Objective: To introduce the Mobile Universal Lexicon Evaluation System (MULES) to the visual assessment of patients with Parkinson’s Disease (PD).

Background: The MULES is a test of rapid picture naming that captures an extensive visual network involving afferent/efferent visual and cognitive pathways. MULES performance is impaired in concussion and multiple sclerosis in which visual impairment is common. Similarly, visual deficits also occur in PD. These visual deficits influence overall motor function and are a risk factor for developing visual hallucinations. Since many of the visual factors captured by the MULES may be abnormal in PD (e.g., visual acuity, color discrimination, object recognition, visual processing speed, and saccadic eye movements), the MULES may serve as a useful screening tool for visual dysfunction in PD.

Method: The MULES, which consists of 54 color photographs of various objects (fruits, animals, and random objects), was administered in a PD cohort and a group of similar-aged disease-free controls.

Results: Among 49 PD patients (median age 70 years old, range 52-82) and 18 disease-free controls (median age 61.5, range 53-90), MULES scores were significantly worse (slower) in PD patients (63.2 seconds, range 37.8-296.3) vs. controls (49.7 seconds, range 38.6-128.6) (p=0.04, accounting for age). Slower MULES times were associated with increased PD motor symptom severity as measured by the Unified Parkinson’s Disease Rating Scale (UPDRS) (rs=0.40, p=0.01). Age, gender, primary language, and disease duration did not predict MULES scores in PD patients.

Conclusion: The MULES captures an extensive visual network, including many aspects of vision, that can be abnormal in PD. This study demonstrates that MULES performance is reduced in PD and may reflect the degree of motor impairment. As such, MULES is a potentially useful performance assessment tool in PD.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/rapid-picture-naming-in-parkinsons-disease-using-the-mobile-universal-lexicon-evaluation-system-mules-test/