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Much like other parents, Merrill Landers, a father of four who chairs 51�Թ������ܿƴ�’s department of physical therapy, often admonishes his children to go outside and play. Sometimes, he admits, he does this so that he and his wife have a moment’s peace. More often, he said, it’s to encourage his children to be more physically active. Landers knows that outdoor activities such as running around in the yard, kicking a soccer ball, or riding a bicycle are crucial to the growth and development of healthy young bodies.

And that may not be the only benefit. According to recent research findings, Landers indicated, an accumulation of steady physical activity during our youth and college years may generate a protective effect in the brain — one that could reduce the risk of, or even prevent, neurodegenerative diseases like Parkinson’s disease.

Landers’ research has focused on Parkinson’s disease since he joined the 51�Թ������ܿƴ� faculty in 2001. His involves examining how exercise might influence the disease’s course and determining whether patients’ physical activity might improve their balance and walking — work that has neatly segued into a broader set of findings on activity and neurodegenerative protective effects within the field, he indicated.

The four cardinal signs in Parkinson’s disease, Landers said, are bradykinesia (slowness of movement), rigidity, resting tremors, and postural instability (poor balance). The first three respond to, and can be improved with medication. Postural instability does not respond to Parkinson’s disease medications; the only treatment approach that has been demonstrated to be beneficial is balance training.

“Falling represents one of the two leading causes of premature death among people with Parkinson’s disease,” said Landers. “The first is aspiration pneumonia. Falling can cause the domino effect of fractures to surgery to post-operative complications to other falls. For me, preventing falls is a big issue.”

One aspect of Parkinson’s disease that piques Landers’ curiosity is how falls affect people with the disease. Healthy adults typically evaluate the circumstances of a fall in two ways. If it’s a fluke, they forget about it. If there is a reasonable chance the fall could happen again, they seek ways to prevent future tumbles.

For people with Parkinson’s disease, it’s more complicated. A fall may cause anxiety or fear, emotions that may result in an unhealthy avoidance of normal activities. They may limit visits to friends, attending church, or venturing out in public. Some become reclusive, a condition that can initiate a spiral of declining health. When fall-averse people with Parkinson’s disease seldom leave their homes, they tend to lose strength, coordination, and balance. These deficits, in a cruel irony, make them more susceptible to falling in their homes as they move from room to room.

“Some level of fear is good and can be protective, but too much can become harmful, especially in this disease population,” said Landers. “Those who shouldn’t be going out can be coached to become more careful and trained to improve their balance. Those who have high levels of fear need additional help.”

During a study involving older adults, Landers first measured “balance characteristics,” or participants’ ability to balance, while asking them to self-report their “balance confidence.” He followed the study participants for one year, noting when and how often they fell. The results indicated the self-assessments were the best predictors of future falls. The next best predictor was fall-avoidance behavior.

Using data obtained from another study, Landers helped rebuild the confidence of those who reported lower levels of balance and stability. Balance training became a key prescription.

As with his own children, Landers said, adults need exercise to maintain and strengthen muscles. Most people with Parkinson’s disease are prescribed a regimen of low-intensity exercise—a level so low, Landers said, it’s ridiculous.

“When we look at someone with Parkinson’s disease and see the poor posture and the slow movements, we assume he or she can’t handle exercise. I think this is a big misconception and became something I wanted to test.”

In 2015, Landers led an “exercise boot camp” study to evaluate the ability of people with Parkinson’s to handle high-intensity exercise, which comprised three components:

strength exercises at greater than 70 percent of the person’s one-repetition maximum, endurance exercises at 70 to 75 percent of the person’s estimated maximum heart rate, and exercises using dynamic and challenging balance-coordination tasks.

The results were clear: Those with high-intensity workouts responded well to the increased level of activity, and they did not experience more falls than the low-intensity group. What’s more, they enjoyed it—even more so than the low-intensity group enjoyed their activity.

Landers next sought to determine whether such intense exercise might act as an inhibitor of the disease’s progression. Many studies among laboratory animals had previously indicated that exercise can protect the brain from the disease. Some of the results even showed small animals actually recovering from the disease.

Landers then found results from five or six studies that indicated exercise during a person’s early adult life could have a cumulative effect and protect against the disease—that is, the risk for Parkinson’s decreased with an increase in physical activity in early adult life. Those results, he said, stimulated his curiosity further.

“As scientists, we know exercise benefits many different body systems, but the evidence strongly suggests that exercise also benefits our brains,” Landers said. “Physiologically, exercise — particularly aerobic exercise — increases a chemical called “brain derived neurotrophic factor,” or BDNF, which stimulates neuronal growth and helps potentiate neuroplasticity.

“BDNF is present when the brain learns a new skill or motor task. It also protects neurons, including the dopaminergic neurons that are affected by PD. So, presumably, having greater quantities of BDNF will protect more of those neurons, thereby slowing the progression of the disease.”

Landers and his team are currently exploring how BDNF (known to increase with aerobic exercise) and anti-inflammatory enzymes influence disease progression and response to exercise, and whether the successes with laboratory animals might apply to human beings. If successful, the study could further validate exercise as a neuroprotective strategy against Parkinson’s disease, either preventing its onset or slowing its progression.

Landers plans to present his findings during the World Parkinson Congress in Portland, Oregon, this October. He hopes his results will help convince those working with Parkinson’s patients that high-intensity exercise is not only safe but more effective than low-intensity workouts.

In the future, Landers said his plans include studying the effects of exercise during midlife and later. He’ll also explore related genetic information, which might allow scientists to gain additional insights into gait and balance function in those with Parkinson’s disease.

As for his children, Landers expects them to make exercise a regular part of their lives. And he plans to join them.