Uruguay's Cannabis Legalization Did Not Increase Youth Use or Risky Consumption ↗
Analysis of 204,730 students found Uruguay's 2013 cannabis legalization was not associated with sustained increases in youth cannabis use, risky use, or frequent use.
Research library — page 67
Browse more cannabis research, findings, methods, and limitations.
Clinical Guideline: Cannabis Effects on Women's Fertility, Contraception, Menopause, and Pelvic Pain ↗
Canadian clinical guideline provided GRADE-based recommendations on cannabis effects on fertility, contraception, menopause, and pelvic pain, emphasizing non-stigmatizing care.
Daily THC Edibles During Pregnancy Impaired Placental Function in Rhesus Monkeys ↗
Rhesus monkeys given daily THC edibles during pregnancy showed reduced placental blood flow, lower fetal oxygen, decreased amniotic fluid, and placental tissue damage with microinfarctions.
Roadside Oral Fluid THC Tests Are Good at Detecting Any Cannabis Use but Poor at Predicting Blood Levels ↗
Meta-analysis of 18,000+ paired samples found oral fluid THC tests detect recent cannabis use well but are unreliable for predicting whether blood THC exceeds legal driving limits.
School Health Program Reduced Marijuana Use by 23% Among High School Students ↗
Multilevel school health program across 237 US schools reduced current marijuana use by 23% among 64,838 students, along with reductions in sexual risk and violence.
Contingency Management Helped People with Mental Health Disorders Reduce Cannabis Use ↗
Systematic review of 6 studies found contingency management effectively reduced cannabis use and achieved abstinence periods in people with psychotic disorders or major depression.
THC Worsened Absence Seizures in Epileptic Rats While CBD Cut Them in Half ↗
In epileptic rats, THC doubled seizure activity while CBD halved it — and smoked high-THC cannabis increased seizures too, highlighting the importance of cannabinoid ratios.
US Cannabis Emergency Department Visits Increased 12% Annually from 2006 to 2014 ↗
US cannabis ER visits rose 12% annually from 2006-2014 and continued increasing after 2016. The Midwest had the largest regional surge (36.8%), with notable increases among children and females.
Young Adults with Childhood Adversity and Low Resilience Increased Marijuana Use During COVID-19 ↗
Longitudinal study of 1,084 young adults found 27% increased marijuana use during early COVID-19. Childhood adversity predicted increases among those with low resilience.
Nabiximols Did Not Affect Blood Pressure or Heart Rate in Post-Stroke Patients ↗
Randomized crossover trial in 34 post-stroke patients found nabiximols caused no blood pressure changes, no heart rate changes, and no cardiovascular events during treatment.
CHS Audit: Young Males Dominated ER Presentations, with 43% Returning Within the Study Period ↗
6-year Melbourne ER audit found 142 CHS presentations from 67 patients, with 43% returning. All were daily cannabis users. Normal lipase and mild CRP helped distinguish CHS from other causes.
Cannabis Industry Spent Over $7 Million Lobbying Colorado's Legislature in 12 Years ↗
Cannabis industry spent $7M+ lobbying Colorado's legislature over 12 years. Nearly half of reports hid the funder's cannabis connection, and some lobbyists represented alcohol, tobacco, and cannabis simultaneously.
First Genomic Study of CHS Found Genetic Mutations That May Explain Who Gets It ↗
First genomic study of CHS found patients carried significantly more mutations in COMT, TRPV1, CYP2C9, DRD2, and ABCA1 genes, potentially explaining why some heavy users develop CHS while others do not.
First Survey of CBG Users: Most Reported It Worked Better Than Conventional Medications ↗
First CBG patient survey found users reported it effective for anxiety (51%), pain (41%), and depression (33%), with 74-80% rating it superior to conventional medications and 44% reporting no side effects.
Parents Secretly Gave CBD to Their Sick 4-Year-Old, Highlighting Legalization-Era Risks ↗
Parents secretly administered a CBD extract to their 4-year-old with brain inflammation, not telling doctors because they assumed the legal product was safe, highlighting risks of unregulated self-prescribing.
