Research team discovered that individuals who used cannabislong-term (for several years or more) and heavily (at least weekly, though a majority in their study used more than four times a week) exhibited impairments across several domains of cognition. Long-termcannabis users' IQs declined by 5.5 points on average from childhood, and there were deficits in learning and processing speed compared to people that did not usecannabis…The study also found that people who knew these long-term cannabis users well observed that they had developed memory and attention problems. The above findings persisted even when the study authors controlled for factors such as dependence on other drugs, childhood socioeconomic status, or baseline childhood intelligence.
When Kalpit Sharma started smoking cannabis, he thought it was just part of "living his life" as a university student. After all, he had been told that the drug was relatively harmless.
That all changed in the summer of 2021, when he started hearing voices in his head.
"I would bike around, and the chain of the bike, it came off. And I thought that I could speak to birds, and birds were telling me how to put the chain back on," said Sharma, who was studying at York University in Toronto at the time.
Those voices are known as auditory hallucinations — a hallmark of psychosis. When they became more frequent and insistent, he went to the Centre for Addiction and Mental Health for an assessment.
Sharma was shocked when he was told that he had been exhibiting signs of psychosis — and eventually he was diagnosed with schizophrenia.
In 2023, Myran co-authored two studies looking into the connection between cannabis and psychosis. They found a 220 per cent increase in emergency room visits in Ontario for cannabis-induced psychosis between 2014 and 2021 — with the number rising from about 400 people to about 1,400 over that seven-year period.
"For men aged 14 to 24, the risk of developing schizophrenia rises to over 40 per cent within three years" of showing up in an ER for cannabis-induced psychosis, he said.
Spend enough time at parties or clubs and you will probably hear this phrase used in instances of peer pressure to use marijuana. But what this reassurance does not convey is that cannabis is four times as potent today as it was just three decades ago.
The amount of Delta-9-tetrahydrocannabinol (commonly known as THC) in marijuana seized by the DEA has spiked from 3.4% in 1993 to 15.34% in 2021.
Higher THC levels in marijuana are linked to increased problems with memory and learning, distorted perception, difficulty in thinking and problem-solving, and loss of coordination. Higher THC also exacerbates the effects associated with regular use of cannabis, including physical dependence and withdrawal following discontinuation, as well as psychological addiction or dependence.
Even more disturbingly, all too often, people are unaware that marijuana, especially when it contains more THC, is a risk factor for psychosis and schizophrenia, as well as the fact that it stunts brain growth, sometimes includes lead and mercury, and can alter male sperm DNA linked to autism.
Development of an anxiety disorder following an emergency department visit due to cannabis use: a population-based cohort study
Interpretation: ED visits for cannabis use were associated with an increased risk of having an incident healthcare visit for an anxiety disorder, particularly in young males. These findings have important clinical and policy implications given the increasing use of cannabis over time and trend towards legalization of cannabis. (The Lancet)
Nearly a third of people who visited the emergency room for a cannabis-related concern developed a new anxiety disorder within three years, according to research released Monday.
The study—published today in The Lancet’s open access journal eClinical Medicine—is said to be the most comprehensive examination of the relationship between cannabis use and anxiety to date.
Canadian researchers examined the health records of more than 12 million people living in Ontario between 2008 and 2019 who had no record of an anxiety disorder, or of receiving treatment for one. Those who had an emergency room visit for cannabis use during that period were more than three times more likely to be diagnosed with a new anxiety disorder—at an outpatient visit, emergency room, or hospital—within three years, the study found. They were also nine times more likely to require another health care visit—an outpatient or ER visit, or a hospitalization—for an anxiety disorder down the road.
Young cannabis users—ages 10-24 and males, in particular—were at particularly elevated risk, researchers noted. (
Cannabis use has increased significantly in recent years, and it has some experts concerned.
By Irina Antonova 12/23/2023
The use of cannabis can lead to changes in DNA that can cause genetic mutations and subsequent serious diseases, according to a new study.
Cannabis—also known as marijuana—is one of the most commonly used drugs in the United States. Its use has increased significantly in recent years, with a recent survey showing 42.3 million people used it in the past month.
The increased use of marijuana has some experts concerned.
The Health Risks of Cannabis Use
The study, published in Molecular Psychiatry, analyzed data from about 9,500 participants from different groups, including parents and children, twins, and older adults.
Researchers assessed DNA methylation, an indicator of potential health outcomes due to how genes are expressed. The genome study analyses were evaluated according to the different genetic groups and adjusted according to age, gender, cigarette smoking, and blood type.
Researchers found that five genes with DNA methylation had sites associated with the use of cannabis, with significant roles in human health conditions. This included one gene (LINC01132) linked to liver cancer and ovarian cancer. A previous study, however, showed a lower incidence of liver cancer among cannabis users.
Researchers also found that chemicals in cannabis, including the active ingredient THC (tetrahydrocannabinol), alter the user’s DNA, which can cause gene mutations that can increase the risks of diseases.
Understanding DNA Methylation
DNA methylation is a fundamental epigenetic mechanism that regulates gene expression without altering the underlying DNA sequence.
Methylation patterns can be heritable and change over time in response to various environmental factors, including diet, lifestyle, and substance exposure.
Altered DNA methylation patterns have been associated with several diseases and conditions, including cancer, developmental disorders, and neurological conditions. Factors such as aging, environmental exposures, and certain medications can influence DNA methylation patterns, potentially impacting gene regulation and cellular functions.
How Does Cannabis Use Affect Future Generations?
The authors of a previous study, Gary Hulse and Albert Stuart Reece from the School of Psychiatry and Clinical Sciences at the University of Western Australia, point to the connection between the use of cannabis and the health risks associated with it and what this may mean for future generations.
The scientists are concerned that even when the user does not develop an illness from gene mutations associated with cannabis use, they can pass the mutation on to their children and grandchildren.
“Even if a mother has never used cannabis in her life, the mutations passed on by a father’s sperm can cause serious and fatal illnesses in their children,” Mr. Reece said in a University of Western Australia media statement on May 24, 2016.
“The parents may not realise that they are carrying these mutations, which can lie dormant and may only affect generations down the track, which is the most alarming aspect.”
Chemicals in cannabis can alter a user’s DNA, and this can slow down the growth of the cells. For a growing fetus, this could lead to underdeveloped limbs or organs or even cancer, the researchers theorize.
“The worst cancers are reported in the first few years of life in children exposed in utero to cannabis effects,” explained Mr. Reece in the press statement.
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