Objective: To evaluate whether Parkinson’s disease (PD) patients with mild activity of daily living (ADL) impairment are at higher risk for developing dementia (PDD).

Background: Mild cognitive impairment (PD-MCI) increases the risk for PDD. However, only a subgroup of PD-MCI patients converts to PDD, while others do not progress or revert to normal cognition. Impairments in ADL primarily caused by cognitive dysfunction are crucial for differentiating between PD-MCI and PDD, and are already observable in some PD-MCI patients to a mild extent. This supports the assumption that ADL performance worsen in prodromal PDD. We examined whether ADL performance predicts dementia conversion.

Method: 164 (baseline: 35.4% PD-MCI) of 269 non-demented PD patients were reassessed after a mean interval of 3.8 (±0.8) years with cognitive batteries, questionnaires and biomarker sampling. Novel scores of the Pfeffer Functional Activities Questionnaire (FAQ), allowing for differentiating between cognitive and motor influences on ADL, were applied. ROC curve analysis was used to identify baseline the FAQ score best predicting onset of Level II diagnosis of PDD.

Results: At follow-up, 56.7% of patients were classified as cognitively normal (PD-CN, stable=48.2%), 32.9% as PD-MCI (stable=18.9%) and 10.4% had converted to PDD. The FAQ quotient (optimal cutoff >1.008, ADL+ n=35 vs. ADL- n=129), indicating more cognitive than motor-associated ADL impairment was identified to predict PDD. Diagnosis of cognitive impairment was more frequent in patients with ADL+ compared to ADL- at both visits (p<0.01, respectively). At baseline, 36.2% PD-MCI patients had ADL+ vs. 13.2% of the PD-NC group. Cox-regression analysis confirmed that PDD conversion was substantially higher in patients with ADL+ vs. ADL- (Hazards ratio, 9.84, 95%-Konf: 3.30-29.3, p<0.001), independent of between group confounders. In total, 31.4% of the total baseline ADL+ group, and 55% of PD-MCI patients with ADL+, developed PDD compared to only 4.7% of the total ADL- group and 11.8% of PD-MCI classified as ADL-. Baseline ADL status was an independent predictor of cognitive impairment at follow-up, in addition to a baseline cognitive, biomarker, and genetic profile.

Conclusion: Cognitive-driven ADL impairment predicts PDD within four years. This risk cohort maybe a valuable target group for clinical trials evaluating cognitive intervention strategies to prevent PDD.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/cognitive-driven-adl-impairment-as-a-predictor-for-pdd/