Browse more cannabis research, findings, methods, and limitations.
Review examines the theoretical basis for combining cannabis terpenes with cannabinoids to treat mood and anxiety disorders, finding preclinical support but limited clinical evidence.
Multisite study of 948 psychosis patients across 6 countries found those who used cannabis had better premorbid social functioning, suggesting social ability may have facilitated cannabis exposure.
Survey of over 26,000 Oregon students found about 75% reported seeing marijuana advertising in the past month after retail legalization, mostly on storefronts and online.
Lab study found five common cannabis terpenes had no detectable activity at CB1 or CB2 receptors and did not modify THC, CBD, or endocannabinoid binding or function.
Case report of a 29-year-old pregnant woman with cannabinoid hyperemesis syndrome caused by chronic cannabis use, highlighting the need to consider CHS in the differential diagnosis of pregnancy-related vomiting.
Expert review of 33 studies and 7,500+ patients finds nabiximols safe and effective for MS spasticity when first-line drugs fail, but no scientific evidence supports smoked marijuana for MS.
First RCT of CBD for cannabis use disorder found 400mg and 800mg daily were safe and more effective than placebo at reducing cannabis use over 4 weeks, with 94% completing treatment.
National Canadian survey found 72% of people with cannabis dependence history achieved remission, but only 43% reached positive mental health, compared to 74% without dependence history.
Mouse study found synthetic cannabinoids combined with alcohol caused worse motor impairment than either alone, mediated by reduced glutamate signaling in the cerebellum via CB1 receptors.
Systematic review of 10 studies found cannabinoids may improve behavioral symptoms, sleep, and hyperactivity in autism, while reducing seizures in those with comorbid epilepsy, though evidence on core ASD symptoms is limited.
Rat study found CBD reduced cocaine self-administration and reward by attenuating dopamine release in the nucleus accumbens, working through CB2, serotonin 5-HT1A, and TRPV1 receptors.
Lab and animal testing found the synthetic cannabinoid EG-018 has high cannabinoid receptor affinity but behaves as a weak partial agonist, producing limited effects only via intravenous administration.
Mega-analysis of 400 IV THC infusions found psychosis-like symptoms in 45% of healthy volunteers, with effects increasing with dose and decreasing with regular cannabis use history.
Systematic review of 8 studies with 210 participants found limited evidence for CBD as an antipsychotic but noted its favorable side effect profile compared to standard medications.
Mouse study found CB1 receptor activation and endocannabinoid boosting raised seizure thresholds in Toxoplasma-infected mice, while CB1 blockade worsened seizure vulnerability.
Pilot study of 10 young epilepsy patients found a THC/CBD cannabis preparation was generally safe, with blood levels correlating to dose, supporting the feasibility of therapeutic drug monitoring.
Study of 119 acutely psychotic patients found cannabinoid users showed an unusual inverse relationship between IL-6 inflammation and psychosis severity, with synthetic cannabinoid users more likely to need emergency sedation.
Systematic review of 34 reports of deaths involving synthetic cannabinoids found no reliable toxic dose ranges could be established, and cause of death often remained unclear.
Observational study of 102 fibromyalgia patients found adding medical cannabis improved sleep in 44%, overall symptoms in 33%, and allowed 47% to reduce other pain medications over 6 months.
Ontario study found frequent cannabis use in youth aged 12-17 was associated with elevated anxiety, depression, and behavioral symptoms, with associations 2-3 times stronger in girls than boys.
Portuguese hospital data showed cannabis-related psychosis hospitalizations increased 29-fold from 2000 to 2015, rising from under 1% to over 10% of all psychosis admissions.
Review finds prenatal cannabis exposure is not linked to a unique birth defect pattern but is associated with impaired attention and memory, plus increased depression, anxiety, and delinquency in offspring.
Survey of 10,035 smokers across 4 countries found higher cannabis co-use in countries with permissive regulations, with tobacco-cannabis mixing far more common in England and Australia than North America.
Mouse study found CBD's anti-seizure effects were abolished in mice lacking the TRPV1 receptor, strongly implicating this receptor in CBD's mechanism of action against seizures.
Review identifies potential cannabis interactions with blood thinners: THC may increase warfarin levels (bleeding risk) and CBD may reduce clopidogrel activation (stroke risk) through liver enzyme inhibition.
