New Study Identifies Key Signs to Predict Parkinson's Disease in Its Early, Prodromal Phase

"In a large-scale study involving 6,108 men, the presence of constipation, probable rapid eye movement sleep behavior disorder, and hyposmia was associated with a 23-fold increased risk of developing PD within three years (risk ratio [RR] = 23.35). Furthermore, individuals with a prodromal PD probability of ≥0.8, according to the Movement Disorders Society criteria, had a 21-fold higher risk (RR = 21.96)," the researchers reported.

Parkinson's Disease, a neurodegenerative disorder, is often diagnosed once symptoms such as tremors, rigidity, and bradykinesia become clinically apparent. However, evidence suggests that changes in the brain may begin years before the disease fully manifests. Considering this, Mario H. Flores-Torres, Department of Nutrition, Harvard T.H. Chan School of Public Health, Boston, MA, and colleagues conducted a prospective evaluation to assess how effectively combinations of signs and symptoms can identify individuals in the prodromal phase of Parkinson's disease.

For this purpose, the researchers included 6,108 men who underwent repeated assessments of key prodromal features and were prospectively followed for the development of Parkinson's disease. Two composite measures of prodromal PD were evaluated: (i) the co-occurrence of constipation, probable rapid eye movement (REM) sleep behavior disorder (pRBD), and hyposmia, and (ii) the probability of prodromal PD based on the Movement Disorders Society (MDS) research criteria. Additionally, the researchers examined the progression and heterogeneity of the prodromal PD phase.

The study led to the following findings:

• A total of 103 individuals were newly diagnosed with Parkinson's disease (PD) over an average follow-up of 3.4 years.
• Men with constipation, probable REM sleep behavior disorder (pRBD), and hyposmia had a 23-fold higher risk of receiving a PD diagnosis in the next 3 years compared to men without these features (risk ratio [RR] = 23.35).
• The risk of PD was 21-fold higher in men with a probability of prodromal PD ≥ 0.8 compared to those with a probability < 0.2 (RR = 21.96).
• The co-occurrence of the three non-motor features and an MDS-based probability ≥ 0.8 were comparable in their predictive value. They were stronger predictors of PD than any of the individual features.
• Two prodromal PD subtypes were identified, with REM sleep behavior disorder (RBD) and visual color impairment as key discriminators.

The authors provide compelling evidence that combinations of key signs and symptoms can strongly predict the future development of clinically manifest Parkinson's disease. These findings suggest that such measures could be incorporated into screening strategies, allowing for the identification of individuals who may benefit from early intervention and enrollment in PD prevention trials.

Reference:

Flores-Torres, M. H., Hughes, K. C., Cortese, M., Hung, A. Y., Healy, B. C., Schwarzschild, M. A., Bjornevik, K., & Ascherio, A. Identifying Individuals in the Prodromal Phase of Parkinson's Disease: A Prospective Cohort Study. Annals of Neurology. https://doi.org/10.1002/ana.27166