Browse more cannabis research, findings, methods, and limitations.
A genome-wide analysis of over 10,000 people found no single gene strongly linked to cannabis use initiation, with common variants explaining only about 6% of variation.
A patient with treatment-resistant stiff-person syndrome showed quality of life improvement across all measured dimensions after 14 months of THC/CBD oral spray.
THC blood levels in suspected impaired drivers in Norway rose 58% from 2000 to 2010, far outpacing increases in alcohol or amphetamine levels in similar drivers.
Rats showed increased CB1 receptor expression in a brain reward center throughout morphine withdrawal, and blocking these receptors reduced drug-seeking behavior.
Independent review found THC/CBD oral spray provided meaningful spasticity relief for about 10% of MS patients not adequately helped by standard medications.
Mouse brain tissue maintained CB1 receptor signaling even when primary 2-AG production enzymes were genetically deleted, revealing backup endocannabinoid production pathways.
Chronic cannabinoid exposure in adolescent rats caused lasting spatial memory deficits linked to reduced hippocampal neurogenesis, while adult rats were unaffected.
Twin study found that initial reactions to tobacco predicted both nicotine and cannabis dependence, while cannabis reactions predicted only cannabis outcomes, with 27-35% heritability for first-use reactions.
Review revealed that COX-2 converts endocannabinoids into novel inflammatory mediators rather than simply destroying them, adding complexity to our understanding of inflammation.
A clinical trial found nabiximols (THC/CBD spray) significantly reduced cannabis withdrawal and improved treatment retention, but provided no long-term advantage over placebo for reducing cannabis use.
Men with poor sperm quality had lower seminal levels of endocannabinoid-related molecules, and adding these molecules improved sperm motility in the lab.
Review found about 70% of bipolar patients used cannabis, with use linked to earlier first mania and more frequent episodes, though causation remained unestablished.
Review found clinical evidence for cannabis in cancer symptom management was only partial, with lab-based anti-cancer findings having no clinical research support.
Analysis of 170 counseling sessions found that student "change talk" mediated the link between counselor skill and reduced marijuana use, supporting it as an active ingredient of motivational interviewing.
Social network analysis of college students found marijuana and alcohol use clustered within friend groups, while exercise did not, suggesting substance use is more socially contagious.
Review documented the endocannabinoid system's roles in multiple liver diseases and the potential for peripherally targeted therapies after early drug safety setbacks.
Three web-based interventions all briefly increased co-smokers' readiness to quit tobacco and cannabis together, but none changed actual use and the motivational effect faded within 8 weeks.
Adolescent cannabis users showed poorer impulse control and abnormal brain connectivity between parietal and cerebellar regions, a pattern that correlated with recent use.
Survey of 628 Canadian therapeutic cannabis users found only 7% accessed it exclusively through legal sources, with physician reluctance, cost, and program complexity as major barriers.
Expert review found clinical evidence for cannabinoids in MS spasticity, refractory pain, and nausea, with emerging evidence for epilepsy, dystonia, tics, and other neurological conditions.
A specific AKT1 gene variant determined whether THC impaired psychomotor control, with carriers showing increased errors and reduced brain activation in a motor control region.
In 376 college students, inattention symptoms were independently linked to worse cannabis outcomes and strengthened the connection between use level and cannabis-related problems.
In 14 regular users, lower dopamine synthesis in associative striatum tracked with higher apathy. No control group, and dose measures did not explain apathy.
In 39 monitored cannabis patients, withdrawal peaked at day 4 and declined by day 16, while 28% still had detectable blood THC after over two weeks of abstinence.
Review of brain imaging studies found cannabis users consistently showed increased brain activity during memory tasks, suggesting greater neural effort needed to maintain performance.
When the UK downgraded cannabis penalties in 2004, researchers found no increases in cannabis use, other drug use, crime, or risky behavior using individual-level panel data.
Longitudinal study of inner-city youth found increasing marijuana use trajectories were associated with over 3x the odds of weapon-related violence compared to no/low use.
Review found THC inhibited brain immune cell migration toward infections, while CBD modulated neuroimmunity differently. Early-life exposure may alter adult immune responses.
Adolescent smokers who frequently used marijuana were 44% less likely to have attempted quitting cigarettes, with boys showing a stronger effect than girls.
Low-dose pesticide exposure increased brain anandamide levels in developing rats at doses below the traditional toxicity threshold, implicating the endocannabinoid system as a sensitive target.
Three patients experienced cardiac arrest after cannabis use through different mechanisms, including one young person without cardiovascular risk factors.
Comprehensive review found synthetic cannabinoids are 2-100x more potent than THC, producing severe adverse effects including psychosis, kidney failure, and cardiac events.
A man with 16 years of severe vomiting and compulsive hot showering from CHS remained completely symptom-free for nine years after quitting marijuana.
Among 972 high school students, cannabis use was not independently linked to suicidal ideation after controlling for borderline and psychopathic personality traits.
Machine learning analysis of brain scans classified heavy cannabis users from controls with 84-88% accuracy based on connectivity patterns spanning cerebellum to prefrontal cortex.
Three adolescents referred for eating disorders actually had cannabis withdrawal syndrome, demonstrating how CWS symptoms can mimic disordered eating.
Leading epilepsy researchers outlined the case for clinical trials of pure CBD in treatment-resistant epilepsy, citing strong preclinical evidence and apparent tolerability.
Review found sleep disturbance and substance use disorders reinforce each other, with cannabis withdrawal showing objective sleep disruption and insomnia treatment identified as a gap.
Women gave higher "Good" and "Take Again" ratings than men after smoking cannabis in controlled conditions, despite identical intoxication — suggesting sex-specific vulnerability to cannabis's reinforcing effects.
In 3,080 twins, both ADHD symptoms and autistic traits independently predicted cannabis use disorders, while autistic traits showed a paradoxical pattern of less alcohol use but higher dependence risk.
Landmark review found CBD showed anticonvulsant, anxiolytic, antipsychotic, and anti-addictive properties but lacked well-powered trials, setting the stage for the clinical program that led to FDA approval.
Cannabis use disorder worsened executive attention in adolescents with schizophrenia but not in healthy teens, with deficits linked to reduced anterior cingulate cortex surface area.
Among 69 veterans on buprenorphine for opioid addiction, positive marijuana urine tests, benzodiazepine use, smoking, and psychiatric comorbidity predicted treatment noncompliance.
Post-marketing data from the UK, Germany, and Spain confirmed THC/CBD spray effectiveness for MS spasticity (41% response rate) with no abuse signal or driving impairment.
Phase III trials confirmed THC/CBD spray helped about one-third of treatment-resistant MS spasticity patients, with no cognition or mood effects after 50 weeks of use.
In mice, orexin-1 signaling supported cannabinoid reward. Blocking it reduced self-administration and erased THC-evoked accumbens dopamine.
Systematic review of 39 human studies found mixed cannabinoid effects on sleep and study quality too uneven for clear answers.
Review found cannabinoids showed potential for multiple neurological diseases, with established uses in MS, nausea, and appetite stimulation, and emerging evidence for neurodegenerative conditions.
The Unplugged program reduced youth substance use across 7 European countries by modifying attitudes and norms, though the mediating effects were generally weak.
Critical review of seven evaluations found little evidence that the widely used Project TND school prevention program effectively reduces cigarette, alcohol, or marijuana use.