Abstract
BACKGROUND: Cognitive decline is a common but variable non-motor manifestation of Parkinson's disease. Chronic liver disease contributes to dementia, but its impact on cognitive performance in Parkinson's disease is unknown. We assessed the effect of liver fibrosis on cognition in Parkinson's disease. METHODS: We conducted a retrospective cohort study using data from the Parkinson's Progression Markers Initiative. Our exposure was liver fibrosis at baseline, based on the validated Fibrosis-4 score. Our primary outcome was the Montreal Cognitive Assessment, and additional outcome measures were the Symbol Digit Modalities Test, the Benton Judgement of Line Orientation, the Letter-Number Sequencing Test, and the Modified Semantic Fluency Test. We used linear regression models to assess the relationship between liver fibrosis and scores on cognitive assessments at baseline and linear mixed models to evaluate the association between baseline Fibrosis-4 score with changes in each cognitive test over five years. Models were adjusted for demographics, comorbidities, and alcohol use. RESULTS: We included 409 participants (mean age 61, 40 % women). There was no significant association between liver fibrosis and baseline performance on any of the cognitive assessments in adjusted models. However, over the subsequent five year period, liver fibrosis was associated with more rapid decline in scores on the Montreal Cognitive Assessment (interaction coefficient, -0.07; 95 % CI, -0.12, -0.02), the Symbol Digit Modalities Test, the Benton Judgement of Line Orientation, and the Modified Semantic Fluency Test. CONCLUSION: In people with Parkinson's disease, the presence of comorbid liver fibrosis was associated with more rapid decline across multiple cognitive domains.