# Verbal Fluency Dual-Tasks Show Greater Age-Related Cognitive-Motor Interference: A Meta-Analysis of Walking Performance

## TL;DR

Older adults show more difficulty walking while doing verbal tasks, suggesting age-related issues with combining thinking and movement.

## Contribution

This study identifies verbal fluency as a unique cognitive task that increases dual-task costs in older adults compared to younger adults.

## Key findings

- Older adults had greater dual-task costs during walking with verbal fluency tasks than younger adults.
- Verbal fluency tasks showed larger age-related differences compared to serial subtraction tasks.
- The findings suggest verbal fluency impacts brain circuits involved in both language and gait control in older adults.

## Abstract

A substantial body of literature has examined gait during cognitive dual-tasking in younger and older adults. However, it remains unclear how, and to what extent, different cognitive tasks uniquely influence gait. This meta-analysis quantified age-related differences in gait speed during dual-task walking. Importantly, we examined cognitive task as a potential moderator. We searched Web of Science for studies comparing young and older adults during single-task and dual-task walking conditions. Twenty-two studies met the inclusion criteria, representing 544 young adults (mean age range: 20–31 years) and 511 older adults (mean age range: 62–85 years). Studies employed primarily serial subtraction tasks (n = 12) and verbal fluency tasks (n = 8); however, one study used digit vigilance, and another used a texting paradigm during walking. Random-effects meta-analysis using standardized mean differences (Hedges’ g) revealed a significant overall effect (g = −0.2612, 95% CI [−0.4914, −0.0310], p = 0.0261), indicating greater dual-task costs in older adults compared to younger adults with a small to medium effect size. Substantial heterogeneity was observed across studies (I2 = 66.53%, p < 0.0001). Subgroup analysis demonstrated that verbal fluency tasks produced a larger and statistically significant age-related difference (g = −0.4744, 95% CI [−0.8712, −0.0777], p = 0.0191), while serial subtraction tasks showed smaller, non-significant effects (g = −0.1412, p = 0.3474). These findings suggest that verbal fluency creates unique neural resource competition in older adults, involving prefrontal, cerebellar, and basal ganglia circuits that support both language production and gait control. The task-specific vulnerability to verbal fluency, and not serial subtraction, provides evidence for age-related changes in cognitive-motor integration. Rehabilitation strategies targeting executive functions may be effective for maintaining mobility in aging populations.