Objective: To explore clinical and cognitive predictors of functional dependence in a cohort of early Parkinson’s Disease (PD) patients.

Background: Parkinson’s Disease (PD) patients are more likely to lose the ability to perform daily activities than healthy controls and this loss of functional independence is a key outcome in the disease progression. Research is needed to determine which factors may influence functional decline early in the disease course.

Method: Data used in the preparation of this abstract were obtained from the Parkinson’s Progression Markers Initiative (PPMI) database (www.ppmi-info.org/access-data-specimens/download-data). 286 patients with idiopathic PD who had completed all yearly visits from baseline to year five were analysed. At all visits, patients underwent clinical, motor, and neuropsychological assessment, and the Schwab and England (S&E) scale assessed functional dependency. PD-MCI was diagnosed if performance on any 2 or more cognitive tests was 1.5 standard deviations below the mean; those not meeting this criterion were classified as cognitively normal. The relationship between baseline cognitive status and functional decline over time was examined using a linear mixed-effects model. Covariates included sex, education, and baseline: age, disease duration, depression, and motor severity. A binary logistic regression was conducted to determine baseline predictors of functional dependency at year 5 (using S&E cut-off score <80%).

Results: At baseline, mean age was 60.95 (SD=9.69), mean S&E score was 93.41 (SD=5.85), and 38 (14.2%) patients were classified as PD-MCI. The linear mixed model only showed main effects of motor severity (Estimate_UPDRS=-0.294, p<0.001) and baseline disease duration (Estimate_Duration=0.095, p=0.001) on S&E change. Significant baseline predictors of functional dependency at year 5 identified by the binary logistic regression [χ²(13)=26.69, p=0.01] were: disease duration [β=-0.06, p=0.04] and performance on the Symbol-Digit Modalities Test [β=0.07, p=0.009]. Patients who were functionally dependent at year 5 had longer disease durations and worse performance on the SDMT at baseline than those who remained independent.

Conclusion: Worse performance on the SDMT, which measures attention and processing speed, predicted functional dependence after five years independent of motor influence, highlighting the cognitive nature of declines in activities of daily living.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/longitudinal-predictors-of-functional-dependence-in-a-multicentric-parkinsons-disease-cohort/