Measuring Freezing of Gait: The Role of Smart Technology in Advancing Parkinson’s Research

In the United States, nearly one million people are living with Parkinson’s disease. Parkinson’s is a progressive disease that damages the brain cells that produce dopamine, a chemical that helps coordinate movement. Parkinson’s can cause symptoms such as uncontrollable shaking, stiffness, tremors, and difficulty walking. It mainly affects older adults, with the average age of diagnosis for Parkinson’s disease being 60.

Freezing of gait is a symptom experienced by many people with Parkinson’s. While freezing of gait has been historically difficult to measure and study, recent advancements in technology and research are shedding new light on the condition. Technological breakthroughs not only deepen our understanding of Parkinson’s disease but offer insight into future approaches to care and treatment.

What is freezing of gait, and why is it difficult to measure? 

The Parkinson’s Foundation defines freezing gait as “the temporary, involuntary inability to move.” When someone has a freezing gait episode, which can last for a second or tens of seconds, it may look like they’re simply standing still. It can also look like a regular walk that transitions into a shuffle and then stops. Freezing of gait can feel like your feet are stuck or glued to the floor.

A combination of factors can trigger freezing of gait episodes, and those factors differ from person to person. For that reason, it is a very unpredictable symptom. It may happen one day and then not happen for a very long time. Alternatively, it may happen multiple times a day.

Not everyone with Parkinson’s experiences freezing of gait. Statistics vary, but one meta-analysis on its prevalence found that 37.9% of those with early-stage Parkinson’s are affected, compared with 64.6% of those with advanced-stage Parkinson’s.

One significant risk is falling. If you’re in the middle of walking or turning and suddenly freeze, it’s very easy to lose balance. Because freezing of gait tends to emerge later in the course of Parkinson’s, which often gets diagnosed during older adulthood, other age-related fall risk factors can make falling more likely as well.

The unpredictability of the symptom has made it challenging to study. Until recent years, what researchers knew about the freezing of gait came from laboratory observation and self-reported questionnaires. However, people did not reliably experience symptoms in the laboratory, and self-reporting can be subject to bias. As a result, it has been difficult to get accurate and measurable data.

That’s the big obstacle with freezing of gait — it’s a common yet dangerous symptom in those who experience Parkinson’s disease yet difficult to quantify, and therefore study, manage, and, importantly, treat. 

Smart technology is redefining how freezing of gait is measured

As the director of the Mobility and Falls Program and an associate scientist at the Hinda and Arthur Marcus Institute for Aging Research, I have conducted extensive research to find better ways to quantify the incidence of gait freezing. We have seen promising results by analyzing data from wearable and smartphone technology. 

Wearable sensors

In one study, our team combined data from global research efforts to build a large database of freezing of gait events recorded while participants wore motion sensors under observation in laboratory settings. We then held a global competition, now published in Nature Communications, where 170 teams developed artificial intelligence models that identified freezing of gait episodes using only data from the sensors. The winning team developed a machine-learning algorithm that can detect freezing episodes both in controlled lab settings and in real-world environments with higher accuracy than ever before.  

Why does measuring freezing of gait matter? One area of opportunity is around medication timing and dosage. 

The effects of Parkinson’s medications designed to reduce tremors and freezing of gait are short-lasting. Because of that, patients often need to experiment to determine the best times of day to take their medications. They also need to return to their physicians often to adjust their medication dosages. However, the sporadic, changing, and self-reported nature of symptoms leaves physicians without the objective data needed to make informed decisions about those adjustments.  

Junhong Zhou, PhD, an assistant scientist at the Marcus Institute who also researches Parkinson’s disease, explains that “patients with Parkinson’s — especially those with freezing of gait — need to go to the hospital quite often to adjust their medication. Sometimes, patients need to return to the hospital to determine a new dosage because they have adapted to medication previously determined by their doctor. Oftentimes, this only occurs after the patient suffers a fall. Soon, using wearable sensors that collect objective symptom data continuously over time will enable doctors to determine the very beginnings of changes in symptom severity, and thus allow them to change medication dosage or timing before dangerous falls occur.” 

Smartphone-based assessment 

In addition to wearable sensors, a smartphone-based assessment is helping us advance Parkinson’s research. Whether or not someone with Parkinson’s experiences freezing of gait, measuring their gait, or the pattern of their walking or movement, is crucial. That’s because even in the absence of freezing, those with Parkinson’s are susceptible to gait impairments that increase the risk of dangerous falls. Measuring gait offers insight into the locomotor control system, which is what allows us to move.

In a study I co-authored alongside Dr. Zhou, we tested a smartphone-based gait assessment in people with Parkinson’s. We measured participants’ gait in a few different ways: at a comfortable walking speed, at a fast walking speed, and while they were engaged in additional tasks (also known as “dual tasking”).  

The smartphone-based assessment offered a specific type of gait analysis typically done in a laboratory setting but enabled participants to perform it from the comfort of their homes. Participants put the phone in their pockets and followed verbal instructions to complete the test. If they had four meters of a straight path, they could complete the test by walking back and forth for a minute, and the app could capture their gait performance.  

It’s not always easy for people with Parkinson's disease to travel to researchers, and conducting research in person was also very difficult during the pandemic. The smartphone-based gait assessment was a way to overcome these obstacles while measuring gait outcomes more regularly than before.

Like the wearables, this is also important for managing Parkinson’s medication. However, it’s more focused on gait under normal conditions and not just freezing. 

The future of fall prevention in Parkinson’s treatment   

Fall risk can change throughout the year without someone realizing it. Wearables and smartphone gait assessments promise to eventually offer patients and providers more timely detection when fall risk changes. 

“Some large hospitals and clinical centers are already using wearables to ask patients to record aspects of their movement or physiology in daily life. The hope is that this data can be used by providers to better manage Parkinson’s disease and minimize the impact of its symptoms on the quality of daily life,” explains Dr. Zhou. 

To date, translating this into clinical practice outside of academic medical centers has been a bit challenging. Physicians are incredibly busy as is and may not have time to parse through large amounts of data. However, as wearable technology develops, I expect this to change. In the future, the focus will be on making large volumes of data accessible and easy to interpret for the patients and providers who could most benefit from it. 

Get personalized fall prevention strategies for your home

If you or a loved one is experiencing movement symptoms related to Parkinson’s disease, Hebrew SeniorLife’s Home Health team may be able to offer valuable support.

Getting to the doctor’s office to get support and ask questions can be tough. With a referral from a doctor, our Home Health professionals can evaluate your risk for falls and recommend home modifications to enhance safety and independence. Learn more about our Home Health services today.

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