Tag: cannabis use

Cannabis Use in Adolescence has Visible Effects on Brain Structure

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Cannabis use may lead to thinning of the cerebral cortex in adolescents according to a recent study.  The study demonstrates that THC – or tetrahydrocannabinol, an active substance in cannabis – causes shrinkage of the dendritic arborisation, neurons’ “network of antennae” whose role is critical for communication between neurons. This results in the atrophy of certain regions of the cerebral cortex – bad news at an age when the brain is maturing.  

The study, led by Graciela Pineyro and Tomas Paus, involved researchers at CHU Sainte-Justine and professors at the Université de Montréal Faculty of Medicine, was published in The Journal of Neuroscience.

“If we take the analogy of the brain as a computer, the neurons would be the central processor, receiving all information via the synapses through the dendritic network,” explains Tomas Paus, who is also a professor of psychiatry and neuroscience at Université de Montréal. “So a decrease in the data input to the central processor by dendrites makes it harder for the brain to learn new things, interact with people, cope with new situations, etc. In other words, it makes the brain more vulnerable to everything that can happen in a young person’s life.”

A multi-level approach to better understand the effect on humans

This project is notable for the complementary, multi-level nature of the methods used. “By analysing magnetic resonance imaging (MRI) scans of the brains of a cohort of teenagers, we had already shown that young people who used cannabis before the age of 16 had a thinner cerebral cortex,” explains Tomas Paus. “However, this research method doesn’t allow us to draw any conclusions about causality, or to really understand THC’s effect on the brain cells.”  

Given the limitations of MRI, the introduction of the mouse model by Graciela Pineyro’s team was key. “The model made it possible to demonstrate that THC modifies the expression of certain genes affecting the structure and function of synapses and dendrites,” explains Graciela Pineyro, who is also a professor in the Department of Pharmacology and Physiology at Université de Montréal. “The result is atrophy of the dendritic arborescence that could contribute to the thinning observed in certain regions of the cortex.”  

Interestingly, these genes were also found in humans, particularly in the thinner cortical regions of the cohort adolescents who experimented with cannabis. By combining their distinct research methods, the two teams were thus able to determine with a high degree of certainty that the genes targeted by THC in the mouse model were also associated to the cortical thinning observed in adolescents. 

With cannabis use on the rise among North American youth, and commercial cannabis products containing increasing concentrations of THC, it’s imperative that we improve our understanding of how this substance affects brain maturation and cognition. This successful collaborative study, involving cutting-edge techniques in cellular and molecular biology, imaging and bioinformatics analysis, is a step in the right direction for the development of effective public health measures.

Source: University of Montreal

Contrary to Some Expectations, Cannabis Use Increases COVID Severity

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At the start of the COVID pandemic in 2020, scientists quickly recognised that a handful of characteristics, including age, smoking history, high body mass index (BMI) and the presence of other diseases such as diabetes, increased the risk of severe disease and death. But one suggested risk factor remains unconfirmed more than four years later: cannabis use. Evidence has emerged over time indicating both protective and harmful effects.

Now, a new study by researchers at Washington University School of Medicine in St. Louis points decisively to the latter: Cannabis is linked to an increased risk of serious illness for those with COVID.

The study, published in JAMA Network Open, analysed the health records of 72 501 people seen for COVID at Midwestern US health centres during the first two years of the pandemic. The researchers found that people who reported using any form of cannabis at least once in the year before developing COVID were significantly more likely to need hospitalisation and intensive care than were people with no such history. This elevated risk of severe illness was on par with that from smoking.

“There’s this sense among the public that cannabis is safe to use, that it’s not as bad for your health as smoking or drinking, that it may even be good for you,” said senior author Li-Shiun Chen, MD, DSc, a professor of psychiatry. “I think that’s because there hasn’t been as much research on the health effects of cannabis as compared to tobacco or alcohol. What we found is that cannabis use is not harmless in the context of COVID. People who reported yes to current cannabis use, at any frequency, were more likely to require hospitalisation and intensive care than those who did not use cannabis.”

