Summary: A new study suggests that exercise reduces depression by boosting motivation through decreased inflammation and improved dopamine function. This understanding could lead to personalized exercise programs as treatment.
The study highlights how aerobic exercise combats anhedonia and lack of energy in depression. Large-scale trials are needed to further test this hypothesis and explore barriers to exercise.
Highlights:
- Exercise reduces inflammation and increases dopamine, improving motivation.
- Aerobic exercise effectively combats symptoms such as anhedonia and lack of energy.
- Personalized exercise programs could become a new treatment strategy for depression.
Source: UCL
The processes in the brain and body by which physical exercise reduces depressive symptoms have been explored by UCL researchers.
Depression is the leading cause of disability worldwide and is associated with disruptions in several brain and psychological processes, including learning and memory impairments. Physical activity, particularly aerobic exercise, has been shown to reduce depressive symptoms, but to date the processes underlying this phenomenon are poorly understood.
In a new review article published in Translational psychiatryResearchers propose a new hypothesis to understand the antidepressant effects of physical exercise. They think the process may depend on motivation, which is very important for alleviating a number of symptoms of depression, such as anhedonia (a lack of interest or joy in life experiences), low energy and “brain fog.”
The team summarized research papers that explored the mechanisms of depression in humans and animals and concluded that depression, particularly anhedonia, is associated with increased inflammation (caused by the body’s immune response). Importantly, inflammation is also linked to disruption of dopamine transmission. These biological changes may represent key processes leading to changes in motivation, and in particular a reduced willingness to exert physical or mental effort.
At the same time, exercise reduces inflammation, boosts dopamine function, and increases motivation. Researchers believe this may be an important reason why exercise has an antidepressant effect.
Lead author Dr Emily Hird (UCL Institute of Cognitive Neuroscience) said: “The antidepressant effect of aerobic exercise has been convincingly demonstrated in randomised controlled trials, but its mechanism is not well understood. This is partly because it likely involves a variety of biological and psychological processes.
“For example, in addition to its positive effect on inflammation, dopamine and reward processing, exercise also reduces oxidative stress and improves self-esteem and self-efficacy.
“However, we suggest that exercise – particularly aerobic activities that make you sweat and get out of breath – decreases inflammation and boosts dopamine release, which in turn increases the desire to exert effort and, therefore, boosts motivation in general.”
The team hopes that this understanding of how exercise reduces symptoms of depression will help inform the development of new treatment strategies, such as personalized exercise programs.
Dr Hird said: “Understanding the mechanisms underlying the antidepressant effects of physical activity on depression could also inform our understanding of the mechanisms underlying depression and the development of new intervention strategies, particularly personalised intervention and social prescribing.”
To further test their hypothesis, the researchers recommend conducting large-scale randomized controlled trials to evaluate the antidepressant effects of exercise, while also measuring the effect on variables such as inflammation, dopamine transmission, and motivation.
It would also be important to study possible barriers to exercise.
Dr Hird said: “Removing barriers to exercise is essential, particularly for people with depression, as regular physical activity can alleviate symptoms, improve mood and help people recover. In this context, finding strategies to encourage exercise is essential.”
The team is currently conducting a trial based on the hypothesis proposed in the study, which will involve 250 participants aged 18 to 60 and is funded by a Wellcome Mental Health Award.
Funding: The review article was funded by the Rosetrees Trust.
About this news on depression and exercise research
Author: Poppy Tombs
Source: UCL
Contact: Poppy Graves – UCL
Picture: Image credited to Neuroscience News
Original research: Free access.
“From Movement to Motivation: A Proposed Framework for Understanding the Antidepressant Effect of Exercise” by Emily Hird et al. Translational psychiatry
Abstract
From movement to motivation: a proposed framework for understanding the antidepressant effect of exercise
Depression is the leading cause of disability worldwide, having a profound negative impact on the quality of life of those who suffer from it.
Depression is associated with disruptions in several closely related neural and cognitive processes, including dopamine transmission, fronto-striatal brain activity and connectivity, reward processing, and motivation. Physical activity, particularly aerobic exercise, reduces depressive symptoms, but the mechanisms underlying its antidepressant effects are poorly understood.
Here we propose a new hypothesis to understand the antidepressant effects of exercise, centered on motivation, across different levels of explanation.
There is strong evidence that aerobic exercise decreases systemic inflammation. Inflammation is known to reduce dopamine transmission, which in turn is heavily involved in effort-based decision-making to obtain a reward.
Drawing on a broad range of research in humans and animals, we propose that by reducing inflammation and boosting dopamine transmission, with consequent effects on effort-reward decision-making, exercise initially specifically improves the “interest-activity” symptoms of depression, namely anhedonia, fatigue, and subjective cognitive impairment, by increasing the propensity to exert effort.
Extending this framework to the topic of cognitive control, we explain how cognitive impairments in depression can also be conceptualized through an effort-based decision-making framework, which may help explain the impact of exercise on cognitive impairments.
Understanding the mechanisms underlying the antidepressant effects of exercise could inform the development of novel intervention strategies, particularly personalized interventions, and stimulate social prescribing.