Exploring the Evolving Role of Scopolamine in Pharmacotherapy: From Cognitive Impairment to Neuroplasticity?―A Narrative Review

Scopolamine, also known as hyoscine, is a naturally occurring tropane alkaloid derived from plants of the Solanaceae family. Clinically, the compound has long been used for the prevention of motion sickness and postoperative nausea and vomiting, as well as for ophthalmological procedures requiring mydriasis and cycloplegia. However, beyond these established indications, increasing attention has been directed toward its broader neuropharmacological actions. This narrative review aims to summarise current knowledge regarding the pharmacological properties of scopolamine, with particular emphasis on its mechanisms of action and emerging implications in neuroscience and neuropsychiatric disorders. Scopolamine acts as a non-selective antagonist of muscarinic receptor subtypes M1-M5, interfering with cholinergic neurotransmission. Experimental and clinical studies demonstrate that scopolamine induces transient cognitive impairment. This property has led to its widespread use as a pharmacological model of Alzheimer's disease, enabling investigation of cholinergic contributions to cognitive decline. More recently, several early clinical studies suggested that intravenous administration may produce rapid reductions in depressive symptoms, possibly through modulation of glutamatergic neurotransmission and activation of mTORC1-dependent synaptic plasticity pathways in the prefrontal cortex. Nevertheless, subsequent trials have yielded inconsistent results, and the therapeutic relevance of these findings remains uncertain. Current evidence indicates that scopolamine's neuropsychiatric effects likely arise from complex interactions between cholinergic, glutamatergic, and neurotrophic signalling systems. Taken together, scopolamine represents both a valuable experimental tool for studying cholinergic function and a mechanistic framework for the development of novel therapeutics targeting rapid neuroplastic processes in neuropsychiatric disorders.