Browse more cannabis research, findings, methods, and limitations.
Twin study of 6,257 people found genetics explain over 60% of cannabis use and dependence variation, with substantial genetic overlap with alcohol.
Cannabis-dependent people with depression had worse social functioning but performed better on some cognitive tests than those without depression.
Review found cannabis-based medicines improved patient-reported MS spasticity but often did not show effects on the Ashworth clinical scale.
Review revealed that P450 enzymes metabolize anandamide into diverse bioactive lipids including CB2 receptor agonists, complicating endocannabinoid drug development.
Eight US patients with cannabinoid hyperemesis averaged 19 years of cannabis use before symptoms, 7 ER visits each, and recovered when they stopped using.
Cannabinoid withdrawal physically shrank VTA dopamine neurons and reduced dendritic spines in the nucleus accumbens shell, supporting a "hypodopaminergic" addicted brain model.
THC-dependent monkeys discriminated withdrawal as a distinct state; cannabinoid agonists and clonidine blocked it, but sedatives and cocaine did not.
Review warned that synthetic cannabinoids in "Spice" products were more potent than natural cannabis, showed addiction potential, and posed identification challenges.
Meta-analysis of 28+ twin studies found genetics explained 40-48% of cannabis initiation and 51-59% of problematic use, with environment more influential for initiation.
Dutch twin study found 44% heritability for cannabis initiation, matching results from countries with stricter cannabis laws.
Comprehensive search found extremely rare nabilone abuse after nearly 30 years of availability, with no street value and minimal law enforcement concern.
Crossover RCT of 29 fibromyalgia patients found nabilone improved sleep quality more than amitriptyline, though neither affected pain in two-week treatment periods.
A 21-year-old with 7 years of cannabis use developed cannabinoid hyperemesis that resolved with abstinence but relapsed repeatedly with resumed use.
Review compared blood, urine, and oral fluid testing for cannabis-impaired driving, finding each has different strengths and no matrix perfectly predicts impairment.
Comprehensive review found recreational cannabis adverse effects were generally minor, with overall harms appearing less serious than alcohol, though vulnerable individuals faced greater risks.
First GWAS of cannabis dependence tested nearly 1 million genetic variants in 3,054 people, finding suggestive signals but no definitive genetic associations.
The Cannabis Withdrawal Scale was developed with excellent reliability, revealing nightmares as the most diagnostic symptom and angry outbursts as the most distressing.
Survey of 1,432 Seychelles adolescents linked cannabis, alcohol, and tobacco use to suicidal ideation, truancy, and poor parental monitoring.
Heavy cannabis-using adolescents had smaller hippocampi than controls even after 6.7 months of abstinence, with volume correlated to amount of prior use.
Chronic cannabis extract reduced sperm count, motility, and testosterone in male mice, with direct effects on testicular cannabinoid receptors.
Review of endocannabinoid roles in reproduction: THC disrupted menstrual cycles and egg development in females, sperm production and motility in males.
600 mg CBD normalized public speaking anxiety in social phobia patients to healthy control levels — no sedation, no cognitive impairment. The foundational CBD anxiety study.
Among 432 male veterans, less PTSD improvement during treatment predicted greater cannabis use at 4 months, specifically linked to avoidance/numbing and hyperarousal symptoms.
Boosting endocannabinoids with URB597 reduced anxiety but not physical symptoms during nicotine withdrawal in rats, with anandamide fluctuating across multiple brain regions.
Review argued that evidence supported medical marijuana for chronic pain, chemo nausea, AIDS wasting, and MS spasms, making federal prohibition ethically unjustifiable.
Pre-illness cannabis use in 109 first-episode patients was linked to better early social skills but worse academics, and daily use predicted acute (rather than gradual) psychosis onset.
Case report tracked executive function from 24 hours to 12 weeks of cannabis abstinence, showing progressive cognitive improvement with clinical implications for treatment.
Among 609 traffic crash victims in Brazil, 13.3% of drivers tested positive for cannabis, and alcohol dependence increased odds of any substance-related crash 5.2-fold.
Review found Sativex (THC+CBD) matched baclofen effectiveness for MS spasticity in mice, with endocannabinoid levels altered in both MS animal models and patient cerebrospinal fluid.
Prenatal cannabis decreased D2 receptor expression in human fetal brain reward center; in rats, THC during pregnancy caused lasting epigenetic changes increasing offspring addiction vulnerability.
In 7,753 Dutch twins/siblings, cannabis initiation heritability was 40% at age 16.5, with environmental influences growing with age, especially factors shared between twins.
Review described how cannabinoids reduce brain inflammation by interacting with Toll-like receptor signaling, part of the innate immune system implicated in neurodegenerative diseases.
CBD reduced Alzheimer's-related brain inflammation and stimulated new neuron growth in rats, both through the PPARgamma receptor pathway.
Fibromyalgia cannabis users reported significant pain and stiffness relief within 2 hours and better mental health scores compared to non-users.
In Finnish teens, general anxiety predicted later substance use (via depression), while social phobia appeared to protect against persistent alcohol use.
Review characterized CHS as a three-phase paradoxical vomiting syndrome from chronic cannabis use, with compulsive hot bathing as a hallmark and frequent misdiagnosis.
First human study of antagonist-elicited cannabis withdrawal: rimonabant at 20-40 mg did not reliably trigger withdrawal in 10 THC-dependent volunteers before the study was terminated.
The generic EQ-5D quality measure only moderately captured quality of life in 103 schizophrenia patients with cannabis abuse, missing domains like relationships and finances.
Seeing marijuana-related images improved creative problem-solving in people who expected marijuana to boost creativity, without any actual drug consumption.
MS patients who used cannabis performed significantly worse on cognitive tests across multiple domains and were twice as likely to be globally cognitively impaired.
Cannabis resin enhanced vaccinia virus infection severity in mice and inhibited immune cell proliferation in vitro, with effects from multiple cannabis compounds beyond THC.
First documented case of marijuana-induced mania in an adolescent with no prior psychiatric history.
In 9 cannabis smokers, Sativex and oral THC at equivalent doses produced similar mild effects with no evidence that CBD attenuated THC's side effects at therapeutic doses.
THC blood levels were nearly identical whether given as Sativex (with CBD) or as pure oral THC, ruling out pharmacokinetic interaction at therapeutic doses.
In a small terminated trial, the CB1 antagonist rimonabant reduced anxiety and hostility in schizophrenia patients but did not produce weight loss.
Male cannabis users had slower motor skills and shifted brain activation from visual to executive regions, with elevated cortisol levels potentially mediating these effects.
Boosting endocannabinoid 2-AG with a MAGL inhibitor prevented NSAID-induced stomach bleeding in mice through CB1 receptors, without tolerance development.
Endocannabinoid-boosting drugs (FAAH and MAGL inhibitors) reduced anxiety-like behavior in mice without sedation, while THC only worked at sedating doses.
CBD reduced MS-like disease severity in mice by suppressing pathogenic T cells and microglial activation through mechanisms independent of CB1 and CB2 receptors.
About half of IBD patients reported lifetime cannabis use, with 33-50% of users specifically using it for symptom relief, especially those with prior surgery and chronic pain.