A study published in Frontiers in Psychology offers insight into the antidepressant effects of physical exercise. The researchers found that patients with major depressive disorder who participated in a physical activity intervention showed increased neuroplasticity that coincided with declines in clinical symptoms.
While the physiological mechanisms behind major depressive disorder (MDD) are not yet fully understood, some studies have suggested a role for impaired neuroplasticity. For example, more severe depression tends to coincide with reduced synaptic density in the brain. In simple terms, neuroplasticity refers to the brain’s ability to adapt itself and make new connections in response to experience. Researchers Wanja Brüchle and team wanted to explore one possible intervention that might improve neuroplasticity among patients with depression.
Studies suggest that physical exercise can increase neuroplasticity in healthy subjects. Notably, there is also evidence that exercise plays a protective role against depression. The researchers wondered whether physical activity might essentially reverse the deficits in neuroplasticity among patients with depression and, in doing so, reduce their clinical symptoms.
Patients with MDD were recruited from a psychiatric hospital in Germany to partake in a clinical intervention study. After participant dropout, 23 patients completed a 3-week physical activity program and 18 patients completed a 3-week control intervention. All participants completed assessments prior to the intervention and again several days after the intervention. These assessments included clinical tests, cognitive tests, and Transcranial Magnetic Stimulation (TMS).
During the physical activity program, participants attended three guided exercise sessions each week that were focused on either endurance, coordination, or strength training. The control intervention involved two longer sessions per week, where patients played cooperative games led by an instructor. The games relied on cognitive skills like strategy and problem solving.
Both groups saw significant decreases in depression symptoms following the intervention period. This was true according to self-ratings using Beck’s Depression Inventory-II (BDI-II) as well as investigator-ratings using the Hamilton Depression Scale-17 (HAMD-17). However, the group that followed the physical activity program saw significantly greater declines in overall HAMD-17 scores compared to the control group.
The findings also revealed reduced long-term-potentiation (LTP)-like plasticity in the motor cortex among both groups prior to intervention. Notably, plasticity was significantly enhanced following the intervention among the physical activity group, but not the control group — suggesting that the physical activity program helped restore deficits in neuroplasticity.
At the start of the study, BDI-II scores were negatively linked to LTP-like plasticity among both groups — which is in line with studies suggesting lower neuroplasticity among people with MDD. Importantly, decreases in BDI-II following the intervention coincided with increases in LTP-like plasticity — especially among the physical activity group. “We showed that a physical activity intervention supports the remission of clinical symptoms and normalizes deficient LTP-induced neuroplasticity in MDD,” the authors report, “and that these two observations are highly correlated.”
The researchers say there are several reasons why people with depression may have lower synaptic plasticity in the brain. One reason relates to trademark symptoms like loss of interest in activities and psychomotor retardation. “A lack of physical and cognitive activity, and of social interaction, deprives the brain of important stimuli, which consequently might contribute to the downscaling or loss of synapses, which are necessary to keep the brain susceptible to plastic changes,” Brüchle and colleagues say. Improving plasticity in the brain — possibly through a physical activity intervention — may therefore be a potential avenue of treatment for people with MDD.
The study, “Physical Activity Reduces Clinical Symptoms and Restores Neuroplasticity in Major Depression”, was authored by Wanja Brüchle, Caroline Schwarzer, Christina Berns, Sebastian Scho, Jessica Schneefeld, Dirk Koester, Thomas Schack, Udo Schneider, and Karin Rosenkranz.
