Browse more cannabis research, findings, methods, and limitations.
Review of 39 studies (12,143 patients) found about 26% of medical cannabis users for chronic pain experience adverse events, but serious harms occur in fewer than 5% of patients.
Longitudinal study of 1,465 young people found cannabis use and suicidal ideation were reciprocally linked from ages 15-20, suggesting they may reinforce each other over time.
In adolescent rats, synthetic cannabinoid WIN 55,212-2 prevented medium-severity convulsions in both sexes and increased hippocampal CaMKII signaling.
Among 23,091 medical cannabis patients in Ontario, cannabis poisoning ER visits occurred at 8 per 10,000 person-years and mental health crises at 15 per 10,000, with prior substance use being the strongest predictor.
Medical cannabis patients in Ontario had 2.45x the risk of drug poisoning ER visits and 2.27x the risk of substance-related mental health ER visits compared to matched controls.
Study of 20 cannabis users found brain glutamate levels were lower than controls during 21 days of abstinence, with declining glutamate strongly correlated with increasing craving.
Mouse study found adolescent THC exposure changed brain gene networks differently by sex, with four key driver genes also linked to human cannabis use disorder vulnerability.
Rats exposed to combined alcohol, cannabinoid, and nicotine during adolescence showed lasting learning deficits in adulthood, with females affected earlier than males.
Pilot trial of 12 adults with Tourette syndrome found vaporized THC reduced tic urges and distress but did not significantly improve video-rated tic severity compared to placebo.
Study of 47 college students found cannabis users were more likely to choose harder tasks for rewards, contradicting the "amotivational syndrome" hypothesis.
Saskatchewan pandemic survey found suicidal ideation was highest (25.8%) among those with both cannabis and alcohol problems, with younger adults and LGBTQIA2S+ individuals at elevated risk.
Perspective argues cannabis should be removed from the WADA prohibited list because it does not enhance performance, its health risks are overestimated, and the ban relies on subjective moral criteria.
Adolescent rats given CBD-enriched cannabis extract showed no behavioral changes but had significant hippocampal synaptic protein alterations, suggesting hidden molecular effects during brain development.
Mouse study found traumatic brain injury depleted endocannabinoids by increasing their metabolizing enzymes, contributing to brain barrier damage, reduced blood flow, and anxiety.
Chart review of 69 Parkinson's patients found 87% reported symptom improvement with medical cannabis, with 56% of opioid users reducing or stopping opioid medications.
10-year study of 704 people found adolescent cannabis initiation caused prefrontal cortex thinning linked to later drug use, while young adult initiation affected temporal areas linked to psychotic symptoms.
A type 1 diabetes patient was hospitalized for DKA 6 times in one year before clinicians discovered cannabis-induced hyperemesis syndrome was triggering the repeated episodes.
Review of 9 studies found recreational cannabis legalization increased cannabis use disorder prevalence but treatment admissions declined, suggesting a growing treatment gap.
Analysis of DEA data from 2006-2021 found medical cannabis legalization did not increase ADHD stimulant prescriptions, contradicting concerns about cannabis-related cognitive effects.
National survey analysis found recreational cannabis laws initially reduced opioid misuse, but the effect faded within 2-3 years when using methods accounting for staggered adoption.
Swedish conscript study found schizophrenia patients with adolescent cannabis history had earlier onset, more hospitalizations, and more hospital days than those without.
A 34-year-old man developed life-threatening lung bleeding (diffuse alveolar hemorrhage) after smoking K2/Spice synthetic cannabis, successfully treated with IV steroids.
Experiment with 700+ participants found that inducing negative mood increased self-reported cannabis problems and negative expectancies, even though actual use did not change.
Study found clinical psychosis risk youth had elevated cannabis, alcohol, and tobacco use, while genetically at-risk youth (22qDel) had lower rates, with social and cognitive factors explaining the difference.
