Cognitive impairment and dementia in Latin American individuals with parkinsonism and Parkinson's disease: A 10/66 Dementia Research Group study

INTRODUCTION: This study aimed to determine the associations between parkinsonism and Parkinson's disease (PD) with cognitive impairment and dementia in a multi-country cohort in Latin America, using data from the 10/66 Dementia Research Group. METHODS: This population-based prospective cohort study was conducted in six Latin American countries, including 11,321 participants 65 years of age or older living in urban and rural areas. RESULTS: At baseline, the prevalence of cognitive impairment in people with parkinsonism and PD was 33% and 26%, respectively. Parkinsonism (odds ratio [OR] 2.2 [95% confidence interval [CI] 1.9–2.6] and PD (OR 1.9 [95% CI 1.4–2.4]) were individually associated with baseline cognitive impairment and incident dementia. The pooled sub-hazard ratios for dementia in fixed-effect meta-analysis were 1.5 (95% CI 1.2–1.9) for parkinsonism and 1.5 (95% CI 1.0–2.2) for PD. DISCUSSION: Parkinsonism and PD were cross-sectionally associated with cognitive impairment and prospectively associated with incident dementia. These findings underscore the importance of routine screening for cognitive impairment in individuals with parkinsonism and PD, to facilitate early detection and intervention strategies that mitigate adverse outcomes. Highlights: The present study is one of the first longitudinal investigations into the association of parkinsonism and Parkinson's disease (PD) with cognitive impairment and dementia incidence in Latin America. Parkinsonism and PD showed strong cross-sectional associations with cognitive impairment, with consistent estimates across countries, independent of demographic factors. Parkinsonism and PD were linked to a significantly higher incidence of dementia over a 4-year follow-up period. Findings emphasize the need for routine cognitive screening in Parkinsonism and PD.