Age-Related Changes in Multiple Sclerosis Pathophysiology and Clinical Function

Older adults with multiple sclerosis (MS) face unique issues related to the combined effects of MS and age-related changes, which often present with overlapping symptoms that complicate assessment and treatment decisions. In this review, based on the Consortium of MS Centers' Aging and MS Consensus Statement committee meeting in 2024, we address the contributions of aging in MS by focusing on direct, biological aging effects on MS pathology and comorbid age-related changes in physical and cognitive function. Features of biological aging include cellular senescence and immune dysregulation, which may drive disease progression in MS through a variety of proinflammatory mediators that may maintain low levels of chronic inflammation in the immune and central nervous system compartments and offset regulatory processes, ultimately impairing remyelination and increasing neurodegeneration. Measuring biological aging in MS may help identify individuals at risk of worse MS outcomes and support gerotherapeutic treatments that target aging mechanisms. Compounding any direct effects of aging on MS pathology, aging-related impairments in neuromuscular function and cognition can worsen functional outcomes in people with MS. Characteristics of cognitive impairments in MS affecting attention and processing speed occur early in the disease course and are distinct from other age-associated neurodegenerative disorders, such as Alzheimer disease, that commonly affect language and executive function domains. As MS clinicians care for growing numbers of older adults with MS, a more comprehensive understanding of the interplay between aging and MS-related changes can improve the timing and modality of treatments to optimize MS neurogeriatric care.