Physical Activity May Lower, Prevent Depression

Numerous linets of research have shown a connection between mood and physical activity—someone who is depressed is also more likely to be less active and feel less energetic. Researchers have been unsure about which of these traits exerts more influence in the relationship. Two studies in JAMA Psychiatry now strengthen the notion that physical activity is the driving force; people who become more active can reduce depression symptoms or maybe even avoid depression altogether.

In the first study, published December 12, 2018, researchers at the National Institute of Mental Health (NIMH) and colleagues assessed real-time activity, energy, and mood data in 242 adults. The group included 24 individuals with bipolar I disorder, 29 with bipolar II disorder, 91 with major depressive disorder (MDD), and 97 people with no lifetime history of a mood disorder. Over the course of two weeks, the participants wore special wrist devices (actigraphs) that tracked movement and sleep patterns. They also completed an electronic diary four times a day (8 a.m., 12 p.m., 4 p.m., and 8 p.m.), in which they detailed their mood and energy levels.

The researchers found that more physical activity in the participants was associated with greater positive changes in mood, energy, and sleep duration at later timepoints. That is, more physical activity in the afternoon was associated with better mood and energy later in the day. This was a one-way relationship; adults who reported better mood in the afternoon did not necessarily have more activity or energy in the evening.

The relationship between activity, mood, energy, and sleep was especially strong among people with bipolar I disorder compared with the other groups, said lead study author Kathleen Merikangas, Ph.D., chief of the Genetic Epidemiology Research Branch at NIMH. She noted that there was even a large difference in the influence of activity on mood between people with bipolar I and bipolar II disorder.

“This is an important finding that further suggests bipolar I and bipolar II are not merely progressive iterations of the same underlying disorder,” Merikangas told Psychiatric News. (The primary diagnostic difference between people with bipolar I and bipolar II disorders is that people with bipolar I disorder typically have full manic episodes while those with bipolar II have more subtle periods of hypomania.)

From a clinical perspective, Merikangas said her study’s findings suggest that medications that boost activity or energy could be useful in treating depression in bipolar I disorder. She noted that the antidepressants known as monoamine oxidase inhibitors (MAOIs) may be one such treatment, as studies have shown that they can boost both energy and mood.

Merikangas acknowledged that some physicians might be wary about providing MAOIs or other energy-boosting medications to people with bipolar disorder for fear of triggering mania, but she said that she believes such medications would be safe if given after a patient is stabilized with lithium or valproate.

Physical activity may not only help reduce existing depressive symptoms, but also help prevent depression from manifesting, according to a separate study published January 23 in JAMA Psychiatry.

For the study, Karmel Choi, Ph.D., a clinical fellow of psychiatry at Massachusetts General Hospital, and colleagues collected data from two large genetic analyses: a U.K.-based study that identified genetic variants associated with greater physical activity (measured with actigraphs) and a multinational study led by the Psychiatric Genomics Consortium that identified genetic variants linked with depression risk. They picked the top 10 genetic variants in each group and examined how they correlated with the other group.

They found that the variants associated with “being active” had similar and proportional effects on lowering depression risk. That is, a larger effect on activity correlated with a larger effect on depression. Though a real-world extrapolation is difficult to calculate from genetics data, Choi and colleagues estimated that if a sedentary person adds one hour of moderate activity or 15 minutes of intense activity to his/her daily routine, the risk of depression lowers by about 25 percent.

As with Merikangas’s study, the study by Choi and colleagues revealed a one-way genetic relationship; genes strongly associated with depression risk had no influence on how physically active people were.

Chad Rethorst, Ph.D., an associate professor of psychiatry at the University of Texas Southwestern who studies the mental health benefits of exercise, said these findings offer yet another strong reason for people to become more active.

“Unfortunately, we all know that behavioral change is hard, even when there are compelling motivators,” Rethorst said. “People who might have some added risk of depression probably have characteristics that would make behavioral change even harder.”

Understanding why some people are more predisposed to exercise or engage in other physical activities could help guide interventions aimed at promoting wellness, he added.

The study by Merikangas was supported by an NIMH Intramural Research Program grant, with additional support from the Johns Hopkins Bloomberg School of Public Health, Rubicon Fellowship, and the European Union Seventh Framework Programme. Choi’s study was supported by grants from the NIMH, with additional support from the Tepper Family Massachusetts General Hospital Research Scholar program and the Demarest Lloyd Jr Foundation. ■

 “Real-Time Mobile Monitoring of the Dynamic Associations Among Motor Activity, Energy, Mood, and Sleep in Adults With Bipolar Disorder” can be accessed here. “Assessment of Bidirectional Relationships Between Physical Activity and Depression Among Adults: A 2-Sample Mendelian Randomization Study” is available here.