Browse more cannabis research, findings, methods, and limitations.
Study of 247 first-episode psychosis patients found childhood violence and environmental adversity was the strongest predictor of premorbid substance use, more than interpersonal abuse or neglect.
Systematic review of 42 studies found purified CBD effective for epilepsy beyond its approved indications, with preliminary evidence for CDKL5, Dup15q, Doose, and other rare syndromes.
Study found four cannabis terpenes activated CB1 receptors and produced cannabinoid-like effects in mice, with selective enhancement of cannabinoid activity providing first strong evidence for the entourage effect.
Analysis of pharmaceutical marketing records found medical cannabis laws had minimal effect on drug company detailing to physicians, with only small, delayed reductions for substitute drugs.
Two experiments with 1,601 young adults found that learning about genetic predisposition for cannabis-related psychosis risk increased intentions to avoid marijuana, especially among prior users.
Mouse study found CBD prevented cocaine relapse, abolished cocaine hyperactivity, and improved withdrawal memory deficits without producing reward itself.
Cohort study of 29,153 medical cannabis patients found authorization associated with a small but significant increase in motor vehicle crash-related healthcare visits, primarily emergency department visits.
A study of 5,373 matched patient pairs in Alberta found that medical cannabis authorization was associated with reduced opioid use, with the largest reductions seen in patients on the highest opioid doses.
A national longitudinal study of 7,821 US adolescents found that existing substance use, particularly other marijuana products and e-cigarettes, strongly predicted starting to vape marijuana.
A systematic review of 43 longitudinal studies found heavy adolescent alcohol use was associated with widespread brain structure changes, while heavy cannabis use showed more localized effects. Co-use studies generally found alcohol effects were more pronounced.
A survey experiment with 870 young Canadians found that branded cannabis packaging increased appeal while health warnings decreased it. Lifestyle imagery made products seem targeted at younger consumers.
A psychophysiology study of 50 young adults found that driving-related cannabis risk messages generated the strongest attention, arousal, and emotional engagement compared to messages about cognition or health.
A validation study of 517 adolescents found the S2BI screening tool accurately identified moderate-to-severe cannabis use disorder (90% sensitivity, 89% specificity) but was less reliable for mild cases.
A MEG study of 45 adults who used both alcohol and cannabis found that alcohol use disorder was associated with blunted occipital alpha brain wave responses, with no independent effect from cannabis use disorder.
A survey of 430 medical students across Israel and Thailand found cultural and legal context shaped attitudes toward medical cannabis, with a notable gap between permissiveness and clinical preparedness.
A study of 70 young frequent cannabis users found those with higher trait mindfulness reported fewer cannabis-related problems, though mindfulness did not predict motivation to reduce use.
An anandamide analog improved memory and reduced amyloid-beta in Alzheimer's model mice by activating CB2 cannabinoid receptors and promoting autophagy, a cellular cleanup process.
A 10-year case series found 34 adolescents with cannabis hyperemesis syndrome at one institution, with clinical features matching adult presentations and no antiemetic proving consistently effective.
In a rat model of interstitial cystitis, activating the cannabinoid receptor GPR18 reduced pain and improved bladder function by inhibiting TRPV1 pain receptors in nerve tissue.
A prospective study of 1,145 Canadian medical cannabis patients found opioid use dropped from 28% to 11% over six months, with a 78% reduction in daily dosage, alongside quality-of-life improvements.
A survey of 2,102 Canadian medical cannabis patients found that among 650 tobacco/nicotine users, 49% reported reducing use and 25% reported quitting after starting medical cannabis.
A Canadian study found that after recreational cannabis legalization, the odds of patients staying in a medical cannabis research study dropped by 72%, raising concerns about the validity of ongoing cannabis research.
A study found chronic cannabis smokers had elevated oral Actinomyces meyeri bacteria. When this bacterium was fed to mice for six months, it decreased activity and increased amyloid-beta production in their brains.
A French nationwide study of 3.3+ million patients found cannabis was the only illicit drug independently associated with higher heart attack risk, though post-heart-attack outcomes were similar for drug users and non-users.
Mice given daily THC throughout adolescence showed no lasting changes in pain sensitivity, morphine effectiveness, or morphine tolerance when tested as adults, suggesting pain circuits may be resilient to moderate adolescent THC exposure.
