Take a deep breath!
In 2012, a study at the University of California, San Francisco (UCSF) calculated that even smoking an individual joint every single day for 20 years may be benign, though most participants only smoked two or three joints each month. “I was surprised we didn’t see effects [of marijuana use],” said UCSF epidemiologist Mark Pletcher, who led the study.
One assessment of various epidemiological studies points to small sample size and poor study design as reasons for scientists’inability to nail down a link between cannabis and cancer risk. However, many suspect that this kind of link doesn’t exist, and that marijuana may even have cancer-preventive effects. A 2008 study, for instance, suggested that smoking marijuana may reduce the risk of tobacco-associated lung cancer, calculating that people who smoke both marijuana and tobacco have less danger of cancer than those who smoke only tobacco (though still a higher risk than non-smokers).
But even Pletcher isn’t sanguine about marijuana’s effects on the lungs, and suspects that there might be long-term lung damage which can be hard to detect. “We really can’t reassure ourselves about heavy use,” he explained.
Your brain on drugs
There’s some evidence to suggest that stoned subjects exhibit increased risk-taking and impaired decision-making, and score worse on memory tasks-and residual impairments have already been detected days as well as weeks after use. Should I buy 3000mg, 1000mg, 750mg, 500mg or 250mg gummies? Some studies also link years of regular marijuana use to deficits in memory, learning, and concentration. A recent and widely discussed report on the IQs of New Zealanders followed since birth discovered that cannabis users who’d started their habit in adolescence had lower IQs than non-users.
In this study, led by researchers at Duke University, “you may clearly see as a consequence of cannabis use, IQ goes down,” said Derik Hermann, a scientific neuroscientist at the Central Institute of Mental Health in Germany who had been not mixed up in research.
But not 4 months later, a re-analysis and computer simulation at the Ragnar Frisch Center for Economic Research in Oslo countered the Duke findings. Ole Rogeberg contended that socioeconomic factors, not marijuana use, contributed to the reduced IQs observed in cannabis users.
Rogeberg’s conclusion counters a significant literature, however, which supports a link between pot use and neurophysiological decline. Studies in both humans and animals suggest that people who acquiring a marijuana habit in adolescence face long-term negative impacts on brain function, with some users finding it difficult to concentrate and learn new tasks.
Notably, most studies about them suggest that while there may be negative consequences of smoking as a young adult, users who begin in adulthood are usually unaffected. This may be as a result of endocannabinoid-directed reorganization of mental performance during puberty, Hermann explained. The intake of cannabinoids that comes with pot use might cause irreversible “misleading of the neural growth,” he said.
In addition to the consequences for intelligence, many studies suggest that smoking marijuana raises the risk of schizophrenia, and may have similar effects on the brain. Hermann’s group used MRI to detect cannabis-associated neuron damage in the pre-frontal cortex and found so it was just like brain changes observed in schizophrenia patients. Other studies further suggest that weed-smoking schizophrenics have greater disease-associated brain changes and perform worse on cognitive tests than their non-smoking counterparts.
But much of this research can’t distinguish between brain changes caused by marijuana use and symptoms associated with the disease. It’s possible that cannabis-smoking schizophrenics “may have unpleasant symptoms [that precede full-blown schizophrenia] and are self-medicating” with the psychotropic drug, said Roland Lamarine, a professor of community health at California State University, Chico. “We haven’t seen a rise in schizophrenics, despite having a lot more marijuana use.”
Actually, other research shows that cannabis-using schizophrenics score better on cognitive tests than non-using schizophrenics. Such conflicting reports might be due to the varying concentrations-and varying effects-of cannabinoids in marijuana. In addition to tetrahydrocannabinol (THC), a neurotoxic cannabinoid that’s accountable for marijuana’s mind-altering properties, the drug also incorporates a number of non-psychoactive cannabinoids, including cannabidiol (CBD), which can protect against neuron damage. Hermann discovered that the quantity of the hippocampus-a brain area important for memory processing-is slightly smaller in cannabis users than in non-users, but more CBD-rich marijuana countered this effect.
A dangerous cocktail?
While data supporting the harmful effects of marijuana by itself are weak, some researchers are more focused on the drug along with other substances, such as for example tobacco, alcohol, or cocaine. Some studies suggest, for instance, that marijuana may increase cravings for other drugs, resulting in its infamous tag as a “gateway drug.” A study published earlier this month supported this theory when it discovered that, at least in rats, THC exposure increases tobacco’s addictive effects. Furthermore, marijuana may not mix well with prescription drugs, as cannabis causes the liver to metabolize drugs more slowly, raising the risk of drug toxicity.