Cannabis use was different than tobacco smoking in one key outcome measure: survival. While smokers were significantly more likely to die of COVID than nonsmokers, a finding that fits with numerous other studies, the same was not true of cannabis users, the study showed.

“The independent effect of cannabis is similar to the independent effect of tobacco regarding the risk of hospitalisation and intensive care,” Chen said. “For the risk of death, tobacco risk is clear but more evidence is needed for cannabis.”

The study analysed deidentified electronic health records of people who were seen for COVID at BJC HealthCare hospitals and clinics in Missouri and Illinois between Feb. 1, 2020, and Jan. 31, 2022. The records contained data on demographic characteristics such as sex, age and race; other medical conditions such as diabetes and heart disease; use of substances including tobacco, alcohol, cannabis and vaping; and outcomes of the illness: specifically, hospitalisation, intensive-care unit (ICU) admittance and survival.

COVID patients who reported that they had used cannabis in the previous year were 80% more likely to be hospitalised and 27% more likely to be admitted to the ICU than patients who had not used cannabis, after taking into account tobacco smoking, vaccination, other health conditions, date of diagnosis, and demographic factors. For comparison, tobacco smokers with COVID9 were 72% more likely to be hospitalized and 22% more likely to require intensive care than were nonsmokers, after adjusting for other factors.

These results contradict some other research suggesting that cannabis may help the body fight off viral diseases such as COVID.

“Most of the evidence suggesting that cannabis is good for you comes from studies in cells or animals,” Chen said. “The advantage of our study is that it is in people and uses real-world health-care data collected across multiple sites over an extended time period. All the outcomes were verified: hospitalisation, ICU stay, death. Using this data set, we were able to confirm the well-established effects of smoking, which suggests that the data are reliable.”

The study was not designed to answer the question of why cannabis use might make COVID worse. One possibility is that inhaling marijuana smoke injures delicate lung tissue and makes it more vulnerable to infection, in much the same way that tobacco smoke causes lung damage that puts people at risk of pneumonia, the researchers said. That isn’t to say that taking edibles would be safer than smoking joints. It is also possible that cannabis, which is known to suppress the immune system, undermines the body’s ability to fight off viral infections no matter how it is consumed, the researchers noted.

“We just don’t know whether edibles are safer,” said first author Nicholas Griffith, MD, a medical resident at Washington University. Griffith was a medical student at Washington University when he led the study. “People were asked a yes-or-no question: ‘Have you used cannabis in the past year?’ That gave us enough information to establish that if you use cannabis, your health-care journey will be different, but we can’t know how much cannabis you have to use, or whether it makes a difference whether you smoke it or eat edibles. Those are questions we’d really like the answers to. I hope this study opens the door to more research on the health effects of cannabis.”

Source: Washington University in St. Louis

Adolescent Behaviour Problems and In Utero Cannabis Exposure: A Biological Link

More evidence shows potential connection between cannabis exposure in womb and adolescent behavioural problems

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Scientists are trying to understand how cannabis may affect long-term neurodevelopment from in utero exposure. Previous work by Washington University in St. Louis researchers Sarah Paul and David Baranger in the Behavioral Research and Imaging Neurogenetics (BRAIN) lab led by Ryan Bogdan found associations between prenatal cannabis exposure and potential mental health conditions in childhood and adolescence, but potential biological mechanisms that could possibly explain this association were unclear.

In research published in Nature Mental Health this month, Bogdan, professor of psychological and brain sciences, and senior scientist Baranger outline some of those potential mechanisms, the intermediate biological steps that could play into how prenatal cannabis exposure leads to behavioural issues down the line.

“We see evidence that cannabis exposure may influence the developing brain, consistent with associations with mental health,” Baranger said.

Trying to draw out the long-term impacts of cannabis exposure during pregnancy is not a simple knot to untangle. There are many confounding factors that affect mental health and behavior.

For example, say someone was exposed in utero to cannabis and later develops attention deficit disorder as a teen – how do you differentiate that as an inherited trait or a trait influenced by environmental factors, versus a trait that cannabis exposure somehow contributed to early on in development? It is also possible that all three potentially could contribute to eventual psychopathology.

