Browse more cannabis research, findings, methods, and limitations.
Survey of 1,833 Ugandan secondary school students found 2.6% marijuana use, with male sex (2.2x odds) and mental illness history (2.9x odds) as the strongest predictors.
Study of 75 adults found 21.3% underreported substance use when hair tests were compared to self-reports, with cannabis frequency and quantity (but not duration) predicting detection.
Mouse study found cannabidiolic acid (CBDA) reached plasma levels roughly 100 times higher than CBD at the same dose, suggesting the acid form may be far more bioavailable.
Daily CBD reversed more than 75% of over 1,000 Alzheimer's-related molecular changes in a mouse model, affecting pathways from inflammation to synaptic plasticity.
CBD treatment reduced pro-death cell signaling and restored glial cell populations in the brains of adult rat offspring born to obese mothers.
Rat study found smoked cannabis during pregnancy produced different and generally milder offspring behavioral changes than injected THC or CBD, with some effects resolving by adulthood.
Among 59 pregnant cannabis users, 61% continued using in the past month, with most using daily and many reporting failed quit attempts. Having five or more reasons for use made continued use 10 times more likely.
In lab tests, a CBD-rich cannabis extract suppressed T cell activation and inflammatory markers more potently than dexamethasone or tacrolimus, two standard immunosuppressants.
PET imaging of 49 participants found reduced brain synaptic density in early psychosis and high-risk states, with cannabis users showing additional reductions linked to worse negative symptoms.
CDC data showed adolescent drug overdose death rates were significantly higher in cannabis-legalizing states, with recreational-legalization states showing the largest increases across sexes and racial groups.
Interviews with 30 older women found those with HIV used cannabis more for appetite and energy than HIV-negative women, with both groups shifting from recreational to therapeutic use over time.
A pilot coaching program helped 22 veterans optimize cannabis use for chronic pain, with pain intensity dropping from 7.1 to 5.7 and 63% reporting much or very much improvement.
A study of medical cannabis programs across seven US states described the demographics of patients and authorizing clinicians, providing a clearer picture of who participates in medical cannabis systems.
Survey of 1,615 Canadians aged 50+ found 44% used cannabis, but over 60% said there was not enough information about its safety or effectiveness, revealing a major information gap.
19 U.S. states list Alzheimer's as a medical cannabis qualifying condition, but <1% of certifications are for AD, and clinical evidence supporting cannabis for dementia agitation is sparse.
Large European case-control study found cannabis-associated psychosis risk declined after quitting and returned to never-user levels after about 37 weeks, though heavy high-potency users may retain elevated risk longer.
Interviews with 15 Israeli medical cannabis patients found international travel regulations are vague and inconsistent, forcing patients into strategies from avoiding travel to obtaining cannabis illegally.
Survey of 2,057 German cannabis users found only 7% had ever discussed their use with a GP, rising to 16-26% among frequent and past-year users.
Multi-modal profiling of HIV-positive youth found marijuana alone linked to anti-inflammatory immune changes, while tobacco use (alone or with marijuana) drove pro-inflammatory responses.
Study of 8,158 cannabis users found they took fewer hits of concentrates than flower (suggesting some self-titration), but users who preferred higher-potency products consumed them in larger amounts and more frequently.
Study of 4,134 daily cannabis users found median consumption of 130 mg THC per day, with 65% meeting DSM-5 criteria for cannabis use disorder. Higher daily THC predicted greater severity.
A very low dose of CBD (1 mg/kg) partially reversed stress-induced behavioral changes in mice and completely restored mature synapse formation in the prefrontal cortex.
Interviews with 13 pregnant sexual minority young people found cannabis use was driven by stress and mental health, with pregnancy motivating reduction attempts but some struggling to quit.
Prospective urine screening in 39 French cardiac ICUs found 21% of elderly patients tested positive for psychoactive substances, with cannabis at 18% of positives (3x lower than younger patients).
Brain imaging of 23 cannabis users and 6 controls found no differences in motor cortex activation between heavy, moderate, light users and non-users during motor tasks.
