While some marijuana users may not realize it, the genes that drive use and misuse are the same that contribute to excessive alcohol use. As marijuana is the most commonly used illicit drug in the United States, roughly eight to ten percent of users are considered to be dependent. According to a new study, the severity of symptoms increase with heavier use.
This study was recently summarized in a Science Daily release and published in the March 2010 issue of Alcoholism: Clinical & Experimental Research. The study highlights the similarities between marijuana use and that of alcohol use.
"Results from a large annual survey of high-school students show that in 2008, 41.8 percent of 12th graders reported having used marijuana," explained Carolyn E. Sartor, a research instructor at Washington University School of Medicine and corresponding author for the study. "Although many may have used the drug on only a few occasions, 5.4 percent of 12th graders reported using it daily within the preceding month."
According to Christian Hopfer, the active ingredient in marijuana is THC, which actually mimics natural cannabinoids that the brain produces. This cannabinoid system is considered to be critical for learning, memory, appetite and pain perception.
While most marijuana users will not develop an addiction to the drug, it is possible that one in 12 actually will. This is a growing concern as there is strong evidence that marijuana increases the risk of developing mental illnesses and can exacerbate pre-existing mental illnesses.
According to Sartor, study findings indicate that many of the same genetic factors that contribute to alcohol use also contribute to marijuana use. At the same time, alcohol dependence symptoms and cannabis dependence symptoms can be traced to some of the same genetic influences.
"In other words," said Hopfer, "the genetic influences on drug use are not specific to individual drugs, but seem to influence a general tendency to engage in drug use. This is important to note because there is a tendency to study drugs in isolation — alcohol, tobacco, marijuana, cocaine, etc. These findings add support to the notion of common mechanisms underlying all addictions."