Another complication is the increasing prevalence of the drug, including among the pregnant population, where cannabis use has increased from 3% to 7% from 2002 to 2017.

Researchers have statistical methods to filter out some of those confounding factors that they used in the previous study, but now they can point to specific biological measurements that further signal a connection to cannabis exposure and adolescent behavioral problems.

Bogdan said that nothing can establish causation with certainty, “but we can look at the plausibility of causation and identifying biological correlates that are associated with exposure and these mental health outcomes suggests it’s plausible.”

Researchers have been using data on the children and their mothers from the Adolescent Brain and Cognitive Development (ABCD) Study, an ongoing research project that includes nearly 12 000 children across the country. As part of that study, they collected data about each mother’s substance use prior to the birth as well as the neuroimaging data of their offspring when they were between 9 and 10 and 11 and 12 years old. Some 370 children were exposed to cannabis prior to the mother’s knowledge of pregnancy, and 195 were exposed before and after learning of pregnancy.

The researchers looked at a variety of neuroimaging measurements that factor into brain development, including measures of brain thickness and surface area, as well as measures reflecting water diffusion in and outside of cells. The patterns found in the group exposed to cannabis are consistent with potential reductions in neuroinflammation.

“It’s possible what we’re seeing is an anti-inflammatory effect of cannabis, which is leading to differences in how the brain is being pruned during neurodevelopment,” Bogdan said.

Much has been touted about the anti-inflammatory effects of cannabis, but it’s not always good to reduce inflammation. It’s all about the timing: too much of a reduction of inflammation at the wrong time could affect how the brain is pruned and primed.

Another theory is that cannabis exposure leads to accelerated aging. But don’t expect to find the smoking gun of biological clues pinning mental health problems to early cannabis exposure.

It might not even be about cannabis effects on pruning but the post-combustion products from smoking cannabis that set off accelerated aging and the downstream cognitive effects, Bogdan said.

Or, it could all come down to sociological factors, he added.

Trying to find the one-to-one connection that proves that prenatal cannabis exposure has negative effects during the teenage years is a challenge and may not be possible with retrospective studies. Baranger notes that the major limitation of this data set is that it was retrospective; mothers reported what their cannabis use was 10 years ago, so he’s looking forward to new data from prospective, longitudinal studies that will offer more recent, accurate and detailed information about cannabis use in pregnancy.

“That will potentially give us more answers to these questions in the future,” Baranger said.

Baranger said these results reaffirm that if someone is thinking about using cannabis while pregnant, they should “talk to their doctor about their choices and what other options there might be.”

Source: Washington University in St. Louis

THC Lingers in Breastmilk with no Clear Peak or Decline

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The psychoactive component THC of cannabis showed up in breastmilk in a study published in the journal Breastfeeding Medicine. Unlike alcohol, when THC was detected in milk there was no consistent time when its concentration peaked and started to decline.

Importantly, the researchers discovered that the amount of THC they detected in milk was low – they estimated that infants received an average of 0.07mg of THC per day. For comparison, a common low-dose edible contains 2mg of THC. The research team stressed that it is unknown whether this amount has any impact on the infant.

“Breastfeeding parents need to be aware that if they use cannabis, their infants are likely consuming cannabinoids via the milk they produce, and we do not know whether this has any effect on the developing infant,” said Courtney Meehan, a WSU biological anthropologist who led the project and is the study’s corresponding author.

Since other research has shown that cannabis is one of the most widely used drugs during breastfeeding, the researchers aimed to uncover how long cannabinoids, like THC, persisted in breastmilk.

For this Washington State University-led study, the researchers analysed milk donated by 20 breastfeeding mothers who used cannabis. The participants, who all had infants younger than six months, provided detailed reports on their cannabis use. They collected milk after abstaining from using cannabis for at least 12 hours and then at regular intervals after use. All of this was done in their own homes, at a time of their choosing and with cannabis they purchased themselves.

The researchers then analyzed the milk for cannabinoids. They found that the milk produced by these women always had detectable amounts of THC, even when the mothers had abstained for 12 hours.

