Perhaps some of us have had an experience similar to this: A patient with complex medical problems on multiple medications tells you that of all the "medications" he or she takes, cannabis (which you are not prescribing) works the best ... for everything.
I live in a state that does not allow for the use of medical or recreational cannabis, and this happens to me. I can only imagine how frequently this happens to practitioners in states that allow it.
Cannabis (or marijuana) is composed of almost 90 cannabinoids. The psychoactive cannabinoid (tetrahydrocannabinol or THC) is associated with fewer therapeutic possibilities than other constituents, such as cannabidiol (CBD). But we don’t know very much about it. Part of the problem is that it is a schedule I drug, which means that we cannot easily study it.
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Despite increasing popularity, medical marijuana is still associated with a number of harmful side effects.
According to recently released data from the 2012 National Survey on Drug Use and Health (NSDUH), cannabis use continues to increase among U.S. individuals aged 12 years and older. An estimated 31.5 million residents reported using cannabis in the past year, compared to approximately 25 million each year from 2002 to 2008.
The legalization of cannabis should be a sociopolitical debate, not a medico-scientific one. The science is clear. Cannabis is a drug ... and not a clean one. And it’s associated with important and significant central nervous system effects, especially in young adults.
Unfortunately, controversy about long-term adverse effects of cannabis still exists despite outstanding data such as that published by Meier and colleagues. Data were collected from a prospective cohort of 1,037 individuals followed from birth (in the years 1972 and 1973) to age 38 years. Thorough neuropsychological testing was done twice: once at 13 years of age before the start of cannabis use and again at 38 years of age after people tend to have developed persistent cannabis use (PNAS 2012;109:E2657-E2664).
The investigators found that persistent use of cannabis was associated with significant declines in neuropsychological function, and the greatest impairments were in the domains of executive functioning and processing speed. Interestingly, deficits could be perceived by social contacts who were asked to report on distractibility and memory problems. As expected, deficits were greatest for persistent users. Of greatest concern, stopping cannabis use did not clearly restore cognitive skills.
Neurophysiological research tells us that the brain continues to develop to 25 years of age. This study supports a neurotoxic effect of cannabis during this critical period of development.
My patient was older than the cohort in this study, and this study does not inform us about the impact of cannabis on older brains. While addressing my patient’s possible drug dependency, I will also work on my other treatments so she may be less likely to resort to an illegal drug to alleviate her symptoms.
Dr. Ebbert is professor of medicine, a general internist, and a diplomate of the American Board of Addiction Medicine who works at the Mayo Clinic in Rochester, Minn. The opinions expressed are those of the author.