Amyotrophic Lateral Sclerosis (ALS) is a rare, rapidly progressive, and fatal neurodegenerative disease. As the disease progresses, there is a decline in functional status, increased dependence, and limitation, which can have a considerable impact on the quality of life of these individuals.

To investigate the correlation between functional status and quality of life in individuals with ALS.

Exploratory cross-sectional study. The study included individuals diagnosed with ALS, following the Awaji criteria, aged 18 years or older, followed by a Neuromuscular Disease Center. Individuals diagnosed with other neurological disorder or who showed signs and symptoms of cognitive alterations could not participate. Functional status and quality of life were measured by Functional Rating Scale-Revised (ALSFRS-R) and ALS Assessment Questionnaire (ALSAQ-40), respectively. To investigate the correlation between the two variables, Pearson's correlation and linear regression were used, considering a significance level of 5%. Statistical tests were performed using SPSS program.

Eighty-four individuals participated in the study with mean age of 56.6 (SD 11.4) years and a median of 1.0 year of diagnosis. Most participants had ALS of appendicular onset (82.1%) and had both appendicular and bulbar involvement (91.7%). The mean ALSAQ-40 score was 265.2 (SD 111.9) and the mean ALSFRS-R score was 30.1 (SD 10.5). There was a strong correlation between functional status and quality of life (r= -0.826; p=0.000). When evaluating the correlation between the domains of ALSFRS-R and quality of life, a strong correlation was found with bulbar domain (r=-0.756; p=0.000), moderate with motor (r=-0.677; p=0.000) and weak with respiratory function (r=-0.214; p=0.050). The ALSFRS-R score explained 82.6% of the variation in the scores of ALSAQ-40 (R2=0,826; p=0,000).

Functional status is correlated with quality of life in individuals with ALS. Therefore, it is essential to considerer the relationship between functional status and quality of life when monitoring this population.

Future studies should investigate strategies for maintaining functional status for as long as possible and whether they are able to improve the quality of life of individuals with ALS.