By Lynda Nwabuobi, MD
Assistant Professor of Clinical Neurology, Assistant Attending Neurologist, New York-Presbyterian/Weill Cornell Medical College
SYNOPSIS: In individuals with Parkinson’s disease (PD), physical activity (PA) at all intensities is associated with reduced all-cause mortality, with the greatest reduction seen in individuals who maintained PA before and after PD diagnosis.
SOURCE: Yoon SY, Suh JH, Yang SN, et al. Association of physical activity, including amount and maintenance, with all-cause mortality in Parkinson disease. JAMA Neurol 2021;78:1446-1453.
Physical activity (PA) and exercise are vital components in the management of Parkinson’s disease (PD) motor and nonmotor symptoms, since they have been shown to improve balance, mobility, cognition, mood, and activities of daily living. Different exercises, including dancing, boxing, tai chi, qi gong, biking, and walking, all have positive effects on PD symptoms. It has been proposed that exercise may offer neuroprotection against dopaminergic cell loss in mice models and may enhance neuroplasticity, thus slowing disease progression. Several studies also have shown a significant reduction in the risk of developing PD with PA. The association between PA and PD mortality has rarely been studied. In this study, the authors sought to determine whether PA intensity, total amount, and maintenance are associated with all-cause mortality in PD individuals.
Using a nationwide population-based cohort in Korea, the authors selected individuals who had been newly diagnosed with PD between Jan. 1, 2010, and Dec. 31, 2013, and all-cause mortality was evaluated up to Dec. 31, 2017. To assess the association between PA maintenance and mortality, only individuals who attended health checkups within two years before and after receiving the diagnosis were included. PA data were collected based on self-report at the time of health checkup, in which participants were asked how many days per week they spent performing each activity by intensity level.
Intensity level was graded as vigorous (such as running, aerobics, fast biking, or climbing for more than 20 minutes), moderate (such as fast walking, riding a bicycle at a normal speed, or doubles tennis for more than 30 minutes), and light (such as walking to and from work or for leisure for more than 30 minutes). Otherwise, the participants were considered physically inactive. Total metabolic equivalent of task (MET) minutes per week was used to quantify the total PA amount for each individual, with ratings of 3, 5, and 8 assigned for light, moderate, and vigorous PA, respectively. Statistical analysis included a comparison of PD individuals who died and those who did not using t-tests or Mann-Whitney U tests for continuous variables or chi-square tests for categorical variables. Cox proportional hazard models were used to assess mortality risk by PA level using three models with adjustment for confounding variables.
Individuals with PD who were physically active had a significantly reduced mortality risk compared to those who were not physically active (P < 0.001), with hazard ratios (HRs) of 0.80 (95% confidence interval [CI], 0.69-0.93) for vigorous-intensity PA, 0.66 (95% CI, 0.55-0.78) for moderate-intensity PA, and 0.81 (95% CI, 0.73-0.90) for light-intensity PA. There was a progressively decreasing risk of mortality with increasing amount of PA, measured in MET. Individuals who were physically active before and after PD diagnosis had the greatest reduction in mortality rate for all PA intensities (vigorous: HR, 0.66 [95% CI, 0.50-0.88]; moderate: HR, 0.49 [95% CI, 0.32-0.75]; light: HR, 0.76; [95% CI, 0.66-0.89]). Those who started PA after diagnosis had a lower mortality risk than those who remained physically inactive. Individuals who discontinued PA after diagnosis did not have a significantly better mortality risk compared to those who were continuously inactive. The inverse association between PA and mortality remained consistent with subgroup analysis of variables including age, sex, comorbidities, alcohol consumption, smoking, and body mass index (BMI). In general, age, disability registration, and Charlson Comorbidity Index were associated with increased mortality, whereas female sex and lower BMI were associated with reduced mortality.
COMMENTARY
The current evidence on the relationship between PA and PD suggests a beneficial role in preventing development of the disease, slowing its progression, and improving motor and nonmotor symptoms. This study adds to the limited available data on how PA affects PD mortality and, importantly, included a large number of participants and relatively long follow-up durations. The authors demonstrated an inverse association between PA and all-cause mortality and showed that maintenance of PA before and after diagnosis had the greatest mortality reduction. Interestingly, moderate-intensity PA was more strongly associated with reduced mortality risk compared to vigorous-intensity PA. This may be the result of longer duration of PA in moderate-intensity exercise. Moreover, vigorous exercise in PD may be limited by common symptoms, such as poor balance and increased risk of falls.
This study is important, since it provides evidence that exercise and PA should be incorporated into the management strategy for all individuals with PD. Maintenance of PA throughout the course of the disease should be stressed and tailored to each individual’s degree of motor impairment. It is important to note there might be reverse causality, since individuals with more severe PD may be limited in their ability to maintain PA, and, naturally, have increased mortality. Prospective studies will be needed to confirm a causal association between PA and PD mortality.
