Chunk #12 — Do cannabinoids cause short-lived positive psychotic symptoms, negative symptoms and cognitive deficits in the general population? — Experimental evidence
disorder and paranoia. The authors specifically described “tracking difficulties” that subjects reported, including racing thoughts, thought blocking, losing their train of thought, etc. Jones et al. [110] did not observe robust psychotomimetic effects in studies of “normal” controls with Δ9-THC (20 mg smoked or 40 mg orally). However, a “few” subjects reported ideas of reference and delusions that the researcher was using secret (unexplained) tests and hidden recording devices. At doses higher than 20 mg smoked or 40 mg orally, psychotomimetic effects, including delusions, loosening of associations, and marked illusions began to emerge. In a 18F-2-fluoro-2-deoxyglucose Positron Emission Tomography (FDG-PET) study of intravenous Δ9-THC (2 mg) on regional brain metabolism, two of eight healthy subjects who occasionally used cannabis experienced paranoid-anxious reactions [229]. Leweke et al. [128] reported the effects of oral synthetic Δ9-THC (120 μg/kg) in 17 healthy individuals under controlled laboratory conditions. The primary outcome measure was binocular depth perception—a model of illusionary perception. Subjective reactions ranged from mild euphoria to more pronounced reactions, including feelings of loss of self-control and body distortion suggestive of psychotic-like symptoms. One subject experienced a transient psychotic episode described as “a paranoid psychotic state with persecutory delusions, delusions of thought insertion, attentional
