Abstract
Chronological age (C-Age), determined by the time elapsed since the birth of an individual, is considered one of the main risk factors for the onset and prognosis of multiple sclerosis (MS). Biological age (B-Age), in contrast, conditioned by genetic, lifestyle, comorbidity, and environmental factors, defines the aging of tissues that contributes to the decline of organ function, the loss of functional reserve, and decrease in the regenerative capacity. In this context immunosenescence is increasingly evidenced as a factor that contributes to the MS progressive course and loss of efficacy of MS drugs. B-Age can be estimated through different measurement strategies such as telomere length, epigenetic clocks and biomarker composites. These biomarkers are gaining attention in MS research since they seem to be associated with disability progression and are modulated by lifestyle interventions. This review summarizes the roles of C-Age and B-Age in MS and highlights implications for prognosis and therapeutic development.