Walking can be troublesome for people with multiple sclerosis. Trying to dual task while walking can cause cognitive impairment.

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Researchers say people with multiple sclerosis can have trouble trying to dual task while walking. Getty Images

Multitasking while walking will slow anyone down, but this dual action can pose greater risks to those with multiple sclerosis.

This cognitive-motor impairment can be caused by moving from one task to two tasks, something called the dual-task cost.

Assessing this difficulty may provide better insights into the lives of people with multiple sclerosis (MS).

About 90 percent of people with MS experience walking difficulties within the first 10 years after diagnosis.

During the same time, between 40 percent and 70 percent experience cognitive difficulties.

These problems affect day-to-day living and, therefore, the quality of life for those living with MS.

A recent systematic review out of Spain found ways to identify and describe cognitive-motor interference as a tool for assessing patients with MS.

Experts measured the effect of this interference on walking, and found the motor variables most sensitive to be speed, cadence, and double support.

MS patients showed significant problems with cognitive-motor impairment when asked to dual task.

“People with MS have much to gain from [this] study,” said Kathy M. Zackowski, PhD, OTR, senior director of patient management, care, and rehabilitation research at the National Multiple Sclerosis Society.

“The study of cognitive-motor interference focuses on the idea that real-life activity requires a motor component and a cognitive component,” Zackowski told Healthline. “For example, you don’t just walk in a straight line. You walk to the store or you walk to school. This requires motor patterns as well as executive function.”

“However, many studies only focus on one of these attributes (motor or cognitive), and interventions often improve that attribute but not both,” she added. “Learning more about how the cognitive and motor impairments interact has the potential to lead to more effective rehabilitation interventions.”

It’s not just people with MS who have trouble multitasking.

“One finding was that gait speed is very sensitive to cognitive interference,” said Prue Plummer, associate professor of physical therapy at the University of North Chapel at Chapel Hill. “But so do healthy people. This doesn’t differentiate MS from other people.”

“This is not new information,” Plummer told Healthline. “What is specific to those living with MS was the need to have both feet on the ground longer than a regular walker.”

This is called “double limb support.”

“Both feet on the ground balances you but slows you down. Healthy people slow down but not going to two-foot walking,” she added.

“The review was an organized analyses, as descriptive as possible, about the dual aspects that have been looked at,” said Plummer.

In the study, experts scanned 1,540 articles for eligibility to make this review. Thirty-one were used for the analyses.

The review separated out tasks by type of cognitive task.

“This is a relatively new area of research for people with MS,” Plummer said.

The main cognitive tests given were verbal fluency, counting backward, alternate letters of the alphabet, and a serial subtracting test.

Counting backward was not difficult enough to determine walking problems.

Both alternate alphabet and serial subtracting exams showed sensitivity to impairment for both MS and healthy subjects.

But, verbal fluency was both sensitive and specific to impairment in MS.

Verbal fluency tests might include asking a patient to list all fruits and vegetables starting with a specific letter in 60 seconds while walking.

The alternating alphabet test has the patient cite alternating letters of the alphabet while walking.

The serial sevens test asks the patient to start at 100, then continuously subtract 7, while stating the answer.

These tasks require a certain part of the brain, specifically the frontal cortex.

The frontal cortex is also an area shown to be susceptible to changes in cognition that affect patients with MS.

“We know cognitive function affects walking. There is not strong evidence that it is related to more falls. But it slows down walking and affects quality of life and might have implications for safety,” Plummer explained.

“We can’t tell people to not walk and talk. So, improving cognitive tasks in supervised therapy can have some benefits,” Plummer said.

Plummer discussed clinical practices as a result of the review.

For safety, practicing cognitive skills while walking should be held under supervised conditions.

In addition, medical professionals can make patients aware of what is happening while they’re walking and can help them be more cautious.

“Conceptually, the issue of cognitive-motor interference makes a lot of sense, but careful research is needed to know how to address [this] issue,” Costello told said.

“The MS community needs to push scientists to study mechanisms that explain why movements and cognition fail in MS,” Costello added. “This is key to the development of more effective rehabilitative interventions.”

Editor’s Note: Caroline Craven is a patient expert living with MS. Her award-winning blog is GirlwithMS.com, and she can be found on Twitter.