Atypical parkinsonian syndromes in French Guiana: Similarities and differences with Caribbean variants.

BackgroundAtypical parkinsonian syndromes are highly prevalent in the French West Indies (FWI), making up 70% of degenerative parkinsonisms and including "Caribbean Atypical Parkinsonism". Environmental neurotoxins from Annonaceae plants are implicated. Despite close ties, parkinsonism data for French Guiana remain limited.ObjectiveThis study aimed to compare atypical parkinsonism frequencies between French Guiana and FWI, assess clinical characteristics in French Guiana, and evaluate potential environmental toxin exposure.MethodsDegenerative parkinsonism patients were recruited from a community-based population in French Guiana and compared with a FWI cohort.ResultsAmong 372 patients (67 from French Guiana, 305 from FWI), atypical parkinsonian syndromes accounted for 41.8% in French Guiana, lower than in FWI (66.2%, p < 0.001). In French Guiana, these syndromes were more common in males (sex-ratio: 3 vs. 1.22 in FWI, p = 0.044; adjusted p-value = 0.281) and often involved cerebellar symptoms (p < 0.001). Cases not fitting classical subtypes were classified as "other atypical parkinsonian syndromes" (35.7% in French Guiana, 41.6% in FWI), with a supranuclear palsy-like phenotype often presenting with additional rapid eye movement (REM) sleep behavior disorder, hallucinations, or orthostatic hypotension. Annonaceae consumption was higher in FWI (93%) than in French Guiana (79.2%, p < 0.001), while alcohol use was more common in French Guiana (p = 0.005).ConclusionsAtypical parkinsonism in French Guiana resembles that in FWI but is less common, with an intermediate prevalence between Caucasian and Caribbean populations. Shared environmental factors, such as Annonaceae exposure, may contribute to this presentation, supporting the term "Caribbean Atypical Parkinsonism" for both regions.