Drooling in Parkinson's Disease: Prevalence and Progression from the Non-motor International Longitudinal Study.
Daniel J van Wamelen, Valentina Leta, Julia Johnson and 6 others
PMID 32130515WHAT IT FOUND
Drooling prevalence was similar at 37.2% and 40.1% over 3.27 ± 1.74 years in 728 Parkinson's patients, and severity did not change.
Older patients had more drooling, and drooling was linked with swallowing difficulty.
Key findings
01Drooling prevalence was 37.2% at baseline and 40.1% after 3.27 ± 1.74 years of follow-up, with no significant change (p = 0.17).
02Drooling severity did not significantly change over follow-up, with mean Non-Motor Symptoms Scale question 19 scores of 1.53 ± 2.71 at baseline and 1.77 ± 3.02 at follow-up (p = 0.12).
03At baseline, swallowing difficulty was reported in 34.3% of patients with drooling and 16.0% of patients without drooling (p < 0.001).
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
Drooling was measured by one patient-reported Non-Motor Symptoms Scale question, not by specialist clinical swallowing or salivation examination. The analysis was retrospective and used last available follow-up assessments, so it cannot describe true progression for every patient. Patients with dementia, defined as Mini Mental State Examination scores of 26 or less, were excluded, so the findings may not apply to Parkinson's patients with significant cognitive impairment. The study did not collect information on drooling treatments, so stable prevalence cannot be interpreted as treatment failure or success. The regression model had a very low R-squared, so it explains little of the variation in drooling severity. The reported associations with age, cognition, sleepiness, and quality of life were small and cannot show cause.
Declared interests
The paper states that the Non-motor International Longitudinal Study was adopted as a national study by the UK National Institute for Health Research; no funding or conflict-of-interest declaration is given.
The easy way to misread this
Do not conclude that drooling worsens over time in Parkinson's disease or that treatment failure explains the similar prevalence. The paper did not test treatment, and drooling prevalence and severity remained similar over follow-up.