Behind Book Recommendations

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It’s Q&A Day!

Each Thursday, we respond to subscriber questions and requests! If it’s something small, we’ll answer it directly; if it’s something bigger, we’ll do a main feature in a follow-up day instead!

So, no question/request to big or small; they’ll just get sorted accordingly

Remember, you can always hit reply to any of our emails, or use the handy feedback widget at the bottom. We always look forward to hearing from you!

Q: What’s the process behind the books you recommend? You seem to have a limitless stream of recommendations

We do our best!

The books we recommend are books that…

  • are on Amazon—it makes things tidy, consistent, and accessible. And if you end up buying one of the books, we get a small affiliate commission*.
  • we have read—we would say “obviously”, but you might be surprised how many people write about books without having read them.
  • pertain in at least large part to health and/or productivity.
  • are written by humans—bookish people (and especially Kindle Unlimited users) may have noticed lately that there are a lot of low quality AI-written books flooding the market, sometimes with paid 5-star reviews to bolster them. It’s frustrating, but we can tell the difference and screen those out.
  • are of a certain level of quality. They don’t have to be “top 5 desert-island books”, because well, there’s one every day and the days keep coming. But they do have to genuinely deliver the value that we describe, and merit a sincere recommendation.
  • are varied—we try to not give a run of “samey” books one after another. We will sometimes review a book that covers a topic another previously-reviewed book did, but it must have something about it that makes it different. It may be a different angle or a different writing style, but it needs something to set it apart.

*this is from Amazon and isn’t product-specific, so this is not affecting our choice of what books to review at all—just that they will be books that are available on Amazon.

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  • Kale vs Watercress – Which is Healthier?

    10almonds is reader-supported. We may, at no cost to you, receive a portion of sales if you purchase a product through a link in this article.

    Our Verdict

    When comparing kale to watercress, we picked the kale.

    Why?

    It was very close! If ever we’ve been tempted to call something a tie, this has been the closest so far.

    Their macros are close; watercress has a tiny amount more protein and slightly lower carbs, but these numbers are tiny, so it’s not really a factor. Nevertheless, on macros alone we’d call this a slight nominal win for watercress.

    In terms of vitamins, they’re even. Watercress has higher vitamin E and choline (sometimes considered a vitamin), as well as being higher in some B vitamins. Kale has higher vitamins A and K, as well as being higher in some other B vitamins.

    In the category of minerals, watercress has higher calcium, magnesium, phosphorus, and potassium, while kale has higher copper, iron, manganese, and zinc. The margins are slightly wider for kale’s more plentiful minerals though, so we’ll call this section a marginal win for kale.

    When it comes to polyphenols, kale takes and maintains the lead here, with around 2x the quercetin and 27x the kaempferol. Watercress does have some lignans that kale doesn’t, but ultimately, kale’s strong flavonoid content keeps it in the lead.

    So of course: enjoy both if both are available! But if we must pick one, it’s kale.

    Want to learn more?

    You might like to read:

    Take care!

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  • Oral vaccines could provide relief for people who suffer regular UTIs. Here’s how they work

    10almonds is reader-supported. We may, at no cost to you, receive a portion of sales if you purchase a product through a link in this article.

    In a recent TikTok video, Australian media personality Abbie Chatfield shared she was starting a vaccine to protect against urinary tract infections (UTIs).

    Huge news for the UTI girlies. I am starting a UTI vaccine tonight for the first time.

    Chatfield suffers from recurrent UTIs and has turned to the Uromune vaccine, an emerging option for those seeking relief beyond antibiotics.

    But Uromune is not a traditional vaccine injected to your arm. So what is it and how does it work?

    9nong/Shutterstock

    First, what are UTIs?

    UTIs are caused by bacteria entering the urinary system. This system includes the kidneys, bladder, ureters (thin tubes connecting the kidneys to the bladder), and the urethra (the tube through which urine leaves the body).

    The most common culprit is Escherichia coli (E. coli), a type of bacteria normally found in the intestines.

