Objective: To explore associations between saccadic measures and i) global motor, ii) non-tremor motor, and iii) tremor severity in Parkinson’s disease (PD).

Background: Impaired voluntary movement is a defining characteristic of PD and frequently overlaps with non-tremor motor symptoms, such as gait and bradykinesia. In PD, dysfunction in voluntary eye and body movements has been associated with cognitive decline, in particular executive dysfunction^1,2. Antisaccades have frequently been used as a proxy for executive function across neurodegenerative diseases. In this study we aimed to understand whether antisaccades are specifically associated with non-tremor motor symptoms in PD.

Method: As part of the Oxford QUantification In Parkinsonism study, PD patients (N=110) were tested using motor (MDS-UPDRS-III) and oculomotor (prosaccades, antisaccades) assessments. MDS-UPDRS-III items were divided into tremor and non-tremor subscores. We performed a preliminary cross-sectional analysis with a subset of patients (n=20) to inform future longitudinal work. Spearman’s correlations were conducted between oculomotor measures (latencies, amplitudes, and antisaccadic error rate [AER]) and motor measures.

Results: MDS-UPDRS-III scores were positively correlated with antisaccadic latency and negatively correlated with AER. More specifically, non-tremor motor subscores were negatively correlated with AER, whereas tremor severity was not correlated with any saccadic measures.

Conclusion: These findings support a specific association between antisaccadic performance and the severity of non-tremor motor symptoms in PD. Executive deficits may contribute to impaired information transfer between fronto-striatal circuits in PD, reducing prefrontal control over voluntary movement. In contrast, non-volitional (e.g., tremor) movements rely less on prefrontal inputs. This work sheds light into the mechanisms underlying oculomotor and motor dysfunction in PD. In future work, we will explore whether these associations are maintained longitudinally.

References: 1. Gibbs, M. C., D’Souza, A., Sotirakis, C., Crawford, T. J., & Antoniades, C. A. (2026). Cognitive function is associated with the progression of non-tremor motor symptoms in Parkinson’s disease. Frontiers in Aging Neuroscience, 18, 1765860.
2. Antoniades, C. A., Demeyere, N., Kennard, C., Humphreys, G. W., & Hu, M. T. (2015). Antisaccades and executive dysfunction in early drug‐naive Parkinson’s disease: The discovery study. Movement Disorders, 30(6), 843-847.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/associations-between-saccadic-and-motoric-symptoms-in-parkinsons-disease/