A new study from the University of Edinburgh has provided early evidence that “Heavy cannabis use is associated with low bone mineral density, low BMI, high bone turnover, and an increased risk of fracture. Heavy cannabis use negatively impacts bone health both directly and indirectly through an effect on BMI.”
This is the first study to look at marijuana’s effects on bones, so it is too early to definitively define those effects. But this early study showed that heavy marijuana use accounted for about 5-6% change in bone density, and that heavy users were more than twice as likely to experience fractures as non-users.
The full article is available on the website of the Journal of the American Medical Association.
There is evidence that maternal marijuana use during pregnancy is associated with some delivery complications; babies being born with low birth-weights; and possibly a ventricular septal defect (a hole in a baby’s heart). There is also some research suggesting that marijuana use during pregnancy is related to abnormal early-childhood and adolescent behavior, and possibly even some cancers. Very early exposure to THC (prenatally or during breastfeeding) may negatively affect brain development, particularly the development of emotional responses. It also seems to be tied to children showing “gaps in problem-solving skills, memory, and the ability to remain attentive.”
A less commonly discussed topic is paternal use of marijuana during pregnancy. There is actually some evidence that “fathers’ marijuana use in the year prior to their children’s births is associated with an increased risk of [a rare but very malignant tumor] in their children.” It may also be correlated with an increased chance of Sudden Infant Death Syndrome.
Overall, the effects of marijuana use on fetuses and babies are unclear, and for this reason most physicians recommend that women avoid its use during pregnancy and breastfeeding. Second-hand marijuana smoke has also been shown to cause altered states of consciousness in infants and young children, which should be avoided particularly since safe limits for this are unknown.
The Psychology of Addictive Behaviors has published a new, contradictory update to a recent journal article that concluded marijuana was harmless. The newer article reports a review of the statistical methods used in the first piece and concludes that, in direct contradiction to the first study’s conclusion, there are 2.5 times as many incidences of psychotic disorders among marijuana users than among non-users.
For more detailed reading, see the full press release at the SAM website.
Many people feel that because marijuana is a plant, that it is “all natural” and good for them. But marijuana can have similar health consequences to tobacco, especially among those who use it regularly. Frequent marijuana users have been found to suffer from chronic bronchitis, coughing on most days, excess phlegm production, shortness of breath, wheezing, and chest sounds without a cold, according to one US study. Marijuana plants can also have mold and fungi on them, as well as remnants of any chemicals used to grow them, and it is possible for users to ingest up to 70 percent of these while smoking, creating increased risks of infection and poisoning. Marijuana, like tobacco, also carries tar, which is associated with lung cancer, though this link has not been definitively proven for marijuana users. Because marijuana smokers keep smoke in their lungs longer than tobacco smokers, their lungs actually face greater exposure to tars, chemicals, and contaminants. In addition, smoking marijuana compromises the overall resistance of the lungs to disease, increasing rates of infection. For a good summary of all the potential health hazards of marijuana, see this article from the National Institute of Drug Abuse.
There are conflicting studies about whether or not marijuana use can create physical changes in the brain or even lower people’s IQs. But even if there are no physical changes to the brain, most agree that there are noticeable changes in the behavior of those who use marijuana. Studies have found that those who began using marijuana during adolescence had lower IQs, and did not recover lost IQ points after discontinuing their marijuana use. For those who did not start until adulthood, no IQ points were lost.
But this does not mean there are no side effects; other studies have shown that marijuana has negative effects on attention, memory, and learning, and that these negative effects can last for days or weeks after use. Understandably, these effects are also especially problematic for students as they negatively impact the processing and retention of knowledge. In school, missing or not understanding even a few lessons can hurt a student’s overall performance since lessons are generally cumulative.
For those interested in reading about these effects in action, look at the links attached to the post on potential marijuana addiction. There are two stories there of people who realized they were dependent on marijuana and the tolls it was taking on their lives.
There has been a lot of discussion surrounding whether marijuana use contributes to or affects mental illness, particularly depression and anxiety. Most studies have shown that those who use marijuana, particularly beginning in adolescence, are more likely to suffer from depression and/or anxiety later on. Frequent use further raises this likelihood. Interestingly, those who suffer from depression and/or anxiety are not any more likely to use marijuana. Causality has not been definitively proven as to whether marijuana use causes depression and/or anxiety, but the relationship has been shown consistently.
Another related, possible consequence of marijuana use, especially for those who use marijuana often, is that it may damage the brain’s ability to process enjoyment. Studies have shown that people who use marijuana produce the same amount of dopamine (the brain chemical tied to pleasure and reward) as non-users, but that it does not create the same physical reaction for them that it does for non-users. And this lack of physical response indicates that marijuana users may have damaged the areas of their brains responsible for creating the feeling of enjoyment. Again, whether marijuana use causes the damage, or whether people use it to make up for existing damage, is unclear.
A chart on mental illness and drug use from SAHMSA.
Some contend that marijuana has become a growing cause of mental illness. In truth, this has not been proven and it is clear that not all people who use marijuana will become mentally ill. There is evidence that supports the idea that marijuana use in adolescents is tied to an increased likelihood of developing depression or psychotic disorders, particularly schizophrenia and bipolar disorder. Use by those with congenital predispositions or certain genes is also tied to development of these disorders; marijuana can exacerbate the disorders’ symptoms and possibly bring them out sooner. Frequent marijuana use among teenagers is believed to be especially problematic because their brains are not yet fully developed; it is also linked to poor school performance. Whether marijuana use contributes to mental illness or not, recent studies have shown that marijuana use in those with mental illness can exacerbate the problem especially by derailing treatment efforts.
For more detailed reading: