Objective: To determine whether the Cats-and-Dogs visuoperceptual task (CnD) predicts cognitive impairment (CI) in Parkinson’s disease (PD) in a diverse population in East London and Dhaka.

Background: Cognitive impairment is common in PD and often emerges with disease progression. Patients with PD may show impaired recognition of distorted images, reflecting higher-order visual perceptual deficits. Previous work using the CnD test showed reduced perception of distorted stimuli in PD [1]. Visual dysfunction has been linked to subsequent cognitive decline in PD, but diagnosing CI is challenging, particularly in diverse populations [2].

Method: This psychophysical visual perception task forms part of the East London Parkinson’s Disease Project. Participants completed the computerised CnD test during hospital or home visits, distinguishing cats from dogs in grayscale images with varying shear. Outcomes included accuracy (Acc; higher better), and psychophysical threshold (PT; shear at 75% accuracy; higher better visuoperception).

Results: We included 151 patients with PD and 85 healthy controls (HC) from East London, and 164 patients with PD and 84 HC from Dhaka. In the East London cohort, 106 participants were South Asian, 105 White, and 25 from other ethnic backgrounds; all participants in the Dhaka cohort were Bangladeshi. Compared with HC, patients with PD had lower mean accuracy (Acc 0.68 [SD 0.10] vs 0.72 [SD 0.10]) and lower perceptual threshold (PT 1.83 [SD 1.38] vs 2.26 [SD 1.40]) (p<0.01). In logistic regression models adjusted for sex, age, ethnicity, LogMAR vision, and education, higher accuracy was associated with lower odds of PD (OR 0.01, 95% CI 0.00-0.18; p=0.003), whereas PT was not associated with PD. When cognitive impairment (CI) was the outcome, higher PT was associated with lower odds of CI (OR per 1-point increase 0.80, 95% CI 0.65-0.98; p=0.03), while Acc showed a similar but non-significant trend. ROC analyses using a 50/50 train-test split showed moderate discrimination (PD: AUC 0.71 for Acc, 0.68 for PT; CI: AUC 0.72 for Acc, 0.73 for PT).

Conclusion: The CnD test captures visuoperceptual differences associated with CI in PD across a diverse population. Although discrimination was modest, performance remained associated with disease status after adjustment for demographic factors. Further work should evaluate its value alongside established cognitive measures.

References: [1] 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.

[2] 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.

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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-2/