According to research by neurologists, irregular arm swings while walking could be an early sign of Parkinson’s disease.
Parkinson’s disease is an age-related disorder involving loss of certain types of brain cells and marked by impaired movement and slow speech. The researchers believe early detection may help physicians apply treatments to slow further brain cell damage until strategies to slow disease progression are available. Parkinson’s disease is currently diagnosed by tremors at rest and stiffness in the body and limbs, but by the time the disease is diagnosed, about 50 to 80 percent of the critical cells called dopamine neurons are already dead.
The neurologists are studying gait, or the manner in which people walk, to understand the physical signs that might be a very early marker for the onset of Parkinson’s disease. They have confirmed that in people with Parkinson’s disease, the arm swing is asymmetrical. In other words, one arm swings much less than the other as a person walks.
“We know that Parkinson’s disease patients lose their arm swing even very early in the disease but nobody had looked using a scientifically measured approach to see if the loss was asymmetrical or when this asymmetry first showed up,” said study author Xuemei Huang. “Our hypothesis is that because Parkinson’s disease is an asymmetrical disease, the arm swing on one arm will be lost first compared to the other.”
The researchers compared the arm swing of 12 people diagnosed three years earlier with Parkinson’s disease, to eight people in a control group. The Parkinson’s disease patients were asked to stop all medication the night before to avoid influencing the test results. The team used special equipment to measure movement accurately, including many reflective markers on the study participants and eight digital cameras that captured the exact position of each segment of the body during a walk. “Images from the cameras were sent to a computer where special software analyzed the data” explained Huang. “When a person walks, the computer was able to calculate the degree of swing of each arm with millimeter accuracy.”
Analysis of the magnitude of arm swing, asymmetry and walking speed revealed that the arm swing of people with Parkinson’s disease has remarkably greater asymmetry than people in the control group, one arm swung significantly less than the other in the Parkinson’s disease patients. When the participants walked at a faster speed, the arm swing increased but the corresponding asymmetry between them remained the same. “We believe this is the first demonstration that asymmetrical arm swings may be a very early sign of the disease,” said Huang. While slightly irregular arm swing occurs in people without Parkinson’s disease, the asymmetry is significantly larger in those suffering from the disease.
References:
1. Xuemei Huang, et al. Arm swing magnitude and asymmetry during gait in the early stages of Parkinson’s disease. Gait & Posture, 2009. doi:10.1016/j.gaitpost.2009.10.013.