    While most types of E. coli are harmless in the gut, it can cause infection if it enters the urinary tract. UTIs are particularly prevalent in women due to their shorter urethras, which make it easier for bacteria to reach the bladder.

    Roughly 50% of women will experience at least one UTI in their lifetime, and up to half of those will have a recurrence within six months.

    A diagram of the urinary system.
    UTIs are caused by bacteria enterning the urinary system. oxo7051/Shutterstock

    The symptoms of a UTI typically include a burning sensation when you wee, frequent urges to go even when the bladder is empty, cloudy or strong-smelling urine, and pain or discomfort in the lower abdomen or back. If left untreated, a UTI can escalate into a kidney infection, which can require more intensive treatment.

    While antibiotics are the go-to treatment for UTIs, the rise of antibiotic resistance and the fact many people experience frequent reinfections has sparked more interest in preventive options, including vaccines.

    What is Uromune?

    Uromune is a bit different to traditional vaccines that are injected into the muscle. It’s a sublingual spray, which means you spray it under your tongue. Uromune is generally used daily for three months.

    It contains inactivated forms of four bacteria that are responsible for most UTIs, including E. coli. By introducing these bacteria in a controlled way, it helps your immune system learn to recognise and fight them off before they cause an infection. It can be classified as an immunotherapy.

    A recent study involving 1,104 women found the Uromune vaccine was 91.7% effective at reducing recurrent UTIs after three months, with effectiveness dropping to 57.6% after 12 months.

    These results suggest Uromune could provide significant (though time-limited) relief for women dealing with frequent UTIs, however peer-reviewed research remains limited.

    Any side effects of Uromune are usually mild and may include dry mouth, slight stomach discomfort, and nausea. These side effects typically go away on their own and very few people stop treatment because of them. In rare cases, some people may experience an allergic reaction.

    How can I access it?

    In Australia, Uromune has not received full approval from the Therapeutic Goods Administration (TGA), and so it’s not something you can just go and pick up from the pharmacy.

    However, Uromune can be accessed via the TGA’s Special Access Scheme or the Authorised Prescriber pathway. This means a GP or specialist can apply for approval to prescribe Uromune for patients with recurrent UTIs. Once the patient has a form from their doctor documenting this approval, they can order the vaccine directly from the manufacturer.

    A woman sitting on a couch taking a pill.
    Antibiotics are the go-to treatment for UTIs – but scientists are looking at options to prevent them in the first place. Photoroyalty/Shutterstock

    Uromune is not covered under the Pharmaceutical Benefits Scheme, meaning patients must cover the full cost out-of-pocket. The cost of a treatment program is around A$320.

    Uromune is similarly available through special access programs in places like the United Kingdom and Europe.

    Other options in the pipeline

    In addition to Uromune, scientists are exploring other promising UTI vaccines.

    Uro-Vaxom is an established immunomodulator, a substance that helps regulate or modify the immune system’s response to bacteria. It’s derived from E. coli proteins and has shown success in reducing UTI recurrences in several studies. Uro-Vaxom is typically prescribed as a daily oral capsule taken for 90 days.

    FimCH, another vaccine in development, targets something called the adhesin protein that helps E. coli attach to urinary tract cells. FimCH is typically administered through an injection and early clinical trials have shown promising results.

    Meanwhile, StroVac, which is already approved in Germany, contains inactivated strains of bacteria such as E. coli and provides protection for up to 12 months, requiring a booster dose after that. This injection works by stimulating the immune system in the bladder, offering temporary protection against recurrent infections.

    These vaccines show promise, but challenges like achieving long-term immunity remain. Research is ongoing to improve these options.

    No magic bullet, but there’s reason for optimism

    While vaccines such as Uromune may not be an accessible or perfect solution for everyone, they offer real hope for people tired of recurring UTIs and endless rounds of antibiotics.

    Although the road to long-term relief might still be a bit bumpy, it’s exciting to see innovative treatments like these giving people more options to take control of their health.

    Iris Lim, Assistant Professor in Biomedical Science, Bond University

    This article is republished from The Conversation under a Creative Commons license. Read the original article.

