Unlock Your Menopause Type – by Dr. Heather Hirsch
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We featured Dr. Hirsch before, here, and mentioned this book which, at the time, we had not yet reviewed. So, here it is:
What sets this apart from a lot of menopause books is that there’s a lot less “eat these foods and your body will magically stop exhibiting symptoms of menopause” and a lot more clinical observations and then evidence-based recommendations.
Which is not to say don’t eat broccoli and almonds; by all means, they’re great foods and contain valuable nutrients that will help. But it is to say that if your doctor’s prescription is just broccoli and almonds, maybe have those as a snack while you’re looking for a second opinion.
Dr. Hirsch goes through various “menopause types”, but it’s not so much “astrology for gynecologists” and more “here are clusters of menopause symptoms set against timeline of presentation, and they can be categorized into six main ways that between them, cover pretty much all my patients, which have been many”.
So if you, dear reader, are menopausal (including peri- or post-), then the chances are very good that you will see yourself in one of those six sets.
She then goes about how to prioritize relief and safety, and personalize a treatment plan, and maintain the best menopausal care for you, going forward.
The style is easy-reading pop-science, punctuated by clinical science and 35 pages of references. She’s also, unlike a lot of authors in the genre, manifestly not invested in being a celebrity or making a personality cult out of her recommendations; she’s happy to stick to the science and put out good advice.
Bottom line: if you or someone you love is menopausal (including peri- or post-), this is a top-tier book.
Click here to check out Unlock Your Menopause Type, and get the best care for you!
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Parsnips vs Potatoes – Which is Healthier?
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Our Verdict
When comparing parsnips to potatoes, we picked the parsnips.
Why?
To be more specific, we’re looking at russet potatoes, and in both cases we’re looking at cooked without fat or salt, skin on. In other words, the basic nutritional values of these plants in edible form, without adding anything. With this in mind, once we get to the root of things, there’s a clear winner:
Looking at the macros first, potatoes have more carbs while parsnips have more fiber. Potatoes do have more protein too, but given the small numbers involved when it comes to protein we don’t think this is enough of a plus to outweigh the extra fiber in the parsnips.
In the category of vitamins, again a champion emerges: parsnips have more of vitamins B1, B2, B5, B9, C, E, and K, while potatoes have more of vitamins B3, B6, and choline. So, a 7:3 win for parsnips.
When it comes to minerals, parsnips have more calcium copper, manganese, selenium, and zinc, while potatoes have more iron and potassium. Potatoes do also have more sodium, but for most people most of the time, this is not a plus, healthwise. Disregarding the sodium, this category sees a 5:2 win for parsnips.
In short: as with most starchy vegetables, enjoy both in moderation if you feel so inclined, but if you’re picking one, then parsnips are the nutritionally best choice here.
Want to learn more?
You might like to read:
- Why You’re Probably Not Getting Enough Fiber (And How To Fix It)
- Should You Go Light Or Heavy On Carbs?
Take care!
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From Dr. Oz to Heart Valves: A Tiny Device Charted a Contentious Path Through the FDA
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In 2013, the FDA approved an implantable device to treat leaky heart valves. Among its inventors was Mehmet Oz, the former television personality and former U.S. Senate candidate widely known as “Dr. Oz.”
In online videos, Oz has called the process that brought the MitraClip device to market an example of American medicine firing “on all cylinders,” and he has compared it to “landing a man on the moon.”
MitraClip was designed to spare patients from open-heart surgery by snaking hardware into the heart through a major vein. Its manufacturer, Abbott, said it offered new hope for people severely ill with a condition called mitral regurgitation and too frail to undergo surgery.
“It changed the face of cardiac medicine,” Oz said in a video.
But since MitraClip won FDA approval, versions of the device have been the subject of thousands of reports to the agency about malfunctions or patient injuries, as well as more than 1,100 reports of patient deaths, FDA records show. Products in the MitraClip line have been the subject of three recalls. A former employee has alleged in a federal lawsuit that Abbott promoted the device through illegal inducements to doctors and hospitals. The case is pending, and Abbott has denied illegally marketing the device.
The MitraClip story is, in many ways, a cautionary tale about the science, business, and regulation of medical devices.
