Impact of Age on Multiple Sclerosis Disease Activity and Progression

Purpose of Review The purpose of this review is to discuss the interaction between aging, progressive disease course, disability worsening, and treatment strategies in multiple sclerosis (MS). Recent Findings The transition from the relapsing-remitting phase to the progressive phase in MS often happens in the fifth decade. In MS, structural central nervous system reserve decreases with aging and MS-associated mechanisms. While clinical and subclinical disease activity decreases with aging, the post-relapse recovery potential decreases with aging as well. Moreover, the efficacy of disease-modifying treatments declines with older age. Aging emerges as the ultimate target for prevention of progressive disease course, which is the most important determinant of disability worsening in MS. While none of our current treatment strategies targets the association between aging and progressive disease in MS, future treatment targets will likely consider the neuron-astrocyte complex, microglia, and oligodendrocyte functions impacted by the aging process.