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  • Study Tips for Exam Season?

    10almonds is reader-supported. We may, at no cost to you, receive a portion of sales if you purchase a product through a link in this article.

    You’ve Got Questions? We’ve Got Answers!

    Q: Any study tips as we approach exam season? A lot of the productivity stuff is based on working life, but I can’t be the only student!

    A: We’ve got you covered:

    • Be passionate about your subject! We know of no greater study tip than that.
    • Find a willing person and lecture them on your subject. When one teaches, two learn!
    • Your mileage may vary depending on your subject, but, find a way of studying that’s fun to you!
    • If you can get past papers, get as many as you can, and use those as your “last minute” studying in the week before your exam(s). This will prime you for answering exam-style questions (and leverage state-dependent memory). As a bonus, it’ll also help ease any anxiety, because by the time of your exam it’ll be “same old, same old”!

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  • Spoon-Fed – by Dr. Tim Spector

    10almonds is reader-supported. We may, at no cost to you, receive a portion of sales if you purchase a product through a link in this article.

    Dr. Spector looks at widespread beliefs about food, and where those often scientifically disproven beliefs come from. Hint, there’s usually some manner of “follow the money”.

    From calorie-counting to cholesterol content, from fish to bottled water, to why of all the people who self-report having an allergy, only around half turn out to actually have one when tested, Dr. Spector sets the record straight.

    The style is as very down-to-earth and not at all self-aggrandizing; the author acknowledges his own mistakes and limitations along the way. In terms of pushing any particular agenda, his only agenda is clear: inform the public about bad science, so that we demand better science going forwards. Along the way, he gives us lots of information that can inform our personal health choices based on better science than indiscriminate headlines wildly (and sometimes intentionally) misinterpreting results.

    Read this book, and you may find yourself clicking through to read the studies for yourself, next time you see a bold headline.

    Bottom line: this book looks at a lot of what’s wrong with what a lot of people believe about healthy eating. Regular 10almonds readers might not find a lot that’s new here, but it could be a great gift for a would-be health-conscious friend or relative

    Click here to check out Spoon-Fed, and bust some myths!

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  • Wakefulness, Cognitive Enhancement, AND Improved Mood?

    10almonds is reader-supported. We may, at no cost to you, receive a portion of sales if you purchase a product through a link in this article.

    Old Drug, New Tricks?

    Modafinil (also known by brand names including Modalert and Provigil) is a dopamine uptake inhibitor.

    What does that mean? It means it won’t put any extra dopamine in your brain, but it will slow down the rate at which your brain removes naturally-occuring dopamine.

    The result is that your brain will get to make more use of the dopamine it does have.

    (dopamine is a neutrotransmitter that allows you to feel wakeful and happy, and perform complex cognitive tasks)

    Modafinil is prescribed for treatment of excessive daytime sleepiness. Often that’s caused by shift work sleep disorder, sleep apnea, restless leg syndrome, or narcolepsy.

    Read: Overview of the Clinical Uses, Pharmacology, and Safety of Modafinil

    Many studies done on humans (rather than rats) have been military experiments to reduce the effects of sleep deprivation:

    Click Here To See A Military Study On Modafinil!

    They’ve found modafinil to be helpful, and more effective and more long-lasting than caffeine, without the same “crash” later. This is for two reasons:

    1) while caffeine works by blocking adenosine (so you don’t feel how tired you are) and by constricting blood vessels (so you feel more ready-for-action), modafinil works by allowing your brain to accumulate more dopamine (so you’re genuinely more wakeful, and you get to keep the dopamine)

    2) the biological half-life of modafinil is 12–15 hours, as opposed to 4–8 hours* for caffeine.

    *Note: a lot of sources quote 5–6 hours for caffeine, but this average is misleading. In reality, we are each genetically predetermined to be either a fast caffeine metabolizer (nearer 4 hours) or a slow caffeine metabolizer (nearer 8 hours).

    What’s a biological half-life (also called: elimination half-life)?

    A substance’s biological half-life is the time it takes for the amount in the body to be reduced by exactly half.

