Take a deep breath!
In 2012, a study at the University of California, San Francisco (UCSF) calculated that even smoking a single joint every single day for 20 years could be benign, though most participants only smoked 2 or 3 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 varied 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. How many 3000mg gummies should I eat? However, many suspect that this kind of link doesn’t exist, and that marijuana might 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 folks who smoke both marijuana and tobacco have a lesser threat of cancer than those that 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 still be long-term lung damage that can be hard to detect. “We really can’t reassure ourselves about heavy use,” he explained.
Your brain on drugs
There is some evidence to declare that stoned subjects exhibit increased risk-taking and impaired decision-making, and score worse on memory tasks-and residual impairments have now been detected days or even weeks after use. 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 found 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 can clearly see as a consequence of cannabis use, IQ decreases,” said Derik Hermann, a scientific neuroscientist at the Central Institute of Mental Health in Germany who was simply not involved in the research.
Although 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 lower IQs seen in cannabis users.
Rogeberg’s conclusion counters a substantial literature, however, which supports a link between pot use and neurophysiological decline. Studies in both humans and animals suggest that folks 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 declare that while there could be negative consequences of smoking as a young adult, users who begin in adulthood are often unaffected. This may be due to endocannabinoid-directed reorganization of the mind during puberty, Hermann explained. The intake of cannabinoids that is included with pot use could cause irreversible “misleading of the neural growth,” he said.
Along with the results for intelligence, many studies declare 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 that it was much like brain changes seen in schizophrenia patients. Other studies further declare that weed-smoking schizophrenics have greater disease-associated brain changes and perform worse on cognitive tests than their non-smoking counterparts.
But much with this research can’t distinguish between brain changes caused by marijuana use and symptoms connected with the disease. It’s possible that cannabis-smoking schizophrenics “could 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 far more marijuana use.”
In fact, other research shows that cannabis-using schizophrenics score better on cognitive tests than non-using schizophrenics. Such conflicting reports may be as a result of varying concentrations-and varying effects-of cannabinoids in marijuana. Along with tetrahydrocannabinol (THC), a neurotoxic cannabinoid that’s responsible for marijuana’s mind-altering properties, the drug also contains a number of non-psychoactive cannabinoids, including cannabidiol (CBD), which can force away neuron damage. Hermann found that the amount 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 life-threatening cocktail?
While data supporting the harmful effects of marijuana on its own are weak, some researchers are more focused on the drug in conjunction with other substances, such as for instance tobacco, alcohol, or cocaine. Some studies suggest, for instance, that marijuana may increase cravings for other drugs, ultimately causing its infamous tag as a “gateway drug.” A study published earlier this month supported this theory when it found that, at the very 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.