Age-Related Differences in Resting-State Functional Connectivity Predict Specific Patterns of Speech Disfluency

Area of Science:

• Neuroscience
• Cognitive Aging
• Speech Production

Background:

• Fluent speech is generally maintained in adulthood, but subtle disfluencies increase with age.
• These changes may stem from cognitive and neural alterations, including executive function (EF) and brain network organization.

Purpose of the Study:

• To investigate if executive function (EF) and resting-state functional connectivity (RSFC) explain age-related speech disfluencies.
• To examine the independent and joint contributions of EF and RSFC to naturalistic speech disfluencies across the adult lifespan.

Main Methods:

• Assessed speech disfluencies, EF, and RSFC in 252 adults (ages 20-81).
• RSFC analyzed network segregation in language, default mode (DMN), and multiple demand (MD) networks.
• Examined age-related differences and relationships between cognitive/neural measures and disfluencies.

Main Results:

• Older age correlated with more disfluencies (pauses, repetitions, revisions), lower EF, and reduced network segregation (language, DMN, MD).
• EF did not predict or mediate age-related disfluencies.
• Higher DMN segregation predicted fewer disfluencies, with age moderating this link for repetitions.

Conclusions:

• While EF may relate to planning, altered brain functional organization, specifically DMN segregation, more directly impacts age-related speech disfluencies.
• DMN segregation partially mediated the age-related increase in revisions, suggesting a role in self-monitoring.
• Brain network changes are key to understanding age-related speech disruptions.