiety disorders and obesity than between mood disorders and obesity; the association between PTSD and obesity is a novel finding. These findings are interpreted in light of research on the role of anxiety in eating pathology, and deserve the further attention of researchers and clinicians.