The endocannabinoid system as a therapeutic target in prodromal psychosis: From molecular mechanisms to clinical applications

This systematic review explores the role of the endocannabinoid system (ECS) in prodromal psychosis and its potential as a therapeutic target. Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, 22 studies published between 2000 and 2025 were analyzed, comprising preclinical research, genetic studies, neuroimaging investigations, and clinical trials. Converging evidence suggests that ECS alterations precede and potentially contribute to the development of psychotic symptoms, with CB1 receptor modifications and endocannabinoid levels correlating with symptom severity and transition risk to full-blown psychosis. Neuroimaging studies revealed reduced CB1 receptor availability in key brain regions in high-risk subjects, and intervention studies, particularly with cannabidiol-though its therapeutic mechanisms likely extend beyond ECS modulation to include dopaminergic and other neurotransmitter pathways-have shown promising results. Proposed mechanisms of action include stress response attenuation, neuroinflammatory modulation, neurodevelopmental stabilization, and normalization of the dopamine-glutamate interface. Despite limitations of existing studies, primarily small size and short duration, this review provides a solid foundation for developing ECS-targeted interventions as a promising approach to modify disease trajectory during the prodromal phase, potentially offering safer and more effective therapeutic options for individuals at clinical high risk for psychosis.