Browse more cannabis research, findings, methods, and limitations.
Analysis of 4,596 drivers found oral fluid THC tests were 79% sensitive and 98% specific for detecting cannabis use, but poorly predicted actual blood THC levels.
Rhesus monkeys given daily THC for 12 weeks showed persistent working memory deficits (but not other cognitive domains) that recovered within 2 weeks of stopping. Dopamine D2/D3 receptors were unaffected.
Study of 169 men found brain volume loss in the prefrontal cortex was linked to total number of substances used, not any single drug. Cannabis showed no independent effect after controlling for polysubstance use.
National database analysis found cannabis use independently predicted heart failure and stroke risk in adults 18-55, even after adjusting for tobacco, alcohol, and traditional cardiovascular risk factors.
Chemical analysis of strains rated most and least effective for anxiety found THC and the terpene trans-nerolidol correlated with anxiety relief, while six other terpenes correlated with reduced effectiveness.
Case report demonstrated successful treatment of cannabinoid hyperemesis syndrome with IV haloperidol after psychiatric consultation clarified the diagnosis.
Selective breeding study found adolescent THC sensitivity in mice was heritable and genetically linked to anxiety-like behavior, pointing to shared genetic factors between cannabis response and anxiety.
Nature Reviews Rheumatology review found emerging evidence for cannabinoid immunomodulatory effects relevant to rheumatic diseases, but concluded evidence is insufficient to recommend cannabis treatment for these conditions.
Survey of 1,666 IBD patients found marijuana users reported high perceived benefits (80.7%) but also had more depression, anxiety, and pain than non-users, likely reflecting harder-to-treat disease.
National survey of 9,003 adults found 81% believe marijuana has benefits and 29% believe it prevents health problems, with public views more favorable than current evidence supports.
Case of a pregnant woman repeatedly hospitalized for vomiting that was actually CHS, not pregnancy-related. Diagnosis was delayed because symptoms mimicked hyperemesis gravidarum.
Cannabis use disorder was the only factor consistently associated with self-injury across all models in Iraq/Afghanistan veterans, with odds ratios of 3.10 for suicidal and 5.12 for nonsuicidal self-injury.
Patient with kidney disease was started on dialysis for vomiting assumed to be from kidney failure. Dialysis did not help. Stopping marijuana did. CHS had been masquerading as uremia.
Population survey of 5,196 adults found ADHD did not predict arrest history, but cannabis misuse did, with a stronger effect in women than men.
Review of 13 synthetic cannabinoids found they are processed by and inhibit multiple drug-metabolizing enzymes, creating potential for dangerous drug-drug interactions in polysubstance users.
European survey found dramatic country-by-country differences in cannabis medicine availability, with THC/CBD spray approved in 21 countries but broader medical cannabis access limited to a few.
Expert consensus guideline recommended capsaicin as first-line CHS treatment, haloperidol/olanzapine as alternatives, avoidance of opioids, and patient education that cannabis cessation is the only lasting solution.
Meta-analysis of 550 patients found CBD reduced seizures by ~20 percentage points in severe childhood epilepsies. The lower dose (10 mg/kg) was similarly effective but safer than the higher dose (20 mg/kg).
Survey of 1,722 cannabis growers found 44% used chemical fertilizers or insecticides, with hydroponic growing as the key predictor. Poor product labeling made it hard to identify harmful chemicals like plant growth regulators.
Pilot study of 25 children with complex motor disorders found CBD-enriched cannabis oil improved spasticity, dystonia, sleep, pain, and quality of life over 5 months, with rare adverse effects.
CB2 agonist LY2828360 suppressed neuropathic pain without tolerance in mice, prevented morphine tolerance, and worked even in morphine-tolerant animals. Its G protein-biased signaling may explain the sustained efficacy.
First neuroimaging study of synthetic cannabinoid users found reduced gray matter volume across multiple brain regions and impaired neural activity during working memory tasks.
Mouse study found 30 days of daily THC did not affect sperm function, testicular structure, IVF outcomes, or DNA methylation, contradicting prior assumptions about THC harming male fertility.
fMRI study found cannabis use disorder participants showed altered prefrontal-striatal brain connectivity during working memory, with compensatory increases in some pathways offsetting decreases in others.
EEG study found cannabis users with high distress intolerance showed enhanced brain conflict-monitoring under stress, which was linked to fewer cannabis problems, challenging the stress-impairment model of addiction.
Practical dosing review recommended medical cannabis THC be limited to 30 mg/day, combined with CBD, started low and titrated slowly over two weeks, with guidance for special populations and drug interactions.