    For example: Let’s say you’re a fast caffeine metabolizer and you have a double-espresso (containing 100mg caffeine) at 8am.

    By midday, you’ll have 50mg of caffeine left in your body. So far, so simple.

    By 4pm you might expect it to be gone, but instead you have 25mg remaining (because the amount halves every four hours).

    By 8pm, you have 12.5mg remaining.

    When midnight comes and you’re tucking yourself into bed, you still have 6.25mg of caffeine remaining from your morning coffee!

    Use as a nootropic

    Many healthy people who are not sleep-deprived use modafinil “off-label” as a nootropic (i.e., a cognitive enhancer).

    Read: Modafinil for cognitive neuroenhancement in healthy non-sleep-deprived subjects: A systematic review

    Important Note: modafinil is prescription-controlled, and only FDA-approved for sleep disorders.

    To get around this, a lot of perfectly healthy biohackers describe the symptoms of sleep pattern disorder to their doctor, to get a prescription.

    We do not recommend lying to your healthcare provider, and nor do we recommend turning to the online “grey market”.

    Such websites often use anonymized private doctors to prescribe on an “informed consent” basis, rather than making a full examination. Those websites then dispense the prescribed medicines directly to the patient with no further questions asked (i.e. very questionable practices).

    Caveat emptor!

    A new mood-brightener?

    Modafinil was recently tested head-to-head against Citalapram for the treatment of depression, and scored well:

    See its head-to-head scores here!

    How does it work? Modafinil does for dopamine what a lot of anti-depressants do for serotonin. Both dopamine and serotonin promote happiness and wakefulness.

    This is very promising, especially as modafinil (in most people, at least) has fewer unwanted side-effects than a lot of common anti-depressant medications.

    Don’t Forget…

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  • Driving under the influence of marijuana: An explainer and research roundup

    10almonds is reader-supported. We may, at no cost to you, receive a portion of sales if you purchase a product through a link in this article.

    Update 1: On May 16, 2024, the U.S. Department of Justice sent a proposed rule to the Federal Register to downgrade marijuana from a Schedule I to a Schedule III drug. This is the first step in a lengthy approval process that starts with a 60-day comment period.

    Update 2: Two recent research studies were added to the “Studies on marijuana and driving” section of this piece on July 18, 2024.

    As marijuana use continues to rise and state-level marijuana legalization sweeps the U.S., researchers and policymakers are grappling with a growing public safety concern: marijuana-impaired driving.

    As of April 2023, 38 U.S. states had legalized medical marijuana and 23 had legalized its recreational use, according to the National Conference of State Legislatures. Recreational or medical marijuana measures are on the ballot in seven states this year.

    The issue of marijuana-impaired driving has not been an easy one to tackle because, unlike alcohol, which has well-established thresholds of impairment, the metrics for marijuana’s effects on driving remain rather elusive.

    “We don’t have that kind of deep knowledge right now and it’s not because of lack of trying,” says Dr. Guohua Li, professor of epidemiology and the founding director of the Center for Injury Science and Prevention at Columbia University.

    “Marijuana is very different from alcohol in important ways,” says Li, who has published several studies on marijuana and driving. “And one of them is that the effect of marijuana on cognitive functions and behaviors is much more unpredictable than alcohol. In general, alcohol is a depressant drug. But marijuana could act on the central nervous system as a depressant, a stimulant, and a hallucinogenic substance.”

    Efforts to create a breathalyzer to measure the level of THC, the main psychoactive compound found in the marijuana plant, have largely failed, because “the THC molecule is much bigger than ethanol and its behavior after ingestion is very different from alcohol,” Li says.

    Currently, the two most common methods used to measure THC concentration to identify impaired drivers are blood and saliva tests, although there’s ongoing debate about their reliability.

    Marijuana, a term interchangeably used with cannabis, is the most commonly used federally illegal drug in the U.S.: 48.2 million people, or about 18% of Americans reported using it at least once in 2019, according to the latest available data from the Centers for Disease Control and Prevention. Worldwide, 2.5% of the population consumes marijuana, according to the World Health Organization.

