New imaging shows how exercise helps ‘normalize’ the Parkinson’s brain
6-month cycling program shifted brain networks in a positive direction
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- Aerobic exercise can "normalize" disrupted brain communication in Parkinson's disease.
- Six months of cycling (3x/week) shifted brain networks, especially dopamine and acetylcholine.
- Exercise helps rewire the Parkinson's brain, suggesting a promising intervention for symptoms.
Six months of regular aerobic exercise can partially “normalize” disrupted brain communication in people with Parkinson’s disease, a new Canadian study suggests. By cycling for an hour three times a week, patients saw shifts in their brain networks that moved in the opposite direction of the disease’s typical pattern, suggesting that exercise may help the brain reorganize circuits related to movement and balance.
Using an advanced imaging technique called Receptor-Enriched Analysis of Functional Connectivity by Targets (REACT), researchers found that these improvements weren’t just general but specifically affected networks powered by dopamine and acetylcholine, two critical chemical messengers that are disrupted as Parkinson’s progresses. This molecular-level shift suggests that structured exercise may be a promising intervention, helping the brain compensate for the loss of nerve cells.
“Our results suggest that exercise may help partially restore normal function in circuits disrupted by [Parkinson’s disease], especially those related to dopamine and acetylcholine,” researchers wrote. “This study provides supporting evidence that exercise changes brain networks in a way that could improve symptoms and supports using molecular-informed imaging to understand these effects.”
The study, “Exercise-Induced modulation of molecular-enriched functional connectivity in Parkinson’s disease,” was published in the Journal of Parkinson’s Disease.
The complex chemistry of Parkinson’s disease
Parkinson’s is a neurological disorder caused by the progressive loss of nerve cells that produce dopamine, a neurotransmitter that helps regulate voluntary movement. As these cells die, dopamine signaling in the brain becomes disrupted, leading to hallmark Parkinson’s symptoms.
Growing evidence, however, suggests that Parkinson’s affects more than just dopamine networks. Multiple brain networks that rely on other neurotransmitters — including serotonin, acetylcholine, and noradrenaline — are also disrupted. Dysfunction in these systems has been linked to both motor and nonmotor symptoms.
Exercise has emerged as a promising therapy for Parkinson’s. Large clinical trials have shown that structured aerobic exercise can ease motor symptoms and may help slow functional decline. Still, exactly how exercise changes brain activity remains unclear.
“Elucidating how exercise influences neurotransmitter related brain networks could provide insight into therapeutic targets and support the development of imaging biomarkers to guide future interventions,” the researchers wrote.
To learn more, researchers in Canada analyzed brain networks in 22 people with mild-to-moderate Parkinson’s enrolled in an observational study called PET/MR (NCT02801110). The study also included 21 healthy individuals of similar age, who served as a comparison group to identify disease-related differences at the study’s start.
Among participants with Parkinson’s, seven completed a six-month supervised aerobic exercise program involving 60-minute stationary cycling sessions three times per week. Each session included a 10-minute warm-up, 40 minutes of steady, moderate-intensity cycling, and a 10-minute cool-down.
Nine participants maintained their usual low levels of physical activity and served as a comparison group to evaluate the effects of the exercise intervention. Six others were not followed over time because they were already exercising regularly, but they were included in the initial comparisons with healthy individuals.
To assess changes, the researchers analyzed resting-state functional MRI scans, a type of brain imaging that measures activity by tracking changes in blood flow while a person is resting quietly. This technique allows scientists to evaluate functional connectivity, or how strongly different brain regions communicate with one another. They then applied REACT to the same MRI data to estimate which neurotransmitter systems were most closely associated with the observed connectivity changes.
At the start of the study, participants with Parkinson’s showed significantly altered communication within motor-related brain networks compared with healthy individuals.
Reorganizing motor circuits
After six months, participants who completed the exercise program showed connectivity changes opposite to the pattern observed between Parkinson’s patients and healthy individuals at the study’s start. In other words, exercise shifted connectivity in the opposite direction of disease-related alterations. Similar shifts were not observed among participants who maintained low levels of physical activity.
“These findings suggest that aerobic exercise may not simply increase or decrease connectivity, but rather reorganize networks in a compensatory direction, working toward normalization of disrupted communication within motor circuits,” the researchers wrote.
When the team examined neurotransmitter-related networks using REACT, they found that exercise-related changes were most evident in networks enriched for dopamine and acetylcholine. In both cases, connectivity patterns shifted in the opposite direction to the disease-related disruptions observed at the study’s start. No significant changes were detected in serotonin- or noradrenaline-related networks.
These findings align with the well-known loss of dopamine-producing cells in Parkinson’s. Notably, exercise also shifted acetylcholine systems, which play a key role in managing balance, walking, and memory.
“Our findings suggest that aerobic exercise may reorganize dopaminergic- and cholinergic-enriched networks in a compensatory direction, working toward counteracting [Parkinson’s]-related connectivity alterations,” the researchers concluded.
They added that the results provide supporting evidence for biological mechanisms linking exercise to symptom easing, highlight its effects across multiple neurotransmitter systems, and reinforce the value of aerobic exercise as a promising intervention for Parkinson’s disease.
