Objective: We investigated cognitive performance in patients with early Parkinson’s disease (PD).

Background: Cognitive impairment is a common non-motor symptom of PD, generally detected later in disease with objective measures. PD patients complain of subjective deficits from disease onset. The profile of cognitive deficits in PD seems broadly multi-domain.  Studies of cognition in PD are limited by small samples, heterogeneous in terms of disease severity, and confounded by effects of chronic dopaminergic therapy.  Previous studies also show that neuropsychiatric symptoms (e.g., anxiety, depression) negatively affect cognition in PD.

Method: We examined Montreal Cognitive Assessment (MoCA) total and sub-scale performance in PD patients (n=714) and healthy controls (n=244) from the Parkinson’s Progression Markers Initiative datase. Patients were tested at ≤ 12 months of disease duration and prior to treatment with dopaminergic therapy. Encoding and retrieval were also measured using the Hopkins Verbal Learning Test- Revised (HVLT-R) in a subset of PD (n=675) and HC (n=243) participants. . Bayesian analyses of covariance were performed on each measure using Age, Sex, Education, and Anxiety and Depression scores as covariates. Bayes factor’s (BF₁₀) were calculated, using JASP, as the ratio of the predictive performance of any given model over the null model (BF₁₀= 1). BF₁₀ values are reported for best predictive model that includes Group.

Results: Patients performed significantly worse than controls in MoCA total score (BF₁₀= 8.74×10⁺¹⁶), and in sub-scores of recall (BF₁₀=1.27×10⁺¹³), language ( BF₁₀= 234015.89), visuospatial executive (BF₁₀= 3.05×10⁺¹¹), abstraction (BF₁₀= 299.32), and attention (BF₁₀= 854.83). Patients and controls did not differ in learning slopes (BF₁₀= 0.51) but retrieval was poorer in PD (BF₁₀= 2725.73) on the HVLT-R.

Conclusion: PD patients ( < 12 months disease duration; dopaminergic therapy-naïve) had poorer global cognition, recall, as well as visuospatial, executive, and attentional processing compared to HCs. . Learning (i.e., memory encoding) was spared. Independent of typical confounds, multi-domain cognitive deficits appear in dopaminergic therapy-naïve PD patients, tested within 12 months of diagnosis relative to HCs.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/investigating-cognitive-impairments-in-early-parkinsons-disease/