Have a deep breath!
In 2012, a study at the University of California, San Francisco (UCSF) calculated that even smoking an individual joint every day for 20 years could be benign, though most participants only smoked several 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 numerous 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. But some suspect that this type of link doesn’t exist, and that marijuana can even have cancer-preventive effects. A 2008 study, for example, suggested that smoking marijuana may reduce the danger of tobacco-associated lung cancer, calculating that individuals who smoke both marijuana and tobacco have a lower danger of cancer than people 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 may nevertheless 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. Can I mix CBD gummies and CBD oil? Some studies also link years of regular marijuana use to deficits in memory, learning, and concentration. A current and widely discussed report on the IQs of New Zealanders followed since birth unearthed 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 could clearly see as a consequence of cannabis use, IQ falls,” said Derik Hermann, a scientific neuroscientist at the Central Institute of Mental Health in Germany who was not active 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 observed in cannabis users.
Rogeberg’s conclusion counters a considerable literature, however, which supports a link between pot use and neurophysiological decline. Studies in both humans and animals suggest that individuals 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 on the subject suggest that while there may be negative consequences of smoking as a young adult, users who begin in adulthood are often unaffected. This may be because of endocannabinoid-directed reorganization of the mind during puberty, Hermann explained. The intake of cannabinoids that accompany pot use could cause irreversible “misleading of the neural growth,” he said.
In addition to the effects for intelligence, many studies suggest that smoking marijuana raises the danger of schizophrenia, and might 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 similar to 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 “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 an increase in schizophrenics, despite a lot more marijuana use.”
In reality, 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 is responsible for marijuana’s mind-altering properties, the drug also includes a variety of non-psychoactive cannabinoids, including cannabidiol (CBD), which can drive back neuron damage. Hermann unearthed 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 dangerous cocktail?
While data supporting the harmful aftereffects of marijuana alone are weak, some researchers are far more focused on the drug in conjunction with other substances, such as tobacco, alcohol, or cocaine. Some studies suggest, for example, 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 unearthed 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 danger of drug toxicity.