Motor Symptoms May Occur 3 Years Before Parkinson Disease Diagnosis, Study Says

In recent years, more attention has been paid to the prodromal signs of Parkinson disease (PD)—that is, the signs and symptoms that appear years before a diagnosis is made. A recent case-control study, published in JAMA Neurology, indicated that individuals who have prodromal or unrecognized PD may have motor symptoms up to 3 years before diagnosis.

Researchers used Medicare-linked data from the National Health and Aging Trends Study (NHATS), a longitudinal, annual survey for a random subsample of Medicare beneficiaries 65 years or older. The sample was first interviewed in 2011 and then again in 2015, with response rates of 71% and 76%, respectively. Black participants and individuals 85 years or older were oversampled by design.

Patients with incident PD were defined as having 2 or more Medicare diagnoses from January 2011 to December 2017 and they had been eligible for Medicare 2 or more consecutive years prior to the first diagnosis. Controls without a PD diagnosis, with the same Medicare eligibility requirements, were also included.

Using logistic regression analysis, researchers sought to determine associations between survey responses and PD diagnosis in the first year of diagnosis and up to 3 years prior—in other words, during the prodromal phase. Analyses were conducted from November 2021 to June 2022.

Each year, participant numbers and case prevalence each year varied from 3492 to 5049 and from 700 to 1180 per 100,000 population, respectively. A total of 6674 participants were included in the analysis.

Fifty-six PD cases were identified and compared with 3466 controls.

The research identified 4 motor function issues that appeared 3 years before a formal PD diagnosis, with individuals indicating they were:

• Less able to walk 6 blocks (odds ratio [OR], 0.34; 95% CI, 0.15-0.82)
• Less likely to stand independently from a kneeling position (OR, 0.30; 95% CI, 0.11-0.85)
• Less able to lift a heavy object above their head (OR, 0.36; 95% CI, 0.15-0.87)
• More likely to report balance difficulties (OR, 2.77; 95% CI, 1.24-6.20)

The authors said their findings, which are in line with other research, support the idea that the prodromal phase of PD "should be recognized as a disease stage in its own right, for which identification will be important for disease-modifying intervention." However, they also said it is possible that the findings indicate that some cases of PD are unrecoognized.

Reference

Miller-Patterson C, Hsu JY, Willis AW, et al. Functional impairment in individuals with prodromal or unrecognized Parkinson disease. JAMA Neurol. Published online December 19, 2022. doi:10.1001/jamaneurol.2022.4621