Objective: To establish whether a visuoperceptual tool (the Cats-and-Dogs test) can predict cognitive impairment (CI) in people with Parkinson’s disease (PwP) in a diverse population.

Background: Some PwP may have difficulties with reading distorted images, suggesting an issue with their visual perception. Visual impairment is associated with cognitive decline, but diagnosis of CI can be challenging, particularly in non-English speaking populations [1]. Previous studies using the Cats-and-Dogs (CnD) test of object invariance have shown attenuated perception of distorted visual stimuli in PwP [2]. Here, we aimed to extend this test to detect CI in a diverse population in East London.

Method: This study is a part of the East London Parkinson’s Disease project and the London-Dhaka Parkinson’s Cognition Study. It was administered during an appointment in the Royal London Hospital or a home visit. The computerised test was presented via MATLAB and involved distinguishing between a cat and dog in black and white photographs with varying degrees of shear. The outcome measures from this test included accuracy, reaction time, and the psychophysical threshold (image shear at 75% accuracy). Participants additionally received other assessments, including tests of motor and non-motor symptoms.

Results: A total of 56 PwP and 50 healthy control (HC) (recruited up to 2nd November 2023) were included in this study. The mean accuracy (SD) for PwP and HC was, respectively, 0.65(0.09) and 0.75(0.09); the mean reaction time was 1.52(0.89) and 1.01(0.47), and mean threshold was 1.16(0.95) and 2.53(1.53). A multiple regression model adjusted for age, sex, ethnicity, years of education, and visual acuity showed that there were significant differences for accuracy and reaction time between PwP and HC (p<0.05), whilst no differences were observed for ethnicity. We found modest classification of PD status for the full cohort of PwP and HC (with an AUC of 0.75 for threshold), classification of CI within PwP reached clinical robustness (AUC of 0.95 for threshold).

Conclusion: Our findings suggest that the CnD test of visual processing is culturally fair and a promising tool for screening for CI and dementia, particularly in PwP in a diverse population. It is crucial to repeat this analysis further on a larger scale in different ethnicities to explore the effectiveness of the CnD test for predicting early cognitive dysfunction.

References: [1] Statucka M, Cherian K, Fasano A, Munhoz RP, Cohn M. Multiculturalism: a challenge for cognitive screeners in Parkinson’s disease. Movement Disorders Clinical Practice. 2021 Jul;8(5):733-42.

[2] Weil RS, Pappa K, Schade RN, Schrag AE, Bahrami B, Schwarzkopf DS, Crutch SJ, O’Keeffe AG, Morris HR. The cats‐and‐dogs test: a tool to identify visuoperceptual deficits in Parkinson’s disease. Movement Disorders. 2017 Dec;32(12):1789-90.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/the-cats-and-dogs-test-predicts-cognitive-impairment-in-parkinsons-disease-in-a-diverse-population/