The Data--and Lack of Data--on Exercise and Mental Health

Emily Deans, MD


June 20, 2016

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Hi. I'm Dr Emily Deans, an adult general psychiatrist and a clinical instructor of psychiatry at Harvard Medical School. I'm here with our video blog on lifestyle interventions and mental health. What are the latest data and what alternative therapies besides medication can we safely recommend to our mental health patients?

Today I'm going to be talking about exercise. In some respects, it seems like a no-brainer. Most of us have experienced that good feeling that comes along with working out. I've certainly had patients come to me for the first time with mental health problems because they had an injury that prevented them from exercising, and so their coping mechanism was gone. Clearly, exercise must be doing something to help us with anxiety or depression.

Unfortunately, the data have not been that great historically. I'm going to restrict our comments today to depression and anxiety in adults and then ADHD in children, where we have a little bit of literature to lead our discussion. First, let's talk about the problems with the research. There are lots of different methods and protocols. Single-blinded is the highest standard that we have, obviously. It's hard to blind whether you're exercising or not. In some of the methodologies, they rely on patient self-report rather than clinical interviews to determine depression symptoms. Many of these methodologic problems, such as small sample size, can actually inflate the effect size, so that's something to consider.

Another big problem, especially in depression and anxiety research, is that sometimes the control condition is also effective for depression or anxiety. This would make the effect size smaller. Things like meditation, tai chi, or yoga aren't great controls. The better meta-analyses of more recent years have tried to take out some of these studies that used an active control.

In the past 10 years or so, just like what has happened with nutrition trials, researchers have come up with more sound and useful trials. A recent meta-analysis by Josefsson and colleagues[1] from 2014 in the Scandinavian Journal of Medicine and Science in Sports concluded that, at best, exercise has a large short-term effect size on depression symptoms. At worst, it's a modest effect. There is little in the way of long-term data for depression, however.

Other randomized controlled trials have shown that those who exercise can be maintained on lower doses of antidepressants in resistant depression than those who don't. What is more interesting is that researchers have begun to measure biological markers as well as depression screenings, which will tell us more about the possible mechanisms of how depression could be helped.[2] I'm sure you can come up with a bunch that you think might be theoretically helpful. They could modulate the autonomic nervous system in a positive way. There are anti-inflammatory effects of exercise. There are social effects. Basic science and animal and human research in exercise and the brain in general have shown us that when done appropriately, exercise is anti-inflammatory, helps energy efficiency, and causes the brain to release mood-enhancing neurotransmitters.

Personally, I have to say that the use of exercise in kids with ADHD is a more interesting tale. Besides attention and other executive functioning difficulties, kids with ADHD tend to be more overweight, less physically active, and less coordinated than their peers who don't have ADHD. This might seem like an oxymoron with the "hyperactive" label of ADHD, but the research has been pretty consistent on this fact.

Exercise programs for these kids seem to help their brains and executive functioning of physical coordination in a way that other behavioral interventions and medications haven't matched. Indeed, controlled studies of children with ADHD who exercise show that they have improvement in behavior and self-regulation, in addition to better memory.[3]

Finally, I wanted to mention the studies of exercise and anxiety. Again, this seems like one of the more obvious ways that exercise can help mental health. There is not as much data as we would like, but when we're talking about aerobic exercise, yoga, or weight training, the effect size tends to be somewhat less than with medication treatment, but beneficial for a variety of anxiety conditions.[4]

Here are some practical tips. The only exercise that people tend to sustain is exercise that they like to do. Research from sports medicine scientists suggests that the greatest benefit and least amount of long-term harm is with lots of low-intensity work and a small amount of high-intensity work. Walking, gardening, hiking, Frisbee, playing in the snow or surf, and fun bike rides with the family are generally very safe to recommend and support. High-intensity work such as sprints or intense weight training obviously have to be tailored to the patient's abilities and health conditions. Even a short steep incline on a hike will naturally weave some high-intensity into a fun and safe afternoon. Things like step-counter competitions or Facebook and other social media interactions are relatively new and can help with motivation, getting people into the gym and helping them with their activity.

I do want to acknowledge that, with our depressed patients, we're obviously up against the cardinal symptoms of depression—lack of motivation and energy—when it comes to getting them to exercise. Motivational interviewing, brainstorming, and bringing in family and peer support are all keys to a successful intervention. I also want to mention that, as psychiatrists, we're often the doctors who see our patients most often. For general physical health, insulin sensitivity, cancer prevention, etc, regular physical activity has been shown to be helpful. I think it's important that we encourage our patients to engage in physical activity.

I also think that we should push for more lifestyle interventions in exercise groups in partial programs, community mental health centers, day programs, and even the inpatient setting alongside the standard medication management psychotherapy and family work that we do. Given the chronic disabling nature of mental illness, we need all of the effective treatment paradigms that we can get.

For those of you who want to look at the actual papers, I've included several resources below. Thank you.


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