Article Title: Impact of Dysphagia on Quality of Life in Machado-Joseph Disease.

Dysphagia is a frequent symptom of spinocerebellar ataxia type 3 (SCA3)/Machado-Joseph disease (MJD), being associated with alterations in nutritional intake and hydration, as well as an increased risk of aspiration pneumonia. This study aims to evaluate the impact of self-perceived dysphagia and its relationship with quality of life in SCA3/MJD mutation carriers. 41 SCA3/MJD mutation carriers from the Azorean cohort were recruited. The Swallowing Quality-of-Life Questionnaire (SWAL-QOL), the Eating Assessment Tool (EAT-10), the Functional Oral Intake Scale (FOIS), the Volume-Viscosity Swallow Test (V-VST), the Scale for the Assessment and Rating of Ataxia (SARA), the Inventory of Non-Ataxia Signs (INAS), and the Activities of Daily Living (ADL) were applied. Dysphagia was confirmed in 40% SCA3/MJD patients, whose SWAL-QOL was significantly decreased when compared to participants without dysphagia (p = 0.001). As expected, SCA3/MJD carriers with worse SWAL-QOL showed a high risk of dysphagia (p < 0.01), a worse functional oral intake of food and liquids (p < 0.01) and more severe ataxia (p < 0.01). Additionally, high severity of dysphagia reported on the INAS scale, (p < 0.01) and high frequency of swallowing disorders, perceived by SCA3/MJD carriers (p < 0.01) were observed in SCA3/MJD carriers with worse SWAL-QOL. Our findings confirm that dysphagia negatively impacts the quality of life of SCA3/MJD carriers, highlighting the need for permanent support by specialized healthcare professionals during disease progression. Additionally, we recommend that SCA3/MJD carriers with a score of 1 or higher on both the INAS dysphagia item and the ADL swallowing item be referred for specialized healthcare support in swallowing disorders.