This home sensor monitors Parkinson’s symptoms

A home monitoring system can help overcome some of the challenges of caring for patients with Parkinson’s disease. Because people with the neurological condition are often elderly and may require assistance with travel, it can be difficult to get specialized care in medical centers. But installing radio sensors allowed researchers to monitor the progress of their symptoms, and even changes in medication, all without the patients having to leave the comfort of their homes. The results were described in the journal Science Translational Medicine on Wednesday.

Parkinson’s is a progressive neurological disorder that affects the whole body but is best known for its impact on mobility – it often manifests first as muscle stiffness and can progress to tremors, weakness and other impediments to movement. About one million Americans are living with the disease, while only 60 percent of Parkinson’s patients on Medicare see a neurologist or other specialist. “We ask a lot of the patient community,” said James Beck, the scientific director of the Parkinson’s Foundation, who was not involved in the study.

The standard assessment of the disease is highly subjective and time-consuming, said Yingcheng Liu, a doctoral candidate in machine perception and health care at the Massachusetts Institute of Technology and the study’s lead author. “We can’t really ask patients to come to the clinic every day or every week,” Liu says. “This technology gives us the ability to continuously monitor patients and provide more objective assessments.”

The approach of the new study involves installing a sensor the size of a picture frame on the walls of 50 people at home: 34 with Parkinson’s and 16 without. The sensor produces radio waves, such as an ultra-weak Wi-Fi signal, which act like a radar that detects people. The researchers used that radar to track walking speed, which they averaged over hours or days to measure a patient’s mobility.

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“There are many different sensors” in development to track Parkinson’s disease, including smart watches and phone apps, Beck says. “The interesting thing about this approach is that it is completely passive. … To be able to track how a person moves in near real time is really exciting.”

The researchers compared mobility at home with common Parkinson’s clinical measurements. After controlling for age and other factors influencing gait, the research team found that a patient’s gait speed, as detected by the sensor, was closely related to an in-depth assessment of the disease: the motor exam portion of a comprehensive test for Parkinson’s, in which a patient’s hand movements, speech and gait are assessed. Rapid evaluations that doctors often use, such as timing someone while they’re out of a chair, don’t align very well with this test.

The home monitor helps prevent the so-called ‘white coat effect’. “When we do a test for a doctor, we try to perform as best we can,” says Liu. A short test in the clinic might reflect a person’s best effort, but not their stamina – kind of like finding the maximum speed of a car, but not the mileage.

The home gait measurements also detected decreases in patient mobility well before clinical measurements could detect the decreases. Everyone’s walking speed decreased over the course of the year-long study, but Parkinson’s patients went twice as fast — progression undetectable on the comprehensive exam.

Gait is just one approach to measuring that day-to-day function, and previous work with the device has shown it can capture a person’s entire silhouette as well — Liu says they’re curious to see if it also captures stride length and hand movements or other motor functions.

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The home monitor could also improve treatment for the disease, the researchers say. Although Parkinson’s is incurable, its symptoms can be managed with a drug called levodopa.

“Basically, when the patient takes this drug, their movement and cognitive function get better,” says Liu. But the effect disappears at different rates for different people. And the drug can cause side effects, including involuntary movements. “I liken it to drinking coffee,” says Liu: too little and you get migraines; too much, and you become nervous and anxious. So patients and doctors need to figure out the optimal dose and timing. “The traditional way to do that is to write in a journal every 30 minutes for two weeks,” says Liu. He says he tried to keep a diary this way, just to understand what the evaluation looked like for a patient. “It’s really heavy.”

Daily gait measurements may allow a physician to see the effects of medication adjustments more clearly. In the study, “when we compare the patient’s walking speed with the diary, we see that they correlate,” Liu says. The study was observational, so the researchers did not intentionally adjust the patients’ medication, but two patients changed their medication schedule over the course of the study. Those changes were reflected in their walking speed every day — they had fewer dips from low mobility. “The doctor might look at this fluctuation curve and try to change the dosage little by little.”

Beck says clinical studies like this are still in the testing phase.” It may take years to become a widely used tool, he says, but “I think this has an edge.”