A randomized, placebo-controlled, double-blind, pilot study of cannabis-related driving impairment assessed by driving simulator and self-report

Abstract

Aims: In the context of increasing cannabis use, understanding how cannabis affects specific driving behaviors is crucial in mitigating risks and ensuring road safety.

Design and setting: The current study included 38 adults aged 18–40 years, administered a single 0.5 g acute dose of vaporized cannabis (5.9% Tetrahydrocannabinol (THC), 13% THC or placebo) in a randomized, within-subject, double-blind, counterbalanced design. Throughout each of the three, 8-h assessment days, at 4 time points, participants underwent simulated driving tests, including lane-keeping, car following, and overtaking tasks, capturing 19 behavioral metrics. An SPSS linear mixed model assessed the main effects of dose, time, and dose × time.

Findings: During lane-keeping, participants exhibited reduced steering reversal rates up to 5.5 h following 13% THC and 3.5 h for 5.9%. For car following, participants showed reduced pedal peak-to-peak deviation and reversal rates, persisting for 1–3 h post-dose (only at 13% THC). During overtaking, following 13% THC, subjects demonstrated a shorter median gap to passed cars, lower time-to-potential collision, and more time in the oncoming lane. Drug effects on driving metrics improved gradually, to varying degrees over time. Approximately 66% of participants reported willingness to drive, despite subjective awareness of being impaired and objectively worse driving performance.

Conclusions: Our study reveals for the first time long-lasting cannabis-induced impairments across multiple driving behaviors, that extend beyond the typical 3-h window explored in most previous research. The observed discrepancy between participants’ willingness to drive and their actual impairment highlights an important public safety concern. In addition, the lack of correlation between cannabinoid metabolite concentrations and driving performance challenges the reliability of blood THC levels as impairment indicators, emphasizing the need for a multifaceted approach to assessing cannabis-impaired driving risk. (Source: Journal of Psychopharmacology)

Also see

• Effects of cannabis on visual function and self-perceived visual quality
• Cannabis (THC) messes with your Executive Functions – Can disrupt and impede good decision making and add to dysregulation
• Cannabis and Driving: Victorian Law Change for ‘Medicinal’ Cannabis Users – But is Road Safety Seriously Compromised?
• ‘Medicinal’ Cannabis & Driving – Is it an Issue? (DRR)

Cannabis use is becoming increasingly common worldwide, with growing accessibility due to global legalisation trends. However, with rising use comes significant risks, particularly in relation to cannabis use disorder (CUD). Recent studies reveal that individuals requiring hospital-based care for CUD face an alarmingly high risk of mortality within five years. This blog explores the findings, the factors contributing to these risks, and why addressing cannabis use disorder mortality is crucial.

What is Cannabis Use Disorder?

Cannabis use disorder (CUD) refers to problematic cannabis use that results in significant impairment or distress. It ranges from dependency issues to difficulty stopping usage despite harm to daily life and health. While cannabis is often perceived as “safe,” emerging evidence suggests the contrary when it comes to chronic consumption and addiction.

Why Cannabis Use Disorder Mortality Matters

A large-scale study conducted in Ontario, Canada, involving 11.6 million individuals, highlights that hospital-based care for cannabis use disorder is a significant risk marker for premature death. Within a five-year follow-up period, individuals treated for CUD were at a 2.8 times higher risk of mortality than the general population. The most significant causes of death included suicide, trauma, and opioid poisoning.

These findings demonstrate that cannabis use, particularly when it progresses to disorder levels requiring hospitalisation, is not without serious, life-altering, and often life-ending consequences.

Cannabis Use Disorder Mortality by the Numbers

To truly comprehend the gravity of the situation, here are some key figures from the study:

• Of 527,972 individuals included, 106,994 had an incident of hospital-based CUD care.
• Within five years, 3.5% of individuals with hospital-treated CUD died, compared to just 0.6% of the general population.
• Specific mortality risks were exacerbated for:
  • Suicide: 9.7 times higher risk
  • Opioid poisoning: 5.03 times higher risk
  • Trauma-related deaths: 4.55 times higher risk
  • Lung cancer: 3.81 times higher risk

With rates like these, it’s clear that cannabis use disorder mortality is a significant public health challenge that warrants urgent attention.

Causes of Increased Mortality in Cannabis Use Disorder - High-Risk Behaviours and Comorbidities

Many individuals with cannabis use disorder engage in high-risk behaviours that exacerbate other health risks. These include high levels of tobacco consumption, alcohol dependency, and polysubstance use, all of which contribute to increased mortality rates.