Manufacturer-sponsored research on the device has long been questioned. In 2013, an outside adviser to the FDA compared some of the data marshaled in support of its approval to “poop.”
The FDA expanded its approval of MitraClip to a wider set of patients in 2019, based on a clinical trial in which Abbott was deeply involved and despite conflicting findings from another study.
In the three recalls, the first of which warned of potentially deadly consequences, neither the manufacturer nor the FDA withdrew inventory from the market. The company told doctors it was OK for them to continue using the recalled products.
In response to questions for this article, both Abbott and the FDA described MitraClip as safe and effective.
“With MitraClip, we’re addressing the needs of people with MR who often have no other options,” Abbott spokesperson Brent Tippen said. “Patients suffering from mitral regurgitation have severely limited quality of life. MitraClip can significantly improve survival, freedom for hospitalization and quality of life via a minimally invasive, now common procedure.”
An FDA spokesperson, Audra Harrison, said patient safety “is the FDA’s highest priority and at the forefront of our work in medical device regulation.”
She said reports to the FDA about malfunctions, injuries, and deaths that the device may have caused or contributed to are “consistent” with study results the FDA reviewed for its 2013 and 2019 approvals.
In other words: They were expected.
Inspiration in Italy
When a person has mitral regurgitation, blood flows backward through the mitral valve. Severe cases can lead to heart failure.
With MitraClip, flaps of the valve — known as “leaflets” — are clipped together at one or more points to achieve a tighter seal when they close. The clips are deployed via a catheter threaded through a major vein, typically from an incision in the groin. The procedure offers an alternative to connecting the patient to a heart-lung machine and repairing or replacing the mitral valve in open-heart surgery.
Oz has said in online videos that he got the idea after hearing a doctor describe a surgical technique for the mitral valve at a conference in Italy. “And on the way home that night, on a plane heading back to Columbia University, where I was on the faculty, I wrote the patent,” he told KFF Health News.
A patent obtained by Columbia in 2001, one of several associated with MitraClip, lists Oz first among the inventors.
But a Silicon Valley-based startup, Evalve, would develop the device. Evalve was later acquired by Abbott for about $400 million.
“I think the engineers and people at Evalve always cringe a little bit when they see Mehmet taking a lot of, you know, basically claiming responsibility for what was a really extraordinary team effort, and he was a small to almost no player in that team,” one of the company’s founders, cardiologist Fred St. Goar, told KFF Health News.
Oz did not respond to a request for comment on that statement.
As of 2019, the MitraClip device cost $30,000 per procedure, according to an article in a medical journal. According to the Abbott website, more than 200,000 people around the world have been treated with MitraClip.
Oz filed a financial disclosure during his unsuccessful run for the U.S. Senate in 2022 that showed him receiving hundreds of thousands of dollars in annual MitraClip royalties.
Abbott recently received FDA approval for TriClip, a variation of the MitraClip system for the heart’s tricuspid valve.
Endorsed ‘With Trepidation’
Before the FDA said yes to MitraClip in 2013, agency staffers pushed back.
Abbott had originally wanted the device approved for “patients with significant mitral regurgitation,” a relatively broad term. After the FDA objected, the company narrowed its proposal to patients at too-high risk for open-heart surgery.
Even then, in an analysis, the FDA identified “fundamental” flaws in Abbott’s data.
One example: The data compared MitraClip patients with patients who underwent open-heart surgery for valve repair — but the comparison might have been biased by differences in the expertise of doctors treating the two groups, the FDA analysis said. While MitraClip was implanted by a highly select, experienced group of interventional cardiologists, many of the doctors doing the open-heart surgeries had performed only a “very low volume” of such operations.
FDA “approval is not appropriate at this time as major questions of safety and effectiveness, as well as the overall benefit-risk profile for this device, remain unanswered,” the FDA said in a review prepared for a March 2013 meeting of a committee of outside advisers to the agency.
Some committee members expressed misgivings. “If your right shoe goes into horse poop and your left shoe goes into dog poop, it’s still poop,” cardiothoracic surgeon Craig Selzman said, according to a transcript.