“Human milk has compounds called lipids, and cannabinoids are lipophilic, meaning they dissolve in those lipids. This may mean that cannabinoids like THC tend to accumulate in milk – and potentially in infants who drink it,” said Meehan.

The research also revealed that people had different peak THC concentrations in their milk. For participants who used cannabis only one time during the study, cannabinoids peaked approximately 30 minutes to 2.5 hours after use and then started to decline. For participants who used multiple times during the study, the majority showed a continual increase in concentrations across the day.

“There was such a range. If you’re trying to avoid breastfeeding when the concentration of THC peaks, you’re not going to know when THC is at its peak in the milk,” said lead author Elizabeth Holdsworth, who worked on this study while a WSU post-doctoral researcher and is now on the faculty of The Ohio State University.

A related qualitative study by the research team revealed that many breastfeeding moms are using cannabis for therapeutic purposes: for the management of anxiety, other mental health issues or chronic pain. The mothers often chose cannabis over using other medications because they felt it was safer.

“Our results suggest that mothers who use cannabis are being thoughtful in their decisions,” said co-author Shelley McGuire, a University of Idaho professor who studies maternal-infant nutrition. “These women were mindful about their choices. This is far from a random lifestyle choice.”

While in most cases, the women were using cannabis as alternative treatment for a variety of conditions, McGuire pointed out that there is no evidence yet whether it is safer or more harmful. In fact, scientists know almost nothing about how many commonly used drugs may impact breastfeeding babies, partly because women, especially those who are breastfeeding, have historically been left out of clinical trials on medicines.

“This is an area that needs substantial, rigorous research for moms to know what’s best,” McGuire said.

Some research has been done regarding alcohol with guidelines for new mothers to wait at least two hours after consuming alcohol before breastfeeding. Nothing similar has been developed for cannabis, which has been growing in popularity.

The collaborative research team is currently working to address some of that knowledge gap with further research on cannabis use in breastfeeding moms, holistic composition of the milk they produce and its effects on infant development.

Source: Washington State University

Cannabis Use Linked to Increase in Heart Attack and Stroke Risk

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An analysis of 430 000 adults in the U.S. found that using cannabis, most commonly through smoking, eating or vaporising it, was significantly associated with a higher risk of heart attack and stroke, even after controlling for tobacco use (combustible cigarettes and other tobacco products) and other cardiovascular risk factors, according to new research published today in the Journal of the American Heart Association.

Although cannabis, or marijuana, is illegal at the federal level, 24 states and Washington, D.C., have legalized the use of recreational cannabis. Additionally, the number of people in the U.S. who use cannabis has increased significantly in recent decades, according to the 2019 National Survey on Drug Use and Health from the Substance Abuse and Mental Health Services Administration of the U.S. Department of Health and Human Services.

The annual survey found that in 2019, 48.2 million people ages 12 or older reported using cannabis at least once, compared to 25.8 million people ages 12 or older in 2002, an increase to 17% from 11%.

“Despite common use, little is known about the risks of cannabis use and, in particular, the cardiovascular disease risks,” said lead study author Abra Jeffers, PhD, a data analyst at Massachusetts General Hospital in Boston. “The perceptions of the harmfulness of smoking cannabis are decreasing, and people have not considered cannabis use dangerous to their health. However, previous research suggested that cannabis could be associated with cardiovascular disease. In addition, smoking cannabis – the predominant method of use – may pose additional risks because particulate matter is inhaled.”

In this study, researchers reviewed survey data collected for 430 000 adults from 2016 through 2020 to examine the association between cannabis use and adverse cardiovascular outcomes including heart disease, heart attack and stroke. The survey data was collected through the Behavioral Risk Factor Surveillance System, a national, cross-sectional survey performed annually by the U.S. Centers for Disease Control and Prevention.

The researchers specifically investigated whether cannabis use was associated with adverse cardiovascular outcomes among the general adult population, among people who had never smoked tobacco or used e-cigarettes, and among younger adults (defined as men under age 55 and women under age 65) at risk for heart disease. They also factored in the number of days per month that people used cannabis.

