How Your Smartwatch Could Help Unlock Secrets of Disease

Sept. 1, 2023 – The future of public health could be in your hands – or on your wrist, to be precise. 

Researchers are using smartwatches and fitness trackers to do rigorous large-scale studies that would have been impossible in the past. It’s a growing trend that may vastly expand our knowledge of an array diseases. 

“There’s really no disease that won’t be touched by this type of research,” said Calum MacRae, MD, PhD, vice chair of scientific innovation for the Department of Medicine at Brigham and Women’s Hospital. 

Wearables are already in use to research heart, respiratory, neurological, and liver diseases, as well as gynecological conditions, certain cancers, diabetes, sleep quality, autism, and mental illness.

In one recent example, as many as 1 million iPhone and smartwatch users may sign up to share data about their menstrual cycles and other health and lifestyle factors like sleep and stress. Already, 100,000 have enrolled in this Apple Women’s Health Study, a 10-year project among Harvard, Apple, and the National Institute of Environmental Health Sciences (NIEHS) that is unprecedented in size and scope. 

Doctors know that an irregular menstrual cycle can be a sign of many things, from infertility to heart disease, diabetes, or even cancer. Many doctors believe menstrual history should be considered a vital sign, like pulse or blood pressure, but they say menstrual and reproductive health is woefully underfunded and understudied. 

With a bigger, more diverse sample of people being studied, researchers hope to advance diagnosis and treatment for health conditions linked to menstrual cycle disturbances. 

“We’re able to ask questions we couldn’t ask before,” said Shruthi Mahalingaiah, MD,  one of the study’s principal investigators and an assistant professor of environmental, reproductive, and women’s health at the Harvard T.H. Chan School of Public Health. 

Rise of the Wearables 

Nearly half of Americans wear smartwatches or fitness trackers, according to a 2022 survey. Beyond calorie burn and steps, the tech can provide – via smartphone apps – information on breathing rate, heart rate, blood oxygen level, and sleep duration. 

Academic medical centers are working with digital giants like Apple, Google, Samsung, Alphabet, and Amazon, as well as tech startups and nonprofits. The coronavirus pandemic sped up the trend, as medical institutions tested wearables to monitor patients from home. Symptom checkers and outbreak apps helped monitor exposure to infection and identify hot spots, and showed how large data sets could be captured in a consistent manner. 

Trials using wearables for data collection account for less than 1% of all trials worldwide. But that number is growing, climbing by several hundred within the past few years, according to clinicaltrials.gov (the National Library of Medicine’s registry of clinical trials). 

This trend goes beyond the wrist to use “smart” glasses, rings, necklaces, “hearables,” and even clothing. And the growing universe of medical-grade wearables helps too: smart patches that track vital signs, blood pressure devices, and continuous glucose monitors, which are often doctor-prescribed but are also becoming available at retailers. 

“You can live anywhere in the country and participate in research using wearables,” said Ray Dorsey, MD, a professor of neurology at the University of Rochester Medical Center’s Center for Health Technology in New York. Volunteers previously had to travel to medical centers for tests and updates, which often limited the scope of studies. 

Big Tech, Big Studies

In recent years, tech companies like Apple, Samsung, and Google have introduced and refined open-source platforms that let researchers build apps and tools that securely capture health information from people using wearables. 

In 2015, a smartphone app, developed by Dorsey’s URMC team and partners, used Apple’s ResearchKit in a Parkinson’s disease trial. The researchers enrolled over 2,000 volunteers in a day, unheard-of numbers at the time. Ultimately, the study enrolled over 9,000 people, who did tasks like walking to measure gait changes. The published findings helped researchers better understand the how Parkinson’s symptoms varied day to day, Dorsey said. 

In 2017, along with Stanford University School of Medicine, the Apple Heart Study enrolled more than 400,000 Apple Watch users from all 50 states in just 8 months. The study showed that smartwatches could identify irregular heart rhythms, like atrial fibrillation. It also paved the way for the FDA to classify the watch’selectrocardiogram (EKG) app as a medical device. Since then, smartwatch EKG apps from Fitbit, Samsung, and Garmin have received similar clearances. 

The Apple Women’s Health Study launched in 2019 along with two other ambitious projects: the Apple Heart and Movement Study, led by MacRae at Brigham and Women’s Hospital, along with the American Heart Association; and the Apple Hearing Study at the University of Michigan. 

The Apple Women’s Health Study taps into more of a mix of people by race, ethnicity, age, socioeconomic position, and location, compared to the much smaller reach of earlier studies. Data collected relates to exercise, sleep, and environmental and behavioral factors, and monthly surveys capture personal details the app can’t.

“This is giving us the ability to take into consideration very granular information in our analyses,” said Huichu Li, PhD, a study co-author and research fellow at Harvard’s School of Public Health. 

Among the early results: The slightly longer menstrual cycles that may be caused by COVID vaccines were found to be temporary. Speaking more generally, irregular and infrequent periods were found to be more prevalent in Black and Asian people studied, while menstrual cycles were longer for Asian, Hispanic, and overweight people. 

An analysis of over 50,000 people provided insights into links between abnormal periods and health conditions like polycystic ovary syndrome, endometrial hyperplasia, and cancer. 

“Future studies will dig deeper into the data, looking at at the impact of environmental exposures, behavior, and stress on menstrual cycles,” Mahalingaiah said. 

Challenges and the Future

The promise of wearables is tempered by challenges. Much more testing is needed to ensure the devices provide clinical-grade data. Concerns remain in health care about privacy and cybersecurity threats, according to research from the professional services firm Deloitte. 

These new kinds of studies have limits. People must own smartwatches and smartphones, tech that is less common in under-represented and rural populations, and they must have reliable internet access. 

But increased acceptance of the devices – by consumers and health care providers – means the trend is likely to grow. 

“I don’t see a world where this kind of research slows down,” said Urvi Shah, a senior manager in Deloitte Consulting’s Life Sciences and Health Care Practice.