Daily diary study of 318 college students found cannabis co-use days were associated with heavier drinking, with more cannabis use predicting higher-intensity alcohol consumption.
Survey of 111 women who vaped during pregnancy/postpartum found 28% vaped cannabis, with most believing vaping is safer than smoking and vaping daily to manage stress and anxiety.
Study of 854 Ohio cancer patients found higher cannabis (19% vs 13%) and opioid (30% vs 21%) use among those in socially disadvantaged areas, with no rural-urban differences.
fMRI study found people with cannabis use disorder had reduced prefrontal activity when evaluating effort/reward but increased posterior cortical activity during integration, despite similar behavioral choices.
Daily diary study found male college students were 7 times more likely to use cannabis the day after experiencing cyber dating abuse, while women showed no such pattern.
Irish longitudinal study of 4,554 youth found earlier alcohol initiation and risky teen drinking independently predicted cannabis and drug use at 20, with dose-response patterns persisting after extensive adjustment.
Survey of 3,490 Norwegian adolescents found 65% of cannabis users reported harms (averaging 4.7), with shame (44%) and adverse effects (42%) most common, predicted by early initiation and alcohol co-use rather than frequency.
fMRI analysis found naltrexone restored brain connectivity disruptions associated with co-occurring cannabis and opioid use disorders, primarily in the default mode network, suggesting potential as a CUD treatment.
Rat study found combining CBD with sub-therapeutic buprenorphine produced significant pain relief while CBD also reduced buprenorphine-induced respiratory depression, suggesting a safer analgesic approach.
Driving simulator study of 118 participants found occasional cannabis users had more lane departures after use, while daily users (including concentrate users) showed minimal changes, suggesting tolerance plays a major role.
Pupillometer study of 126 participants found diminished pupil dynamics (light response and recovery) were moderately predictive of recent cannabis use, with AUC of 0.73-0.75.
In-home EEG study of 339 nights found cannabis use altered multiple sleep stages, but effects on deep sleep and REM differed significantly depending on whether the person had chronic pain.
Study of 192 young adults found cannabis use disorder was associated with lower oral bacterial diversity and more anaerobic bacteria compared to other substance use disorders, with heavier use linked to greater changes.
Blood tests from 8,328 injured Canadian drivers found 54.9% positive for at least one substance — THC was the most common drug detected after alcohol in this post-legalization dataset.
Controlled trial of 130 participants found single-dose THC impaired cognition but did not worsen psychosis in people with schizophrenia and cannabis use disorder, though higher THC blood levels predicted worse negative symptoms.
Study of 115 college cannabis users found imposter syndrome was linked to more cannabis problems through a pathway of social anxiety leading to coping-motivated use.
Study of 254 Black American cigarette smokers found racism-related emotional distress (but not general anxiety or depression) was linked to cannabis problems, partly through increased cannabis consumption.
National survey of 58,034 Americans found the sharpest increase in cannabis use occurred between adolescence and young adulthood specifically among those with low risk perception, identifying a critical prevention window.
Retrospective study of 15 children with drug-resistant epilepsy found CBD reduced seizures in 11 (2 seizure-free), with improved social participation and a good safety profile, including off-label use.
Retrospective study of CVS patients found 19% used cannabis and treatment response was best when patients stopped opioids and cannabis alongside low-dose amitriptyline therapy.
California Health Interview Survey data (2018-2023) showed no overall increase in adult cannabis use after legalization, but significant variation by race/ethnicity with increases among some minority populations.
California survey of 21,463 adults found alcohol-cannabis co-use highest among White (17%) and multiracial (17.7%) adults, with Hispanic, Black, and Asian populations less likely to co-use.
Five-year monitoring of 38 children on pharmaceutical CBD found zero detectable THC in blood at any timepoint, with CBD levels rising predictably with dose.
Two toddlers who accidentally ate cannabis edibles had THC blood levels of 45-55 mcg/L, with elimination half-lives of 22-53 hours, far slower than adult THC clearance.
Vaporized high-potency cannabis during rat pregnancy altered hippocampal synapse structure, reduced CB1 receptors, increased neural excitability, and caused lasting memory deficits in offspring of both sexes.