The analyses of found:

  • Any cannabis use (smoked, eaten or vaporized) was independently associated with a higher number of adverse cardiovascular outcomes (coronary heart disease, myocardial infarction and stroke) and with more frequent use (more days per month), the odds of adverse outcomes were even higher. The results were similar after controlling for other cardiovascular risk factors, including tobacco and/or e-cigarette use, alcohol consumption, body mass index, Type 2 diabetes and physical activity.
  • Both daily and non-daily cannabis users had an increased risk of heart attack compared to non-users; daily cannabis users had 25% higher odds of heart attack compared to non-users.
  • The odds of stroke for daily cannabis users were 42% higher compared to non-users, with lower risk among those who used cannabis less than daily.
  • Among younger adults at risk for premature cardiovascular disease (defined as men younger than 55 years old and women younger than 65 years old) cannabis use was significantly associated with 36% higher combined odds of coronary heart disease, heart attack and stroke, regardless of whether or not they also used traditional tobacco products. A separate analysis of a smaller subgroup of these adults who had never smoked tobacco cigarettes or used nicotine e-cigarettes also found a significant association between cannabis use and an increase in the combined odds of coronary heart disease, heart attack and stroke.

“Our sample was large enough that we could investigate the association of cannabis use with cardiovascular outcomes among adults who had never used tobacco cigarettes or e-cigarettes,” Jeffers said. “Cannabis smoke is not all that different from tobacco smoke, except for the psychoactive drug: THC vs. nicotine. Our study shows that smoking cannabis has significant cardiovascular risk risks, just like smoking tobacco. This is particularly important because cannabis use is increasing, and conventional tobacco use is decreasing.”

Study background and details:

  • Survey participants were ages 18-74, with an average age of 45 years.
  • About half of the participants self-identified as female. 60.2% self-identified as white adults, 11.6 self-identified as Black adults, 19.3 self-identified as Hispanic adults and 8.9% self-identified as other.
  • Nearly 90% of adults did not use cannabis at all; 7% used it less than daily; and 4% were daily users. Among current cannabis users, 73.8% reported smoking as the most common form of cannabis consumption. More than 60% of total respondents had never used tobacco cigarettes; 28.6% of daily cannabis users had never used tobacco cigarettes; 44.6% of non-daily cannabis users had never used tobacco cigarettes and 63.9% of participants who did not use cannabis had never used tobacco cigarettes.

The study had several limitations, including that cardiovascular conditions and cannabis use were self-reported, making them potentially subject to recall bias (potential errors in memory); that the authors did not have health data measuring participants’ baseline lipid profile or blood pressure; and the study captured data for only a single point in time for the participants. The authors note that there is a need for prospective cohort studies to examine the association of cannabis use and cardiovascular outcomes while accounting for frequency of cannabis use.

“The findings of this study have very important implications for population health and should be a call to action for all practitioners, as this study adds to the growing literature that cannabis use and cardiovascular disease may be a potentially hazardous combination,” said Robert L. Page II, PharmD, MSPH, FAHA, chair of the volunteer writing group for the 2020 American Heart Association Scientific Statement: Medical Marijuana, Recreational Cannabis, and Cardiovascular Health. Page is professor of clinical pharmacy, medicine and physical medicine at the Skaggs School of Pharmacy and Pharmaceutical Sciences at the University of Colorado School of Medicine in Aurora, Colorado. Page was not involved in this study.

“In the overall population, the study findings are consistent with other studies indicating that daily cannabis use was associated with an increase in heart attack, stroke and the combined endpoint of coronary heart disease, heart attack and stroke,” he said. “As cannabis use continues to grow in legality and access across the U.S., practitioners and clinicians need to remember to assess cannabis use at each patient encounter in order to have a non-judgmental, shared decision conversation about potential cardiovascular risks and ways to reduce those risks.”