CUD is also strongly associated with severe mental health conditions such as schizophrenia, bipolar disorder, and depression. These comorbidities not only make treatment challenging but often compound the likelihood of complications like suicide or accidental overdoses.

Physiological Effects of Chronic Cannabis Use

Cannabis use itself is not without direct health consequences. Tetrahydrocannabinol (THC), the active compound in cannabis, has been linked to long-term cardiovascular risks, including heart disease. Additionally, chronic exposure to cannabis smoke increases the risk of respiratory illnesses and lung cancer.

Social and Structural Determinants

From access to adequate healthcare to financial instability, social determinants of health also play a role. Many individuals with cannabis use disorder come from socio-economically disadvantaged communities, further compounding the mortality risk.

Cannabis Use Disorder Compared to Other Substance Disorders

While the risks associated with cannabis use and CUD are severe, how does it compare to other substance use disorders like alcohol, stimulants, or opioids? The study found that:

• Individuals with alcohol use disorder have a 1.3 times higher risk of mortality than those with CUD.
• Those with stimulant use disorder had a 1.69 times higher risk, and
• Those with opioid use disorder faced a 2.19 times higher risk.

However, the key takeaway here is the rapid growth of CUD diagnoses worldwide, driven by more frequent and high-potency cannabis use. This trend means more individuals than ever are at risk, and the overall public health impact of CUD could climb rapidly.

The Broader Context of Cannabis Use

The legalisation and commercialisation of cannabis have made the substance accessible to more people, often under the assumption that it is benign. However, this shift has also led to higher rates of regular and heavy consumption, increasing the prevalence of cannabis use disorders.

A Volatile Public Perception - Cannabis’ perception as a “safe” drug contributes to complacency. This belief may prevent individuals from adequately addressing early signs of problematic use. The data says otherwise, with mortality risks linked to hospital-based CUD matching or exceeding those for other substances in several critical areas.

What Needs to Be Done to Address Cannabis Use Disorder Mortality

The findings of the study underscore the need for preventive and policy measures to mitigate the risks associated with cannabis use disorder. While addressing the complex ecosystem of harm requires nuanced interventions, some immediate areas for focus include:

• Strengthening Early Detection Efforts: Identifying CUD early can prevent escalation into more severe stages requiring hospitalisation.
• Educating the Public: Combat the misconception that cannabis use, particularly habitual and high-potency use, is harmless.
• Access to Appropriate Treatment: Expand access to mental health, addiction treatment, and support services for individuals struggling with CUD and other co-occurring substance dependencies.
• Policy Development: Address legal loopholes that allow the unchecked commercialisation of high-potency cannabis products.

A Need for Proactive Action

The sobering reality is that cannabis use disorder isn’t just a problem for the individuals directly impacted—it’s a growing public health issue. The dramatic increase in hospitalisations and mortality rates related to CUD reflects wider trends in substance use and mental health that require immediate attention.

If you or someone you know is struggling with problematic cannabis use, seeking support early could save a life. Together, we can work toward a healthier, safer future. 

(Source: Jama Network)

The system uses a saliva collection device to test impaired drivers for marijuana use as well as other drugs.

Over the last year, a group of officers with the Minnesota State Patrol carried a new piece of equipment in their squad cars. It looked like a Keurig machine, only this device doesn't make coffee; It analyzes saliva for THC — the chemical in marijuana that makes people high.

The machines were part of a pilot program that ended earlier this year, and the state patrol is preparing its results for state lawmakers. Minnesota is one of several states where police have tried this tool. They're doing so in response to changing behaviors: Most Americans now live in a state where marijuana is legal, more people are using it, and millions are doing so before driving.

Every state has a law that prohibits driving under the influence of drugs in some way, whether it be setting a permissible limit for legal drugs or not allowing any amount, but marijuana is difficult to regulate, and states are grappling with how to prevent people from driving under the influence.

"Essentially we've let the horse out of the barn," says Pam Shadel Fischer, senior director of external engagement with the Governors Highway Safety Association. "We need to make sure that we have things in place to protect others in the event that someone chooses to consume cannabis and get behind the wheel and be impaired."

Studies show THC can impair driving. It slows down driving speeds and reaction times and makes people swerve. Yet that varies widely by a person's tolerance to the drug, and the data is unclear on how big a problem driving while high actually is. In Colorado, for instance, fatal car crashes where a driver had THC in their blood went up after legalization. But it's difficult to determine whether a person was actively high at the time they crashed.

"When it comes to alcohol, the breath alcohol level is correlated very strongly with your blood alcohol level, which is correlated very strongly with your brain alcohol level," says Cinnamon Bidwell, an associate professor of psychology and neuroscience at the University of Colorado Boulder.

