Obesity gene could protect against depression

It has long been thought that people who are obese are more likely to be depressed — whether because of self esteem and discrimination issues resulting from their appearance, the perceived lack of physical activity and healthy eating habits, or the fact that anti-depressants are known to cause weight gain.

A new study at McMaster University in Ontario has found the opposite to be more likely. While it is common knowledge that depression has a genetic component, no gene has been found to be associated with the illness.

Researchers decided to test how the obesity gene may be linked to depression, and the results showed that a variant of the FTO gene may actually give carriers a lower risk for depression, no matter its effect on their weight. The new findings challenge the common stereotype that overweight people are depressed, since researchers found that those with the genetic mutation were actually protected from the disease.

“This suggests that the FTO gene may have a broader role than initially thought with an effect on depression and other common psychiatric disorders,” they wrote in the study report.

This protective effect was found to be the case regardless of ethnicity, as it was consistent in four different studies around the world.

For the McMaster study, led by David Meyre, associate professor in clinical epidemiology and biostatistics, researchers analysed the FTO gene mutation in 6,591 people with depression, along with 21,000 others who were not diagnosed with the disease.

While the study may not affect the way doctors diagnose and treat depression, researchers hope it will change the biased and limiting view that obesity leads to depression. Next steps include an examination of the 59 other genes associated with obesity as well as similar research with various diseases linked to obesity, such as Type 2 diabetes.