    Marijuana is legal in several countries, including Canada, where it was legalized in 2018. Despite state laws legalizing cannabis, it remains illegal at the federal level in the U.S.

    As states grapple with the contentious issue of marijuana legalization, the debate is not just about public health, potential tax revenues and economic interests. At the heart of the discussion is also the U.S. criminal justice system.

    Marijuana is shown to have medicinal qualities and, compared with substances like alcohol, tobacco, and opioids, it has relatively milder health risks. However, it’s not risk-free, a large body of research has shown.

    Marijuana consumption can lead to immediate effects such as impaired muscle coordination and paranoia, as well as longer-term effects on mental health and cognitive functions — and addiction. As its use becomes more widespread, researchers are trying to better understand the potential hazards of marijuana, particularly for younger users whose brains are in critical stages of development.

    Marijuana and driving

    The use of marijuana among drivers, passengers and pedestrians has increased steadily over the past two decades, Li says.

    Compared with the year 2000, the proportion of U.S. drivers on the road who are under the influence of marijuana has increased by several folds, between five to 10 times, based on toxicology testing of people who died in car crashes, Li says.

    A 2022 report from the National Transportation Safety Board finds alcohol and cannabis are the two most commonly detected drugs among drivers arrested for impaired driving and fatally injured drivers. Most drivers who tested positive for cannabis also tested positive for another potentially impairing drug.

    “Although cannabis and many other drugs have been shown to impair driving performance and are associated with increased crash risk, there is evidence that, relative to alcohol, awareness about the potential dangers of driving after using other drugs is lower,” according to the report.

    Indeed, many U.S. adults perceive daily marijuana use or exposure to its smoke safer than tobacco, even though research finds otherwise.

    Several studies have demonstrated marijuana’s impact on driving.

    Marijuana use can reduce the drivers’ ability to pay attention, particularly when they are performing multiple tasks, research finds. It also slows reaction time and can impair coordination.

    “The combination is that you potentially have people who are noticing hazards later, braking slower and potentially not even noticing hazards because of their inability to focus on competing things on the road,” says Dr. Daniel Myran, an assistant professor at the Department of Family Medicine and health services researcher at the University of Ottawa.

    In a study published in September in JAMA Network Open, Myran and colleagues find that from 2010 to 2021 the rate of cannabis-involved traffic injuries that led to emergency department visits in Ontario, Canada, increased by 475%, from 0.18 per 1,000 traffic injury emergency department visits in 2010 to 1.01 visits in 2021.

    To be sure, cannabis-involved traffic injuries made up a small fraction of all traffic injury-related visits to hospital emergency departments. Out of 947,604 traffic injury emergency department visits, 426 had documented cannabis involvement.

    Myran cautions the increase shouldn’t be solely attributed to marijuana legalization. It captures changing societal attitudes toward marijuana and acceptance of cannabis use over time in the lead-up to legalization. In addition, it may reflect an increasing awareness among health care providers about cannabis-impaired driving, and they may be more likely to ask about cannabis use and document it in medical charts, he says.

    “When you look at the 475% increase in cannabis involvement in traffic injuries, rather than saying legalizing cannabis has caused the roads to be unsafe and is a public health disaster, it’s that cannabis use appears to be growing as a risk for road traffic injuries and that there seem to be more cannabis impaired drivers on the road,” Myran says. “Legalization may have accelerated this trend. Faced with this increase, we need to think about what are public health measures and different policy interventions to reduce harms from cannabis-impaired driving.”

    Setting a legal limit for marijuana-impaired driving

    Setting a legal limit for marijuana-impaired driving has not been easy. Countries like Canada and some U.S. states have agreed upon a certain level of THC in blood, usually between 1 to 5 nanograms per milliliter. Still, some studies have found those limits to be weak indicators of cannabis-impaired driving.

    When Canada legalized recreational marijuana in 2018, it also passed a law that made it illegal to drive with blood THC levels of more than 2 nanograms. The penalties are more severe for blood THC levels above 5 nanograms. The blood test is done at the police station for people who are pulled over and are deemed to be drug impaired.

