Isolating the Effect of Major Depression on Obesity: Role of Selection Bias

Abstract

There is suggestive evidence that rates of major depression have risen markedly in the U.S. concurrent with the rise in obesity. The economic burden of depression, about $100 billion annually, is under-estimated if depression has a positive causal impact on obesity. If depression plays a causal role in increasing the prevalence of obesity, then policy interventions aimed at promoting mental health may also have the indirect benefits of promoting a healthy bodyweight. However, virtually the entire existing literature on the connection between the two conditions has examined merely whether they are significantly correlated, sometimes holding constant a limited set of demographic factors. This study utilizes multiple large-scale nationally-representative datasets to assess whether, and the extent to which, the positive association reflects a causal link from major depression to higher BMI and obesity. While contemporaneous effects are considered, the study primarily focuses on the effects of past and lifetime depression to bypass reverse causality and further assess the role of non-random selection on unobservable factors. There are expectedly no significant or substantial effects of current depression on BMI or overweight/obesity, given that BMI is a stock measure that changes relatively slowly over time. Results are also not supportive of a causal interpretation among males. However, among females, estimates indicate that past or lifetime diagnosis of major depression raises the probability of being overweight or obese by about seven percentage points. Results also suggest that this effect appears to plausibly operate through shifts in food consumption and physical activity. We estimate that this higher risk of overweight and obesity among females could potentially add about 10% (or $9.7 billion) to the estimated economic burden of depression.

Determining the cost of obesity and its common comorbidities from a commercial claims database

“…For instance, the economic burden of depression is $ 100 billion annually; however, according to Dave et al, this burden is underestimated if depression has a positive causal impact on obesity (10). Other diseases that present a tremendous economic burden on the US healthcare system such as diabetes mellitus, hypertension and CHF also contribute to the rising cost of obesity (11)(12)(13).…”

Prevalence and healthcare costs of obesity-related comorbidities: evidence from an electronic medical records system in the United States

“…6,7 Among female patients with depression, the positive association between depression and being overweight or obese was expected to increase the economic burden of depression by 10%. 8 With respect to research on multiple comorbidities, a recent study evaluated the healthcare costs of diabetes, hypertension, depression, and congestive heart failure among obese patients from claims data in the US. 9 Also a German study has examined the cost contributions of diabetes and three cardiovascular comorbidities (myocardial infarction, hypertension, and stroke) to the costs of obesity.…”

When Mood Worsens after Gastric Bypass Surgery: Characterization of Bariatric Patients with Increases in Depressive Symptoms Following Surgery

“…Obesity is a global health concern associated with substantial economic costs [1] and various medical and psychiatric co-morbidities, including depression [2, 3]. The relationship between obesity and depression is complex; a recent meta-analysis of longitudinal studies suggested a bidirectional link between depression and obesity [4].…”