Among 611 substance use inpatients, cannabis use disorder was the strongest predictor of 3-month relapse (53.3% rate, OR=2.31) in patients with co-occurring psychiatric disorders.
Meta-analysis of 3,053 schizophrenia patients found cannabis use associated with more positive symptoms and excitement but fewer negative symptoms, with no link to depression or disorganization.
Survey of 1,063 Australian medical cannabis users found 28% reported driving under the influence, with half typically driving within 6 hours of use and low perception of impairment.
Trial of 40 medical cannabis patients found no cognitive impairment after standard prescribed doses, with some test scores actually improving, though vaporized flower felt more impairing subjectively.
Canadian economic analysis found each dollar of medical cannabis sold was associated with $0.74-$0.84 less in alcohol sales, suggesting cannabis substitutes for alcohol at the population level.
Review found CBD therapeutic effects emerge at 300+ mg/day, with best evidence for anxiety and addiction. Most OTC products fall below this threshold.
Mouse study found cannabinoid cessation reduced sleep during normal sleep periods, providing an animal model for human cannabis withdrawal sleep disturbance.
Review found recreational cannabis legalization mostly did not increase youth use, but accidental pediatric edible ingestion rose significantly, along with some increases in adolescent alcohol and vaping.
Study of 133 veterans found cannabis use and perceived value reinforced each other over 6 months, with use driving demand more strongly than demand driving use.
Survey of 424 cannabis users found frequent users waited less before driving and perceived less impairment, with even those who acknowledged impairment not waiting longer.
Study of 168,589 pregnancies found children of prenatal cannabis users were 43% more likely to miss their 12-month check-up, with 36% missing two or more visits by age 3.
Patient on buprenorphine treatment presented with psychiatric symptoms from K2 use, but standard drug screens missed the synthetic cannabinoids and cathinones, requiring advanced GC-MS testing.
California data showed prenatal cannabis use (4.9%) was more than double cigarette smoking (2.1%), with cannabis being the more common substance during pregnancy statewide.
Survey of 267 cancer patients found 26% used cannabis, reporting benefits for sleep, nausea, and pain but worse overall symptoms compared to non-users.
Researchers and heavy drinkers co-created cannabis education resources for managed alcohol programs, establishing standard cannabis units and drawing on lived experience for harm reduction guidance.
New Zealand survey of 11,405 teens found regular cannabis use stable despite declining lifetime use, with 24% of users vaping and highest rates among Maori, LGBTQ+, and disadvantaged youth.
California study of 34,544 births with maternal CUD found 40% higher infant mortality in the first year (1.0% vs 0.4%), driven by perinatal conditions and sudden unexpected infant death.
Controlled human study shows CBD (640 mg) inhibited four major drug-metabolizing enzyme families while THC alone had minimal effects — important for anyone combining CBD with prescription medications.
Qualitative study found young people ride with cannabis-impaired drivers during routine daytime activities, citing trust and familiarity, with safety concerns developing only in young adulthood.
JAMA Oncology study of 58,000+ cancer patients found medical marijuana legalization was associated with reduced opioid dispensing and fewer pain-related hospital visits.
Translational study found psychosis patients with prior cannabis use had lower CDK5 (a psychosis-linked enzyme) and fewer social deficits than those without cannabis history.
Triple-blind crossover trial found women had significantly higher blood CBD levels than men at the same dose, with CBD detectable up to 50 days after stopping.
RCT found adolescents who quit cannabis experienced trouble falling asleep during the first week, but sleep returned to normal by week two and stayed there through week four.
Study of 74,501 Canadian students found those in areas with greater income inequality were 25% more likely to use cannabis daily, independent of individual-level factors.
Animal study found a whole cannabis extract and a pure 1:1 THC:CBD mix produced different pain-relief patterns and engaged different brain receptors, despite matching THC:CBD ratios.
Animal study found the endocannabinoid system in the prefrontal cortex develops on different timelines in male and female rats, with females maturing earlier.