    In the U.S., five states — Ohio, Illinois, Montana, Washington and Nevada — have “per se laws,” which set a specific amount of THC in the driver’s blood as evidence of impaired driving, according to the National Conference of State Legislatures. That limit ranges between 2 and 5 nanograms of THC per milliliter of blood.

    Colorado, meanwhile, has a “permissible inference law,” which states that it’s permissible to assume the driver was under the influence if their blood THC level is 5 nanograms per milliliter or higher, according to NCSL.

    Twelve states, most which have legalized some form of marijuana of use, have zero tolerance laws for any amount of certain drugs, including THC, in the body.

    The remaining states have “driving under the influence of drugs” laws. Among those states, Alabama and Michigan, have oral fluid roadside testing program to screen drivers for marijuana and other drugs, according to NCSL.

    In May this year, the U.S. Department of Transportation published a final rule that allows employers to use saliva testing for commercially licensed drivers, including truck drivers. The rule, which went into effect in June, sets the THC limit in saliva at 4 nanograms.

    Saliva tests can detect THC for 8 to 24 hours after use, but the tests are not perfect and can results in false positives, leading some scientists to argue against using them in randomly-selected drivers.

    In a 2021 report, the U.S. National Institute of Justice, the research and development arm of the Department of Justice, concluded that THC levels in bodily fluids, including blood and saliva “were not reliable indicators of marijuana intoxication.”

    Studies on marijuana and driving

    Over the past two decades, many studies have shown marijuana use can impair driving. However, discussions about what’s the best way to measure the level of THC in blood or saliva are ongoing. Below, we highlight and summarize several recent studies that address the issue. The studies are listed in order of publication date. We also include a list of related studies and resources to inform your audiences.

    State Driving Under the Influence of Drugs Laws
    Alexandra N. Origenes, Sarah A. White, Emma E. McGinty and Jon S. Vernick. Journal of Law, Medicine & Ethics, July 2024.

    Summary: As of January 2023, 33 states and D.C. had a driving under the influence of drugs law for at least one drug other than cannabis. Of those, 29 states and D.C. had a law specifically for driving under the influence of cannabis, in addition to a law for driving under the influence of other drugs. Four states had a driving under the influence of drug laws, excluding cannabis. Meanwhile, 17 states had no law for driving under the influence of drugs, including cannabis.  “The 17 states lacking a DUID law that names specific drugs should consider enacting such a law. These states already have expressed their concern — through legislation — with drug-impaired driving. However, failure to name specific drugs is likely to make the laws more difficult to enforce. These laws may force courts and/or law enforcement to rely on potentially subjective indicators of impairment,” the authors write.

    Associations between Adolescent Marijuana Use, Driving After Marijuana Use and Recreational Retail Sale in Colorado, USA
    Lucas M. Neuroth, et al. Substance Use & Misuse, October 2023.

    Summary: Researchers use data from four waves (2013, 2015, 2017 and 2019) of the Healthy Kids Colorado Survey, including 47,518 students 15 and older who indicated that they drove. They find 20.3% of students said that they had used marijuana in the past month and 10.5% said they had driven under the influence of marijuana. They find that the availability of recreational marijuana in stores was associated with an increased prevalence of using marijuana one to two times in the past month and driving under the influence of marijuana at least once. “Over the study period, one in ten high school age drivers engaged in [driving after marijuana use], which is concerning given the high risk of motor vehicle-related injury and death arising from impaired driving among adolescents,” the authors write.

    Are Blood and Oral Fluid Δ9-tetrahydrocannabinol (THC) and Metabolite Concentrations Related to Impairment? A Meta-Regression Analysis
    Danielle McCartney, et al. Neuroscience & Biobehavioral Reviews, March 2022.

    Summary: Commonly used THC measurements may not be strong indicators of driving impairment. While there is a relationship between certain biomarkers like blood THC concentrations and impaired driving, this correlation is often weak. The study underscores the need for more nuanced and comprehensive research on this topic, especially as cannabis usage becomes more widespread and legally accepted.