Randomized study found clozapine reduced cannabis craving and amygdala cue reactivity significantly more than risperidone in schizophrenia patients with cannabis use disorder.
Critical review found CBD shows distinct promise for psychosis, anxiety, and withdrawal symptoms, each through different pharmacological mechanisms, but needs larger controlled trials.
First case report of the triad of CHS, H. pylori gastritis, and preeclampsia in a cannabis-using pregnant woman, raising questions about cannabinoid-related pathways in pregnancy complications.
Study of 203 daily cannabis users found that the tendency to experience negative emotions explained why people with low distress tolerance have more cannabis problems, worse withdrawal, and less confidence in quitting.
Study of 198 HIV-positive patients found heavy cannabis use was associated with reduced immune activation and inflammatory markers, suggesting potential anti-inflammatory benefits in treated HIV infection.
Human Connectome Project analysis found cannabis-dependent individuals had hyperconnectivity in dopamine-related brain regions (striatum, midbrain), most pronounced in those who started youngest and reported high negative emotionality.
Survey of 1,987 cancer patients found 43% had ever used cannabis and 18% used it recently, mostly for pain and nausea. Only 10% got it from medical dispensaries; 80% got it from friends.
Study of 721 college users found tobacco-marijuana co-users prioritized quitting cigarettes over marijuana, with higher importance ratings but lower confidence for cigarette cessation. Different factors predicted quitting each substance.
Case report documented driving impairment from synthetic cannabinoid 5F-ADB, detected at 26.37 ng/mL in blood with no other drugs present. One of the first cases conclusively linking synthetic cannabinoids to impaired driving.
Open-label trial of 20 Dravet syndrome children found CBD/THC cannabis oil achieved 70.6% median seizure reduction and 63% responder rate, with significant quality of life improvement over 20 weeks.
Study of 459 SUD patients found a graded pattern: childhood trauma plus PTSD showed the worst cannabis and psychiatric outcomes, trauma-only was intermediate, and no-trauma had the best outcomes.
Obstetrics review found marijuana crosses the placenta and enters breast milk, with meta-analyses and cohort studies suggesting associations with growth restriction, preterm birth, and neurobehavioral effects. Women advised to avoid use during pregnancy and lactation.
Study of 214 transgender women found daily marijuana use was the only substance linked to HIV risk behavior during sex, but only among those with higher overall marijuana use rates.
THC lowered mouse eye pressure by 28% via CB1 and GPR18 receptors, with stronger effects in males. CBD had opposing effects on eye pressure and blocked THC's beneficial IOP reduction.
A young woman had an acute heart attack (anterior STEMI) shortly after using synthetic cannabis, highlighting the serious cardiovascular risks of these potent compounds.
Largest GWAS of cannabis initiation timing found 38% heritability and identified ATP2C2 (calcium signaling gene) as a candidate, linking cannabis initiation to the same pathway implicated in cocaine and opioid dependence.
MTA follow-up found adults with ADHD who persistently used substances perceived cannabis as improving both mood and ADHD symptoms, though broad substance-mood perceptions did not differ from non-ADHD users.
Case report of CHS improvement with topical capsaicin supported a new mechanistic model: chronic cannabis decreases TRPV1 receptor signaling, explaining why both hot water and capsaicin (TRPV1 activators) provide relief.
Randomized crossover trial found vaporized CBD at 2:1 ratio did not block THC-induced psychotic symptoms or memory impairment. CBD alone helped only light users, not frequent users.
Study of 265 early psychosis patients found CUD was a significant violence risk factor, with two high-risk profiles: CUD + impulsivity, or CUD + lack of insight + non-adherence. Good insight and adherence moderated the risk.
Cochrane review of 16 trials (1,750 patients) found cannabis-based medicines provide modest neuropathic pain relief (NNT 20 for 50% relief) with significant side effects (61% nervous system AEs, 17% psychiatric AEs). Harms may outweigh benefits.
Cannabis use altered DNA methylation at nearly 4,000 sites in human sperm, affecting Hippo Signaling and cancer pathways. Same pathways were affected in THC-exposed rat sperm, and changes overlapped with offspring brain methylation.
Cluster RCT of 2,190 Australian students found school-based prevention programs increased cannabis knowledge for 2 years, but effects on actual cannabis use and harms were inconclusive over 3 years.
Review of 11 systematic reviews found cannabinoids may have modest benefits for MS pain and spasticity, but evidence for other symptoms is insufficient and no studies compare cannabinoids to existing treatments.