UCL researchers have examined how physical exercise can alleviate depressive symptoms through various processes in the brain and body.
Depression holds the title of the leading cause of disability globally and is linked to several disruptions in brain function and psychological processes, particularly affecting learning and memory. It has been demonstrated that engaging in physical activity, particularly aerobic exercises, can lessen symptoms of depression, yet the underlying mechanisms have remained largely unclear until now.
A new review published in Translational Psychiatry presents an innovative hypothesis aimed at explaining the antidepressant effects of exercise. The researchers suggest that a key factor may be motivation, which plays a crucial role in alleviating various symptoms associated with depression, including anhedonia (the lack of enjoyment in life), fatigue, and mental cloudiness.
The research team compiled findings from studies on both humans and animals and concluded that depression, especially the aspect of anhedonia, is often linked to increased inflammation driven by the immune system. Notably, this inflammation is also associated with disrupted dopamine signaling. These biological alterations may be significant contributors to decreased motivation, particularly a reduced willingness to engage in physical or mental activities.
Conversely, exercise is known to lower inflammation, enhance dopamine function, and improve motivation. The researchers propose that these effects could largely explain why exercise has antidepressant properties.
Dr. Emily Hird, the lead author from UCL’s Institute of Cognitive Neuroscience, explained: “While randomised controlled trials have convincingly shown the antidepressant benefits of aerobic exercise, the underlying mechanisms remain unclear. This lack of understanding arises partly because it likely involves a complex interplay of different biological and psychological factors.”
“For instance, in addition to its beneficial effects on inflammation, dopamine, and the processing of rewards, exercise also reduces oxidative stress and enhances self-esteem and self-efficacy.”
“We’re suggesting that aerobic exercise—especially activities that elevate your heart rate and make you breathe harder—reduces inflammation and enhances dopamine signaling, ultimately fostering a greater desire to put forth effort, thereby improving overall motivation.”
The researchers believe that their insights into how exercise helps mitigate symptoms of depression could pave the way for the creation of new therapeutic approaches, such as customized exercise plans.
Dr. Hird added: “By understanding the biological mechanisms driving the antidepressant effects of physical activity, we can also gain insights into the root causes of depression and the development of innovative intervention strategies, like personalized treatments and social prescribing.”
To validate their hypothesis further, the team recommends conducting large randomized controlled trials to evaluate the antidepressant effects of exercise while simultaneously measuring parameters like inflammation, dopamine activity, and motivation.
Additionally, it’s essential to explore any obstacles that may hinder individuals from exercising.
Dr. Hird remarked: “Overcoming barriers to exercise, especially for those suffering from depression, is vital, as regular physical activity could help ease symptoms, boost mood, and empower individuals in their recovery journey. Finding effective strategies to promote exercise is crucial.”
The research team is currently conducting a trial based on their proposed hypothesis, involving 250 participants aged 18 to 60, and this is financed by a Wellcome Mental Health Award.
This review study received funding from the Rosetrees Trust.