    The Effects of Cannabis and Alcohol on Driving Performance and Driver Behaviour: A Systematic Review and Meta-Analysis
    Sarah M. Simmons, Jeff K. Caird, Frances Sterzer and Mark Asbridge. Addiction, January 2022.

    Summary: This meta-analysis of experimental driving studies, including driving simulations, confirms that cannabis impairs driving performance, contrary to some beliefs that it might enhance driving abilities. Cannabis affects lateral control and speed — typically increasing lane excursions while reducing speed. The combination of alcohol and marijuana appears worse than either alone, challenging the idea that they cancel each other out.

    Cannabis Legalization and Detection of Tetrahydrocannabinol in Injured Drivers
    Jeffrey R. Brubacher, et al. The New England Journal of Medicine, January 2022.

    Summary: Following the legalization of recreational marijuana in Canada, there was a notable increase in injured drivers testing positive for THC, especially among those 50 years of age or older. This rise in cannabis-related driving incidents occurred even with new traffic laws aiming to deter cannabis-impaired driving. This uptick began before legalization became official, possibly due to perceptions that cannabis use was soon-to-be legal or illegal but not enforced. The data suggests that while legalization has broad societal impacts, more comprehensive strategies are needed to deter driving under the influence of cannabis and raise public awareness about its risks.

    Cannabis and Driving
    Godfrey D. Pearlson, Michael C. Stevens and Deepak Cyril D’Souza. Frontiers in Psychiatry, September 2021.

    Summary: Cannabis-impaired driving is a growing public health concern, and studies show that such drivers are more likely to be involved in car crashes, according to this review paper. Drivers are less affected by cannabis than they are by alcohol or cocaine, but the problem is expected to escalate with increasing cannabis legalization and use. Unlike alcohol, THC’s properties make it challenging to determine direct impairment levels from testing results. Current roadside tests lack precision in detecting genuine cannabis-impaired drivers, leading to potential wrongful convictions. Moreover, there is a pressing need for research on the combined effects of alcohol and cannabis on driving, as well as the impact of emerging popular forms of cannabis, like concentrates and edibles. The authors recommend public awareness campaigns about the dangers of driving under the influence of cannabis, similar to those against drunk driving, to address misconceptions. Policymakers should prioritize science-based decisions and encourage further research in this domain.

    Demographic And Policy-Based Differences in Behaviors And Attitudes Towards Driving After Marijuana Use: An Analysis of the 2013–2017 Traffic Safety Culture Index
    Marco H. Benedetti, et al. BMC Research Notes, June 2021.

    Summary: The study, based on a U.S. survey, finds younger, low-income, low-education and male participants were more tolerant of driving after marijuana consumption. Notably, those in states that legalized medical marijuana reported driving after use more frequently, aligning with studies indicating a higher prevalence of THC detection in drivers from these states. Overall, while the majority perceive driving after marijuana use as dangerous, not all research agrees on its impairment effects. Existing studies highlight that marijuana impacts motor skills and executive functions, yet its direct correlation with crash risk remains debated, given the variations in individual tolerance and how long THC remains in the system.

    Driving Under the Influence of Cannabis: A Framework for Future Policy
    Robert M. Chow, et al.Anesthesia & Analgesia, June 2019.

    Summary: The study presents a conceptual framework focusing on four main domains: legalization, driving under the influence of cannabis, driver impairment, and motor vehicle accidents. With the growing legalization of cannabis, there’s an anticipated rise in cannabis-impaired driving cases. The authors group marijuana users into infrequent users who show significant impairment with increased THC blood levels, chronic users with minimal impairment despite high THC levels, and those with consistent psychomotor deficits. Current challenges lie in the lack of standardized regulation for drivers influenced by cannabis, primarily because of state-to-state variability and the absence of a federal statutory limit for blood THC levels. European nations, however, have established thresholds for blood THC levels, ranging from 0.5 to 50.0 micrograms per liter depending on whether blood or blood serum are tested. The authors suggest the combined use of alcohol and THC blood tests with a psychomotor evaluation by a trained professional to determine impairment levels. The paper stresses the importance of creating a structured policy framework, given the rising acceptance and use of marijuana in society.

