Nongenetic Factors Associated with Age at Onset and Disease Severity in Spinocerebellar Ataxia Type 3: A Cross‐Sectional Cohort Study

BACKGROUND: Beyond genetic factors, demographic and environmental associations with onset and severity in spinocerebellar ataxia type 3 (SCA3) remain incompletely understood. OBJECTIVE: The aim of this study was to identify the association of nongenetic factors with onset and severity of SCA3. METHODS: Associations of nongenetic factors with age at onset (AAO) or Scale for the Assessment and Rating of Ataxia (SARA) scores were examined using generalized linear models. RESULTS: In the cohort of 324 patients with SCA3, higher education level was associated with lower SARA scores but earlier AAO. Smoking was associated with earlier AAO. Tea consumption was inversely associated with SARA scores. Body mass index, coffee consumption, alcohol consumption, as well as other assessed variables, were not associated with AAO or SARA scores. CONCLUSIONS: These findings support the associations of nongenetic factors and onset or severity in SCA3, while highlighting the need for cautious interpretation given the observational design.