Longitudinal Associations Between Brain Volume and Knee Extension Peak Torque

Area of Science:

• Neuroscience
• Gerontology
• Human Physiology

Background:

• Muscle strength and brain volume naturally decrease with aging.
• The relationship between age-related brain volume changes and muscle strength loss has not been previously studied longitudinally.
• The Baltimore Longitudinal Study of Aging provided data for this investigation.

Purpose of the Study:

• To longitudinally examine the association between changes in brain volume and knee extension peak torque in older adults.
• To test the hypothesis that brain volume changes contribute to age-related strength decline.
• To identify specific brain regions associated with age-related muscle strength loss.

Main Methods:

• 678 participants from the Baltimore Longitudinal Study of Aging were included (baseline age 50.1-97.2 years).
• Brain volumes and isokinetic concentric knee extension peak torque were measured.
• Bivariate linear mixed-effects models were used to analyze longitudinal changes, adjusting for covariates.

Main Results:

• Significant correlations were found between greater muscle strength decline and atrophy in multiple gray matter regions, including frontal, temporal, and occipital areas (r = 0.30-0.77, p < .05).
• After adjusting for multiple comparisons, a larger decrease in the middle temporal gyrus remained significantly associated with a larger decrease in muscle strength (q = 0.045).

Conclusions:

• Age-related declines in knee extension muscle strength are associated with gray matter atrophy in specific brain regions.
• Findings support a link between age-related muscle strength loss and atrophy in brain areas involved in motor control.
• The middle temporal gyrus is specifically implicated in the decline of muscle strength with aging.