The idea that obesity is linked to mood disorders has been posited since at least 2004.
Rising obesity rates over the last 40 years have prompted researchers to look for both causes as well as ways to combat the epidemic. But assuming that obesity results just from overeating, and is driven by behaviors identical to those that cause alcohol or drug addiction, misses the mark, according to a new analysis that appears in Nature Human Behavior.
Obesity rates have tripled worldwide since 1975, according to the World Health Organization, and are rising fastest among lower socioeconomic groups. While factors like the availability of low-cost, high-calorie food and sedentary lifestyles contribute to obesity, those who study the condition point out that people cannot entirely give up food. Both obesity and addiction can have both genetic and environmental links, and the rise of obesity has been linked to factors that have contributed to increased inflammation, including chronic stress, the increase in shift work and multiple jobs, which interfere with circadian rhythms, and changes in the environment that have altered the gut microbiome.
The quandary prompted a team led by Alain Dagher, MD, of The Neurological Institute-Hospital in Montreal, to seek new ways to measure behaviors linked to obesity as well as those linked to well-known addictive behaviors, in search of common threads.
Dagher is a neurologist who is well-known for his studies of the role of dopamine in cognition, including its role in Parkinson disease.
In this study, a postdoctoral fellow in Dagher’ lab, Uku Vianjik, who is now with the University of Estonia, Tartu, culled existing studies of obesity and addiction to identify related personality traits. A common personality test, called the NEO Personality Inventory, takes 30 measures on whether people are impulsive, assertive, or altruistic; the test produces a score on what are known as the “Big 5” personality traits: agreeableness, extraversion, neuroticism, conscientiousness, and openness.
Team members compared personality profiles against a data from 18,611 participants across 22 studies, and found that addictions had highly similar personality traits, suggesting strong behavioral overlap. The link to overeating, however, was more tenous; by contrast, the personality traits in obesity overlapped more strongly with mood disorders and some personality disorders.
The possibility that obesity and mood disorders might be related has been posited for at least 15 years; a 2004 review in the Journal of Clinical Psychiatry found a strong overlap between the 2 conditions that authors said may be more than coincidental. By 2006, researchers from Group Health in Seattle found that people who are obese are 25% more likely to suffer mood or anxiety disorders and 25% less likely to suffer substance abuse disorders.
“Our research suggests that obesity treatments may benefit from borrowing methods from addiction treatments to improve people’s self-control capabilities,” Dagher said in a statement. “However, obesity treatments should not focus on how people with addictions handle sensation-seeking, as this is not as much of an issue for people with obesity. Current results suggest that we should take whatever is useful from the limited similarities that obesity and addictions share, and then look elsewhere to fully comprehend the behavioral profile of obesity.”
An accompanying editorial said the findings show that obesity and addiction “are less similar than previously thought,” which suggests that treatment will call for a more nuanced approach.
Vainik U, Misic B, Zeighami Y, et al. Obesity has limited behavioural overlap with addiction and psychiatric phenotypes [published online October 28, 2019]. Nat Human Behav. 2019. doi: 10.1038/s41562-019-0622-6.