One of the go-to arguments of those who oppose the legalization of marijuana is the assertion that it is an addictive substance. In this post, we explain biological elements of this perspective and evaluate its real world applications, in hopes of refuting its claims. In order to understand marijuana’s potential for addiction, it is important to review its biological effects. According to the Drug Enforcement Administration (DEA), THC, the active ingredient in marijuana, binds to cannabinoid receptors (particularly CB1 receptors) in the brain. Because THC is a partial agonist, a chemical that binds to some receptor of a cell and triggers a response by that cell, it does not activate receptors to their full capacity.
What most don’t realize, is that there is a significant amount of interaction between the cannabinoid receptor system and the same receptor systems as opiates (i.e. heroin, morphine, oxycotin, etc.). Opiod receptors activate the dopamine reward pathway, a mechanism that functions as the substructure to many of the addictive properties of drug abuse. Yet, without the activation of the CB1 receptors, it has been found that opiates, alcohol, nicotine, and stimulants (like methamphetamine) lose some of their rewarding properties.
This essentially means that drug rewards depend upon the receptor system as well; and since this is the main target for THC, we can discern that the same implications apply to marijuana. Therefore, because there are similarities between the targets of THC and the addictive ingredients of many other drugs, marijuana’s classification as an addictive substance is not entirely unrealistic.
However, Science magazine states that “anything pleasurable activates this [previously discussed dopamine reward pathway] reward system” and no extraordinary “affinity between marijuana and opiates” has been demonstrated (1997). This is not to say that no real correlation exists, but more so suggests that a wide variety of enjoyable substances, food for example, would illicit the same type of reaction from dopamine neurons.
It is also important to note that withdrawal from marijuana typically consists of flu-like symptoms; including irritability, anxiety, insomnia, nausea, a loss of appetite, and sweating (Gruber & Pope). Since most individuals are able to prevail over these relatively mild withdrawal symptoms without much difficulty, only about 9% of marijuana users will develop a serious addiction; while 15% of alcohol consumers and 32% of tobacco smokers exhibit symptoms of drug dependence (Concepts of Chemical Dependency, Doweiko).
Given then, that biological research on the addictive effects of marijuana is still largely inconclusive, and the withdrawal symptoms resulting from regular marijuana use are easily surmountable; the criminalization of marijuana on the basis that it is an addictive drug is invalid, and must come to an end.