The committee voted 5-4 against MitraClip on the question of whether it proved effective. But members voted 8-0 that they considered the device safe and 5-3 that the benefits of the device outweighed its risks.
Selzman voted yes on the last question “with trepidation,” he said at the time.
In October 2013, the FDA approved the MitraClip Clip Delivery System for a narrower group of patients: those with a particular type of mitral regurgitation who were considered a surgery risk.
“The reality is, there is no perfect procedure,” said Jason Rogers, an interventional cardiologist and University of California-Davis professor who is an Abbott consultant. The company referred KFF Health News to Rogers as an authority on MitraClip. He called MitraClip “extremely safe” and said some patients treated with it are “on death’s door to begin with.”
“At least you’re trying to do something for them,” he said.
Conflicting Studies
In 2019, the FDA expanded its approval of MitraClip to a wider set of patients.
The agency based that decision on a clinical trial in the United States and Canada that Abbott not only sponsored but also helped design and manage. It participated in site selection and data analysis, according to a September 2018 New England Journal of Medicine paper reporting the trial results. Some of the authors received consulting fees from Abbott, the paper disclosed.
A separate study in France reached a different conclusion. It found that, for some patients who fit the expanded profile, the device did not significantly reduce deaths or hospitalizations for heart failure over a year.
The French study, which appeared in the New England Journal of Medicine in August 2018, was funded by the government of France and Abbott. As with the North American study, some of the researchers disclosed they had received money from Abbott. However, the write-up in the journal said Abbott played no role in the design of the French trial, the selection of sites, or in data analysis.
Gregg Stone, one of the leaders of the North American study, said there were differences between patients enrolled in the two studies and how they were medicated. In addition, outcomes were better in the North American study in part because doctors in the U.S. and Canada had more MitraClip experience than their counterparts in France, Stone said.
Stone, a clinical trial specialist with a background in interventional cardiology, acknowledged skepticism toward studies sponsored by manufacturers.
“There are some people who say, ‘Oh, well, you know, these results may have been manipulated,’” he said. “But I can guarantee you that’s not the truth.”
‘Nationwide Scheme’
A former Abbott employee alleges in a lawsuit that after MitraClip won approval, the company promoted the device to doctors and hospitals using inducements such as free marketing support, the chance to participate in Abbott clinical trials, and payments for participating in “sham speaker programs.”
The former employee alleges that she was instructed to tell referring physicians that if they observed mitral regurgitation in their patients to “just send it” for a MitraClip procedure because “everything can be clipped.” She also alleges that, using a script, she was told to promote the device to hospital administrators based on financial advantages such as “growth opportunities through profitable procedures, ancillary tests, and referral streams.”
The inducements were part of a “nationwide scheme” of illegal kickbacks that defrauded government health insurance programs including Medicare and Medicaid, the lawsuit claims.
The company denied doing anything illegal and said in a court filing that “to help its groundbreaking therapy reach patients, Abbott needed to educate cardiologists and other healthcare providers.”
Those efforts are “not only routine, they are laudable — as physicians cannot use, or refer a patient to another doctor who can use, a device that they do not understand or in some cases even know about,” the company said in the filing.
Under federal law, the person who filed the suit can receive a share of any money the government recoups from Abbott. The suit was filed by a company associated with a former employee in Abbott’s Structural Heart Division, Lisa Knott. An attorney for the company declined to comment and said Knott had no comment.
Reports to the FDA
As doctors started using MitraClip, the FDA began receiving reports about malfunctions and cases in which the product might have caused or contributed to a death or an injury.
According to some reports, clips detached from valve flaps. Flaps became damaged. Procedures were aborted. Mitral leakage worsened. Doctors struggled to control the device. Clips became “entangled in chordae” — cord-like structures also known as heartstrings that connect the valve flaps to the heart muscle. Patients treated with MitraClip underwent corrective operations.
As of March 2024, the FDA had received more than 17,000 reports documenting more than 22,000 “events” involving mitral valve repair devices, FDA data shows. All but about 200 of those reports mention one iteration of MitraClip or another, a KFF Health News review of FDA data found.
Almost all the reports came from Abbott. The FDA requires manufacturers to submit reports when they learn of mishaps potentially related to their devices.
