MINIMAL DETECTABLE CHANGE IN DUAL-TASK COST FOR OLDER ADULTS WITH AND WITHOUT COGNITIVE IMPAIRMENT

BACKGROUND & OBJECTIVE

Dual Tasking occurs when an individual performs two concurrent tasks that could be performed independently. Each task has a separate goal and assessment. Typically, it includes one motor task, such as walking, and either a secondary motor task (e.g. carrying an item) or a cognitive task (e.g. thinking about the groceries you need to buy). As we age, our ability to dual task significantly declines.

For older adults, dual tasking requires increased attention to one or both tasks resulting in decreased performance of one or both tasks. This type of decrement is called dual task cost (DTC) and is highly correlated with fall risk. When an individual develops a cognitive impairment (CI) their ability to complete each component of a dual task decreases significantly, affecting DTC exponentially. The effect of aging/cognition on DTC and its strong correlation to falls risk highlights the importance of DTC assessment in all older adults. DTC can be assessed during Self-Selected Walking Speed (SSWS) and Timed Up and Go (TUG) tasks. See Box 1 for the DTC formula and an example.

Box 1: Dual Task Cost

This article examined test-retest reliability and minimal detectable change (MDC) values for DTC in older adults with and without cognitive impairments, as well as for dual tasks of varying difficulty.

METHODS

Design: test-retest design Subjects: adults 65 years and older who were able to walk at least 10 meters independently and see enough to complete cognitive testing. They were excluded if they had Parkinson's disease or if they were receiving physical therapy for balance or gait. Assessment: 2 testing sessions 7-14 days apart

Assessing Cognition: Montreal Cognitive Assessment (MOCA). Participants were categorized into high (MOCA score ≥ 26/30) and low (MOCA score < 26/30) cognitive groups.

Assessment:

• Single motor task: 6-meter SSWS (3-meter acceleration and deceleration) and TUG

• Single cognitive task: counting forward by ones starting at a random number between 10 and 20 and counting backward by threes starting at a random number between 70 and 90.

• Dual Task - combined cognitive and motor tasks:

  * SSWS1: SSWS while counting forward by ones
  * SSWS3: SSWS while counting backward by threes
  * TUG1: while counting forward by ones
  * TUG3: TUG while counting backward by threes

RESULTS

Difference between High and Low Cognitive Groups:

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