MRI glymphatic markers associated with drooling in Parkinson’s disease

An observational study in BMC Medicine examined whether MRI markers of glymphatic function were associated with drooling in Parkinson’s disease. Researchers enrolled 36 patients with drooling, 36 without drooling, and 38 age-matched healthy controls. Participants underwent MRI and standardized clinical assessments. Imaging measures included diffusion tensor image analysis along the perivascular space (DTI-ALPS), choroid plexus volume, and enlarged perivascular spaces.

Patients with drooling had lower left, right, and bilateral-average ALPS indices than patients without drooling (p=0.032, p=0.004, and p=0.004, respectively) and healthy controls (all p<0.001). Both Parkinson’s groups had higher choroid plexus volume relative to intracranial volume than controls, whereas relative enlarged perivascular space volumes did not differ significantly. Lower ALPS indices correlated with greater disease and drooling severity. The bilateral-average ALPS index distinguished patients with and without drooling with an AUC of 0.725; its adjusted association with drooling had an odds ratio of 0.063 (95% CI 0.004–0.938; p=0.045).

These findings suggest an association between drooling and MRI features consistent with impaired glymphatic function. However, the measures provide indirect evidence, the sample was small, and the adjusted estimate was imprecise. Group discrimination does not establish that ALPS measurements can predict future drooling or progression, and clinical utility remains unestablished.