Source: American Heart Association

The Effect of Cannabis Use in Binge Eating Disorder

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New research published in the journal Experimental and Clinical Psychopharmacology examined how often people experiencing binge eating are also using cannabis recreationally, and whether patients who use cannabis experience more severe eating disorder symptoms or symptoms of struggling with mental health. The results indicated that many cannabis users with binge eating disorder feel a strong desire to use cannabis, as well as having greater risks for drinking problems.

Though much research has focused on the impact of cannabis on eating habits, less is known about the effects of cannabis use on individuals with a binge eating disorder. Binge eating is the experience of feeling out of control when eating or unable to stop eating. Cannabis may play a particular role in maintaining binge eating as research suggests cannabis can increase how pleasurable or rewarding people find high sugar or high fat foods.

The research from Drexel University’s Center for Weight, Eating and Lifestyle Science (WELL Center) found that more than 23% of the 165 study participants reported using cannabis in the past three months – either “once or twice” or “monthly.” These participants were individuals seeking treatment for binge eating and reported their cannabis and alcohol use as part of that process.

“Distinguishing the relationship between cannabis use, eating disorder severity and other psychiatric symptoms in binge eating patients is necessary for informing screening and clinical recommendations,” said lead author Megan Wilkinson, a doctoral student in Drexel’s College of Arts and Sciences.

While study participants who used cannabis reported “a strong desire or urge to use cannabis” and they also drank alcohol more frequently and reported more problems related to their alcohol use; the research team noted that participants with binge eating disorders who used cannabis did not have more severe eating disorder or depression symptoms.

“Both alcohol and cannabis can impact an individual’s appetite and mood. Our finding that patients with binge eating who use cannabis also drink more alcohol may suggest that these individuals are at a higher risk for binge eating, given the compounded effects on appetite and mood from these substances,” said Wilkinson. “Treatments for binge eating should explore how substance use affects hunger, mood, and eating for patients.”

Participants also completed surveys and interviews about their binge eating, other eating disorder symptoms and depression. The research team compared individuals who reported cannabis use to individuals who did not report cannabis use to see if there were statistically significant differences in their alcohol use, eating disorder symptoms, or depression symptoms.

The findings indicate that a notable subset of the participants with binge eating disorders use cannabis and experience strong desires or urges to use cannabis. Additionally, using cannabis appears to be related to drinking patterns and problems with drinking (eg, needing more alcohol to feel intoxicated, inability to control drinking) for patients with binge eating.

“We hope this research is helpful for clinicians treating patients with binge eating, as it can provide them with updated information about the prevalence of cannabis use in their patients,” said Wilkinson. “We recommend that clinicians screen for cannabis and alcohol use in all their patients and assess any potential problems the patient may be experiencing related to their substance use.”

Wilkinson also noted that updated research on cannabis use in patients with binge eating will be required regularly due to changing social norms and laws related to cannabis in the United States. Next, Wilkinson and her colleagues are planning to explore the ways that cannabis use may impact hunger and mood for patients with binge eating, and therefore potentially exacerbate their binge eating symptoms.

Source: Drexel University

Cannabis Users Found to Have Higher Levels of Empathy

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A study of regular cannabis users and non-users found that users tend to have a greater understanding of the emotions of others, based on psychological assessments. Brain imaging tests also revealed that cannabis users’ anterior cingulate – a region generally affected by cannabis use and related to empathy – had stronger connectivity with brain regions related to sensing the emotional states of others within one’s own body.

The study, published in the Journal of Neuroscience Research, included 85 regular cannabis users and 51 non-consumers who completed psychometric tests and a subset of 46 users and 34 nonusers who underwent functional magnetic resonance imaging exams.

“Although further research is needed, these results open an exciting new window for exploring the potential effects of cannabis in aiding treatments for conditions involving deficits in social interactions, such as sociopathy, social anxiety, and avoidant personality disorder, among others,” said co-author Víctor Olalde-Mathieu, PhD, of the Universidad Nacional Autónoma de México.

