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Gait-way to dementia
Tuesday November 13, 2012

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For many aging adults and their family members, the early signs of dementia can create an uneasy sense of dread as they foresee a future of themselves or their loved ones getting lost, forgetting appointments and eventually losing track of their own identities.

New research, however, suggests that evaluating the way a person walks may provide clues about that person’s brain years before he or she starts to show more noticeable signs of dementia. Early treatment can make a significant difference in prolonging cognitive function, according to research presented at the Alzheimer’s Association International Conference held in Canada in July.

“I feel that physical therapists are going to play a role in that early detection,” said Dina Drubach, PT, DScPT, who assisted in one of the studies presented at the conference. “In many cases, the patients may not pick up on the fact that their gait is changing, but physical therapists who know what to look for can identify a problem. Right now, people come to the doctor and say they got lost in the parking lot, and that is already 10 years too late.”

Speed and stride offer clues

Although changes in gait patterns are expected as people age, Drubach’s study at the Mayo Clinic in Rochester, Minn., explored which specific gait abnormalities may be associated with future cognitive decline. The researchers measured stride length, cadence and velocity of more than 1,300 subjects using a computerized gait instrument called the GAITRite System, manufactured by CIR Systems Inc. The study participants also took cognition tests to evaluate memory, executive functioning, language and visuospatial ability. Fifteen months later, they returned for repeat tests.

The researchers discovered that participants who experienced a reduction in walking speed and stride length between the two visits experienced significantly larger declines in executive function, memory and global cognition. This correlation is not surprising because walking is a highly complex cognitive and motor task which requires perfect integration of many parts of the brain, said Rodolfo Savica, MD, MSc, the lead researcher for the study.

Drubach said she believes that if PTs do not have access to instruments like those used in the study, the simple Timed Up and Go test could be effective, particularly if performed regularly over time. “I think the TUG test could be used to get a baseline for patients, and then it will be easier to detect a change six months later,” she said. “It’s also important to ask a family member if they are seeing changes in a patient’s gait pattern because the patient may not be able to perceive it.”

Tests that measure gait speed may help identify the risk for development of dementia, but formal tests can have one disadvantage: potential performance enhancement. Lisa Silbert, MD, MCR, an associate professor in the neurology department at Oregon Health & Science University, Portland, presented a study at the same conference that found walking speed tests may overestimate the walking abilities of the elderly.

The researchers installed infrared motion sensor detectors in the homes of 19 study participants. The sensors measured gait speed in the hallway 400 times during a one-month period, and these results were compared to speed clocked during a 9-meter walking test onsite. They found the study participants walked faster during the single test than during continuous in-home monitoring. They also found that participants with slower in-home walking speed had smaller brain sizes when measured using MRI.

“We know that the brain shrinks in certain diseases associated with cognitive impairment, so in-home monitoring may be a better reflection of brain health,” Silbert said.

Silbert’s findings suggest that PTs who see patients regularly may be able to detect changes over time. Any signs of slowed walking can be followed up with other simple tests to identify the root of the problem. “There can be many reasons why gait speed can be affected, but if people struggle with dual tasking, then that can be an early warning sign,” she said. “For example, if someone’s walking falls apart when you ask them to count or do a simple math problem while walking, then this may be an indication to start asking questions about subtle changes in their memory or thinking.”

Benefits of early detection

Research suggests that early intervention may slow the progression of dementia. Teresa Liu-Ambrose, PT, PhD, an assistant professor in the department of physical therapy at the University of British Columbia,Vancouver, recently studied whether resistance training improved cognitive function in women with signs of mild cognitive impairment. Twice a week for six months the women in one group participated in resistance training for their upper and lower bodies. These results were compared to those from a group that performed aerobic exercise, and another that performed tone and balance exercises.

“Not all older adults have the ability to do aerobic activities, so we looked at whether resistance training can have similar benefits, and surprisingly we found that it does,” Liu-Ambrose said. “It improved not only their cognitive performance, but it also led to positive changes in three regions of the brain according to functional MRI results.”

PTs may encounter patients at risk when they seek treatment for such problems as back pain or repeated falls. For Colin Hoobler, PT, DPT, of C.H. Physical Therapy in Portland, Ore., these encounters are opportunities to provide valuable education and help. Hoobler teaches patients with dementia that it is important to challenge themselves using adequate intensity measured by RPE (rate of perceived exertion.) For example, using a scale of zero to 10, he suggests that patients push themselves to a six or seven when performing as few as three simple exercises: squats, knee push-ups and calf raises.

Hoobler said he witnessed the cognitive benefits of exercise when he started seeing a 68-year-old man with moderate Alzheimer’s who suffered from back pain. When the man first arrived, his wife explained that he would forget things she had recently told him and the names of friends he had just visited. This patient was highly motivated to improve not only his back, but also his mental function. He regularly practiced his strength and endurance program at home, and after just six weeks, his forgetfulness had improved significantly — along with his back pain.

“The most tragic part is that exercise is one of the most powerful forms of medication available for Alzheimer’s, but there is no standardized exercise course for our profession,” Hoobler said. “It’s fascinating to see areas of life improve for the patients who use it. Some can remember names, where they put things and rediscover the courage to initiate conversations.” •

Heather Stringer is a freelance writer.


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Tuesday November 13, 2012
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