A paper published by scientists from the University of South Australia and the University of Exeter in the UK, shows that obesity can lead to depression even in the absence of other weight-related health problems.

There has long been a link between obesity and depression, but “the causal relationship between obesity and depression is complex and uncertain” as the authors noted in their paper, According to their work published in the International Journal of Epidemiology, the team has found evidence that a higher body mass index (BMI) can cause  depression.

Taking a genetic approach to test the relationship between obesity and depression, researchers gathered data from the UK Biobank for more than 48,791 individuals who met the criteria for being depressed as characterized by hospital records or self-reports. They then looked at 73 genetic variants linked to high BMI but also associated with other diseases, like heart disease and diabetes. For these genetic traits, depression risk increased and could be explained by both biological or psychological mechanisms. Higher BMI was strongly associated with higher odds of depression.

The researchers were able to separate the psychological aspects of BMI-depression relationships from physiological ones.

The data was taken from people born in England between 1938 and 1971 and it’s unknown whether the same results follow for younger people or those born elsewhere. Additionally, the authors noted that the definition of depression was not the gold standard” s some cases were self-reported. Nevertheless, the work adds to our understanding of whether obesity causes depression so that we may address public health and medical intervention planning.

Resources

Jessica Tyrrell, Anwar Mulugeta, Andrew R Wood, Ang Zhou, Robin N Beaumont, Marcus A Tuke, Samuel E Jones, Katherine S Ruth, Hanieh Yaghootkar, Seth Sharp, William D Thompson, Yingjie Ji, Jamie Harrison, Rachel M Freathy, Anna Murray, Michael N Weedon, Cathryn Lewis, Timothy M Frayling, Elina Hyppönen, Using genetics to understand the causal influence of higher BMI on depression, International Journal of Epidemiology, Volume 48, Issue 3, June 2019, Pages 834–848, https://doi.org/10.1093/ije/dyy223

Reviewed by: Monica Valencia, MD