Until now, researchers couldn’t find out if physical activity actually reduced the risk of depression, or if it was depression that caused a reduction in physical activity.
It is now genetically proven: physical activity reduces the risk of depression, according to a new study published in the JAMA Psychiatry. When a person is going through a depression, their body starts functioning in slow motion. Some patients then have real difficulty in moving, and therefore in practicing physical activity. As a result, researchers have not been able to know so far whether physical activity actually reduces the risk of depression, or whether it is depression that leads to a reduction in physical activity.
Invest in preventative strategies
Thanks to the team of Karmel Choide, from the Unit of Genetics, Psychiatry and Neurodevelopment at Massachusetts General Hospital, it seems that the first answer is the right one. “Using genetic data, we have provided evidence that higher levels of physical activity can reduce the risk of depression,” describes the researcher. “Knowledge is important, because we want to invest in preventive strategies that really work” against this mental illness, he adds.
To achieve these results, the researchers used a method called “Mendelian randomization”. This technique uses genetic markers to reduce the risk of bias, with the aim of estimating the causal relationship between a risk factor and a disease, or more simply to solve the riddle of the chicken and the egg. Developed since 2003, Mendelian randomization has established itself as an important research tool in epidemiology, making it possible to explore many complex associations, especially when randomized controlled trials are unavailable*.
Bracelets worn on the wrist by more than 91,000 people
Baseline data was collected in two different ways. The first was based on the self-reported physical activities of 377,000 participants, while the second identified movements through wristbands worn by more than 91,000 people.
“Any activity seems to be better than nothing,” continues Karmel Choide. “Our rough calculations suggest that replacing sitting with 15 minutes of heart-pounding activity such as running, or one hour of moderate activity such as walking, is sufficient to decrease the risk of depression,” concludes -he. These new data may prove to be particularly useful for people genetically predisposed to depression, for example, or for those who evolve in stressful environments, known to be a risk factor.
The prevalence of depression in France has increased
Depression is the most common psychiatric illness and affects all ages. In France, it is estimated that nearly one person in five has suffered or will suffer from depression during their lifetime. The prevalence of depression in France increased by 1.8 points between 2010 and 2017, according to a recent report by Public Health France, particularly among women (+3 points), 35-44 year olds (+4 points) , the unemployed (+5 points) and people on low incomes (+3 points).
* source: Iumsp (University Institute of Social and Preventive Medicine).
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