Being overweight significantly moderated the association between major depressive disorder (MDD) and willingness to make efforts for rewards, a new study found. Researchers investigated the moderating effect of overweight on the willingness to expand efforts for reward in individuals with MDD and healthy controls (HC). 41 adults (MDD n=21, HC n=20) completed the Effort Expenditure for Rewards Task, clinical and cognitive measures. Among the findings:
- Interactions between reward magnitude, group, and OW were observed.
- The OW-MDD group chose the hard task significantly less than the normal weight-HC (NW-HC) group, whereas there were no differences between NW-MDD and HCs.
- Within individuals with MDD, the proportion of hard task choices was more strongly correlated with body mass index and insulin resistance than with depressive symptoms.
Mansur, et al. Effort-based decision-making is affected by overweight/obesity in major depressive disorder. [Published online ahead of print June 4, 2019]. J Affect Dis. doi: 10.1016/j.jad.2019.06.002.
This paper by Mansur et al. determined pretty clearly that being overweight lowered the drive to make decisions where tasks were viewed as being more difficult, longer or with less reward. This suggests possible errors in the reward pathways of the brain in patients who are overweight. Depressed patients also can exhibit this effect. Given these findings, clinicians who treat depressive disorder may need to focus more toward aggressively treating amotivation and anhedonia especially in patients who are also overweight. For example, these comorbid patients may be engaged in more behavioral activation approaches or perhaps by using psychopharmacological approaches that theoretically target the dopaminergic reward systems (bupropion, methylphenidate, amphetamine as examples). Additionally, it would be interesting to determine if weight loss treatment would actually improve motivation, drive and enjoyment and act as an antidepressant itself. If this were the case, clinicians might rather provide antidepressants that generally afford weight loss side effects (bupropion), or by more aggressively treating obesity with diet, exercise or weight loss medications. —Thomas L. Schwartz, MD; Senior Associate Dean of Education, Interim Chair/Professor of Psychiatry, SUNY Upstate Medical University.