Minimal Detectable Change in Dual-Task Cost for Older Adults With and Without Cognitive Impairment

Area of Science:

• Gerontology
• Rehabilitation Science
• Cognitive Neuroscience

Background:

• Dual-task (DT) training is a common intervention for balance and mobility issues in older adults.
• Minimal detectable change (MDC) is crucial for distinguishing true improvements from measurement error in clinical settings.
• Limited research exists on DT reliability and MDC in older adults with cognitive impairment (CI).

Purpose of the Study:

• To determine the test-retest reliability and MDC for dual-task cost (DTC) in older adults with and without cognitive impairment.
• To examine how varying DT difficulty affects DTC reliability and MDC.
• To provide data for clinicians using DT training for older adults.

Main Methods:

• Fifty older adults (≥65 years) completed two test sessions within 7-19 days.
• Participants were categorized into high (MoCA ≥ 26) and low (MoCA < 26) cognitive groups.
• Gait data were collected using a pressure-sensing walkway during four DTs (TUG and SSWS with two secondary tasks), and DTC was calculated.

Main Results:

• Intraclass correlation coefficients (ICCs) for DTC ranged from 0.02 to 0.76.
• MDCs were generally larger for individuals with low cognition and for more challenging DTs (e.g., backward counting).
• Individuals with low cognition exhibited greater DTC, and more difficult tasks (TUG3, SSWS3) showed greater DTC than easier tasks (TUG1, SSWS1).

Conclusions:

• This study provides essential MDCs for DTC in older adults undergoing DT training.
• Clinicians should expect larger DTC changes in individuals with low cognition and for more complex DTs to confirm real improvement.
• Cognitive status and task difficulty are critical factors to consider when interpreting changes in DTC during DT interventions.