Over the past twenty years, there’s been a revolution in healthcare.
Not an overnight, French Revolution style revolution, though. One that’s more akin to the revolution the earth makes around the sun. Or a turning of the earth in a garden to expose the fresh soil beneath. It’s been a necessary change. One that’s helped us get out of a rut. The rut that said healthcare follows one pattern: get sick, go to the doctor, get a prescription, take some pills, get better.
That’s an oversimplification, of course.
But when we think about it, that’s what most of us grew up with.
Things are different now, especially in the way we treat chronic diseases. We know that in addition to medication, it’s vitally important to make lifestyle changes when recovering from chronic illness. It’s true for diseases like cancer, diabetes, hypertension, and more. We know that regular exercise, a healthy diet, good sleep, and stress management all play a key role in managing these illnesses.
We also know these lifestyle changes have a significant impact on chronic mental health disorders, too. That’s why things like exercise, mindfulness, and nutrition are core components of mental health treatment in the 21st century: they work. They’re part of an all of the above approach to recovery that’s no longer novel. In fact, most highly regarded providers use these types of lifestyle modifications to treat people living with mental health disorders.
Perhaps we should call it an evolution rather than a revolution.
Either way, we have questions about this evolution. Specifically, about the relationship between physical activity – i.e. exercise – and mental health. We know an active lifestyle improves mood and overall well-being.
Is exercise really that powerful?
Physical Activity and Depression: The Latest Studies
Decades of research shows that yes, physical activity can help people with major depressive disorder (MDD) manage symptoms. However, most of that research focuses on adults, and most of the studies on adults were cross-sectional, as opposed to longitudinal. That means they looked at a specific moment in time, and even if they repeat the studies, they don’t follow the same people over that time period. Longitudinal studies, on the other hand, follow the same group of people over a period of time – the longer the better – and ask the exact same questions on every follow-up. That means they can track how behavior – and in this case, depressive symptomology – and attitudes change over time. Longitudinal studies can also identify how events or circumstances at one point in life can affect an individual later in life.
And that’s why a recent meta-analysis published by the American Academy of Pediatrics (AAP) caught our eye: Children’s Physical Activity and Depression: A Meta-Analysis. It focused primarily on the effect of physical activity during childhood and adolescence on depressive symptoms later in life, with preference given to longitudinal studies, i.e. those that followed children and adolescents from youth through young adulthood. Researchers included cross-sectional studies in the meta-analysis, but they drilled down on the data in the longitudinal studies to determine the effects of early physical activity on later depression for the reasons mentioned above: they’re designed to identify and measure change over time.
Here’s what they found:
- Physical Activity (PA) during childhood and adolescence is negatively associated with current depressive symptoms.
- PA is not negatively associated with clinical MDD diagnosis.
- PA is weakly negatively associated with future depressive symptoms.
Don’t worry – we’ll translate some of that jargon, starting with the key points.
Let’s take the first bullet: negatively associated in that sentence means that children and adolescents who engaged in regular physical activity showed fewer depressive symptoms than those who did not engage in physical activity.
Now, for the second bullet point: PA is not negatively associated with clinical MDD diagnosis. This means that for children or adolescents with a clinical diagnosis of major depressive disorder, the presence or level of physical activity had no measurable effect.
The third bullet point is fairly direct, since we know what negatively associated means: physical activity in childhood or adolescence has a small – but positive – effect on the presence of depressive symptoms later in life.
Now let’s have a look at some of the data that researchers didn’t expect. We’ll call them quirks.
- Cross-sectional studies showed stronger effect size
- Longitudinal studies showed weak negative association of PA with future depressive symptoms
- Studies with validated measures of PA showed stronger negative associations between PA and depressive symptoms
- High social risk groups reported weaker associations between PA and depressive symptoms
We’ll take these one at a time too.
In the first bullet, researchers found that studies that looked at a specific point in time showed stronger associations between physical activity and depressive symptoms. These studies showed the presence of physical activity was associated with fewer depressive symptoms.
In the second, researchers found that although PA had a positive effect on later depressive symptoms, the association was weak, at best.
The third point showed that the type and quality of physical activity mattered. Studies that used unverified measures of physical activity showed weaker negative associations between physical activity and depression. This basically means that if a study included specific, known methods – 30 minutes of weight training followed by thirty minutes of stationary cycling, for instance – the positive effect on depressive symptoms was greater than studies that used general, non-specific measures, such as 30 minutes of hard activity followed by 30 minutes of moderate activity.
Finally, researchers found that individuals living in social situations with a high risk of depression, such as low income neighborhoods, neighborhoods where violence is common, or where youth are engaged in social or foster services, the protective effect of exercise – with regards to depressive symptoms – was weaker than for individuals living in low-risk social situations.
Mixed Results, Positive Directions
To understand what this study means for the general public, we’ll look at two sentences from the study itself.
The first, from the introduction:
“The objective of this meta-analysis was to investigate the potential preventative effect of child and adolescent PA on depression.”
The second, from the conclusion:
“PA in childhood and adolescence is associated with improved concurrent symptoms, but effects on future depressive symptoms is weak, but positive.”
What they found was something most people know, intuitively. Regular physical activity is a good buffer against depression and depressive symptoms. The significance of the study its size and scope: the researchers examined data from 50 studies that included 89, 984 participants overall. With a sample size that large, the findings are about as definitive as findings can get: the more physical activity a child or teen engages in, the less likely they are to experience depressive symptoms. Therefore, in answer to the question, “Does exercise help with depression?” The answer is yes. The science is in: exercise is a great buffer against depression.
The next thing they found is new. Physical activity as a child or adolescent has a weak, but positive, effect on future depression. Again, the size and scope of the study make this a significant finding. 50 studies, almost 90,000 people – that’s enough to make initial generalizations. And enough to answer the question, “Does exercise during youth protect against depression as an adult?” The answer is yes – but only a little bit.
The Takeaway: Tools for Now, Ideas for New Research
Both findings give hope for mental health professionals working with children and adolescents. They offer solid evidence for the use of exercise and physical activity during treatment for depression, and suggest that in the future, the intentional use of specific types of exercise may show more than a weak effect on future depression. When used in the right way, at the right time, the effect could be strong.
At the moment, that’s speculation. But informed, evidence-based speculation. Which means fertile ground for future research on the long-term, preventive effect of exercise on depression. We patiently await the next round of studies on this subject. As soon as the data is in, we’ll share it with you.