Simple Walking Test Helps Diagnose Treatable Cause of Dementia

February 27, 2018

A simple walking test may help identify one cause of dementia that may be reversible but is often misdiagnosed, a new study suggests.

Idiopathic normal-pressure hydrocephalus (iNPH) is estimated to affect about 2.7 million people in the United States and Europe. It is caused by excess fluid in the brain and can often be reversed with the insertion of a ventriculoperitoneal shunt. However, it is usually not diagnosed because it shares symptoms with other neurologic conditions, such as walking and balance dysfunction and cognitive impairment.  

The other condition most often confused with iNPH is progressive supranuclear palsy (PSP), a neurodegenerative disease with no cure.

Researchers from Germany have reported new results suggesting that these two conditions can be distinguished from each other by a dual-task walking test. This involves assessing how fast a person can walk while doing something else at the same time, such as counting backwards or carrying a tray.

The study was published online on February 21 in Neurology.

"iNPH is one of the rare causes of a potentially treatable and reversible dementia syndrome and gait disorder, but it is still underdiagnosed," lead author, Charlotte Selge, MD, Ludwig Maximilian University of Munich, Germany, told Medscape Medical News.

"It is important that iNPH is accurately diagnosed as treatments are available," she added. "A simple walking test may help determine if a person has iNPH or PSP relatively early in the course of the disease. Our study found that adding another task while someone walks, and evaluating how it affects their walking ability, improves accuracy of the diagnosis."

The study included 27 patients with iNPH, 38 patients with PSP, and 38 healthy individuals matched by age and sex.

For the test, all participants walked along a 22-foot-long pressure-sensitive carpet to assess their gait. They were asked to walk at three different speeds and then to also perform another task involving cognitive function, counting backwards, or motor function (carrying a tray).

Results showed that the cognitive dual task showed a greater reduction of walking speed in those with PSP than in those with iNPH. Walking speed was reduced by 34% in those with PSP and by 17% in those with iNPH.

In addition, when patients were engaged in the motor dual task, gait worsened for those with PSP but actually improved for those with iNPH.

"People with PSP appear to be more sensitive to these dual-task walking tests than people with iNPH," Selge said.

By just assessing gait, researchers were able to accurately differentiate between patients with PSP and those with iNPH 82% of the time. But when both dual-task tests were added to the assessment, diagnostic accuracy increased to 97%.

"Our findings suggest that adding these dual-task tests would be an inexpensive and effective way to improve diagnosis of iNPH," Selge concluded.

"Future studies may want to increase the complexity of tasks to see if they provide even more accuracy, as well as insight into how the two diseases affect gait," she added.

The study was supported by the German Federal Ministry of Education and Research.

Neurology. Published online February 21, 2018. Abstract

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