Tel Aviv University team studies why patients with Parkinson’s disease have difficulty transitioning from walking to sitting, leading to greater instability and falls
People with Parkinson’s disease — a debilitating degenerative disorder that affects the motor system, causing tremors, shaking and rigidity — are known to have difficulty in turning around and then sitting down.
A new Tel Aviv University study provides an understanding as to why these patients may have difficulty transitioning from walking though turning around to sitting. The results suggest new ways to help improve the rehabilitation of these kind of patients.
“Parkinson’s patients can be challenged when they try to turn as they walk,” said Prof. Jeffrey Hausdorff of Tel Aviv University’s Sackler Faculty of Medicine and the Center for the Study of Movement, Cognition, and Mobility at Tel Aviv Sourasky Medical Center.
While most healthy older adults turn and then sit in a precise sequence that clearly distinguishes the two components of the task, in contrast “we found that most Parkinson’s patients start to sit while they are still turning,” he said.
“We originally speculated that, when transitioning from a walking or standing position to a sitting position, people with Parkinson’s would first turn and then start the process of sitting,” Hausdorff said. “But we found that this wasn’t true.”
The research was led by Hausdorff in collaboration with Prof. Anat Mirelman and Prof. Nir Giladi, also of the university and the Tel Aviv Medical Center, and colleagues at Rush University in Chicago. It was published in January in the journal Gait & Posture.
According to the study, when healthy older adults turn to sit, about 80 percent of them complete the turn before starting to sit, in what the researchers called a “distinct strategy.” But in about 20% of the subjects, part of the turning and sitting take place at the same time, in what the researchers called an “overlapping strategy.”
The researchers evaluated the strategies employed by people with Parkinson’s as they transitioned from standing through turning to sitting. In one experiment, 96 participants with Parkinson’s, assessed both on medication and after its effects wore off, were asked to turn to sit while wearing a body-fixed sensor. The researchers then quantified the turning-to-sitting transition and determined whether the distinct or the overlapping strategy had been employed. The use of the sensor revealed subtle but important distinctions that were previously overlooked based on visual observation alone.
The scientists then stratified the cases, using models adjusted for age, gender, height and weight, to identify the associations with their sitting strategies and with the Parkinsonian characteristics and cognition.
“Interestingly, we found that the individuals who employed the overlapping strategy experienced more severe postural instability compared to those who used the distinct strategy,” Hausdorff said.
They also found that anti-Parkinsonian medications did not affect the strategy choice, “suggesting that the decision may be regulated by networks and brain areas that are less directly affected” by the drugs.
Hausdorff said that it is important for people who suffer from Parkinson’s disease and their physical therapists and others to be aware of this issue.
Based on the study, he said in an emailed comment to The Times of Israel, “one can speculate that some of the rehabilitation and continuous care process should be devoted to teaching people with Parkinson’s that when they are turning to sit down, they should break the process into two separate pieces: first turn, briefly stop, and then sit down.”
“This is the way that healthy young and healthy older adults generally carry out this common task,” and they are much less prone to falls than people with Parkinson’s disease, he said.
Stopping along the turn “may, therefore, be safer and less prone to problems than doing this movement all at once,” he said.
Even so, he added, “it remains to be seen” if interventions designed to make this change in the turning process are indeed effective.