04/14/2019 / By Edsel Cook
Genes do not lie when it comes to determining what is good and healthy for the mind and body. When Massachusetts-based researchers conducted a genetic variation-based study of physical activity, they found strong evidence that exercise could help protect its practitioners from depression.
There is a distinct difference between “physical activity can reduce the effects of depression” and “depression causes a decrease in the levels of physical activity.” The Massachusetts General Hospital (MGH) researchers sought to determine what causal relationship applied to exercise and mood. They published their findings in the journal JAMA Psychiatry.
To achieve this end, they employed Mendelian randomization, an approach which used gene variants to analyze the effects of a non-genetic factor. They looked at the genetic variation of people and then checked if there was any connection between a particular gene variant and certain levels of physical activity.
Genetic variants are usually inherited at random. This randomness reduced the potential bias in participants, thereby increasing the accuracy of the experimental outcome.
Furthermore, the Mendelian randomization approach could identify causative traits. It could show which trait led to another, making it a good way of figuring out if exercise affected depression or vice versa. (Related: Prevent depression with one hour per week: Landmark study proves importance of consistent exercise.)
For data on gene variants, the MGH researchers tapped genome-wide association studies conducted in the U.K. and around the world. The U.K.-based studies focused on physical activity, while the global ones covered depression.
The data of the physical activity-centered studies came from two different populations: The self-reported levels by a total of 377,000 participants, and the readings f