The reports are not proof that devices caused problems, and the same event might be reported multiple times. Other events may go unreported.
Despite the reports’ limitations, the FDA provides an analysis of them for the public on its website.
MitraClip’s risks weren’t a surprise.
Like the rapid-fire fine print in television ads for prescription drugs, the original product label for the device listed more than 60 types of potential complications.
Indeed, during clinical research on the device, about 6% of patients implanted with MitraClip died within 30 days, according to the label. Almost 1 in 4 — 23.6% – were dead within a year.
The FDA spokesperson, Harrison, pointed to a study originally published in 2021 in The Annals of Thoracic Surgery, based on a central registry of mitral valve procedures, that found lower rates of death after MitraClip went on the market.
“These data confirmed that the MitraClip device remains safe and effective in the real-world setting,” Harrison said.
But the study’s authors, several of whom disclosed financial or other connections to Abbott, said data was missing for more than a quarter of patients one year after the procedure.
A major measure of success would be the proportion of MitraClip patients who are alive “with an acceptable quality of life” a year after undergoing the procedure, the study said. Because such information was available for fewer than half of the living patients, “we have omitted those outcomes from this report,” the authors wrote.
If you’ve had an experience with MitraClip or another medical device and would like to tell KFF Health News about it, click here to share your story with us.
KFF Health News audience engagement producer Tarena Lofton contributed to this report.
KFF Health News is a national newsroom that produces in-depth journalism about health issues and is one of the core operating programs at KFF—an independent source of health policy research, polling, and journalism. Learn more about KFF.
Subscribe to KFF Health News’ free Morning Briefing.
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Should We Skip Shampoo?
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It’s Q&A Day at 10almonds!
Have a question or a request? We love to hear from you!
In cases where we’ve already covered something, we might link to what we wrote before, but will always be happy to revisit any of our topics again in the future too—there’s always more to say!
As ever: if the question/request can be answered briefly, we’ll do it here in our Q&A Thursday edition. If not, we’ll make a main feature of it shortly afterwards!
So, no question/request too big or small 😎
❝What’s the science on “no poo”? Is it really better for hair? There are so many mixed reports out there.❞
First, for any unfamiliar: this is not about constipation; rather, it is about skipping shampoo, and either:
- Using an alternative cleaning agent, such as vinegar and/or sodium bicarbonate
- Using nothing at all, just conditioner when wet and brushing when dry
Let’s examine why the trend became a thing: the thinking went “shampoo does not exist in nature, and most of our body is more or less self-cleaning; shampoos remove oils from hair, and the body has to produce more sebum to compensate, resulting in a rapid cycle of dry and greasy hair”.
Now let’s fact-check each of those:
- shampoo does not exist in nature: true (except in the sense that everything that exists can be argued to exist in nature, since nature encompasses everything—but the point is that shampoo is a purely artificial human invention)
- most of our body is more or less self-cleaning: true, but our hair is not, for the same reason our nails are not: they’re not really a living part of the overall organism that is our body, so much as a keratinous protrusion of neatly stacked and hardened dead cells from our body. Dead things are not self-cleaning.
- shampoos remove oils from hair: true; that is what they were invented for and they do it well
- the body has to produce more sebum to compensate, resulting in a rapid cycle of dry and greasy hair: false; or at least, there is no evidence for this.
Our hair’s natural oils are great at protecting it, and also great at getting dirt stuck in it. For the former reason we want the oil there; for the latter reason, we don’t.
So the trick becomes: how to remove the oil (and thus the dirt stuck in it) and then put clean oil back (but not too much, because we don’t want it greasy, just, shiny and not dry)?
The popular answer is: shampoo to clean the hair, conditioner to put an appropriate amount of oil* back.
*these days, mostly not actually oil, but rather silicon-based substitutes, that do the same job of protecting hair and keeping it shiny and not brittle, without attracting so much dirt. Remember also that silicon is inert and very body safe; its molecules are simply too large to be absorbed, which is why it gets used in hair products, some skin products, and lube.
See also: Water-based Lubricant vs Silicon-based Lubricant – Which is Healthier?
