Supplementary Material for: Clinical characterization of probable Dementia with Lewy Bodies based on the initial clinical presentation in a Latin American Low- and Middle- Income Country

Background: Dementia with Lewy Bodies (DLB) is a distinct form of dementia characterized by the accumulation of alpha-synuclein in the brain. Early presentations are often heterogeneous, and the impact of this variability on disease progression remains poorly understood. This study explored the initial clinical presentation of DLB among Peruvian patients and its influence on the clinical course. Methods: We conducted a retrospective study of patients diagnosed with DLB and Alzheimer’s disease (AD) using standard clinical criteria. Cognitive function was assessed using MMSE, INECO Frontal Screening (IFS), and Uniform Data Set (UDS). We classified DLB patients based on their initial symptoms (hallucinations or parkinsonism) and compared their clinical and neuropsychological characteristics. Statistical analyses (ANOVA, chi-squared, Wilcoxon tests, and multivariate linear regression) were used to evaluate group differences and examine how initial symptoms influenced disease progression and cognitive decline. Results: Forty-six patients with probable DLB between June 2018 and May 2023 were included. The median time from symptom onset to diagnosis was five years. Cognitive symptoms were the most frequent initial presentation, followed by motor and behavioral signs. No significant clinical or neuropsychological differences were found between presentation subgroups at evaluation. Compared to AD patients, those with DLB scored higher on cognitive measures (MMSE, RUDAS) and behavioral symptoms (NPI). Neuropsychological testing revealed DLB patients had more pronounced deficits in visuospatial and executive functions than those with AD. Conclusions: In our cohort, patients in the cognitive-onset group reached the threshold for dementia more rapidly. However, the initial presenting symptoms did not result in worse severity across specific cognitive or behavioral domains.