New study shows the benefits of regular exercise

Exercise in Parkinson disease (PD) has been shown to improve motor and non-motor signs and symptoms of PD, may slow disease progression (1), can improve slowness of movement (bradykinesia) (2,3), balance (4,5), quality of life (6,7), cognition(8–10), and mood (11).  This form of physical activity has been thought to cause improved dopamine release at a part of the basal ganglia called the dorsal striatum, which improves motor function, and another part called the ventral striatum which improves mood and reduces apathy.  For more on the basal ganglia, see the MPDN Summer, 2017 article: Levodopa at 50.

A recently published study which took place in Vancouver was designed to investigate dopamine release  at the above described brain regions (12).  Researchers used a brain imaging technology called [11C]raclopride (RAC) PET “in response to an acute bout of vigorous cycling” to evaluate the dorsal striatum.  And, functional MRI was used to measure “reward-related activation” in the ventral striatum.  The “reward” occurred when subjects won money in a card game.  Seventeen habitual exercisers with mild-to-moderate PD, ages 45 to 70, were compared with nine sedentary people(not exercisers) with moderate PD. 

Among the habitual exercisers baseline dopamine release was higher on initial PET scan.  In other words, even at rest they had healthier brain dopamine levels.  As you might expect, after vigorous cycling on a stationary bike for 30 minutes there was greater dopamine release in the brains of the habitual exercisers than the sedentary group.  This response is evidence of a more intact, healthy, responsive system.  Habitual exercisers also had less bradykinesia and better gait test results.   

As the saying goes, correlation does not equal causation, though this study is one more piece of evidence that exercise, especially regular exercise, is associated with better outcome and better brain dopamine function in PD. 

Symptomatic benefits of exercise are thought to arise from increased activity in dopamine pathways of the brain via increased release of dopamine, higher dopamine receptor density, or both.  These changes likely lead improved synaptic strength, or better connections between neurons.  Exercise likely increases the survival of neurons and may result in formation of new neurons, the release of growth factors in the brain, improved immune responses, and enhanced function of mitochondria: the energy factories of cells in the brain and body (13). 

The preservation of mitochondria is a key strategy in saving neurons, as is the normalization of the brain’s immune response.

Interestingly, habitual exercisers also stimulated the ventral striatum at higher levels than the sedentary group during the reward task.  The ventral striatum is part of the so-called mesolimbic system, which is involved in anticipation of reward.  This increased function was associated with better mood, less apathy, and higher feelings of well-being in habitual exercisers than the sedentary group.  

This study is important because it gives imaging and clinical support to the increasing body of literature on the benefits of regular exercise in PD.  Here in Maine we have several groups of people with PD who meet to exercise on a regular basis, and you can find out about some of them at these links: Belfast, Boothbay Harbor, Brunswick, Cape Elizabeth, Damariscotta, Lewiston, and Freeport. If you would like to know more on the topic of exercise, read Dr. Michael Kleinman’s fall 2016 MPDN article Exercise and Parkinson’s disease. You should check with your doctor if you have any concerns about whether or not you can participate in regular exercise.

“Get up!”

James Brown

“Get busy living…”

Andy Dufresne, the Shawshank Redemption

REFERENCES

1. Ahlskog, et al. Does vigorous exercise have aneuroprotective effect in Parkinson disease? Neurology 2011;77:288-294.
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3. Ridgel, et al. Active-assisted cycling improves tremor and bradykinesia in Parkinson’sdisease. Arch Phys Med Rehabil 2012;93:2049-2054.
4. Allen, et al. Balance and falls in Parkinson’s disease: a meta-analysis of the effectof exercise and motor training. Mov Disord 2011;26:1605-1615.
5. Li, et al. Tai chi and postural stability in patients with Parkinson’s disease. NewEngl J Med 2012;366: 511-519.
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8. Murray, et al.  The effects of exercise on cognition inParkinson’s disease: a systematic review. Transl Neurodegener 2014;3:5.
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10. David, et al. Exercise improves cognition in Parkinson’s disease: the PRET-PDrandomized, clinical trial. Mov Disord 2015;30:1657-1663.
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12. Sachelli, et al. Habitual Exercisers Versus SedentarySubjects With Parkinson’s Disease: Multimodal PET and fMRI Study.  Mov Disord 2018, Oct 30. doi:10.1002/mds.27498. [Epub ahead of print]
13. Petzinger, et al. Exercise-enhancedneuroplasticity targeting motor and cognitive circuitry in Parkinson’s disease.Lancet Neurol 2013;12:716-726.