Objective: This study aims to identify predictors of cognitive decline in cognitively normal Parkinson’s disease patients by analyzing the 10 years-long PD registry.

Background: Cognitive impairment is a critical complication of PD that significantly impacts daily functioning and quality of life. It also increases caregiver burden, healthcare costs, and the risk of institutionalization and mortality. While many studies have focused on the motor symptoms of PD, fewer have comprehensively examined long-term cognitive decline and its association with other symptoms.

Method: We analyzed data of the Osaka University Registry Study of Parkinson’s Disease (OURSPD), which included comprehensive assessment of motor and non-motor symptoms in hospitalized PD patients. Among 713 participants who were enrolled from August 2015 to September 2024, 130 underwent at least two evaluations, of whom 75 had an initial Mini-Mental State Examination (MMSE) score of 28 or higher. These cognitively normal patients were classified into two groups based on their rate of cognitive decline: the Cognitive Stable Group (annual MMSE decline < 1 point) and the Cognitive Decline Group (annual MMSE decline ≥ 1 point). Baseline characteristics and symptoms were compared between groups, and multiple regression analysis was performed with annual MMSE decline as the dependent variable.

Results: The Cognitive Stable Group comprised 58 patients (male 22, female 36, mean age 64.6) with an average follow-up period of 48 months, while the Cognitive Decline Group comprised 17 patients (male 13, female 4, mean age 66.5) with an average follow-up period of 19 months. Comparison between the two groups revealed that male gender, lower Montreal Cognitive Assessment score at baseline, and non-motor symptoms such as hyposmia, pareidolia, rapid eye movement sleep behavior disorder (RBD), impulsive-compulsive disorders, and autonomic dysfunction were associated with cognitive decline (p < 0.05). Multiple regression analysis identified male gender (B = 1.065, 95% CI [0.261, 1.869], t = 2.657, p = 0.010) and RBD questionnaire score (B = 0.284, 95% CI [0.127, 0.441], t = 3.633, p < 0.001) as independent predictors of cognitive decline.

Conclusion: These findings highlight key factors associated with cognitive decline in PD patients. Male gender and higher score in RBD questionnaire may be predictors of cognitive decline. These findings align with previous studies.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/cognitive-decline-in-parkinsons-disease-a-decade-long-registry-analysis-of-prevalence-and-risk-factors/