Paranoia

Cannabis-induced paranoia is an acute, transient state of persecutory ideation, hypervigilance, suspiciousness, and distrust of others, produced dose-dependently by Δ9-THC. D'Souza et al. (2004 Neuropsychopharmacology) demonstrated that intravenous THC (2.5–5 mg) produced schizophrenia-like positive symptoms including paranoid ideation on the PANSS. Freeman et al. (2015 Schizophr Bull) used IV THC in a virtual-reality paradigm to show that THC induced paranoia in approximately 50% of healthy participants, mediated by increased anxiety, negative affect, and anomalous perceptual experiences rather than by direct delusional mechanism. Risk is elevated by high THC dose, low CBD content, personal or family history of psychosis, younger age of first use, genetic vulnerability (e.g., AKT1 polymorphisms), and set/setting. CBD's capacity to buffer THC-induced paranoia is contested: Englund et al. (2013) and Morgan et al. (2010) found protective effects, but the 2025 RCT in schizophrenia (Englund et al. Neuropsychopharmacology) did not. A 2025 meta-analysis of experimental and observational studies confirmed a consistent dose-dependent cannabinoid-paranoia association (Solmi et al. Neurosci Biobehav Rev). Citations: D'Souza DC et al. Neuropsychopharmacology. 2004;29:1558-1572; Freeman D et al. Schizophr Bull. 2015;41:391-399; Solmi M et al. Neurosci Biobehav Rev. 2025.