The longitudinal relations between physical activity, inflammation, and depression in the Health and Retirement Study

Area of Science:

• Gerontology
• Psychiatry
• Immunology

Background:

• Physical activity is linked to reduced depression, but biological mechanisms are unclear.
• Inflammation is associated with depression and inversely with physical activity, suggesting a potential mediating role.

Purpose of the Study:

• To examine longitudinal associations between physical activity, inflammation, and depression symptoms in older adults.
• To investigate if inflammation mediates the relationship between physical activity and depression over time.

Main Methods:

• Utilized data from 13,461 older adults from the Health and Retirement Study.
• Employed random intercept cross-lagged panel models (RI-CLPM) to analyze associations over three time points, four years apart.
• Measured physical activity, depression symptoms, and high-sensitivity C-reactive protein (hsCRP) for inflammation.

Main Results:

• Higher physical activity was associated with lower hsCRP and depression scores at the between-person level.
• Higher hsCRP was correlated with higher depression scores.
• No within-person evidence supported inflammation change as a mediator for the physical activity-depression link.

Conclusions:

• Robust associations exist between stable trait levels of physical activity, inflammation, and depression.
• Changes in inflammation do not longitudinally mediate the association between physical activity and changes in depressive symptoms.
• Further research with shorter intervals may clarify temporal dynamics.