Plasma pTau217 and pTau231 predict progression to dementia in Parkinson's disease: a prospective longitudinal study

This prospective study evaluated the prognostic utility of Alzheimer's disease-related plasma biomarkers (phosphorylated tau [pTau217 and pTau231], the amyloid-β [Aβ] 42/40 ratio) and neurofilament light chain (NfL) in 123 Parkinson's disease (PD) patients and 40 controls. Over a mean 5.1-year follow-up, 35 of 109 initially non-demented PD patients (32.1%) progressed to dementia. Plasma pTau217 and NfL levels were elevated, whereas the Aβ42/40 ratio was reduced, in cognitively impaired PD groups versus controls. Baseline pTau217 accurately differentiated dementia converters from non-converters (AUC = 0.877; 95% CI: 0.798-0.956). Patients with pTau217 ≥ 0.268 pg/mL had a higher risk of dementia progression (HR: 5.49; 95% CI: 2.37-12.74). This risk was further elevated in patients in the highest quartile ( ≥ 0.36 pg/mL; HR: 11.35; 95% CI: 2.60-49.59) versus the lowest quartile ( < 0.20 pg/mL). Similarly, the pTau231 cut-off ( ≥ 2.575 pg/mL) predicted an increased risk of dementia (HR: 3.89; 95% CI: 1.67-9.03). Both pTau217 and pTau231 demonstrated high predictive performance in Cox models (C-index: 0.806 and 0.796, respectively). Plasma NfL exhibited longitudinal increases during follow-up. Baseline plasma pTau217 and pTau231 serve as surrogate markers for predicting dementia progression in PD. Further validation of these biomarker cut-off values is warranted.