Myocardial infarction (MI) is associated with a moderately decreased risk for Parkinson disease (PD) and secondary parkinsonism, according to an analysis published in the Journal of the American Heart Association.
PD is primarily considered to be a neurodegenerative disease, but parkinsonism is known to have several underlying causes besides primary neurodegenerative processes, such as stroke, the researchers explained. However, smoking and increased cholesterol levels, which are cardiovascular risk factors, are associated with a lower risk for PD. Among patients with PD, the risk of cardiovascular disease is increased, but the risk of PD in survivors of MI is unknown.
The objective of the current study was to explore the risk for PD and secondary parkinsonism among 1-year survivors of MI.
A nationwide, population-based matched cohort study was conducted that used Danish medical registries between January 1, 1995, and December 31, 2016. The cumulative population evaluated in the study period comprised 8, 262,736 Danish residents. The Danish National Patient Registry was used to identify all patients with a first-time inpatient diagnosis of MI during the study period. All patients with MI were recognized with the use of both primary and secondary diagnoses.
A general population comparison cohort was created using the Danish Civil Registration System. For each of the patients in the MI cohort, 5 individuals from the general population without a diagnosis of MI were randomly chosen and matched according to age, sex, and calendar year of MI diagnosis.
The MI admission date defined the index date for all patients who experienced an MI and their matched counterparts in the general population cohort. In an effort to ensure the capture of only incident cases of PD and secondary parkinsonism, patients with MI and those in the matched comparison cohort who had received a prior diagnosis of any of the diseases were excluded from the study.
A total of 181,994 patients with MI and 909,970 matched comparison control individuals were identified. The median participant age was 71 years; 62% of the participants were men. In the MI cohort after 21 years of follow-up, the cumulative incidence was 0.9% for PD and 0.1% for secondary parkinsonism. Compared with the general population cohort, MI was shown to be associated with a decreased risk for PD (adjusted hazard ratio [aHR], 0.80; 95% CI, 0.73 to 0.87) and for secondary parkinsonism (aHR, 0.72; 95% CI, 0.54 to 0.94).
The study results show that MI was associated with a 20% decreased risk for PD and a 28% decreased risk for secondary parkinsonism. The researchers believe this decreased risk might be reflective of an inverse relationship between cardiovascular risk factors and PD.
The study had several limitations, including its observational design. The researchers noted “residual and unmeasured confounding cannot be ruled out and may partly underlie our results.” Furthermore, the study did not include information on smoking and did not completely capture hypercholesterolemia, which both have a positive association with MI and a negative association with PD.
“In this nationwide matched population-based cohort study with virtually complete follow-up of 181 994 MI survivors for 21 years, we found a moderately lower risk of both Parkinson disease and secondary parkinsonism compared with the general population,” the researchers noted.
Disclosure: None of the study authors has declared affiliations with biotech, pharmaceutical, and/or device companies.
Sundbøll J, Szépligeti SK, Szentkúti P, et al. Risk of Parkinson disease and secondary parkinsonism in myocardial infarction survivors. J Am Heart Assoc. Published online February 16, 2022. doi:10.1161/JAHA.121.022768