Dawn Venema, PT, PhD is an assistant professor in the Division of Physical Therapy Education at the University of Nebraska Medical Center. Her clinical experience as a physical therapist and research interests focus on balance and mobility in older adults.
ElderBranch interviewed Dr. Venema to discuss her paper, “Tasks matter: a cross-sectional study of the relationship of cognition and dual-task performance in older adults.” Dr. Venema wrote the paper along with Dr. Emily Bartels and Dr. Ka-Chun Siu, both also of the University of Nebraska Medical Center.
What led you to research this topic? Why is it important, and how does it augment previous work on the topic?
I first became interested in the impact that dividing attention had on quality of movement when I was a practicing physical therapist. Much of my clinical experience involved working with older adults to improve their balance and mobility, and therefore, reduce their risk of falling. Many of my patients had to really concentrate on walking, rather than having this movement be automatic.
For some people, even if they were simply trying to engage in a conversation at the same time they were walking, they would become unsteady, slow down, or even have to stop moving. It may sound silly, but some people had trouble walking and talking at the same time. The term we use for this phenomenon in research is “dual-tasking,” which simply means doing two things at once so that your attention is divided. Dual-tasking is something that we need to do often in daily life. Some other examples beyond walking and having a conversation include carrying a glass of water up the stairs without spilling it, or walking through the grocery store trying to remember your shopping list.
As I moved through my career and became trained in research, I maintained my interest in this phenomenon. There is a lot of research evidence to supplement my clinical impression that some older adults have trouble dual-tasking. This difficulty is even more pronounced in individuals who have cognitive impairment, such as those with Alzheimer’s disease. There is a small, but growing, body of research that shows some promise that the quality of movement during dual-tasking can be improved with dual-task training (combining movement and thinking exercises).
However, only one study that my research team knows of has studied the effects of dual-task training in individuals with cognitive impairment. Our current study was done to describe the problem more thoroughly, and determine how the difficulty of the tasks impacts the relationship between cognitive level and dual-task performance. The level of difficulty of training exercises is one parameter that must be selected when designing a training program such as this.
Please describe your study – what were your hypotheses and how did you test these?
Our research team hypothesized that the relationship between dual-task performance and cognitive level would be linear. A linear relationship would mean that the deterioration in performance under dual-task conditions relative to single-task conditions (such as walking without doing an additional task) would steadily increase as cognitive level decreased. We also hypothesized that the level of difficulty of combined tasks in a dual task condition would impact the strength of this linear relationship.
To test our hypotheses, we enrolled 23 older adults (≥ 65 years old) with a wide range of cognitive levels. Some individuals lived independently in their own homes. Others had cognitive impairment severe enough that they were living in secure memory-support assisted living communities.
All individuals completed all study activities during a single test session. Individuals first completed the Mini-Mental State Examination. This is a cognitive test that is commonly used in health care to screen for dementia. This test was used to describe the cognitive level of individuals in our study.
Individuals then completed two timed movement tests. The first movement test was the “Timed Up and Go,” which involves standing up from a chair, walking 10 feet, turning, and returning to the chair. The second movement test was “Self-Selected Walking Speed,” which involves simply walking across the room at a comfortable pace. The Timed Up and Go is the more complex movement task of the two, because it involves getting in and out of a chair and changing direction, in addition to straight-line walking.
Lastly, individuals performed each of the movement tasks while doing simultaneous cognitive tasks: counting forward by 1’s (the easier cognitive task) and counting forward by 3’s (the harder cognitive tasks). This created 4 different dual-tasks, with the easiest task being Self-Selected Walking Speed while counting forward by 1’s, and the hardest task being the Timed Up and Go while counting backwards by 3’s. Performance for the 4 different dual tasks s was calculated as the difference in speed between dual- and single-task conditions. Performance was then correlated with scores on the Mini-Mental State Examination to determine if linear relationships existed between dual task performance and cognitive level, and if so, how strong these relationships were.
What were the key findings from your research?
We found linear relationships between dual-task performance and cognitive level for 3 of the 4 dual-task combinations: Timed Up and Go and counting forward by 1’s, Timed Up and Go and counting backwards by 3’s, and Self-Selected Walking Speed while counting backwards by 3’s. For these tasks, the amount of deterioration in performance under dual-task conditions relative to single-task conditions increased as cognitive level decreased, which suggests that walking isn’t just an automatic process, especially for those with cognitive impairment.
We did not find a linear relationship between dual-task performance and cognitive level for the easiest dual-task: Self-Selected Walking Speed while counting forward by 1’s. This suggests that this task may be too easy to be considered a viable candidate for a task that could be used in training programs. It may not challenge anyone enough, regardless of their cognitive level, to have a training effect.
Lastly the fact that we found linear relationships for the 3 more difficult tasks suggests that people with cognitive impairment may be able to engage in more challenging tasks than might be assumed. If they were unable to even attempt the dual tasks in our study, we believe that we would not have seen linear relationships, or perhaps we would have observed a sharp deterioration in dual task performance at a certain cognitive level, rather than a general, linear decline.
What are the implications from your findings? Do you have any specific recommendations as a result of your work?
Physical therapists should be aware that patients’ movement will worsen under dual-task conditions, more so for older adults with cognitive impairment, and particularly when more challenging combinations of tasks are used. As such, physical therapists may need to educate other caregivers about the impact dual-tasks may have on the safety of patients with cognitive impairment during movement.
On the contrary, if a physical therapist wants to assess a patient’s dual task ability, more complex combinations of tasks might be more informative, as excessively easy combinations of tasks may not produce enough challenge. In fact, for patients with cognitive impairment, our data suggest that physical therapists should not underestimate these patients’ ability to engage in harder dual-tasks.
What are the next steps to further your work in this area?
We have already completed a small pilot study of dual-task training in 5 individuals with diagnosed dementia. Three individuals completed a more challenging version of the training, while 2 individuals completed a less challenging version of the training. The more challenging version of the training showed more consistent and greater gains in dual task ability than the less challenging version of the training. We are currently writing a manuscript with these results to submit for publication.
We are also currently collecting data for a study that replicates our first one, but adds more sophisticated analysis of individuals’ walking patterns beyond the measures of time and speed used in our first study. Many of the walking patterns that we will be analyzing in this current study provide information about how steady people are when they walk.