Study examines how hand preference might influence impact of Parkinson’s symptoms

Study examines how hand preference might influence impact of Parkinson’s symptoms

By Sean Gorman

Whether you’re left-handed or right-handed might do more than shape daily routines — it could help researchers better understand, screen for and treat Parkinson’s disease.

That’s the idea behind a study Brooke Dexheimer, Ph.D., is conducting on how hand preference might impact the daily life of a patient in the early stage of Parkinson’s.

“We’re interested in the really early stages of Parkinson’s disease, when those motor symptoms are pretty subtle — tremor, rigid muscles, and so on — and lead to changes in movement that prompt people to seek out a neurologist,” says Dexheimer, who is pursuing the research in partnership with the Parkinson’s and Movement Disorders Center (PMDC). “We think the symptoms may look the same in each hand, but the ways they impact your day-to-day life are different.”

That varying impact could stem from each hand’s unique role when doing joint tasks — with the dominant hand accomplishing a task as the non-dominant hand stabilizes an object, Dexheimer says. For example, someone might use their non-dominant hand to hold a glass steady as their dominant hand pours water into it from a bottle.

Dexheimer, a VCU assistant professor of occupational therapy at the College of Health Professions, notes previous research by PMDC neurologist Matthew Barrett, M.D., indicates that people who have initial symptoms in their non-dominant hand generally are diagnosed more quickly than those whose first symptoms arise in their dominant hand.

“We’d all kind of intuitively think that if we had a tremor, if we had some issue with our dominant hand, we’d be quicker to notice and seek out our physician who would send us to a neurologist,” Dexheimer says. “But actually, the research suggests otherwise: that people with non-dominant symptoms are the ones who are quicker to get diagnosed.”

That might be because a common symptom of Parkinson’s, like a tremor, might be more noticeable in a person’s nondominant hand as it’s being used to stabilize an object, she says.

“Maybe there’s something about the non-dominant hand or its specialization that’s more disrupted,” Dexheimer says. “That’s our guess.”

Dexheimer is pursuing the research through the C. Kenneth and Dianne Wright Center for Clinical and Translational Research that oversees the K12 Mentored Career Development Grant funding this research. These grants, funded by the National Institutes of Health, support early career researchers like Dexheimer who are seeking answers that can help guide clinical treatment.

One part of the study is also examining whether current Parkinson’s assessments are adequately picking up on the fine motor skills deficits in a patient’s dominant and nondominant hands.

Working with the PMDC, Dexheimer is enrolling patients in the early stages of Parkinson’s. They will each work on two iPad tablets and a pair of Apple Pencils attached by a rubber band. Study participants will hold one stylus on one tablet screen and then use the other stylus to draw on the other tablet.

“This tablet task we programmed is meant to mimic the way our hands work together on functional tasks,” she says.

This is a collaborative project pursued by Dexheimer and PMDC Director Brian Berman, M.D., who is serving as her primary mentor.

“He’s overseeing the project and sharing his expertise,” Dexheimer says. “He has that insight into this population and the subtlety of their fine motor symptoms. So he’s been a guiding light for me in terms of pointing me in certain directions.”

Peter Pidcoe, Ph.D., VCU’s director of Engineering and Biomechanics Lab, and Dean Krusienski, Ph.D., director of VCU’s Advanced Signal Processing in Engineering and Neuroscience Lab, are also mentors on the project. Barrett, the PMDC neurologist, is collaborating on the research as well.

“Our team consists of experts in occupational therapy, physical therapy, neurology and biomedical engineering. It’s a project that spans across a lot of fields,” Dexheimer says.

Dexheimer was drawn to Parkinson’s research by a personal connection: her uncle lives with the disease, and her aunt passed away after being diagnosed with Parkinson’s.

“For me, it’s personal. But beyond that, it’s one of the more common neurological disorders,” she says. “Everyone I’ve talked to knows someone who’s had it. So it feels like the work we’re doing can have more of a direct impact, hopefully quicker.”