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.
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.
“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.
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.
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.”
A registry-based study on cannabis users in Denmark spanning 39 years found that young males were more than twice as likely to develop schizophrenia as young females. The researchers, who published their findings in Psychological Medicine, estimated that about 15% of schizophrenia in this population group is due to cannabis use.
Previous research suggests an increase in schizophrenia population attributable risk fraction (PARF) for cannabis use disorder (CUD). However, sex and age variations in CUD and schizophrenia suggest the importance of examining differences in PARFs in sex and age subgroups.
Moreover, cannabis potency measured by the percentage of delta-9-tetrahydrocannabinol (THC) (main psychoactive component of cannabis) has increased dramatically, eg from 13% in 2006 to 30% in 2016 in Denmark. CUD has also increased markedly – past-year CUD rose significantly from 4.9% in 2014 to 5.9% in 2018 among US 18–25-year-olds.
A growing body of evidence suggests that the relationship between CUD and schizophrenia may differ by sex. Male sex and early heavy or frequent cannabis use are associated with earlier onset of psychosis.
The researchers conducted a nationwide Danish register-based cohort study including all individuals aged 16–49 at some point during 1972–2021, identifying CUD and schizophrenia status.
The researchers examined 6 907 859 individuals, with 45 327 cases of incident schizophrenia during follow-up. Males had slightly higher risk for schizophrenia with CUD (142%) than females (102%). But among 16–20-year-olds, the risk for males (284%) was more than twice that for females (81%). They also found that during the 39-year study period, the annual average increase in PARF for CUD in schizophrenia incidence was 4.8% among males and 3.2% among females. In 2021, among males, this risk fraction was 15%; among females, it was around 4%.
The researchers concluded that “Young males might be particularly susceptible to the effects of cannabis on schizophrenia. At a population level, assuming causality, one-fifth of cases of schizophrenia among young males might be prevented by averting CUD. Results highlight the importance of early detection and treatment of CUD and policy decisions regarding cannabis use and access, particularly for 16–25-year-olds.”
With growing legalisation and recreational use of cannabis comes a change in attitudes. Research has shown that dispensaries often recommend cannabis for the easing of pregnancy symptoms, especially morning sickness.
Growing evidence links cannabinoid consumption during pregnancy with poor child outcomes, though the exact effects on the developing foetus remain unclear. In a study published in Frontiers in Pediatrics, researchers in the US have now examined how timing of cannabis exposure during pregnancy impacts foetal development.
“We show that even when marijuana use occurred only in the first trimester of pregnancy, birth weight was significant reduced, by more than 150g on average,” said senior author Dr Beth Bailey, professor and director of population health research at Central Michigan University. “If that use continued into the second trimester, newborn head circumference was significantly decreased as well.”
Continued exposure results in largest deficiencies
“These findings are important as newborn size is one of the strongest predictors of later child health and development,” added study first author Dr Phoebe Dodge.
Recent work, including the research by Dodge et al., has shown significant effects of cannabis use on newborn size. “Size deficits were largest among newborns exposed to marijuana throughout gestation,” Bailey explained. The babies born after continued in-utero exposure were nearly 200g lighter, and their head circumference was nearly 1cm less than that of babies who had not been exposed. Pregnancy cannabis use did not significantly predict newborn length in this study.
The effects the scientists observed have also shed light on patterns of use. Their study showed that occasional use, such as for first trimester morning sickness, may reduce fetal growth in the same way as continued use throughout pregnancy. The same is true for other use in early stages, including cases when someone uses cannabis not knowing they are pregnant.
Quitting before pregnancy is best recommendation
The authors pointed out that in their study they did not have information about how much or how often participants used cannabis. Their results were based on whether people did or did not use it at certain times in pregnancy. Therefore, the study could not establish if there was a connection between heavy use and more pronounced outcomes in newborn growth.
More studies are needed to determine whether timing or amount of use is most important when it comes to effects on newborn size, they wrote.
