Impaired Gait, Postural Instability, and Rigidity in Relation to CB1 Receptor Availability in Parkinson's Disease

Background: In Parkinson's disease (PD), postural instability and gait disorder (PIGD) symptoms are associated with a worse prognosis for an unknown reason.

Objective: The objective was to explore the relationship between cannabinoid receptor type 1 (CB1R) availability and motor symptoms in PD with [¹⁸F]FMPEP-d₂ positron emission tomography (PET).

Methods: Fifteen individuals with PD underwent [¹⁸F]FMPEP-d₂ PET to measure cerebral CB1R availability. The Unified Parkinson's Disease Rating Scale motor part (UPDRS-III) was used to evaluate the motor symptoms.

Results: A negative correlation was observed between [¹⁸F]FMPEP-d₂ V_T and PIGD score (P = 0.002) as well as rigidity subscore (P < 0.001). Both clusters covered widespread areas of both hemispheres. In contrast, tremor or bradykinesia did not correlate to [¹⁸F]FMPEP-d₂ V_T.

Conclusions: Gait, postural instability, and rigidity in PD are associated with decreased CB1R availability, unlike tremor or bradykinesia, suggesting that the endocannabinoid system has a role in the pathophysiology of different motor symptoms in PD. © 2024 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.