Aim:
A systematic review which aims to assess the evidence regarding the function of the autonomic heart rate
regulation system among Parkinson‟s disease (PD) patients. The main objective of the study is to compare heart rate
variability (HRV) between those with and without PD from published studies. The subgroup analyses aimed to investigate
the impact of treatment and disease duration on heart rate variability (HRV), assessed by measuring sympathetic and
parasympathetic activity via low-frequency (LF) and high-frequency (HF) power spectrum scores, in patients with
Parkinson‟s disease (PD).
Methods:
PubMed, Cochrane Library, Embase and Web of Science were searched using the keywords “Parkinson‟s
disease” and “heart rate variability”. Studies that reported at least one HRV variable were included. The quality of the
included studies was evaluated, and the relevant information was extracted. Then, a meta-analysis was carried out with
Stata software.
Results:
Thirteen references (16 studies) were included in our analysis. The LF values (g -0.27; 95% confidence interval
(CI) -0.53 to -0.01) of the patients with PD were lower than the controls. No significant differences in HF values (g -0.11;
95% CI -0.28 to 0.06) were observed between groups. Subgroup analyses of HRV outcomes in patients stratified by
treatment status and disease duration were performed. For LF, patients with a disease duration of less than 5 years
presented lower HF (g -0.25; 95% CI -0.44 to -0.06) values than controls. Regarding HF, patients receiving treatment
presented lower HF (g -0.22; 95% CI -0.40 to 0.05) values than controls, and patients with a disease duration greater than
5 years also presented lower HF (g -0.29; 95% CI -0.56 to -0.03) values than controls.
Discussion:
We have confirmed and elaborated on the hypothesis of sympathovagal imbalance in PD. Knowledge of the
effect of sympathovagal balance on HRV may inform the design of therapeutic regimens for PD. However, between-study
heterogeneity and methodological issues limit the generalizability of the evidence; thus, future studies employing strict
methodologies are warranted.
Conclusion:
Our meta-analysis found that PD is associated with reduced HRV values, which indicates that both
sympathetic and vagal activity are decreased. Patients in the early stage of PD have sympathetic autonomic nerve
dysfunction with only minor damage to sympathetic activity.
Mechanism of autonomic nerve regulation system (VIII)
