Does muscle strength predict working memory? A cross-sectional fNIRS study in older adults

Area of Science:

• Neuroscience
• Gerontology
• Kinesiology

Background:

• Previous studies linked muscle strength to general cognition in older adults.
• The relationship between muscle strength and specific advanced cognitive functions, such as working memory (WM), remains less understood.
• Investigating this connection is crucial for understanding cognitive aging.

Purpose of the Study:

• To examine the relationship between muscle strength, WM performance, and brain activity in older adults.
• To explore how prefrontal cortex (PFC) hemodynamics are associated with muscle strength and WM.

Main Methods:

• Eighty-one older adults participated.
• Muscle strength assessed via grip and lower limb tests.
• WM performance measured using reaction time (RT) and accuracy (ACC) in the N-back task.
• Cortical hemodynamics of the PFC measured using functional near-infrared spectroscopy (fNIRS).

Main Results:

• Positive correlations found between grip strength and WM accuracy (ACC), and negative correlation with reaction time (RT).
• Grip strength positively correlated with oxygenated hemoglobin (HbO2) and negatively with deoxygenated hemoglobin (Hb) in PFC regions.
• WM performance (RT) correlated with specific patterns of Hb and HbO2 in PFC regions.
• Cortical hemodynamics did not mediate the muscle strength-WM relationship.

Conclusions:

• Grip strength emerged as a significant predictor of WM performance in this cross-sectional study.
• PFC hemodynamics show potential as biomarkers for predicting WM capabilities in older adults.