The Definition of Psoriasis Severity and Treatment Target of Psoriasis: Korean Expert Consensus Using the Modified Delphi Method.

Methamphetamine use disorder (MUD) remains among the most treatment-resistant substance misuse conditions. No pharmacotherapy with proven efficacy has been approved [, ], and while psychosocial interventions yield some positive outcomes, their impact is limited by persistently high relapse rates [, ]. A critical factor underlying this therapeutic challenge is that MA misuse does more than disrupt specific neurotransmitter systems and brain regions [, ]. It fundamentally alters the brain's learning and memory processes, inducing maladaptive plasticity that disproportionately strengthens drug-related behaviors while diminishing responsiveness to natural rewards [, , ]. Exercise has garnered increasing attention as a safe, accessible non-pharmacological intervention for MUD [–]. Both acute and chronic exercise benefit brain health and cognitive function [–], and growing evidence from MUD intervention studies indicates that exercise reduces cravings, improves cognitive performance, corrects attentional biases, and modulates the gut microbiota [–]. However, a cohesive theoretical framework that systematically explains how exercise modulates the complex neurobiology of MA addiction has yet to be established. Without such a framework, it is difficult to optimize exercise prescriptions or integrate exercise rationally with other therapeutic modalities. To elucidate the mechanisms by which exercise contributes to rehabilitation in individuals with MUD, this review introduces an integrative theoretical framework centered on the concept of metaplasticity. Metaplasticity, as defined by Abraham and Bear (1996), refers to the “plasticity of plasticity”, meaning that prior neuronal or synaptic activity can influence the subsequent ability or threshold to induce synaptic plasticity, such as long-term potentiation (LTP) or long-term depression (LTD) []. Unlike synaptic plasticity, which directly alters synaptic efficacy, metaplasticity regulates the very rules governing synaptic learning. By adjusting the sensitivity and response patterns of plasticity mechanisms, metaplasticity enables the nervous system to recalibrate future plastic changes based on prior experiences []. In essence, metaplasticity determines the conditions under which, and the rules by which, the brain engages in learning and memory. Exercise, as a physiological intervention, plays a pivotal role in modulating brain metaplasticity across various levels.