Psychedelics in Multiple Sclerosis: Mechanisms, Challenges, and Prospects for Neuroimmune Modulation and Repair.

Multiple Sclerosis (MS) therapies effectively modulate peripheral immune responses but largely fail to promote neural repair within the central nervous system. This review evaluates whether psychedelic compounds (PSYs), via 5-HT2A activation, can fill a critical therapeutic gap: the need for agents that simultaneously suppress neuroinflammation and promote regeneration. We dissect the evidence suggesting PSYs can reprogram the neuroimmune milieu by downregulating key pro-inflammatory cytokines (e.g., TNF-α, IL-6) in glial cells while concurrently upregulating crucial neurotrophic factors (e.g., BDNF) that promote synaptic plasticity and oligodendrocyte support. However, we argue that the current evidence, largely derived from non-specific inflammation models, is insufficient to predict clinical efficacy in an autoimmune disease like MS. We critically analyze the significant translational barriers-from cardiovascular and psychiatric risks to profound legal and ethical challenges-that temper the immediate clinical promise. Finally, we propose a forward-looking perspective, suggesting that the true value of PSYs may lie not in their direct clinical use, but in uncovering novel therapeutic pathways. The emergence of non-hallucinogenic, functionally selective 5-HT2A agonists, inspired by psychedelic pharmacology, represents a more viable strategy to harness these mechanisms for MS therapy, demanding rigorous preclinical validation in disease-relevant models.