A chart review of 50 ADHD patients found heavy cannabis use was associated with significantly worse cognitive test performance, more fine motor hyperactivity, and higher self-reported impulsivity compared to ADHD patients without substance use.
Three clinical trials found topical CBD and PEA products caused no skin irritation or sensitization in healthy adults, with only mild phototoxicity from one hemp seed oil product.
A lab study comparing six purified CBD samples found no pharmacological differences between plant-derived and synthetic CBD across cancer, stroke, and intestinal inflammation models.
A nationwide VA study of 1.2+ million patients found cannabis use independently associated with 2.65 times the odds of premature cardiovascular disease, with greater risk in women and polysubstance users.
Two patients with untreated schizophrenia caused severe eye injuries to themselves while intoxicated on synthetic cannabinoid K2, both hallucinating a bug behind their eye.
A 26-year-old chronic cannabis user developed heart block requiring a pacemaker. Electrophysiology testing revealed a novel pattern suggesting cannabis may directly damage cardiac conduction tissue.
All 10 of the most-viewed YouTube videos about THC oil for skin cancer were rated poor quality and misleading, yet nearly all viewer comments were positive or neutral.
A national study of 37,870 high school students found sexual minority girls had higher odds of marijuana use while sexual minority boys had lower odds, revealing important sex-based differences in substance use patterns.
Focus groups in rural South Africa found 11 factors sustaining adolescent marijuana farming, from family tradition and economic necessity to favorable soil conditions and lax law enforcement.
A study of 604 pregnant women found continued cannabis use was associated with higher anxiety and depression scores, and women with more depression symptoms were nearly 3 times more likely to keep using rather than quit.
The first blood-based epigenome-wide study of cannabis use identified a replicated DNA methylation marker in the CEMIP gene, though its ability to predict cannabis use history was modest.
A study of 5,987 young Swiss men found four distinct cannabis use disorder trajectories from ages 20-25, with mental health problems and peer drug use predicting who remained stuck at high severity.
Among 239 ADHD patients with substance use disorders, those seeking cannabis treatment had more anxiety, earlier substance use onset, and similar ADHD severity compared to those seeking cocaine treatment.
A study of 1.9 million adolescent hospitalizations found cannabis-related admissions increased after legalization, with the steepest rises in recreational states, younger teens, and those without prior mental health diagnoses.
A young cannabis user developed a rare, life-threatening blood clot in the left main coronary artery, raising questions about cannabis as a potential trigger for coronary thrombosis.
A case series of 38 fibromyalgia patients found medical cannabis significantly improved pain and disability, but nearly half stopped treatment due to side effects like mental confusion.
A meta-analysis of 80 studies found THC impairs driving-related skills at peak effect, with impairment from inhaled cannabis generally resolving within 3-5 hours. Researchers recommended waiting at least 5 hours before driving.
A randomized trial found daily moderate-intensity cycling during inpatient cannabis withdrawal improved objective sleep duration and efficiency compared to stretching, though participants did not perceive the difference.
A survey of 1,813 Ontario adults found most people recognize cannabis-impaired driving risks, but male frequent cannabis users were the most likely to dismiss these risks, and safety concerns predicted actual driving behavior more than fear of legal consequences.
A CB1 receptor positive allosteric modulator called GAT211 showed antipsychotic-like effects in rats by reducing dopamine-related hyperactivity, unlike THC which did not block the same signaling pathway.
Cannabis use before first psychiatric hospitalization in Ontario rose from 17% to 26% over a decade, with nearly half of young adults (18-24) using cannabis before admission by 2017.
A meta-analysis of 31 randomized controlled trials found only limited evidence that cannabinoid products help with certain psychiatric symptoms short-term, and no evidence for mid- to long-term effectiveness for any psychiatric disorder.
An Australian cohort study spanning 16 years found persistent cannabis, tobacco, and binge drinking from adolescence through young adulthood predicted gambling problems in the early 30s.
A US survey of 434 dispensary workers found most based cannabis recommendations on customer experience rather than clinical evidence, and few counseled about serious risks like cannabis use disorder or psychotic reactions.
CBD treatment in rats protected hippocampal neurons from ischemia damage, preserved dendritic spines and BDNF levels, and prevented ischemia-induced memory deficits.