“The best recommendation is that women should be advised to quit marijuana use prior to becoming pregnant,” Dodge said. However, quitting as soon as possible after getting pregnant is the second-best option to avoid long term adverse health and developmental outcomes. “There are some benefits of quitting among those who begin pregnancy using marijuana,” she continued.
Analysis of US poison centre data has shown that suspected suicidal cannabis exposures have increased 17% annually, over a period of 12 years. According to the study published in the journal JAMA Network Open, more than 92%, involved other substances in addition to cannabis, and the data cannot show a direct causal link between cannabis and suicide attempts.
Still, the findings are cause for concern, the researchers said, especially since the increase was more pronounced among children and women during and after the pandemic.
“This study adds to already ample evidence that cannabis use, particularly by younger people, has significant implications for mental health,” said study co-author Tracy Klein, a WSU associate professor of nursing. “We don’t have evidence that cannabis alone was the primary driver of a suicide attempt, but we do know that cannabis can worsen certain mental health conditions and increase impulsivity.”
The researchers found 18,698 cases of intentional, suspected suicide cannabis exposures reported to U.S. poison centers from 2009 to 2021. Of these cases, 9.6% resulted in death or major outcomes such as permeant disability. The researchers noted that while more of these exposures involved younger people, severe consequences occurred more often among people 65 and older.
U.S. poison centers take calls 24-hours a day from households and healthcare facilities to provide toxicology expertise in suspected poisoning cases. They also investigate the causes, often following up with patients and doctors to determine if patients took substances intentionally or not.
It is well known that accidental cannabis poisonings have been increasing since many states legalized cannabis. Some policies can help prevent these unintentional cases, Klein said, such as packaging guidelines so edible cannabis products are not mistaken for candy.
Intentional cannabis poisonings, on the other hand, have not been well studied, which is one of the reasons the researchers undertook this analysis, and their findings point to the need for more mental health services.
“We have a significant shortage of mental health and primary care providers in the United States,” Klein said. “We know that mental health needs not only changed but became even more acute during the COVID-19 emergency. Cannabis is one part of that.”
Other research has shown that cannabis use is associated with depression and anxiety in youth and that it may interfere with brain development as well. Recent studies have also suggested a link between suicidal ideation and cannabis use in young people. Given this evidence, it is especially important to limit youth access to cannabis, said Janessa Graves, first author and a WSU nursing associate professor.
“Children and adolescents shouldn’t be able to purchase or access cannabis,” Graves said. “We also need to educate kids and parents around the risks of cannabis. I think many people just aren’t aware the impacts cannabis can have on brain development, and on behavioural and mental health, especially in adolescents and young adults.”
Far more children and adolescents could be using drugs than admitted to in surveys, according to a new US survey using hair analysis to test for actual drug intake. Published in the peer-reviewed journal American Journal of Drug and Alcohol Abuse, the study of nearly 1300 children aged 9–13 found that, in addition to the 10% self-reporting drug use, an additional 9% had used drugs as determined by hair analysis.
The paper suggests hair analysis far outweighs the accuracy of assessing drug use compared to survey alone, and experts recommend that future research should combine both methods.
“It’s vital that we understand the factors that lead to drug use in teenagers, so that we can design targeted health initiatives to prevent children from being exposed to drugs at a young age,” says study leader Natasha Wade, an assistant professor of psychology at the University of California, San Diego.
Adolescent substance use is a serious public health issue, with 5% of US 8th graders (ages 13–14) reporting cannabis use in the last year. The numbers are even higher for alcohol and nicotine use, with 26% of 8th graders admitting to drinking and 23% to smoking nicotine in the past year. These numbers are worrying, as substance use in adolescence is linked to negative life outcomes, but they may be even higher.
To find out a multidisciplinary team of experts, led by Dr Wade, asked 1390 children whether they had taken drugs in the last year. Hair samples were then also taken so that independent tests could confirm whether recent drug-taking had taken place.
Of the children who were asked if they had taken drugs, 10% agreed that they had. Hair analyses also showed that 10% of adolescents overall tested positive for at least one drug, with 6.1% testing positive for cannabinoids, 1.9% alcohol, 1.9% amphetamines, and 1.7% cocaine.