54% of Cannabis TikTok Videos Portrayed Use Positively, None Were Age-Restricted ↗
Analysis of 881 TikTok cannabis videos found 54% portrayed use positively with 417 million views. 72% used humor. None were age-restricted despite massive youth exposure.
CBD Altered Exercise Physiology Without Hurting Performance in Trained Runners ↗
Pilot RCT of 9 trained runners found 300 mg CBD appeared to increase oxygen consumption, exercise pleasure, and VO2max without affecting endurance performance or heart rate.
UK Medical Cannabis Registry Shows Improved Health in First 678 Patients ↗
UK's first medical cannabis registry enrolled 678 patients (mostly chronic pain and anxiety). Preliminary 3-month data showed significant self-reported health improvement with moderate-to-large effect size.
Nearly Two-Thirds of Canadian MS Patients Have Tried Medical Cannabis ↗
Survey of 344 Canadian MS patients found 65% had tried medical cannabis, primarily for sleep (84%), pain (80%), and spasticity (68%). 74% learned about it outside the healthcare system.
Prenatal THC exposure caused sex-specific brain and behavior changes in rat offspring ↗
Rat study found prenatal THC caused sex-specific brain lipid disruptions and neuropsychiatric-like behaviors in offspring, with males more persistently affected.
Cannabis use did not worsen cognition in first-episode schizophrenia, but methamphetamine did ↗
Two-year study found methamphetamine, but not cannabis, predicted worse cognitive outcomes in first-episode schizophrenia patients.
Drivers with alcohol interlock devices increased cannabis use, and it persisted after device removal ↗
Study of 189 DUI-convicted drivers found those with alcohol interlock devices increased cannabis use, and this substitution persisted after device removal.
CBD-rich cannabis did not improve sleep better than placebo in children with autism ↗
Placebo-controlled trial of 150 children with autism found CBD-rich cannabis treatment was not better than placebo for any aspect of sleep.
Cannabis formulations reduced tamoxifen effectiveness against breast cancer cells in lab ↗
Lab study found cannabinoid formulations diminished tamoxifen's effectiveness against breast cancer cells, with recreational cannabis ratios showing the largest effect.
Cannabis exposure altered DNA methylation at autism-linked genes in lab-grown sperm cells ↗
Lab model of human sperm development showed cannabis exposure altered DNA methylation at autism-linked and imprinted genes.
Cannabis-related sperm DNA changes were detectable in rat offspring, who also had enlarged hearts ↗
First whole-genome sperm methylome study of cannabis exposure found 3,321 altered sites in rats, with changes detectable in offspring and associated with heart enlargement.
Veterans with bipolar disorder who currently used cannabis had better working memory and functioning ↗
Study of 254 veterans with bipolar disorder found current cannabis users had better working memory and functioning than past or non-users, but also higher rates of PTSD and suicidal ideation.
A palliative care patient developed cannabinoid hyperemesis syndrome from prescribed nabilone ↗
Case report of a 70-year-old cancer patient who developed cannabinoid hyperemesis syndrome from prescribed nabilone, resolving after the drug was stopped.
Systematic review identified multiple treatments for cannabinoid hyperemesis syndrome ↗
Systematic review of 17 studies found cannabis cessation is the best CHS treatment, with capsaicin, haloperidol, hot baths, and other options providing symptom relief.
Cannabis ex-users with first-episode psychosis recovered attention closest to healthy levels over 3 years ↗
Three-year study of 461 first-episode psychosis patients found those who quit cannabis showed the most attention recovery, reaching scores closest to healthy controls.
Brain imaging showed less damage in cannabis-induced psychosis compared to schizophrenia with cannabis use ↗
Brain imaging study of 60 participants found cannabis-induced psychosis had fewer white matter abnormalities and more gray matter than schizophrenia with cannabis use.
Reducing cannabis use risk level was linked to less anxiety and fewer cannabis-related problems ↗
Analysis of 225 participants found reducing cannabis use to lower risk levels was associated with less anxiety, depression, and cannabis-related problems.
Oral cannabis produced higher urine drug test concentrations than vaporized cannabis ↗
Controlled study of 21 people found oral cannabis produced positive urine tests 97.6% of the time versus 59.5% for vaporized cannabis at standard workplace cutoffs.