If you go “no poo”, then what will happen is either you dry your hair out much worse by using vinegar or (even worse) bicarbonate of soda, or you just have oil (and any dirt stuck in it) in your hair for the life of the hair. As in, each individual strand of hair has a lifespan, and when it falls out, the dirt will go with it. But until that day, it’s staying with you, oil and dirt and all.
If you use a conditioner after using those “more natural” harsh cleaners* that aren’t shampoo, then you’ll undo a lot of the damage done, and you’ll probably be fine.
*in fact, if you’re going to skip shampoo, then instead of vinegar or bicarbonate of soda, dish soap from your kitchen may actually do less damage, because at least it’s pH-balanced. However, please don’t use that either.
If you’re going to err one way or the other with regard to pH though, erring on the side of slightly acidic is much better than slightly alkaline.
More on pH: Journal of Trichology | The Shampoo pH can Affect the Hair: Myth or Reality?
If you use nothing, then brushing a lot will mitigate some of the accumulation of dirt, but honestly, it’s never going to be clean until you clean it.
Our recommendation
When your hair seems dirty, and not before, wash it with a simple shampoo (most have far too many unnecessary ingredients; it just needs a simple detergent, and the rest is basically for marketing; to make it foam completely unnecessarily but people like foam, to make it thicker so it feels more substantial, to make it smell nice, to make it a color that gives us confidence it has ingredients in it, etc).
Then, after rinsing, enjoy a nice conditioner. Again there are usually a lot of unnecessary ingredients, but an argument can be made this time for some being more relevant as unlike with the shampoo, many ingredients are going to remain on your hair after rinsing.
Between washes, if you have long hair, consider putting some hair-friendly oil (such as argan oil or coconut oil) on the tips daily, to avoid split ends.
And if you have tight curly hair, then this advice goes double for you, because it takes a lot longer for natural oils to get from your scalp to the ends of your hair. For those of us with straight hair, it pretty much zips straight on down there within a day or two; not so if you have beautiful 4C curls to take care of!
For more on taking care of hair gently, check out:
Gentler Hair Care Options, According To Science
Take care!
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Shoe Wear Patterns: What They Mean, Why It Matters, & How To Fix It
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.
If you look under your shoes, do you notice how the tread is worn more in some places than others? Specific patterns of shoe wear correspond to how our body applies force, weight, and rotational movement. This reveals how we move, and uneven wear can indicate problematic movement dynamics.
The clues in your shoes
Common shoe wear patterns include:
- Diagonal wear on the outside of the heel: caused by foot angle, leg position, and instability, leading to joint stress.
- Rotational wear at specific points: due to internal or external rotation, often originating from the hip, pelvis, or torso.
- Wear above the big toe: caused by excessive toe lifting, often associated with a “lighter” or kicking leg.
Fixing movement issues to prevent wear involves correcting posture, improving balance, and adjusting how the legs land during walking/running.
Key fixes include:
- Aligning the center of gravity properly to prevent leg overcompensation.
- Ensuring feet land under the hips and not far in front.
- Stabilizing the torso to avoid unnecessary rotation.
- Engaging the glutes effectively to reduce hip flexor dominance and improve leg mechanics.
- Maintaining even weight distribution on both legs to prevent excessive lifting or twisting.
Posture and walking mechanics are vital to reducing uneven wear, but meaningful, lasting change takes time and focused effort, to build new habits.
For more on all this plus visual demonstrations, enjoy:
Click Here If The Embedded Video Doesn’t Load Automatically!
Want to learn more?
You might also like to read:
Steps For Keeping Your Feet A Healthy Foundation
Take care!
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Take This Two-Minute Executive Dysfunction Test
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Roll For Initiative
Some of us struggle with executive dysfunction a lot; others, a little.
What Is Executive Dysfunction?
• Executive function is a broad group of mental skills that enable people to complete tasks and interact with others.
• Executive dysfunction can impair a person’s ability to organize and manage behavior
• Executive dysfunction is not a specific stand-alone diagnosis or condition.
• Instead, conditions such as depression and ADHD (amongst others) can affect a person’s executive function.
Take This Two-Minute Executive Dysfunction Test
How did you score? (8/16 here!)
