Temporal processing variability as a scalable marker for Parkinson’s disease progression

Parkinson’s disease (PD) is associated with disruptions in the temporal organization of motor and non-motor behavior, likely arising from dysfunction within basal ganglia–thalamocortical circuits. Despite extensive evidence for impaired timing in PD, the relationship between temporal processing variability, disease progression, and established clinical severity markers remains poorly defined. We conducted a systematic meta-analysis to quantify temporal processing efficiency in PD using the coefficient of variation (CV), a standardized measure of performance variability across timing tasks. CV values were extracted from empirical studies encompassing a broad range of temporal processing paradigms. Associations between CV, participant age, and disease severity were examined using Unified Parkinson’s Disease Rating Scale (UPDRS) scores and Hoehn and Yahr (H&Y) stages. Results revealed a robust positive correlation between CV and UPDRS score, independent of age, indicating that increased temporal variability reflects disease-specific dysfunction rather than normal aging. In contrast, CV correlated negatively with H&Y stage and age, consistent with medication-related influences on motor symptom severity. Secondary analyses showed no reliable differences in CV across task type, temporal range, or medication status, supporting the notion of a generalized temporal processing impairment in PD. Together, these findings suggest that temporal processing variability represents a sensitive marker of disease progression and may inform diagnostic assessment and intervention strategies.