Young adult with cannabis use, COVID history, and severe psychosis made a complete recovery ↗
Case report of a young adult with cannabis use, COVID history, and other complicating factors who developed severe psychosis but achieved complete recovery.
Systematic review found cannabis may help reduce several autism-related symptoms ↗
Systematic review of 9 studies found cannabis products reduced hyperactivity, anxiety, sleep problems, and irritability while improving cognition and social interaction in autism.
Meta-analysis confirmed CBD reduces seizures by 33% in treatment-resistant epilepsy ↗
Meta-analysis of 6 trials with 1,034 patients confirmed CBD reduces seizure frequency by 33% in Dravet syndrome, Lennox-Gastaut, and tuberous sclerosis complex.
Meta-analysis of 57 studies confirmed cannabis impairs driving, comparable to low blood alcohol ↗
Meta-analysis of 57 driving studies found cannabis impairs lane control at levels comparable to low blood alcohol, with cannabis plus alcohol producing the worst impairment.
Most endometriosis patients using cannabis obtained it illicitly despite legal access ↗
Survey of 237 endometriosis patients found 72-88% used illicit cannabis despite legal access, with over 60% reporting more than 50% reduction in pain medication use.
Australian women with period pain want medicinal cannabis but face major access barriers ↗
Focus groups with 26 Australian women found interest in medicinal cannabis for period pain was high, but cost, stigma, drug driving laws, and prescriber bias blocked access.
Perceived parental approval of marijuana and heavy drinking predicted simultaneous use in young adults ↗
Study of 1,023 young adults found perceived parental approval of marijuana and heavy drinking was the strongest predictor of simultaneous alcohol-marijuana use.
Cannabis use was associated with up to 87% higher cardiovascular disease risk scores ↗
NHANES study of 7,159 adults found cannabis use associated with 60-87% higher odds of elevated cardiovascular disease risk scores in a dose-dependent pattern.
Largest fMRI study found no reward processing differences between cannabis users and non-users ↗
Largest fMRI study of cannabis and reward processing (125 participants) found no differences between users and non-users in reward anticipation, with adolescents showing no extra vulnerability.
Cannabis strain labels like "indica" and "sativa" don't reliably predict chemical content ↗
Analysis of commercial cannabis across 6 US states found strain names and indica/sativa labels do not reliably predict actual chemical content.
Smoking high-THC cannabis changed DNA methylation enzyme levels in blood cells within hours ↗
Study of 24 cannabis users found smoking high-THC cannabis changed DNA methylation enzyme levels in blood cells within hours, a potential link to psychosis risk.
THC improved memory and movement recovery after traumatic brain injury in mice ↗
Mice given THC for 3 days after brain injury recovered working memory and motor function, with increased brain repair factors BDNF, GDNF, and G-CSF.
Large genetic study identified shared DNA between smoking, cannabis use, and schizophrenia ↗
Genome-wide study of 780,000+ people found shared genetic factor explaining 8.6% of schizophrenia risk, highlighting NCAM1 as a key gene linking smoking, cannabis, and psychosis.
Cannabis use was linked to aggression in people with PTSD and psychotic disorders, but causation unproven ↗
Systematic review of 15 studies found cannabis use associated with aggression in PTSD and psychotic disorders, but causal conclusions cannot be drawn due to methodological limitations.
More than a third of medical cannabis patients also used nicotine products ↗
Survey of 697 medical cannabis patients found 39.3% also used nicotine, with nicotine delivery method predicting cannabis consumption method.
CBD-rich cannabis oil showed no significant blood chemistry changes in 59 children with autism ↗
Phase III interim analysis of 59 children with autism found CBD-rich cannabis oil (20:1 CBD:THC) produced no clinically significant blood chemistry changes over 3 months.
Students with ADHD reported cannabis helped with hyperactivity, impulsivity, and medication side effects ↗
Survey of 1,738 students found those with ADHD reported cannabis helped with hyperactivity, impulsivity, and medication side effects, with frequent use moderating executive dysfunction.