Heavy Marijuana Use Reduces Bone Density, Increases Risk of Fractures

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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.

Marijuana Use During Pregnancy And Breastfeeding

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.

Increasing numbers of children admitted to hospitals with marijuana exposure

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A new study shows that the number of children being admitted to hospitals with lung irritation who have been exposed to marijuana is increasing. At this point, 16 percent of children (about 1 in 6) admitted for bronchiolitis show signs of contact with THC, the psychoactive compound in marijuana. This number has gone up since recreational marijuana use became legal in Colorado in 2014. In addition to psychoactive properties, marijuana can contain carcinogens and other toxic chemicals, and most of these chemicals’ effects on children have not been tested.

Visit Science Daily for the full press release.



This issue is receiving increased attention, as seen in a recent article from the New York Times.   The piece discusses a new study from the Journal of the American Medical Association, which says that Colorado’s rate of pediatric exposures to marijuana has increased by more than 150% since the state began allowing the legal use of recreational marijuana in 2014.  Many of the affected children were accidentally exposed by ingesting marijuana-infused edible goods.  Kids are particularly at risk for accidental exposure because they cannot distinguish between these products and the harmless cookies, brownies, and candies they’re used to.  One researcher also commented that many marijuana edibles are packaged in bright colors that attract children’s attention.

A report (pictured above) from the Washington Poison Center shows similar occurrences in the state.  Like Colorado, Washington has also had an increase in calls to poison control centers due to marijuana exposure and poisoning, and again, many of those calls or for children.  Another similarity is that the biggest increase in the number of calls came after recreational use of marijuana was legalized.

Article Update Revises Previous Findings: Marijuana Not Harmless

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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.

Changes in the Brain and Decreases in IQ


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.

Lung Diseases and Infections


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.

Potential for Addiction

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Though it is uncommon, it is possible for people to become addicted to marijuana. The National Institute on Drug Abuse estimates that between nine and ten percent of marijuana users will become addicted. For those who begin regularly using marijuana as adolescents, it is around 17 percent, and for those who use the drug everyday, it is between 25 and 50 percent. As mentioned in another post, average THC levels in marijuana have been on the rise in recent years, further contributing to an increased likelihood of addiction, especially for those who use concentrated forms of marijuana.

Many still contend that it is only possible to be psychologically, not physically, addicted to marijuana. Even if that’s true, in the long run it can be harmful to one’s mind, body, and life; even a psychological dependence involves changes in the brain. In a recent Vice article, the author gives her personal account of realizing she was addicted to marijuana and the negative impacts it had on her. Another article, an op-ed from the LA Times, gives the personal account of the impact that marijuana had on the writer’s life, and of what she understands now that she has removed it from her life. Both writers realized that there was more to life than what they had and that it was marijuana that was preventing them from attaining those things. Whether it was only psychologically or not, they both dependened on marijuana just to make it through the day, and eliminating it improved their lives. Without it, they were more productive, and focused more on the people and goals they had been neglecting.

For further reading on potential addiction to marijuana:



Effects on Mental Illness

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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:



Depression and Anxiety


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.

Increasing DUIs


There has been great concern that with increases in the number of places that allow legal marijuana use, incidents of people driving while under the influence of marijuana would see a corresponding increase. A study in New Zealand found that people who frequently used marijuana, especially before driving, were more likely to be injured in car accidents than those who did not. Another study in France showed that, even controlling for accidents in which alcohol played a part, marijuana users were twice as likely to cause fatal accidents than non-users.

A newer study, done by the National Highway Traffic Safety Administration and released in February 2015, concluded that there is no definitive link between using marijuana and an increased chance of being in an auto accident. When the study controlled for demographic variables, its results showed that marijuana users had a probability of being in an accident equal to that of drivers who had not used alcohol or other drugs. Regardless, the study still concluded that marijuana users have an overall 25 percent higher likelihood of being in auto accidents than non-users.

Guidelines regarding what level of THC is considered a DUI vary by state, and traces of THC may stay in the body for days or weeks after use (especially for frequent users). So avoiding driving soon after marijuana use is still a good idea.