We were astounded to learn from a recent article in the American Journal of Psychiatry (AJP) about a dramatic increase in the number of persons who have registered to obtain medical marijuana in Colorado. 

Colorado approved the use of medical marijuana over a decade ago.  In January 2009, 5,051 people were registered to purchase medical marijuana.  Less than three years later (June 2011), the number with valid registration had jumped to 128,698.  This represents more than 2% of the total population of Colorado.  According to the Colorado Department of Public Health and Environment's website, 69% of registrants are male.  The average age is 40.  The most common condition listed to justify the use of medical marijuana is pain.   

Marijuana's most active ingredient, THC, stimulates specific brain receptors known as cannabinoid receptors.  This common receptor system was not created to respond to external marijuana; rather, the brain makes its own marijuana-like neurotransmitters (called endocannabinoids) that stimulate these receptors.  Thus, the brain has an internal system of neurotransmitters and receptors that marijuana usurps.  This system is involved in key bodily functions, including energy balance regulation (food intake, weight, etc.), pain regulation, mood systems, and motivational systems.

Not unlike alcohol, many people find the occasional use of marijuana to be relaxing and pleasurable and do not experience severe behavioral reactions.  However, just as with alcohol, some people become addicted to marijuana, and the use of this drug can have substantial behavioral consequences.  Contrary to popular belief and much like all other abused drugs including alcohol, regular marijuana use and abuse can have serious repercussions and adversely affect thinking, motivation, and emotion.

There is increasing evidence that the use of marijuana by young people is associated with an earlier onset of psychotic symptoms (hallucinations and delusions) in those genetically predisposed to psychotic illnesses.  Some data suggest that marijuana use may be associated with an increased risk of developing psychosis even in those who are not genetically predisposed to such illnesses.  Some reports indicate that early use of marijuana may also be associated with an increased risk of using more addictive drugs such as cocaine and heroin.

We, as a society, spend a great deal of money pursuing, prosecuting, treating, and incarcerating users and distributors of marijuana.  There is a substantial black market for the sale of this drug.

With all of this said, we were surprised by the large number of people in Colorado (over 2% of the population) who have convinced physicians that they have a medical condition that would benefit from marijuana.  It makes us wonder what percent of these people suffer from conditions that respond to marijuana such as severe nausea from chemotherapy or severe pain states.  We also are curious about how many of these people have milder pain states that marijuana may help.  Is marijuana being used instead of opiates for chronic pain states?  We wonder what percent of these people have little or no true clinical indication for marijuana, but instead have obtained permits so that they can purchase the drug for recreational use without fear of legal prosecution.  Finally, we wonder about the rationale of physicians who broadly prescribe this drug based on the limited data supporting its therapeutic uses and the drug's known abuse liability.  The substantial increase in use of medical marijuana appears to be time-linked to the decision by the federal government not to pursue people who are lawfully obtaining medical marijuana in states that have legalized its use.

The data from Colorado suggests that marijuana use is gradually being decriminalized.  This may be occurring via the political will of people who want to legalize the use of marijuana.  Whether good or bad, right or wrong, it seems that the medical profession may be the mechanism that is increasingly being used to make this drug commonly available.  It is unclear whether this is a good idea, and the long term consequences of this trend on society's health are yet to be determined. 

This column was written by Eugene Rubin MD, PhD and Charles Zorumski MD.

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