However, the children that self-reported drug-taking were not the same as those who tested positive through hair samples. In fact, of the 136 cases that self-reported any substance use and 145 whose hair samples were positive for any drug, matches were found for only 23 cases.
Most importantly, hair drug analysis revealed an additional 9% of substance use cases over and above self-report alone, nearly doubling the number of identified substance users to 19%.
“A long-standing issue in substance use research, particularly that relating to children and adolescents, is a reliance on self-reporting despite the known limitations to the methodology. When asked, children may mis-report (unintentionally or intentionally) and say they take drugs when they don’t, or conversely deny taking drugs when they actually do,” Dr Wade adds.
“But rather than scrapping self-reporting of drug use altogether, a more accurate picture of teenage substance use can be gained by measuring both.
“Self-reporting has its own strengths, for instance young people may be more willing to disclose substance use at a low level, but are less likely to when frequent drug-taking patterns emerge.
“Conversely, hair assays are not sensitive enough to detect only one standard drink of alcohol or smoking one cannabis joint. Instead, the method is better at detecting frequent and moderate to heavy drug use.
“Combining both methodologies is therefore vital to accurately determine the levels of substance use in the teenage population.”
Commenting on the findings of their paper, the authors also add however, that it is important to note that there is a chance that some, perhaps even many, of these youth are unaware that they even used a substance, as it could have been given to them by a parent or peer or they may have simply forgotten they had used it.
The decriminalisation of cannabis for private use does not include the workplace, a Johannesburg Labour Court judge has ruled.
Judge Connie Prinsloo, in a recent ruling, said submissions by the National Union of Metalworkers of South Africa (NUMSA) that the Constitutional Court had ruled that cannabis was no longer a “drug” but just a “plant or a herb” were wrong.
She said the Concourt “Prince” judgment in 2018 did not offer any protection to employees against disciplinary action should they contravene company policies or disciplinary codes.
She said the apex court had not said cannabis was no longer a drug, as the union had argued, but had merely allowed for its personal consumption, in private, by adults.
The case before Judge Prinsloo was a review of the dismissal of two PFG Building Glass employees in October 2020 who had tested positive for cannabis while on duty. The National Bargaining Council for the Chemical Industry had found their dismissal to be fair. The union said it was unfair since cannabis was not a drug according to the Constitutional Court.
The company, through its witnesses, presented evidence that being under the influence of alcohol or drugs within the workplace was an offence for which dismissal was the prescribed sanction for the first offence.
This was because the company took workplace safety very seriously and it had a moral and legal duty to ensure that the working environment was safe.
On site, there was gas, large forklifts, extremely hot processes and dangerous chemicals used to make heavy glass which could potentially cut or crush someone.
The company followed the Occupational Health and Safety Act and had a zero-tolerance policy towards alcohol and drugs.
Referring to evidence at the bargaining council, Judge Prinsloo said it had been suggested by the employees that the company was “sticking to the old stigmatisation” of cannabis, whereas the Constitutional Court, in the Prince judgment, had said it was “just a plant … a herb” and could be legally possessed and used.
Company representatives, however, said it was still recognised as a drug and an employee was not permitted to be on site under the influence of alcohol or drugs.
One of the dismissed employees, Mr Nhlabathi, testified that he had used cannabis three days before he reported to work on the day he tested positive. He said he had been employed since 2016 and had “been smoking dagga and doing his job properly”. He disputed that the alcohol and drug policy related to cannabis but only to “alcohol and substances”.
His colleague, Mr Mthimkhulu, also relied on the Constitutional Court judgment that “dagga was a herb and not a substance”. Both claimed they were not aware that they could be fired for testing positive for cannabis.
Judge Prinsloo said the arbitrator had accepted that the company had a zero tolerance policy and that it treated cannabis as a drug because it was a “mind altering substance”.
The arbitrator had said the Prince judgment did not overrule the provisions of the Occupational Safety Act.