Source: Wiley

Cannabis Use in Pregnancy Linked to Adverse Birth Outcomes

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A meta-analysis of studies published over the past 40 years on cannabis use during pregnancy has found an association between foetal exposure to cannabis in the womb and preterm delivery, low birth weight and the need for neonatal intensive care admission (NICU). The study was published today in the journal Addiction

Previous research has indicated that THC, the main psychoactive component in cannabis, can cross the placenta to the foetus during pregnancy and bind to receptors in the foetal brain.

The meta-analysis examined the results of 57 studies around the world that included almost 13 million infants in total.  Based on either self-reports from pregnant women, or blood and saliva testing depending on the study, just over 100 000 infants were found to be exposed to cannabis in the womb. While none of the studies found a direct causal relationship between cannabis use during pregnancy and adverse birth outcomes, the combined results indicated that newborns exposed to cannabis during pregnancy were twice as likely to require NICU admission, twice as likely to have a low birth rate and one and a half times more likely to be born early.

While there has been little research on cannabis use during pregnancy since cannabis was legalised in Canada five years ago, an American study has indicated an increase in cannabis use during pregnancy in states where it has been legalised and the perceived risk of harm from cannabis has decreased. The study states that overall cannabis use in pregnancy has doubled in the past 20 years, with approximately 10% of pregnancies associated with cannabis exposure. Some studies indicated it was being used to alleviate symptoms of nausea, poor appetite, insomnia or anxiety during pregnancy.

Canada’s Lower Risk Cannabis Use Guidelines, developed by a nationwide team led by CAMH scientists, recommends cannabis abstinence during pregnancy.

“This research emphasizes the importance of healthcare providers making an effort to create a safe space talking to pregnant women and women planning to be pregnant about their cannabis use and their motivations for using it to educate them about the potential risks and empower them to make informed decisions for their child,” says lead author Maryam Sorkhou, a PHD student within the addictions division at CAMH as well as the University of Toronto. Ms Sorkhou is overseen at CAMH by Senior Scientist and paper co-author Dr Tony George.

Source: Centre for Addiction and Mental Health

High Levels of Metal In Blood and Urine of Exclusive Marijuana Users

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Researchers have detected significant levels of metals in the blood and urine among marijuana users, concluding that marijuana may be an important and under-recognised source of lead and cadmium exposure. This is among the first studies to report biomarker metal levels among marijuana users and most likely the largest study to date, that links self-reported marijuana use to internal measures of metal exposure, rather than just looking at metal levels in the cannabis plant. The results are published online in the journal Environmental Health Perspectives.

Measurements reported by participants for exclusive marijuana use compared to nonmarijuana-tobacco had significantly higher lead levels in blood (1.27ug/dL) and urine (1.21ug/g creatinine). 

“Because the cannabis plant is a known scavenger of metals, we had hypothesised that individuals who use marijuana will have higher metal biomarker levels compared to those who do not use,” said first author Katelyn McGraw, postdoctoral researcher. “Our results therefore indicate marijuana is a source of cadmium and lead exposure.”

The researchers, from Columbia University Mailman School of Public Health, combined data from the National Health and Nutrition Examination Survey for the years 2005-2018, a biannual programme of studies designed to assess the health and nutritional status of adults and children in the U.S.

McGraw and colleagues classified the 7254 survey participants by use: non-marijuana/non-tobacco, exclusive marijuana, exclusive tobacco, and dual marijuana and tobacco use. Five metals were measured in the blood and 16 in urine. 

The researchers used four NHANES variables to define exclusive marijuana and tobacco use: current cigarette smoking, serum cotinine levels, self-reported ever marijuana use, and recent marijuana use. Exclusive tobacco use was defined as individuals who either answered yes to ‘do you now smoke cigarettes, or if individuals had a serum cotinine level >10ng/mL.

The study found higher levels of cadmium (Cd) and lead (Pb) in blood and urine among participants reporting exclusive marijuana use compared to non-smokers. Cd and Pb levels were also higher in exclusive marijuana users who reported using marijuana within the last week. Cd biomarker levels were higher in those who smoked only marijuana than , either because of differences in frequency of use or differences in Cd levels in the tobacco and cannabis plants themselves. However, blood and urinary Pb levels among exclusive marijuana users and exclusive tobacco users were similar. Dual marijuana and tobacco users also had higher levels of Cd and Pb compared with non-smokers.

