Inter-individual differences in fMRI entropy measurements in old age

Area of Science:

• Neuroscience
• Cognitive Psychology
• Biomedical Imaging

Background:

• Cognitive performance declines with age, but individual differences persist.
• Understanding the neural basis of cognitive variability in aging is crucial.
• Previous research has not extensively linked brain signal entropy to cognitive function in older adults.

Purpose of the Study:

• To investigate the association between brain signal entropy and cognitive performance in old age.
• To explore the utility of approximate entropy (ApEn) derived from fMRI data as a marker for cognitive differences.
• To determine if this association is influenced by childhood intelligence or current cognitive ability.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was used to measure approximate entropy (ApEn) during a visual information processing task (inspection time).
• Participants (n=40) from the Aberdeen Birth Cohort 1936 (ABC1936) completed cognitive assessments including childhood intelligence (Moray House Test) and adult non-verbal reasoning (Raven's Progressive Matrices).
• ApEn was calculated from fMRI data to quantify regional signal entropy.

Main Results:

• Higher regional signal entropy was significantly associated with better cognitive performance (inspection time, Raven's Progressive Matrices).
• This relationship remained significant even after controlling for childhood intelligence.
• The association was dependent on current cognitive ability, suggesting entropy reflects ongoing cognitive processes.

Conclusions:

• Approximate entropy (ApEn) measured via fMRI offers a novel neuroimaging marker for individual differences in cognitive ability in older age.
• Brain signal entropy may reflect neural mechanisms underlying cognitive function and its variability in aging.
• Findings highlight the potential of fMRI-derived entropy measures for understanding cognitive aging trajectories.