Cannabis Use and Risk of Psychiatric Disorders Prospective Evidence From a US National Longitudinal Study

With many states beginning to legalize cannabis, whether medicinal or recreational, there has been an increase in interest as to what kind of consequences it might have.  This particular study wanted to test the psychiatry of those smoking cannabis–particularly if it would affect their tendencies to abuse other drugs afterwards.  They also attempted to evaluate whether smoking marijuana would cause mood disorders, like bipolar disorder or anxiety, as some studies have previously.

The study was conducted in two “waves.” One was held 2001-2002 and the second was held from 2004-2005 with the same participants to make it a longitudinal study.  The participants were screened for psychiatric disorders like depression, anxiety, substance abuse, etc. and assessed according to the DSM-IV.  This was done at the onset of the trial and again at the end.  34,653 participants were interviewed, and of those 1,279 used cannabis.

Those who were smoking cannabis at the time of Wave 1 were much more likely to struggle with mental health issues or substance abuse by the time of Wave 2.  However, after adjusting their data, the only firm conclusion they made was that smoking cannabis indeed increased the risk of abusing other substances like alcohol, nicotine, or other drugs.  They did not conclude that marijuana induced or worsened mental disorders.  They reasoned that maybe the mental health issues came first and the cannabis use was a result, making this relationship correlational but NOT causal.


Blanco C, Hasin DS, Wall MM, et al. Cannabis Use and Risk of Psychiatric Disorders-Prospective Evidence From a US National Longitudinal Study. JAMA Psychiatry. doi:10.1001/jamapsychiatry.2015.3229 (published 17 February 2016).

Metabolic Syndrome Among Marijuana Users in the United States: An Analysis of National Health and Nutrition Examination Survey Data

The National Institute of Health and Drug Abuse sponsored a research study the relationship between marijuana use and a person’s overall metabolism and health. Medical marijuana has been legalized and THC-based medications are used to decrease pain, inflammation, and control muscle spasms and epileptic seizures.

In this study, 20-59 year olds completed surveys from 2005-2010 and categorized their marijuana use as never used, past used (not within the last 30 days) or current use. The age groups were split and analyzed for metabolic syndrome. The research study defined metabolic syndrome as having 3 or more of the following diagnostic states: elevated fasting glucose, high triglycerides, low HDL, elevated hypertension, and increased waist circumference.

The results of the study showed that 13.8% of current marijuana users and 17.5% of past marijuana users presented metabolic syndrome. 19.5% of never users had the syndrome. Adults ages 20-30 who were current users were 54% less likely to present metabolic syndrome than adults in that same age range that never used marijuana. The study concluded that marijuana use was linked to lower odds of metabolic syndrome but there is no researched reason for these outcomes yet.

I thought this article was very interesting seeing that marijuana is slowly being legalized in more and more cities. Its important to note that thought this article seems to show benefits of marijuana use, there are definitely consequences of it also. I wonder if there is any way that the drug can be compounded differently to only exhibit the positive effects of it and not the CNS effects that coincide with marijuana use. Could this be a new preventative obesity pill in the future?


Am J Med. 2016;129(2):173-179.

Possible Association Between Marijuana Use and Cognitive Function

With the number of states considering and approving the use of medical marijuana as well as recreational use increasing, the possible negative long-term effects of using marijuana should also be brought to light. A recent article uncovered a study that followed research participants from 1986 to 2011 who documented their marijuana use periodically as well as their tobacco and other drug use and possible issues with depression. The study began with 5115 randomly selected black and white, male and female participants between 18 and 30 years old. On seven different occasions throughout the twenty-five years of the study, participants were asked how many days in the last month did they use marijuana. They were also asked at the beginning of the study how many times in their life they had used marijuana to gauge what their lifetime exposure to the drug was. Years using marijuana was then estimated based on the number of days in the last thirty that person reported used marijuana and using the scale that 365 days using marijuana is equal to one marijuana year.

3326 participants returned after the full twenty-five years for assessment regarding three cognitive outcomes. Although most of the participants had reported using marijuana throughout the years of the study, they had not accumulated many total marijuana use years. The study used standardized tests of verbal memory, processing speed, and executive function both at the start and end of the time period to determine if there was a significant difference both between their scores before and after and between scores of those with no marijuana exposure compared to a large amount of exposure.

A larger amount of lifetime exposure to marijuana was associated with lower verbal memory, with no significant differences based on race and sex. Current use was associated with both lower verbal memory and processing speed. Although their findings were significant, the researchers pointed out that the marijuana use was self-reported and more studies should be done in the future to solidify their evidence.

When you consider the huge potential benefits that some may receive by taking marijuana for medical purposes now, do you think this impairment in verbal memory in their future still makes it worth it?

Reference: Auer R, Vittinghoff E, Yaffe K, et al. Association between lifetime marijuana use and cognitive function in middle age: the coronary artery risk development in young adults study. Jama Intern Med. Published online February 1, 2016. Accessed February 6, 2016.