Persons with Parkinson’s disease (PwP) fall a lot! In fact, they are three times more likely to fall then persons their same age without Parkinson’s. (1,2) Why is this? Recurrent falls in persons with idiopathic Parkinson’s disease (PD) are often attributed to deficits in postural stability, gait, saccades, and cognition. When completing two things at one time or dual tasking while walking, PwP demonstrate decreased step length and velocity, as well as increased double-support time and freezing of gait. (3)

Currently there are no clinical tests that assess the PwP’s ability to safely complete the dual task of walking, scanning, and processing the environment accurately and safely. Just having a PwP turn their head while walking such as in the Functional Gait Assessment (FGA) is not enough to understand the interplay of vision and cognitive challenge. The visual-verbal Stroops test can be used to measure a person's selective attention capacity and processing speed. (4)

Recently a cohort study was conducted (spring of 2022) to assess the PwP’s ability to safely complete the dual task of walking 10 meters while scanning, reading, and verbally reporting visual-verbal Stroops (e.g. the word “RED” is colored blue and the participant needs to state the color, not the written word). Twenty PwP, (average age 73) and 20 older adults (average age 71) were compared to 20 younger adults (average age 29) as they completed this timed dual task assessment. 

The results showed that the older adults without Parkinson’s were faster than PwP and made fewer errors. In fact, although the older adults were typically slower than the younger adults, the older adults without Parkinson’s made the same number of errors as the younger adults.  The PwP made more errors and were slower than the older adults without Parkinsons. These errors in processing while walking are one of the reasons PwP fall more often as their ability to attend to a task is reduced without completing specific types of dual task practice. Research has shown, with a lot of practice, PwP can improve their ability to perform dual tasks while walking equal to adults their same age without Parkinson’s.

Currently, there are no clinical tests that assess a PwP’s ability to complete the dual task of visual scanning and accurately processing their environment while walking safely. The new 10-meter walk test with visual-verbal Stroops may be able to assess PwP’s ability to safely navigate in the community. This test is completed on a 14-meter walkway with visual Stroops placed at eye level every 7 feet along the 14 meters.  The participant will then walk as quickly and safely as possible while alternately turning their head from side to side, reading the placed word and reporting their answer.  The middle 10 meters of the 14-meter walkway are timed and errors counted. The authors recommend a baseline 10-meter walk test time be taken and compared to the second trial of the 10-Meter walk test with visual-verbal Stroops as the first trial is used as a practice test. Current data shows on average, there is not more than a 10% difference between the 10-meter walk test and the 10-meter walk test with visual-verbal Stroops in the young and older adult participants with zero errors. For PwP, the average increase in time between these two tests is over 20% difference with the average amount of errors equaling two. An error is counted if the participants begin to say or says the word and not the color of the word.

Before completing the 10-meter walk test with visual-verbal Stroops, it is necessary for clinicians to complete tests and measures that can accurately assess the PwP’s cognitive capability in a single cognitive task without the gait task involved.  Therefore, the PwP needs to complete a sitting visual verbal Stroops test, either on paper or on a computer, to determine their capability to complete this task before adding gait.  This way the clinician can receive a baseline for the single task and gain an understanding of the PwP’s cognitive capabilities to complete incongruent cognitive tasks.  This paper or computer-based test will start with a congruent cognitive challenge (the word and the color match) and then will progress to an incongruent challenge where the word and the color do not match.  This way you can see how well the PwP performs on the single task before adding the gait/dual task challenge of the 10 Meter Walk test with visual-verbal Stroops.

It is critical for clinicians to accurately assess a PwP’s dual task capability to move in and process their environment safely. Knowing that PwP are slower and make more errors than healthy older and young adults while completing the 10-meter walk test with visual-verbal Stroops, can help us to understand how to create interventions that might be able to reduce falls in PwP. Further, this new test can be used to evaluate effects of interventions that target dual task practice and the relationships of dual tasking and falls in PwP.

1. Creaby, M. W., & Cole, M. H. (2018). Gait characteristics and falls in Parkinson's disease: A systematic review and meta-analysis. Parkinsonism & related disorders, 57, 1-8.

2. Raffegeau, T. E., Krehbiel, L. M., Kang, N., Thijs, F. J., Altmann, L. J., Cauraugh, J. H., & Hass, C. J. (2019). A meta-analysis: Parkinson's disease and dual-task walking. Parkinsonism & related disorders, 62, 28

3. Monaghan, A. S., Johansson, H., Torres, A., Brewer, G. A., & Peterson, D. S. (2022). The impact of divided attention on automatic postural responses: A systematic review and meta-analysis. Experimental Gerontology, 162, 111759.

4. Yang, Y. R., Cheng, S. J., Lee, Y. J., Liu, Y. C., & Wang, R. Y. (2019). Cognitive and motor dual task gait training exerted specific training effects on dual task gait performance in individuals with Parkinson’s disease: A randomized controlled pilot study. PloS one, 14(6), e0218180.

Valerie Carter PT, DPT, NCS, GCS (Neurologic and Geriatric Certified Specialist) is a Clinical Professor at the Northern Arizona University Department of Physical Therapy and Athletic Training. She was an abstract presenter at the WPC 2023 in Barcelona.

Ideas and opinions expressed in this post reflect that of the author solely. They do not reflect the opinions or positions of the World Parkinson Coalition®