Adjunctive Non-Disease-Modifying Therapies in Multiple Sclerosis: Immunometabolic, Neuroprotective and Remyelination-Oriented Approaches

Disease-modifying therapies (DMTs) are the standard treatment for multiple sclerosis (MS) and effectively reduce inflammatory disease activity; however, their effects on neurodegeneration, remyelination failure, and long-term symptom burden vary across disease stages and patient populations. Adjunctive non-DMT approaches have therefore been investigated to target biological processes not primarily addressed by conventional immunomodulatory treatment. These strategies often involve agents originally developed for non-neurological indications, whose mechanisms of action extend beyond their primary clinical use and may intersect with pathways relevant to MS pathophysiology. This narrative review summarizes pharmacological agents, nutraceuticals, and selected bioactive compounds evaluated as adjunctive interventions in MS, with emphasis on immunometabolic regulation and remyelination-related mechanisms. Evidence from experimental models, translational studies, and clinical trials is examined to assess repurposed drugs and metabolic modulators with reported effects on immune responses, glial function, and myelin repair. Particular emphasis is placed on the distinction between mechanistic rationale and clinical outcomes, highlighting the challenges of translating biologically plausible effects into consistent therapeutic benefit. Available data indicate that most adjunctive strategies do not demonstrate consistent disease-modifying effects, although some interventions influence specific biological pathways relevant to neuroinflammation, cellular metabolism, and oligodendrocyte biology. Reported outcomes vary according to disease stage, treatment duration, and selected clinical or imaging endpoints. Overall, adjunctive non-DMT strategies remain investigational and require further evaluation in biologically stratified clinical studies.