Source: Live Science

Getting a few hours of exercise a week may reduce the risk of depression, even in people who are genetically prone to the condition, a new study suggests.

The authors found that, although certain genes boost a person’s risk of depression, increased levels of exercise essentially canceled out this genetic risk. 

Overall, for every 4 hours of exercise per week (about 35 minutes per day), participants saw a 17% reduction in their chances of experiencing bouts of depression over the next two years. This protective effect of exercise held even for those at high genetic risk for depression.

“Our findings strongly suggest that, when it comes to depression, genes are not destiny and that being physically active has the potential to neutralize the added risk of future episodes in individuals who are genetically vulnerable,” study lead author Karmel Choi, postdoctoral fellow in psychiatry at Massachusetts General Hospital, said in a statement.

The study is published today (Nov. 5) in the journal Depression and Anxiety.

Genetic risk

Depression can run in families, which suggests that genetic factors contribute to the risk of developing the disease, according to the National Institutes of Health (NIH). Although research on the genetics of depression is in its infancy, studies suggest that multiple genes, each with a small effect, combine to increase a person’s risk of the disease, according to the NIH.

In addition, previous studies have found that exercise can reduce people’s risk of depression. But it wasn’t clear if this benefit applied to those with certain risk factors, such as a genetic risk for depression, the authors said. 

In the new study, the researchers analyzed information from nearly 8,000 participants in the Partners HealthCare Biobank, a database intended to help researchers better understand how people’s genes, environment and lifestyle affect their health. Participants provided a blood sample, had their genomes analyzed and filled out a survey about their lifestyle behaviors, such as how much exercise they typically get in a week. This information was then linked with people’s electronic health records (EHRs) within Partners HealthCare, a Boston-based health care system.

To be included in the new study, participants could not be currently depressed, and so the researchers excluded people who had visited a medical professional for depression within the past year. The authors then looked to see which of those remaining participants experienced a new episode of depression — based on billing codes from their EHRs — within the next two years.

The researchers also used genomic data to calculate a person’s genetic risk for depression, and gave people a “score” based on their risk. This allowed the researchers to divide participants into three groups: those with low, intermediate and high genetic risk for depression.

Protective effect

The researchers found that, not surprisingly, those with a high genetic risk for depression were 50% more likely to experience a new episode of depression within the next two years, compared with those at low genetic risk.

However, across all risk groups, people who were more physically active were less likely to experience a new episode of depression. For example, among those in the high-risk group, the incidence of depression was nearly 13% for those who didn’t exercise, compared with just 8% for those who exercised for about 3 hours a week.

What’s more, both high-intensity exercises, such as running, and low-intensity exercises, such as yoga, were linked with a decreased risk of depression.

However, the study only found an association and cannot prove that a lack of exercise causes depression (although previous research has suggested that exercise likely helps ward off depression). In addition, the EHRs used in the study do not capture the severity of a depressive episode and do not reflect care outside of the Partners HealthCare system.

Still, the study provides “promising evidence” that doctors can use to counsel patients and “make recommendations to patients that here is something meaningful they can do to lower their risk even if they have a family history of depression,” Choi said.

Of course, in addition to reducing depression risk, regular exercise has a slew of other health benefits, such as reducing people’s risk of heart disease, type 2 diabetes and some cancers, according to the Centers for Disease Control and Prevention (CDC). However, less than a quarter Americans meet national exercise guidelines, according to the CDC’s National Center for Health Statistics.

Source: Live Science