Risk of Premotor Symptoms in Patients with Newly Diagnosed PD: A Nationwide, Population-Based, Case-Control Study in Taiwan

I like this study although there are some limitations. The diagnostic criteria for PD are a little loose, as are the criteria for RBD. But the effect size estimates for other prodromal features appear pretty standard (adding credence to the overall findings), and whilst the interval between onset of non-motor features and diagnosis is conservative, it is perhaps to be expected given the methods of data collection. Some people will reject the effect size estimate for RBD and say it is too small... this may be true... or it may reflect the fact these subjects were diagnosed with PD rather than parkinsonism....

http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0130282

PLoS One. 2015 Jun 24;10(6):e0130282. doi: 10.1371/journal.pone.0130282.

Wu YH, Liao YC, Chen YH, Chang MH, Lin CH.

BACKGROUND:

To evaluate the risk of premotor symptoms, namely rapid eye movement behavior disorder (RBD), constipation, and depression among patients with newly diagnosed Parkinson disease (PD).

METHODS:

A total of 705 PD patients and 2,820 control subjects were selected from the Taiwan National Health Insurance Research Database. Patients were traced back for a maximum of 14 years to determine the diagnoses of RBD, depression, and constipation. Logistic regression analysis was used to identify risk of premotor symptoms for PD. Moreover, subgroup analyses were performed by dividing the patients into a middle-age onset group (≤ 64 years) and an old-age onset group (≥ 65 years). The associations between these premotor symptoms and age of PD onset were further examined.

RESULTS:

An association was found between a history of premotor symptoms and newly diagnosed PD in which a high occurrence of premotor symptoms was identified in PD patients as compared to selected controls (4.3% vs. 1.2% for RBD, 40.4% vs. 24.0% for constipation, and 13.0% vs. 5.1% for depression). The strength of this association remained statistically significant after adjustment for potential confounders (3.69 fold risk for RBD, 2.36 for constipation, and 2.82 for depression, all p < 0.0001). The average interval between premotor symptoms and PD ranged from 4.5 to 6.2 years. RBD and depression carried higher risks for PD in the middle-age onset group than in the old-age onset group (7.20- vs. 2.24-fold risk for RBD, 6.06 vs. 1.40 for depression).

CONCLUSION:

The prevalence of premotor symptoms was higher among the PD patients than in the controls. Premotor symptoms appeared to be associated with a higher risk for PD in subjects with an earlier age of onset.