Objective: Based on the importance of progressive dysfunction of posterior cortical regions in cognitive deterioration in PD, we explored whether posterior cortical dysfunction in early PD patients assessed by validated tasks measuring functionality of temporal-parietal-occipital regions, behaves as a marker of more pervasive cognitive impairment.

Background: MDS Task Force Criteria (MDS-TF) for Parkinson’s disease Mild Cognitive Impairment (PD-MCI) accurately screen for PD-MCI from the earliest stages of the disease. However, when subtyping among the five cognitive domains explored, a large heterogeneity of PD-MCI appears with so many combinations that make it difficult to anticipate which PD-MCI subtypes have a greater risk to evolve to dementia.

Methods: Prospective sample of PD patients with ≤5 years of evolution who underwent neuropsychological examination applying MDS-TF PD-MCI criteria. Z-scores were used to detect patients with ≥1.5 SD in tasks assessing recognition memory (Buschke cued recall), language (Boston, Token), and visuospatial skills (JLOT, VOSP), and ROC curves were plotted to look for discriminative cut-off scores.

Results: Thirty-two (35.2%) out of 91 PD patients (age 70.1±7 y; evolution 1.8±1.7 years) accomplished PD-MCI criteria. Multiple domain MCI involving ≥2 domains (93.7%) was predominant, with multiple combinations of domain impairment. 26.7% of the sample had impairment in any posterior cortical task. Within PD-MCI patients, 58,6% had posterior cortical impairment (43.8% visuospatial, 28.1% Buschke, 33.3% language). Best discriminative tests of posterior cortical impairment were Buschke’s total (≤34) and delayed total (≤11) recall, Boston naming (≤45), Token test (≤31), and VOSP number location + position discrimination tests (≤27). AUC were >0.85 for all ROC curves, with sensitivity and specificity >85%. Interestingly, only 19% of PD patients with no impairment in any posterior cortical task had MCI, while 74% of patients with impairment in any of these tests had MCI (χ², p<0.0001).

Conclusions: The use of cut-off scores in selected tasks assessing posterior cortical dysfunction, helps overcoming the large heterogeneity of PD-MCI subtypes, and might stand as a more operative approach for selecting PD-MCI patients with a higher risk to develop dementia.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/screening-of-posterior-cortical-dysfunction-in-early-parkinsons-disease-with-mild-cognitive-impairment-as-an-approach-to-select-patients-at-higher-risk-for-developing-dementia/