Unlocking the Link Between Muscle Health and Depression

Building muscle has been linked to benefits that extend beyond physical health, potentially offering protection against depression

Research published in the Journal of Affective Disorders indicates that adults with stronger grip strength and greater muscle mass tend to exhibit a lower likelihood of experiencing depression. These findings point to the potential of muscle-strengthening exercises as a strategy for enhancing mental well-being.

Depression, a prevalent mental health condition, is marked by persistent feelings of sadness, diminished energy, and reduced enjoyment in activities. It remains a leading cause of disability, imposing substantial challenges on communities and healthcare systems. Despite advancements in therapeutic and pharmaceutical interventions, recurrent episodes remain common, emphasizing the importance of exploring preventive approaches.

Muscle mass and strength naturally decline with age and are influenced by lifestyle factors such as dietary habits and physical activity levels. Although earlier research has hinted at a connection between muscle health and mental health, findings have varied due to differences in study designs and measurement methods. A recent study, conducted under the leadership of Linjie Qiu at the China Academy of Chinese Medical Sciences, sought to clarify this relationship by analyzing a large and representative dataset from the United States.

Data from the National Health and Nutrition Examination Survey, a large-scale program collecting health information across the United States, served as the foundation for analysis. The study examined data from 2011 to 2014, focusing on 4,871 individuals after excluding those under 18 years old, pregnant, or missing key data.

Depression symptoms were evaluated using the Patient Health Questionnaire-9 (PHQ-9), a standardized tool aligned with the Diagnostic and Statistical Manual of Mental Disorders. Scores ranged from 0 to 27, with higher scores reflecting greater symptom severity. A score of 10 or above indicated the presence of depression.

Muscle mass was assessed through dual-energy X-ray absorptiometry, a precise technique for measuring lean mass in the arms and legs. Grip strength, an indicator of muscle strength, was measured using a dynamometer to record the maximum force exerted by the hands. Each participant completed three grip tests per hand, with the highest combined score used for analysis.

The analysis revealed a significant inverse relationship between muscle strength, muscle mass, and depression risk. A 5-kilogram increase in grip strength was associated with a 5.7% reduction in depression likelihood. Participants in the top quartile of grip strength demonstrated a 39.9% lower risk of depression compared to those in the lowest quartile.

Similarly, a 1-kilogram increase in appendicular lean mass correlated with a 5.5% decrease in depression likelihood. Those in the highest quartile of muscle mass experienced a 44.1% lower risk of depression than those in the lowest quartile.

Certain subgroups exhibited stronger associations. The relationship between muscle strength and depression appeared more pronounced among individuals aged 40 to 59, aligning with the natural decline in muscle mass starting around age 30. The link between muscle mass and depression was particularly evident in individuals with a healthy body mass index and in male participants.

The study highlighted intriguing non-linear patterns in the data. For grip strength, a threshold effect was observed, where the protective benefits against depression seemed to plateau once a certain level of strength was surpassed.

Various factors that could influence the results were accounted for, including age, race, marital status, education, income, physical activity levels, body mass index, smoking, alcohol use, hypertension, and diabetes. However, some limitations must be noted. Since data were collected at a single point in time, it remains unclear whether reduced muscle mass and strength contribute to depression or if depression leads to declines in muscle health. Longitudinal studies are necessary to better understand this relationship.

Future research could examine the mechanisms linking muscle health to depression. Physical activity, for instance, is known to stimulate the release of brain-derived neurotrophic factor, a protein that supports brain health and mood regulation. Exploring these pathways may help shape targeted strategies for prevention.

“In summary, our study found that lower appendicular lean mass (ALM) and grip strength are associated with an increased likelihood of developing depression. This finding may inform public health policy makers and clinicians that enhancing muscle mass and strength through exercise could help prevent and mitigate depression. However, further large-scale prospective studies are required to validate our findings.”

https://doi.org/10.1016/j.jad.2024.07.139