These observations marijuana use is an important and underrecognised source of Cd and Pb exposure independent of tobacco use, the researchers concluded.

Marijuana is the third most commonly used drug in the world behind tobacco and alcohol. As of 2022, 21 states and Washington D.C., covering more than 50 percent of the U.S. population, have legalised recreational use of marijuana; and medical marijuana is legal in 38 states and Washington D.C. However, because marijuana is still illegal at the federal level, regulation of contaminants in all cannabis-containing products remains piecemeal and there has been no guidance from federal regulatory agencies like the FDA or EPA. As of 2019, 48.2 million people, or 18% of Americans, report using marijuana at least once in the last year.

While 28 states regulate inorganic arsenic, cadmium, lead, and total mercury concentrations in marijuana products, regulation limits vary by metal and by state. 

“Going forward, research on cannabis use and cannabis contaminants, particularly metals, should be conducted to address public health concerns related to the growing number of cannabis users,” said Tiffany R. Sanchez, PhD, assistant professor of environmental health sciences at Columbia Public Health, and senior author.

Foetal Exposure to THC could Lead to Long-lasting Health Impacts

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Consuming THC (Delta-9-tetrahydrocannabinol) while pregnant could potentially affect development of the foetus and lead to life-long health impacts for offspring, according to a new study published in the journal Clinical Epigenetics.

THC is the main psychoactive ingredient in cannabis, which is growing in popularity and availability. The prevalence of cannabis use in pregnancy is also rapidly increasing, especially during the first trimester, when the foetus is most vulnerable to environmental exposures, to mitigate common symptoms like morning sickness. However, the potential effects of prenatal cannabis use on foetal development remain inconclusive, in part due to a lack of safety data. This study aimed to identify the potential long-term health impacts of THC use during pregnancy.

In a non-human primate model, Oregon Health & Science University researchers found that exposing a pregnant subject to THC altered placental and foetal epigenetics. Researchers also found that that these changes to gene regulation and expression are consistent with those seen with many common neurobehavioural conditions, including autism spectrum disorder.

“Cannabis is one of the most commonly used drugs and is widely available across the country, so there is a common perception that its completely safe to use,” said the study’s lead author Lyndsey Shorey-Kendrick, PhD, a computational biologist in the Division of Neurosciences at OHSU’s Oregon National Primate Research Center, or ONPRC. “The reality is that cannabis still carries many health risks for certain populations, including those who are pregnant. If we’re able to better understand the impacts, we can more effectively communicate the risks to patients and support safer habits during the vulnerable prenatal period.”

In a model using nonhuman primates, researchers administered THC in a daily edible and compared its effects to a group receiving a placebo. Specifically, researchers evaluated the epigenetic changes in several key areas that indicate healthy prenatal development: the placenta and foetal lung, brain and heart.

When looking at these areas, analyses showed that THC exposure altered the epigenome, meaning a process in which the information encoded in a gene is turned into a function or observable trait. Genes are all specifically coded to contribute to different functions of the body and brain, so any impact on epigenetic processes due to drug exposure is concerning, especially during a critical developmental window such as pregnancy.

Researchers found that significant changes involved genes associated with common neurobehavioral disorders, including autism spectrum disorder and attention deficit hyperactivity disorder. These conditions are linked to adverse health outcomes in childhood and adolescence, including poorer memory and verbal reasoning skills, and increased hyperactivity, impulsivity and inattention.

The research team hopes findings from this study will add to the limited existing literature on THC use during pregnancy, and help guide patient counselling and public health polices focused on cannabis in the future.

“It’s not common practice for providers to discuss cannabis use with patients who are pregnant or trying to conceive,” said the study’s corresponding author, Jamie Lo, MD, MCR, associate professor of obstetrics and gynaecology (maternal-foetal medicine) at OHSU. “I hope our work can help open up a broader dialogue about the risks of cannabis use in the preconception and prenatal period, so we can improve children’s health in the long run.”

Source: Oregon Health & Science University