    Additional research

    Cannabis-Involved Traffic Injury Emergency Department Visits After Cannabis Legalization and Commercialization
    Daniel T. Myran, et al. JAMA Network Open, September 2023.

    Driving Performance and Cannabis Users’ Perception of Safety: A Randomized Clinical Trial
    Thomas D. Marcotte, et al. JAMA Psychiatry, January 2022.

    Medicinal Cannabis and Driving: The Intersection of Health and Road Safety Policy
    Daniel Perkins, et al. International Journal of Drug Policy, November 2021.

    Prevalence of Marijuana Use Among Trauma Patients Before and After Legalization of Medical Marijuana: The Arizona Experience
    Michael Levine, et al. Substance Abuse, July 2021.

    Self-Reported Driving After Marijuana Use in Association With Medical And Recreational Marijuana Policies
    Marco H. Benedetti, et al. International Journal of Drug Policy, June 2021.

    Cannabis and Driving Ability
    Eric L. Sevigny. Current Opinion in Psychology, April 2021.

    The Failings of per se Limits to Detect Cannabis-Induced Driving Impairment: Results from a Simulated Driving Study
    Thomas R. Arkell, et al. Traffic Injury Prevention, February 2021.

    Risky Driving Behaviors of Drivers Who Use Alcohol and Cannabis
    Tara Kelley-Baker, et al. Transportation Research Record, January 2021.

    Direct and Indirect Effects of Marijuana Use on the Risk of Fatal 2-Vehicle Crash Initiation
    Stanford Chihuri and Guohua Li. Injury Epidemiology, September 2020

    Cannabis-Impaired Driving: Evidence and the Role of Toxicology Testing
    Edward C. Wood and Robert L. Dupont. Cannabis in Medicine, July 2020.

    Association of Recreational Cannabis Laws in Colorado and Washington State With Changes in Traffic Fatalities, 2005-2017
    Julian Santaella-Tenorio, et al. JAMA Internal Medicine, June 2020.

    Marijuana Decriminalization, Medical Marijuana Laws, and Fatal Traffic Crashes in US Cities, 2010–2017
    Amanda Cook, Gregory Leung and Rhet A. Smith. American Journal of Public Health, February 2020.

    Cannabis Use in Older Drivers in Colorado: The LongROAD Study
    Carolyn G. DiGuiseppi, et al. Accident Analysis & Prevention, November 2019.

    Crash Fatality Rates After Recreational Marijuana Legalization in Washington and Colorado
    Jayson D. Aydelotte, et al. American Journal of Public Health, August 2017.

    Marijuana-Impaired Driving: A Report to Congress
    National Highway Traffic Safety Administration, July 2017

    Interaction of Marijuana And Alcohol on Fatal Motor Vehicle Crash Risk: A Case–Control Study
    Stanford Chihuri, Guohua Li and Qixuan Chen. Injury Epidemiology, March 2017.

    US Traffic Fatalities, 1985–2014, and Their Relationship to Medical Marijuana Laws
    Julian Santaella-Tenorio, et al. American Journal of Public Health, February 2017.

    Delays in DUI Blood Testing: Impact on Cannabis DUI Assessments
    Ed Wood, Ashley Brooks-Russell and Phillip Drum. Traffic Injury Prevention, June 2015.

    Establishing Legal Limits for Driving Under the Influence of Marijuana
    Kristin Wong, Joanne E. Brady and Guohua Li. Injury Epidemiology, October 2014.

    Cannabis Effects on Driving Skills
    Rebecca L. Hartman and Marilyn A. Huestis. Clinical Chemistry, March 2014.

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    Resources for your audiences

    The following resources include explainers from federal agencies and national organizations. You’re free to use images and graphics from federal agencies.

    This article first appeared on The Journalist’s Resource and is republished here under a Creative Commons license.

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