Post by Shireen Parimoo
What's the science?
Parkinson’s disease (PD) is a progressive neurodegenerative disorder that arises from the loss of dopamine neurons in the substantia nigra, resulting in motor symptoms like bradykinesia (slow movement), impaired posture, and resting tremors. Patients are typically treated with medications that increase dopamine levels in the brain or mimic the effects of dopamine, such as Levodopa or dopamine agonists, respectively. Although these medications help to reduce motor symptoms, they are often not as effective in the long-term. Previous studies linked exercise to an improvement in motor symptoms among PD patients; for example, a recent treadmill study showed attenuation of motor symptoms after aerobic exercise in unmedicated PD patients. However, few studies have investigated the long-term effects of aerobic exercise in PD patients, particularly in those who regularly take medication to treat symptoms. This week in The Lancet Neurology, van der Kolk and colleagues examined the impact of aerobic exercise on the severity of motor symptoms over a six-month period in patients with Parkinson’s disease.
How did they do it?
One hundred and thirty patients with mild PD participated in a double-blind, randomized controlled trial. Patients were randomly assigned to an aerobic exercise treatment group or an active control stretching group for six months. In the treatment group, participants exercised on a stationary cycle for 30-45 minutes at least three times a week, whereas the control group performed stretching and flexibility exercises for 30 minutes three days a week. Participants completed these exercises at home using a tablet-based application, and the stationary cycle included virtual reality software with videos to make the exercises more engaging. The groups were randomized based on sex and medication status, and the trial was double-blind. The authors assessed the following measures at the beginning of the study (baseline) and after six months: (i) severity of motor symptoms using the motor section of the Movement Disorders Society – Unified Parkinson’s Disease Rating Scale (MDS-UPDRS), (ii) other motor symptoms such as frequency of falls and finger-tapping performance, (iii) non-motor symptoms like sleep and depression, and (iv) cardiovascular fitness. Importantly, to rule out acute effects of medication on these outcomes, these symptoms were assessed during the off-state when at least 12 hours had passed since patients had taken their medication. On the MDS-UPDRS, a higher score is associated with more severe symptoms, thus, a bigger difference in scores after treatment suggests a worsening of symptoms. To determine if aerobic exercise improved the severity of motor symptoms, the authors compared the change in MDS-UPDRS scores after six months between the two groups.
What did they find?
There were no differences in baseline measures across the treatment and control groups. After six months, the score for motor symptoms on the MDS-UPDRS increased by 1.3 points in the treatment group but by 5.6 points in the control group. In other words, the motor symptoms became more severe in the control group after six months than in the treatment group. This difference of 4.2 points between the two groups is clinically relevant (>3.5 points), and provides support for the effectiveness of aerobic exercise in mitigating motor symptoms in PD. Cardiovascular fitness also increased in the treatment group but decreased in the control group. Interestingly, the severity of motor symptoms evaluated during the on-state (within 12 hours of taking medication) as well as other motor symptoms like the frequency of falls and finger-tapping performance did not differ across the two groups after the trial. Moreover, patients who exercised did not differ from those in the control group in non-motor symptoms. Thus, the specific effect of exercise during patients’ off-state indicates it can be a promising complementary treatment approach to medication in alleviating the severity of motor symptoms in PD.
What's the impact?
This study is the first to demonstrate that consistent aerobic exercise can attenuate the progression of motor symptoms in patients with PD. These findings have important implications for the treatment approaches available to PD patients and open the door for future research to investigate the longer-term impact of exercise on both motor and non-motor symptoms.
Van der Kolk et al. Effectiveness of home-based and remotely supervised aerobic exercise in Parkinson’s disease: a double-bind randomised controlled trial. The Lancet Neurology (2019). Access the original scientific publication here.