Phase II crossover trial found oral THC:CBD capsules nearly doubled complete response for refractory chemo nausea (25% vs 14%), with 83% of patients preferring cannabis to placebo despite more side effects.
Study comparing 201 cannabis-dependent patients to 285 controls found specific methylation differences at dopamine transporter gene sites bound by nervous system development transcription factors.
National survey of nearly 88,000 adolescents found cannabis use linked to higher depression and suicide attempts, but the relationship between use frequency and depression was unexpectedly non-linear.
Study of 40 synthetic cannabinoid users found significantly elevated DNA damage, oxidative stress, and inflammatory markers compared to healthy controls, suggesting measurable biological harm from regular use.
Study of 165 schizophrenia patients found substance use disorder quadrupled self-harm risk, with cannabis and synthetic cannabinoids most commonly abused among those who self-injured.
Review of cannabis policy options finds each approach involves trade-offs, with commercialization likely to increase use based on alcohol and tobacco industry precedents, and prohibition reducing use but creating criminal justice harms.
Canadian survey data shows the association between monthly cannabis use and depression/suicidal ideation strengthened from 2002 to 2012, with monthly users in 2012 having ~1.5 times the odds of both outcomes vs 2002 users.
Survey of 201 IBD patients found those self-medicating with cannabis had higher impulsivity, more depression, and greater substance misuse vulnerability compared to recreational cannabis users.
Umbrella review of 26 meta-analyses confirms cannabis use is linked to increased psychosis risk, dose-dependent onset, earlier presentation, and higher relapse rates in psychotic patients.
Study of 45 brain tumor patients found cannabinoid receptor expression increased with tumor grade, with CB2 particularly elevated in blood vessels of high-grade astrocytomas.
Canadian cancer patient surveys found cannabis use increased 26% after recreational legalization, but access problems also doubled, mainly because preferred products like edibles were not legally available.
Exploratory study of 112 dispensary patients found those who reduced alcohol after starting cannabis were more likely to have anxiety, PTSD, and sleep disorders, suggesting a substitution pattern.
Small study of 59 ADHD patients using medical cannabis found higher CBN consumption was associated with lower ADHD symptom scores, and higher-dose users more often stopped ADHD medications.
Survey of 548 MS patients found cannabis use for symptoms was 4.5 times more likely in recreationally legal states, more common in men and those with severe disability.
Meta-analysis of 15 controlled studies confirms THC induces psychotic, negative, and general psychiatric symptoms with large effect sizes in healthy people, while CBD shows no consistent protective effect.
Systematic review of 10 studies found cannabinoids may reduce PTSD symptoms, especially sleep disturbances and nightmares, but all evidence was of low quality with only one controlled trial.
Study of 65 frequent concentrate users found dabbing impaired arm speed for at least 1 hour and balance immediately, with motor impairment poorly correlated to blood THC levels.
Mouse study found cannabinoids were more potent in aged mice than young adults, with stronger pain relief and movement suppression, suggesting elderly users may need lower doses.
Rat study found offspring of THC-exposed fathers showed hyperactivity and cognitive deficits despite mothers never being exposed, suggesting paternal cannabis use before conception can affect offspring.
Case report of a patient in opioid treatment whose persistent fentanyl-positive tests were traced to fentanyl-contaminated street cannabis, resolving after switching sources.
NIOSH commentary identified that cannabis legalization outpaced workplace research — drug testing can't measure current impairment, and safety policies lack evidence.
Rat study found long-term THC weakened prefrontal cortex control of the brain's reward center while strengthening emotional region (amygdala/hippocampus) input, potentially explaining cannabis-related cognitive and psychiatric effects.
Review of the 2019 EVALI outbreak links cases primarily to vaping unlicensed THC products containing vitamin E acetate, with about 2% mortality and predominant presentation in young men.
Rat study found endocannabinoid-boosting drugs reduced persistent fear after predator stress through CB2 (not CB1) receptors, with CB2 gene expression upregulated in the prefrontal cortex by stress.
Mouse study found the CB2 agonist LY2828360 synergized with morphine for neuropathic pain relief while blocking morphine reward and partially reducing physical dependence.