Did you do it? (it honestly is really two minutes and is quite informative)
If not, here’s your cue to go back up and do it
For almost all of us, we sometimes find ourselves torn between several competing tasks, and end up doing… none of them.
For such times, compile yourself a “productivity buffet”, print it, and pin it above your desk or similar space.
What’s a productivity buffet?
It’s a numbered list of 6, 8, 10, 12 or 20 common tasks that pretty much always need doing (to at least some extent!). Doesn’t matter how important they are, just that they are frequently recurring tasks. For example:
- Tidy desk (including that drawer!)
- Reply to emails/messages
- Drink water
- Collect stray one-off to-dos into a list
- Stretch (or at least correct your posture!)
- Extend that Duolingo streak
- Read one chapter of a book
- Etc
Why 6, 8, 10, 12, or 20?
Because those are common denominations of polyhedral dice that are very cheap to buy!
Keep the relevant die to hand (perhaps in your pocket or on your desk), and when you know you should be doing something but can’t decide what exactly, roll the die and do the item corresponding to the number you roll.
And if you find yourself thinking “damn, I got 12, I wanted 7!” then go ahead and do item 7—the dice aren’t the boss of you, they’re just there to break the ice between you and your to-do list!
The Housekeeper In Your Pocket?
If you found the tidying tips (up top) helpful, but don’t like cleaning schedules because you just can’t stick to them, this one’s for you.
It’s easy to slip into just doing the same few easy tasks while neglecting others for far too long.
The answer? Outsource!
Not “get a cleaner” (though if you want to and can, great, go for it, this one won’t be for you after all), but rather, try this nifty little app that helps you keep on top of daily cleaning—which we all know is better than binge-cleaning every few months.
Sweepy keeps track of:
- What jobs there are that might need doing in each room (or type of room) in the house
- How often those jobs generally need doing
- How much of your energy (a finite resource, which it also takes into account!) those jobs will take
- How much energy you are prepared to spend per day (you can “lighter/heavier” days, or even “off-days”, too)
…and then it populates a small daily task list according to what needs cleaning and how much energy it’ll take.
For example, today Sweepy gives me (your trusty writer, hi! ) the tasks:
- Bathroom: clean sink (every 3 days, 1pt of energy)
- Dining room: clean and tidy table (every day, 1pt of energy)
- Bedroom: vacuum floor (every 7 days, 2pts of energy)
- Kitchen: clean coffee machine (every 30 days, 2pts of energy)
And that’s my 6pts of energy I’ve told Sweepy I’m happy to spend per day cleaning. There are “3 pts” tasks too—cleaning the oven, for example—but none came up today.
Importantly: it does not bother me about any other tasks today (even if something’s overdue), and I don’t have to worry my pretty head about it.
I don’t have to feel guilty for not doing other cleaning tasks; if they need doing, Sweepy will tell me tomorrow, and it will make sure I don’t get behind or leave anything neglected for too long.
Check it out (available for both iOS and Android)
PS: to premium or not to premium? We think the premium is worth it (unlocks some extra customization features) but the free version is sufficient to get your house in order, so don’t be afraid to give it a try first.
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Learn to Age Gracefully
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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 2020Cannabis-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 2017Interaction 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.Acute Cannabis Consumption And Motor Vehicle Collision Risk: Systematic Review of Observational Studies and Meta-Analysis
Mark Asbridge, Jill A. Hayden and Jennifer L. Cartwright. The BMJ, February 2012.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.
- CDC’s main marijuana page.
- CDC’s marijuana data and statistics.
- Marijuana Drug Facts from the National Institute on Drug Abuse.
- Health Effects of Marijuana from the CDC.
- Learn About Marijuana Risks from the Substance Abuse and Mental Health Services Administration.
- Marijuana and Lung Health from the American Lung Association.
- Substance Use Disorder 101 from the U.S. Department of Health & Human Services.
- What You Need To Know About Marijuana Use and Driving from the CDC.
- Does marijuana use affect driving? from the National Institute on Drug Abuse.
- Drug-Impaired Driving from the National Highway Traffic Safety Administration.
This article first appeared on The Journalist’s Resource and is republished here under a Creative Commons license.
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