Browse more cannabis research, findings, methods, and limitations.
Study of 1.2 million women found cannabis use disorder associated with 48% higher cardiovascular risk and doubled hemorrhagic stroke risk over up to 30 years.
10-year follow-up found women had higher early psychosis recovery rates (50% vs 31%) during specialized care, but the gap narrowed after discharge to community services.
Despite strong animal evidence, controlled human studies do not support cannabis replacing opioids for pain or producing significant opioid-sparing effects.
Review concludes there is no known safe level of cannabis in pregnancy, with prenatal exposure linked to neurodevelopmental effects persisting into adulthood.
First meta-analysis of cannabis withdrawal prevalence: 47% of regular/dependent users experienced clinically significant withdrawal across 23 studies and 27,000+ participants.
South Australian data show illicit drugs now detected in more crash victims than alcohol, with drug-positive rates rising as alcohol rates fell over a decade.
Survey of 478 pregnant Canadians found high awareness that cannabis reaches the fetus, but 4.2% continued using, with provider counseling paradoxically more common among users.
A man developed respiratory depression and bradycardia after gas station CBD gummies, highlighting the dangers of unregulated CBD products.
Systematic review of 17 neuroimaging studies found CBD consistently modulated brain activity in regions relevant to psychosis and anxiety, often opposite to THC effects.
Review found cannabinoids may help older adults with pain and nausea, with moderate risks, but few studies have specifically included elderly patients.
Survey of 93 Australian gastroenterologists found only 21% support cannabis for IBD, despite 39% having patients using it and ranking it safer than standard IBD drugs.
Review of cannabis for fibromyalgia finds patient surveys suggest significant benefit, but randomized trial evidence remains limited and questioned.
Survey of 200 people found most who used cannabis for opioid withdrawal reported improvement, especially in anxiety, tremors, and sleep.
Simulations suggest CBD's seizure reduction in Lennox-Gastaut syndrome may be explained by its interaction with clobazam rather than direct anti-seizure effects.
Study of 49 confirmed synthetic cannabinoid patients found concomitant drug use in 69.4%, with significantly worse outcomes than synthetic cannabinoid use alone.
Adolescent rat study found THC given after concussions reduced anxiety, depression, and memory deficits, but THC before injury had no effect.
Meta-analysis of pivotal trials found CBD has independent anti-seizure effects, though the benefit is amplified by interaction with clobazam.
A cannabinoid agonist that improved fear extinction in adult rats impaired it in adolescent and juvenile rats, with younger animals showing higher CB1 receptor levels in brain regions tied to fear processing.
A narrative review found consistent evidence linking adolescent cannabis use to alterations in brain structure, function, and connectivity, with some changes appearing to persist into adulthood.
A systematic review of 12 neuroimaging studies found cannabis users show altered brain activation during memory tasks, with verbal memory particularly affected and some evidence suggesting a causal role for cannabis.
A small crossover trial found that 600mg of CBD increased blood flow to the hippocampus by an average of 15 mL/100g/min, with increased orbitofrontal blood flow correlating with faster working memory reaction times.
A CDC/NEJM study found vitamin E acetate in 94% of EVALI patients' lung fluid across 16 states, with 94% of patients linked to THC vaping, identifying the primary toxicant behind the 2019 vaping lung injury outbreak.
A genome-wide study found a P2RX7 gene variant associated with psychotic experiences in cannabis users, replicated in a second cohort. THC and CBD affected the P2X7 receptor differently depending on genotype.
A longitudinal study of 1,606 Quebec adolescents found depression predicted subsequent weekly cannabis use, while the link between cannabis and suicidal ideation was fully explained by other substance use.
Adolescent rat offspring exposed to THC during fetal development showed impaired emotional memory, reduced neuropeptide Y neurons, and increased alcohol-seeking behavior, suggesting prenatal THC may create lasting vulnerability.
Synthetic cannabinoids JWH-073 and AM-2201 caused significantly more seizures in mice than THC, while endogenous cannabinoid analogs caused none, with effects mediated through CB1 receptors.
THC interacts with common medications through shared liver enzymes (CYP3A4, CYP2C9), and genetic variants in up to 35% of Caucasians increase THC bioavailability.
