Browse more cannabis research, findings, methods, and limitations.
Legalization cut adult cannabis possession arrests by 40-76%, even in states that already decriminalized, but did not change youth arrest rates or racial disparities.
Colorado county-level analysis found dispensary openings increased cannabis-related hospitalizations but not traffic crash rates.
Cannabis decriminalization in 11 states cut arrests 70% for adults, 40% for youth, and reduced Black-White adult arrest disparity by 17%.
THC modulates reward-related brain regions in ways that correlate with psychotic symptoms. CBD appears to act in the opposite direction on the same regions.
Meta-analysis of 372 participants found THC's brain effects are dose-dependent and track with CB1 receptor density across regions.
Pediatric clinicians in Canada support medical cannabis under harm reduction principles but face authorization barriers and want more neurodevelopmental research.
Topical CBD may promote hair growth at low concentrations but cause loss at high concentrations. One trial saw a 93.5% increase in hair count over 6 months.
In 28 chronic pain patients, three months of medical cannabis produced no significant changes in blood sugar, cholesterol, insulin, cortisol, or body weight.
Among 70 Canadian healthcare providers, 56% felt uncomfortable with their cannabis knowledge, and uncertainty about dosing was the top barrier to prescribing.
82 children with autism who completed 6 months of CBD-rich cannabis showed significant improvements in social communication on both clinical and parent-reported measures.
Cannabis-based treatments, especially nabiximols spray and oral cannabinoids, consistently helped with MS pain and spasticity but showed only slight improvement for other MS symptoms.
Meta-analysis of 45 fMRI studies (2,702 youth) found cannabis users showed altered activation in prefrontal and cingulate regions, varying by sex, severity, and psychiatric comorbidity.
In 15 daily cannabis smokers, the COX-2 inhibitor celecoxib did not reduce withdrawal symptoms or change endocannabinoid levels, and it increased cannabis craving.
Among 422 pediatric ER patients testing positive for cannabis, 71% presented after legalization. Suicidal ideation was the most common complaint at 43%.
Employers face conflicting laws and unreliable drug tests — a practical framework for cannabis workplace policies addresses safety, legal protections, and impairment measurement.
Six rhesus macaques given daily THC edibles experienced 58% testicular volume loss and hormone shifts consistent with testicular failure, in a dose-dependent pattern.
Review argues antidepressants are likely less effective in cannabis-using teens, based on overlapping neurochemical pathways, but no clinical trials have tested this directly.
Blocking CB1 receptor desensitization delayed THC tolerance in male mice but not females, revealing sex-specific mechanisms. Females were also less sensitive to cannabinoid pain relief.
First case of pneumorrhachis (spinal air leak) linked to cannabinoid hyperemesis syndrome, caused by severe, repeated vomiting.
People with ADHD may use cannabis to manage self-regulation deficits, but evidence for therapeutic benefit is limited and the risk of problematic use is elevated.
Among 608 US veterans with PTSD, frequent cannabis users were 3-4x more likely to have depression, anxiety, and suicidal ideation, and 8-12x more likely to rely on avoidance coping.
Multimodal brain imaging of 24 heavy cannabis users found distinct structural and functional changes linked to serotonin, dopamine, and opioid receptor systems.
Standard ASD medications often cause side effects that mimic ASD symptoms. Early evidence suggests CBD-rich cannabis may be effective and better tolerated, but controlled trials are needed.
Among 9,863 US adolescents, racial bullying involvement predicted different substance use patterns by ethnicity, with African American bully-victims more likely to use marijuana.
Analysis of 1,174 young adults found five distinct cannabis use disorder profiles with different patterns of consumption, control, and withdrawal symptoms.
Cannabis with equal THC and CBD caused less anxiety than THC alone. CBD fully blocked THC anxiety in calm users but not in those with high baseline anxiety.
Among 910 young Canadian adults who drive after cannabis use, four distinct profiles emerged, from well-adjusted youth to those with generalized risky behavior and high distress.
Schizophrenia patients with cannabis use disorder showed different blood biomarker patterns than those with schizophrenia alone, with elevated serotonin receptors and inflammation markers absent in dual-diagnosis patients.
Mouse pups exposed to CBD prenatally showed sex-specific disruptions: males gained extra weight and changed vocalizations, while females had impaired motor and discrimination abilities.
Animal studies consistently show prenatal cannabis/THC exposure causes cognitive, emotional, and drug sensitivity changes in offspring, supporting their classification as developmental toxicants.
Among 3.3 million cannabis hospitalizations, pulmonary circulation disorders increased 200% over 7 years, with patients facing 2x the in-hospital mortality risk.
Cannabinoids show some pain benefits for rheumatic conditions but carry drug interaction risks with common rheumatology medications, leading the review to conclude they are more foe than friend.
Cannabinoids including CBD and CBGA have anti-inflammatory and antiviral properties that could theoretically help with COVID-19, but no clinical evidence exists.
In 71 patients, blood levels of the synthetic cannabinoid 5F-MDMB-PICA followed a dose-response pattern with CB1 receptor activation, and higher activation predicted greater loss of consciousness.
Among 4,270 French students, ADHD symptoms predicted continued cannabis use after one year but did not drive new cannabis initiation.
In a schizophrenia rat model, THC-only cannabis vapor worsened brain oscillation deficits while balanced THC/CBD vapor preserved or enhanced brain activity.
In rats with nerve injury pain, CBD enhanced morphine's effectiveness at sub-therapeutic doses and partially prevented morphine tolerance development.
Children of caregivers who smoked marijuana had 26% more viral respiratory infections per year compared to unexposed children in a survey of 1,500 families.
Lab testing found THC in 65% of 80 CBD products, including 24% of those labeled "THC-Free," with concentrations up to 2 mg/mL.
Nearly half of 80 CBD products tested had CBD concentrations more than 10% off their labels, with some containing less than half the advertised amount.
Among 1,540 newborns with meconium drug testing, THC-exposed infants weighed 0.16 kg less and had 1.9x the odds of low birth weight.
Marijuana causes bronchitis but the evidence suggests it does not cause COPD and probably does not cause lung cancer, a distinctly different pattern from tobacco.
National data from 2011-2017 found marijuana associated with teen suicidal ideation and attempts at rates comparable to tobacco and alcohol, with a dose-response pattern.
In rats, CBD reduced risperidone-induced blood sugar elevation, movement abnormalities, and muscle stiffness without impairing cognition.
Frequent cannabis users showed peak psychomotor impairment immediately after smoking but recovered significantly within one hour, replicated across two studies.
In Lebanon, cannabis use disorder nearly tripled the odds of needing intensive psychiatric outreach for psychosis, alongside other severity markers.
Cannabis use was linked to suicidal ideation in 412 youth aged 13-18, but existing school prevention policies did not weaken this association.
Among 835 high schoolers, buying cannabis from someone or using a medical card at a dispensary predicted continued and more frequent use six months later.
CBD and THC do not boost athletic performance. CBD's anti-inflammatory potential remains untested in sport. Some CBD products may trigger positive drug tests due to THC contamination.
THC withdrawal in mice disrupted dopamine release, sleep patterns, and behavior in ways that mirror human withdrawal, with more pronounced effects in males.