In other words, an alcohol breathalyzer is a good stand-in for how drunk and impaired a person is, but THC can stay in a person's system for hours, or even days, after they are no longer high.

"Can we detect THC accurately and reliably? The answer is yes. We can detect it in saliva. We can detect it in blood. We're working on reliable ways to detect it in breath," Bidwell says. "But what does that mean? And is there a level that means somebody recently used or that somebody is actively impaired? The data aren't there yet."

Without that, she says states risk over-punishing people who do use but don't drive while high.

Researchers, private companies and state governments are racing to find a tool that detects marijuana impairment with the ease and reliability of the alcohol breathalyzer.

In addition to Minnesota, officers in Alabama, Indiana, Michigan, Colorado and Wisconsin use or have piloted saliva tests. In Missouri, police have tested goggles that measure a driver's pupil size and movement. In Colorado, Bidwell is part of a team of researchers studying THC breathalyzers. In Vermont and Illinois, researchers have developed apps that could test a person's cognitive abilities roadside.

"We're all circling around the same question, which is, did you use recently?" says Ashley Brooks-Russell, an associate professor at the Colorado School of Public Health. "If someone's done something to cause a crash or be pulled over for a DUI, we want to know, are they impaired?"

Col. Matthew Packard, chief of the Colorado State Patrol, says with or without a test to back officers up, it's crucial to teach them what to look for. A test, he says, is just another tool.

"All that is, is confirming or supporting what you saw on the roadside," he says. "To use an ice cream analogy, the test is kind of like the cherry on the top, but ice cream is still great even if it doesn't have whipped cream and cherry." (for complete article  NPR)

Also see Cannabis and Driving: Victorian Law Change for 'Medicinal' Cannabis Users – But is Road Safety Seriously Compromised? - WRD News

Key Takeaways

• Data from over 222,600 mother-child pairs were analysed in this linkage cohort study.
• This study examined maternal cannabis use disorder (CUD) and the risk of disruptive behavioural disorders (DBDs) in offspring.
• Children exposed to maternal CUD had a 3-fold increased risk of behavioural disorders after adjusting for covariates, suggesting CUD as an independent predictor of childhood DBD risks.
• Results emphasise the need for interventions to reduce cannabis use among reproductive-age women.

Cite https://doi.org/10.1016/j.psychres.2025.116404Get rights and content

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Analysis Reveals Widespread Use of Synthetic Cannabinoids, Extreme Potencies, and Systemic Tax Evasion in the Unregulated “Hemp” Market

SACRAMENTO, CA — A new analysis of 104 so-called “hemp” products from 68 brands has uncovered a public health crisis in California’s unregulated hemp market. 

The white paper, The Great Hemp Hoax, reveals that 95 percent of tested products contained chemically synthesized cannabinoids, which are prohibited in California.  

“Much of what’s being sold as ‘hemp; today isn’t hemp at all — it’s a cocktail of synthetic intoxicants and illicit THC masquerading as a natural, legal product. It’s essentially the ultra-processed junk food of cannabis, but far more dangerous,” said Tiffany Devitt, Director of Regulatory Affairs at Groundwork Holdings, Inc. “These companies aren’t just skirting regulations – they’re putting consumers at serious risk with designer drugs that look a whole lot more like ‘Spice’ than natural hemp.”

Laboratory testing also found alarming potency levels:

• Some gummies contained 32 times more THC than what’s legally allowed in California’s regulated cannabis market.
• Vape products had THC equivalencies averaging 268% above California’s legal threshold.
• Nearly half of the tested products contained THCP, a synthetic compound up to 30 times more potent than natural THC.
• Other products included psychoactive substances such as kratom and hallucinogenic mushrooms — all sold under the guise of hemp.

“We’re not just seeing high-potency THC; we’re seeing an influx of synthetic compounds with unknown health risks,” said Josh Swider, PhD, Co-founder and CEO of Infinite Chemical Analysis Labs. “Many of these substances are unregulated, untested, and more potent than anything found in nature.”

Beyond the public health concerns, these unregulated products are undermining California’s legal cannabis industry and evading taxes:

• 91% of tested products failed to collect California sales taxes.
• None of the vendors remitted required cannabis excise taxes when required to do so.

“These illicit operations aren’t just dangerous — they’re undercutting California’s regulated cannabis businesses and workers,” said Kristin Heidelbach, Legislative Director of the United Food and Commercial Workers, Western States Council. “While licensed cannabis businesses provide good union jobs and comply with strict labor standards, many synthetic ‘hemp’ producers manufacture out-of-state or import from overseas, dodging California’s labor laws and tax obligations.” (for complete story UFCW)

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