A small crossover trial found cannabis-intoxicated drivers showed decreased theta brain waves that correlated with worse lane-keeping in a simulator, suggesting EEG patterns could help identify cannabis impairment.
A mouse model of a human FAAH gene variant showed that adolescent females had enhanced dopamine reward circuitry and stronger THC preference that lasted into adulthood, while males were unaffected.
A review found CB1 neutral antagonists and FAAH inhibitors show the most promise among endocannabinoid-based approaches for tobacco addiction, after the CB1 inverse agonist rimonabant was withdrawn due to psychiatric side effects.
In a large NAPLS study of 543 individuals at clinical high risk for psychosis, slower startle responses predicted psychotic conversion (especially in females), and cannabis use showed opposite effects on sensory gating compared to healthy controls.
A critical review of five studies (827 participants) found cannabinoid treatments showed promise for fibromyalgia pain, but significant methodological limitations in the research prevent definitive conclusions about efficacy.
A cross-sectional study of 1,462 Colombian high school students found lifetime cannabis use associated with 1.88 times the odds of high suicide risk, though the study could not determine direction of the relationship.
A prospective study of 49 children with drug-resistant epilepsy in Argentina found 80% responded to add-on CBD therapy, with a median 66% seizure reduction and mild side effects.
A synthetic cannabinoid that blocks CB1 and activates CB2 receptors reduced brain injury and white matter damage in newborn rats even when given 3 hours after oxygen deprivation.
A study of 1,059 tobacco quitline callers in states with legal marijuana found 24% also used marijuana, with 43% of those users wanting to quit or reduce their marijuana consumption.
A Canadian survey of 14,520 high school students found a strong dose-response relationship between perceived cannabis risk and impaired driving, with low-risk perceivers far more likely to drive or ride high.
When Italy accidentally liberalized CBD products in 2017, prescription sales of anxiolytics, sedatives, opioids, antidepressants, and antipsychotics dropped significantly in provinces where the products became available.
A review found cannabis associated with improved IBD symptom scores and quality of life, but the lack of standardized preparations, doses, and routes of administration prevents establishing treatment guidelines.
Female rat offspring exposed to a cannabinoid agonist prenatally had reduced ovarian reserve in adulthood, an effect mediated by CB1 receptors. The delay between exposure and impact suggests a programmed developmental effect.
A systematic review found 12 cases of acute eosinophilic pneumonia from marijuana, vaping, and other non-cigarette products. Most patients were young, many needed ICU care, but all recovered with corticosteroid treatment.
A review found suggestive evidence that CBD may reduce anxiety and fear responses in PTSD, but cannabis use may worsen depression. Well-designed randomized trials remain largely absent across these conditions.
A small RCT found THC-rich cannabis oil significantly improved fibromyalgia scores in 17 women over 8 weeks, with gains in pain, fatigue, ability to work, and overall well-being.
Before cannabis legalization, a Canadian pediatric hospital saw 114 cannabis poisonings over 3 years. Most involved teens using cannabis with other substances, while rare accidental ingestions by toddlers all involved family-owned cannabis at home.
A 30-day mobile monitoring study of 60 young adults found slight but significant cognitive slowing and accuracy decreases on phone-based tasks when participants reported being high from marijuana.
A review of 63 neuroimaging studies found adolescent cannabis users show altered frontoparietal brain structure and function, but adult studies examining onset age gave mixed results, leaving the question of adolescent-specific vulnerability unresolved.
A 24-day inpatient detox study of 78 cannabis-dependent adults found urine THC metabolite levels moderately predicted withdrawal severity, with females showing prolonged elimination and withdrawal symptoms.
A critical review found that the cannabis "entourage effect," widely used to market whole-plant products, rests on poorly defined and largely unsubstantiated pharmacological claims, with the original literature commonly overinterpreted.
A review found preliminary evidence that cannabis may help PTSD patients and reduce use of more harmful drugs, but rigorous clinical trials are needed to establish whether cannabis-based medicines should be integrated into treatment.
A study of 128 participants found chronic synthetic cannabinoid users had higher neuroticism, lower agreeableness, and greater schizotypal traits than natural cannabis users or non-users, suggesting SC users may be more psychiatrically vulnerable.