Increased functional connectivity supports language performance in healthy aging despite gray matter loss

Area of Science:

• Neuroscience
• Cognitive Aging
• Brain Imaging

Background:

• Language function is generally preserved in aging.
• The impact of aging on language functional networks remains unclear, with possibilities of deterioration or reorganization.
• Understanding age-related changes in language networks is crucial for cognitive health.

Purpose of the Study:

• To investigate age-related differences in language functional networks using resting-state functional magnetic resonance imaging (rs-fMRI).
• To examine the relationship between brain structure, functional connectivity, and language performance in younger and older adults.
• To explore potential reorganization within and between language networks and the multiple-demand system in healthy aging.

Main Methods:

• Recruited 23 younger adults and 24 healthy older adults.
• Assessed volumetric gray matter differences using voxel-based morphometry.
• Performed seed-based analyses, integrated local correlations, and within- and between-network connectivity analyses.

Main Results:

• Older adults exhibited differences in language networks, including increased connectivity both inside and outside the language network, despite widespread gray matter atrophy.
• Integrated local correlation analyses revealed subtle alterations not detected by other methods.
• Gray matter loss did not correlate with language performance, but connectivity differences positively correlated with fluency in older adults.

Conclusions:

• Healthy aging involves language network reorganization with enhanced internetwork connections, rather than deterioration, which may explain preserved language abilities.
• These findings contrast with other cognitive networks in aging, suggesting unique adaptive mechanisms for language.
• The observed brain reorganization aligns with the scaffolding theory of aging and cognition.