Browse more cannabis research, findings, methods, and limitations.
Lab study found cannabinoids preserved 70-89% of neuron viability (vs. 40% with chemo alone) and limited axon shortening to 23-44% (vs. 63%), suggesting potential for preventing chemotherapy-induced nerve damage.
Meta-analysis of 15 studies found medicinal cannabis had no effect on depression, anxiety, or stress in cancer patients, but increased appetite 12-fold. Higher THC doses doubled the likelihood of anxiety events.
Analysis of 3.1 million California pregnancies found combined prenatal cannabis and nicotine exposure associated with 2.2x infant death, 1.9x SGA, and 1.8x preterm delivery risk, exceeding the risk of either substance alone.
Canadian data from 2020 found residents of health regions with higher COVID-19 rates were more likely to use cannabis and use it more often, even after accounting for pre-pandemic use levels and demographics.
Study of 3,814 CUD outpatients found women with children who used cannabis before treatment were most likely to drop out, with sex moderating the relationship between childcare responsibilities and treatment adherence.
Chronic pain and addiction share a common neurobiological root — reduced dopamine signaling — explaining why pain patients who self-medicate with opioids or cannabis are vulnerable to escalating into misuse.
Qualitative interviews with 36 cannabis-using mood/anxiety patients found most continued for symptom relief despite recognizing cognitive dysfunction and worsening mood over time, rarely consulting doctors about their use.
Mixed-methods study of 87 autistic children found 75% adhered to 6-month CBD-rich cannabis treatment with mild side effects and substantial reported benefits, though dosing complexity and unrealistic expectations were barriers for some families.
Longitudinal study of 1,105 veterans found a self-reinforcing cycle: insomnia increased stress, stress increased cannabis use, and cannabis use worsened both stress and insomnia, challenging its use as a sleep or stress remedy.
In adolescent rats, THC exposure caused lasting anxiety and depression-like behaviors linked to brain changes in the nucleus accumbens. The antioxidant NAC prevented all of these effects.
Population study of 910 adults 65+ found 20% had used marijuana and 5% used recently — current users showed more depression, anxiety, and functional impairment.
In a Brazilian community sample, cannabis use was linked to worse disorganization symptoms among people at risk for psychosis but did not predict transition to full psychiatric disorders over 2.5 years.
A cluster RCT of 950 Australian students found an online harm reduction program slowed uptake of binge drinking, cocaine, and prescription drug misuse over 12 months, but had no significant effect on cannabis use.
A California study of 5.8 million births found prenatal cannabis use disorder was associated with 30-50% higher risk of gastroschisis, with the strongest link in mothers over 34.
A Swedish study of 1,820 patients with first-episode psychosis and cannabis use disorder found clozapine and long-acting injectable antipsychotics were most effective at preventing relapse and rehospitalization.
National database analysis of 8.4 million young adult admissions found cannabis use disorder was associated with lower odds of pulmonary embolism hospitalization but longer stays and higher costs.
After Oklahoma legalized medical marijuana, neonatal THC exposure increased significantly (16.2 to 22.2 per 1,000 births) while opioid exposure showed no significant change across 16,804 births.
Prenatal THC, CBD, and THC+CBD exposure all caused low birth weight and sex-specific brain and behavioral changes in adolescent rats, with disrupted endocannabinoid signaling in the prefrontal cortex and hippocampus.
Psychotic subjects showed elevated DNA methylation at cannabinoid and dopamine receptor genes compared to controls, but active THC use reversed these changes, complicating their potential as biomarkers.
Analysis of 177,636 spine fusion patients found cannabis use disorder was linked to higher neurological, wound, and cardiac complications but also decreased opioid dependence after surgery.
Meta-analysis of nearly 18 million joint replacement patients found cannabis use disorder associated with 33-106% higher odds of various surgical complications including cardiac events, infections, and implant failure.
In a nationally representative study of 5,585 US youths, concurrent tobacco and cannabis use was linked to nearly double the odds of behavioral problems compared to using either substance alone.
Lab testing of legal cannabis oils in Ontario found that labeled THC and CBD concentrations did not always match actual contents, raising questions about product reliability in regulated markets.
Blocking the CB2 cannabinoid receptor in mice with glioblastoma improved survival from 28 to 40+ days by reducing immunosuppressive macrophages and boosting cancer-killing T cells in the tumor.
