Cannabis

This review describes the ethnopharmacological and pharmacological aspects of Cannabis sativa, suggesting that phytocannabinoids are involved in various pathophysiological mechanisms, but does not report a specific effect direction.

review

This case-control study found that people with first-episode psychosis were more likely to be daily cannabis users (OR=6.4) and to have used high-potency cannabis (OR=6.8) compared to controls, supporting the hypothesis that THC increases psychosis risk.

case-control study Sample size: 454

This RCT found that pre-treatment with 600 mg CBD reduced THC-elicited paranoia and the odds of clinically significant positive psychotic symptoms (OR=0.22), and mitigated THC-induced memory impairment, supporting the idea that high-THC/low-CBD products are riskier.

randomized controlled trial Sample size: 48

This crossover trial found that THC increased anxiety and autonomic arousal to fearful faces, while CBD reduced arousal and dampened limbic brain activation, correlating with an anxiolytic trend.

double-blind, randomized, placebo-controlled crossover trial Sample size: 15

This review argues that synthetic cannabinoids in Spice products pose serious health risks including psychosis and death, and that their variability and legal status make them appealing yet dangerous, particularly to young and drug-naive users.

review

This review argues that CBD shows anxiolytic and antipsychotic-like properties and may be a safe alternative treatment for schizophrenia, based on animal models, healthy volunteer studies, and open case reports.

review

This review argues that healthcare providers must become familiar with synthetic cannabinoids and other novel psychoactive substances because these Internet-available drugs, often perceived as safe, can cause life-threatening adverse effects.

review

This observational study found that ayahuasca-assisted therapy is associated with statistically significant improvements in factors related to problematic substance use, suggesting positive psychological and behavioral changes.

observational study

This observational study suggests that even typical recreational doses of ecstasy, possibly in conjunction with cannabis, may cause neurotoxicity and cognitive decline in otherwise healthy young people.

observational

This RCT found that THC produced anxiety, dysphoria, positive psychotic symptoms, sedation, subjective intoxication, and increased heart rate, while CBD showed no differences from placebo on any measure.

randomized controlled trial Sample size: 16

This cross-sectional survey found that alcohol, tobacco, and cannabis are frequently co-administered with each other and with other substances, and that the pattern of use depends on the combination of substances.

cross-sectional survey Sample size: 149

This RCT found that THC increased psychotic symptoms and altered parahippocampal and ventrostriatal brain activation during verbal learning, while CBD had no significant effects.

randomized controlled trial Sample size: 15

This systematic review found that current evidence for medicinal cannabis in psychiatry is nascent and insufficient to recommend cannabinoid-based interventions, though isolated positive studies show tentative support for CBD in social anxiety and mixed evidence for adjunctive use in schizophrenia.

systematic review

This review argues that cannabis and THC acutely affect neurocognitive systems via endocannabinoid and neurotransmitter interactions, with heavy adolescent use linked to increased risk of addiction and psychosis, while CBD may offset some acute effects.

review

This observational cohort found that ritual ayahuasca use is not associated with the deleterious psychosocial effects typically caused by other drugs of abuse, as assessed by the Addiction Severity Index.

observational cohort Sample size: 127

This review argues that a Christian ethical perspective on THC use must integrate neurobiological, clinical, public health, and social evidence with theological and ethical frameworks, and that such an evaluation should distinguish among medical, recreational, and spiritual contexts.

review

This narrative review argues that evidence for meaningful modulation of THC's effects by minor cannabinoids and terpenes in humans is exceptionally limited, with CBD exacerbating THC effects when orally coadministered but not when inhaled, and THCV possibly reducing some subjective and cognitive effects.

narrative review

This pilot study found that a 25 mg oral dose of THC produced subjective experiences similar to 25 mg psilocybin, and dronabinol was mistaken for a classic hallucinogen by both a psychedelic-naive and a psychedelic-experienced participant.

pilot human laboratory study, double-blind, placebo-controlled, within-subject crossover Sample size: 4

This systematic review argues that higher THC potency is dose-dependently associated with increased risk of psychotic episodes, and that adolescent-onset cannabis use markedly elevates the probability of transitioning to chronic psychotic disorders.

systematic review

This RCT found that cannabis intoxication attenuates neuroendocrine and electrodermal stress responses while elevating cardiovascular arousal, but subjective stress reductions were comparable to placebo, suggesting expectancy effects rather than cannabis effects.

randomized, double-blind, placebo-controlled trial Sample size: 120

This qualitative study identified four domains influencing psychedelic use among cannabis-using emerging adults: context, expectancies, motives, and practices, with motives including self/spiritual exploration, social connection, and self-treatment.

qualitative study Sample size: 33

This observational study found that psychedelics were most semantically similar to dreams but uniquely coupled with meditation on ASC themes including personal growth, while cannabis was semantically similar to meditation but not aligned on themes such as personal growth.

observational study Sample size: 2242

This cross-sectional survey estimated that 19% of respondents reported lifetime use of psilocybin, LSD, MDMA, or ketamine, with psilocybin being the most commonly used, and over a third of past-year users reported experiencing an adverse health effect.

repeated cross-sectional survey

This systematic review and meta-analysis found that THC was consistently associated with increased risk of psychotic symptoms, cognitive impairment, and anxiety, whereas CBD demonstrated potential antipsychotic, anxiolytic, and neuroprotective effects, but evidence for cannabis-based products in treating psychiatric disorders was limited.

systematic review and meta-analysis Sample size: 14

This perspective argues that cannabis, particularly high-potency THC, may contribute to psychosis and violence, and that toxicology in violence cases often omits THC testing.

perspective