Abstract
This dissertation examines cognitive-motor dual-task (DT) interference during walking. Guided by three aims, this work examines the differential effects of four memory tasks during DT walking, two involving auditory memory encoding (story memory, list learning encoding) and two involving verbal memory retrieval (verbal fluency, list learning retrieval)—on gait and cognitive performance under DT conditions. Aim 1 compares the impact of these memory tasks on gait and cognitive outcomes and quantifies cognitive-motor interference (CMI). Aim 2 characterizes CMI patterns based on task type and difficulty. Aim 3 examines how CMI differs across younger, middle-aged, and older adults. A cross-sectional design measured gait parameters and memory performance during single-task (ST) and DT conditions. Dual-task effect (DTE) was calculated to quantify interference. Chapter Two (N=37, mean age=65.14±10.2) addresses Aim 1. All DT conditions reduced gait metrics compared to ST walking and impaired memory relative to ST conditions. Retrieval tasks caused greater gait decline than encoding tasks, with list retrieval producing the highest interference. More challenging memory tasks led to higher memory interference. Chapter Three (same sample) addresses Aim 2. Challenging tasks (list encoding/retrieval) induced mutual interference (affecting gait and cognition), whereas less demanding tasks (story memory/verbal fluency) primarily affected gait. Overall, gait was more susceptible to interference than memory. Chapter Four (32 younger mean age=25.2±2; 18 middle-aged mean age=56.2±5.8; 19 older mean age=73.6±4.6) addresses Aim 3. Older adults had greater DT gait declines and motor interference than younger adults, with middle-aged adults showing intermediate effects. Memory interference was similar across age groups. CMI seems to change with aging incrementally. Chapter Five synthesizes these findings, underscores their clinical significance in assessment, fall risk management, and rehabilitation, and suggests directions for future research.