Judge Prinsloo said it was evident that the union and the employees had confused issues relating to the decriminalisation of the use of cannabis in private and the rights of employers to take disciplinary action against an employee who contravened a disciplinary code.
The Prince judgment declared specific provisions of the Drugs and Trafficking Act to be inconsistent with the right to privacy and therefore invalid to the extent that they made the use or possession of cannabis in private, by an adult person, a criminal offence.
The Constitutional Court had held, however, that it was common cause that cannabis was a harmful drug.
“The court did not interfere with the definition of a drug, nor did it declare dagga to be a plant or a herb,” Judge Prinsloo said.
“The applicant’s understanding of the judgment was either very limited or totally wrong,” she said.
The company was entitled to set its own standards of conduct and dismissal was an appropriate sanction, she said, dismissing the review.
Airway inflammation and emphysema are more common in marijuana smokers than cigarette smokers, according to a study published in Radiology. Researchers said the difference may be due to the way that marijuana is smoked, which is usually inhaled more deeply and without a filter.
Marijuana is one of the most widely used psychoactive substances in the world and the most-commonly smoked substance after tobacco. Its use has increased in recent years amid legalisation of recreational marijuana in many countries. The growing use has created an urgent need for information on marijuana’s effects on the lungs, something that is currently lacking.
“We know what cigarettes do to the lungs,” said study author Giselle Revah, MD, a cardiothoracic radiologist and assistant professor at the University of Ottawa. “There are well researched and established findings of cigarette smoking on the lungs. Marijuana we know very little about.”
To find out more, Dr Revah and colleagues compared chest CT results from 56 marijuana smokers with those of 57 non-smoking controls and 33 tobacco-only smokers.
Lack of filtering partly to blame
Three-quarters of the marijuana smokers had emphysema, a lung disease that causes difficulty with breathing, compared with 67% of the tobacco-only smokers. Only 5% of the non-smokers had emphysema. Paraseptal emphysema, which damages the tiny ducts that connect to the air sacs in the lungs, was the predominant emphysema subtype in marijuana smokers compared to the tobacco-only group.
Airway inflammation was also more common in marijuana smokers than non-smokers and tobacco-only smokers, as was gynecomastia, enlarged male breast tissue due to a hormone imbalance. Gynecomastia was found in 38% of the marijuana smokers, compared with 11% of the tobacco-only smokers and 16% of the controls.
The researchers found similar results among age-matched subgroups, where the rates of emphysema and airway inflammation were again higher in the marijuana smokers than the tobacco-only smokers.
There was no difference in coronary artery calcification between age-matched marijuana and tobacco-only groups.
Dr. Revah said the results were surprising, especially considering that the patients in the tobacco-only group had an extensive smoking history.
“The fact that our marijuana smokers – some of whom also smoked tobacco – had additional findings of airway inflammation/chronic bronchitis suggests that marijuana has additional synergistic effects on the lungs above tobacco,” she said. “In addition, our results were still significant when we compared the non-age-matched groups, including younger patients who smoked marijuana and who presumably had less lifetime exposure to cigarette smoke.”
The reasons for the differences between the two groups is likely due to several factors. Marijuana is smoked unfiltered, Dr Revah noted, while tobacco cigarettes are usually filtered. This results in more particulates reaching the airways from smoking marijuana.
In addition, marijuana is inhaled with a longer breath hold and puff volume than tobacco smoke.
“It has been suggested that smoking a marijuana joint deposits four times more particulates in the lung than an average tobacco cigarette,” Dr Revah said. “These particulates are likely airway irritants.”
The higher incidence of emphysema may also be due to the way that marijuana is smoked. Full inhalation with a sustained Valsalva manoeuvre, an attempt at exhalation against a closed airway, may lead to trauma and peripheral airspace changes.
More research is needed, Dr Revah said, with larger groups of people and more data on how much and how often people are smoking. Future research could also look at the impact of different inhalation techniques, such as through a bong, a joint or a pipe.
“It would be interesting to see if the inhalation method makes a difference,” Dr Revah said.