The effect of five day dosing with THCV on THC-induced cognitive, psychological and physiological effects in healthy male human volunteers:A placebo-controlled, double-blind, crossover pilot trial

Rationale: Cannabis is mostly grown under illegal and unregulated circumstances, which seems to favour a product increasingly high in its main cannabinoid ∆-9-tetrahydrocannabinol (THC). ∆-9-tetrahydrocannabivarin (THCV) is a relatively untested cannabinoid which is said to be a cannabinoid receptor neutral antagonist, and may inhibit the effects of THC. Objectives: To explore the safety and tolerability of repeated THCV administration and its effects on symptoms normally induced by THC in a sample of healthy volunteers. Methods: Ten male cannabis users (&lt;25 use occasions) were recruited for this within-subjects, placebo-controlled, double-blind, cross-over pilot study. 10mg oral pure THCV or placebo were administered daily for five days, followed by 1mg intravenous THC on the fifth day. Results: THCV was well tolerated and subjectively indistinguishable from placebo. THC did not significantly increase psychotic symptoms, paranoia or impair short-term memory, while still producing significant intoxicating effects. Delayed verbal recall was impaired by THC and only occurred under placebo condition ( Z=-2.201, p=0.028), suggesting a protective effect of THCV. THCV also inhibited THC-induced increased heart rate ( Z=-2.193, p=0.028). Nine out of ten participants reported THC under THCV condition (compared to placebo) to be subjectively weaker or less intense (χ2=6.4, p=0.011). THCV in combination with THC significantly increased memory intrusions ( Z=-2.155, p=0.031). Conclusion: In this first study of THC and THCV, THCV inhibited some of the well-known effects of THC, while potentiating others. These findings need to be interpreted with caution due to a small sample size and lack of THC-induced psychotomimetic and memory-impairing effect, probably owing to the choice of dose. </jats:sec

Psychosis and autism: magnetic resonance imaging study of brain anatomy

BACKGROUND: Autism-spectrum disorder is increasingly recognised, with recent studies estimating that 1% of children in South London are affected. However, the biology of comorbid mental health problems in people with autism-spectrum disorder is poorly understood. AIMS: To investigate the brain anatomy of people with autism-spectrum disorder with and without psychosis. METHOD: We used in vivo magnetic resonance imaging and compared 30 adults with autism-spectrum disorder (14 with a history psychosis) and 16 healthy controls. RESULTS: Compared with controls both autism-spectrum disorder groups had significantly less grey matter bilaterally in the temporal lobes and the cerebellum. In contrast, they had increased grey matter in striatal regions. However, those with psychosis also had a significant reduction in grey matter content of frontal and occipital regions. Contrary to our expectation, within autism-spectrum disorder, comparisons revealed that psychosis was associated with a reduction in grey matter of the right insular cortex and bilaterally in the cerebellum extending into the fusiform gyrus and the lingual gyrus. CONCLUSIONS: The presence of neurodevelopmental abnormalities normally associated with autism-spectrum disorder might represent an alternative 'entry-point' into a final common pathway of psychosi