Ontario study matching 54,006 medical cannabis patients to 161,265 controls found a 38% higher risk of psychosis-related ER visits, increasing to 63% for those with no prior psychosis history.
A longitudinal study of 850 teens found that affiliation with delinquent peers partially mediated the link between cannabis use and aggression, suggesting social context matters as much as substance use itself.
A rural Michigan harm reduction program documented the first US case study of cannabis donation to people using more dangerous substances, finding it was operationally feasible and financially sustainable.
In a prospective study of 545 young women of color, frequent cannabis use (20+ times monthly) predicted increased depression, delinquency, and school suspension over 6-12 months.
An EMA study of 106 older adults found medical cannabis reduced pain, mood, nausea, and trauma symptoms throughout the day, but the use-then-relief pattern was linked to developing cannabis use disorder symptoms.
Mouse study found THC withdrawal disrupted both motivation and attention, but during abstinence only motivational deficits persisted, suggesting these are qualitatively distinct withdrawal states.
A 33-year-old daily cannabis user developed cannabis hyperemesis syndrome after stopping use while traveling, with symptoms overlapping withdrawal. Recovery occurred within 10 days on tramadol, promethazine, and mirtazapine.
A survey of 575 cannabis-educated providers found most did not routinely ask older adult patients about medical cannabis, significantly less often than they asked about alcohol or tobacco.
National database study of 39,992 patients found cannabis use disorder was not linked to cardiovascular events or arrhythmias but was significantly associated with higher in-hospital mortality.
10-year DEA analysis shows cannabis THC rising across all U.S. regions with virtually no other cannabinoids present — legal and illegal markets have converged on THC monoculture.
UK survey estimated 1.77 million adults use illicit cannabis to self-treat chronic health conditions, despite legal medical cannabis being available since 2018, highlighting barriers to accessing prescribed products.
Controlled fMRI study found vaporized cannabis disrupted five major brain networks equally in teens and adults, and CBD co-administration did not reduce THC effects, challenging assumptions about CBD safety.
In King County, Washington, cannabis use declined among students from 2008-2021, but female students surpassed male students in current use prevalence for the first time in 2021.
Among 1.56 million Veterans, those with both TBI and cannabis use disorder had 3.26 times higher cognitive disorder risk, suggesting the combination compounds vulnerability to early-onset cognitive decline.
In 11,530 children from the ABCD Study, prenatal cannabis exposure was linked to subtle but reliable reductions in white matter integrity of the fornix, a brain pathway important for emotion and memory.
A trans-ancestry epigenome study of 9,436 people identified four DNA methylation sites linked to cannabis use independent of smoking, with an additional site found in never-smokers.
Brain imaging study found people at risk for cannabis use disorder had more fluid and unstable dynamic brain connectivity patterns across multiple networks compared to controls.
A new 8-item screening tool for problematic medical cannabis use was developed from 390 chronic pain patients, focusing on negative consequences rather than dependence criteria, with excellent reliability.
First systematic survey of 109 HHC users found frequent use (~10 days/month) primarily for anxiety and pain, with 17% reporting adverse effects and 20% of quitters experiencing withdrawal symptoms.
A negative allosteric modulator of the CB1 receptor reversed synthetic cannabinoid effects in mice even after exposure, without triggering withdrawal, offering a potential first antidote for cannabinoid overdose.
Network analysis of 1,217 weekly cannabis users found daily tobacco co-use strengthened connections between craving, depression, and failed quit attempts in the CUD symptom network.
Meta-analysis of 14 studies found 26.9% lifetime prevalence of cannabis use disorder in people with ADHD, with nearly 3 times higher risk compared to the general population.
Among 5,281 Americans aged 13-40, co-use of tobacco and cannabis was linked to higher depression rates than either substance alone, with e-cigarettes plus smoked cannabis the most common combination among depressed co-users.
Genomic analysis found cannabis use disorder has causal genetic effects on opioid, alcohol, and nicotine disorders, with bidirectional influences. CUD and simple cannabis use are genetically distinct.
A Colombian case series of 24 patients found 12 months of CBD oil (100-120 mg/day) reduced significant anxiety from 100% to 37.5% and improved sleep disturbances from 47% to 12.5%, with no significant adverse effects.
Qualitative interviews with 30 people who inject drugs in LA revealed three ways cannabis co-use facilitated reduced opioid use: maintaining cessation, managing withdrawal, and leveraging easier accessibility.