MARIJUANA AND THE HUMAN BRAIN by Jon Gettman High Times, March 1995


The next century will view the 1988 discovery of the THC receptor site in the brain as the pivotal event which led to the legalization of marijuana.

Before this discovery, no one knew for sure just how the psychoactive chemical in marijuana worked on the brain. Throughout the 1970s and 1980s, researchers made tremendous strides in understanding how the brain works, by using receptor sites as switches which respond to various chemicals by regulating brain and body functions.

The dominant fear about marijuana in the 20th century has been that its effects were somehow similar to the dangerously addictive effects of opiates such as morphine and heroin. Despite widespread decriminalization of marijuana in the United States in the 1970s, this concern has remained the basis for federal law and policies regarding the use and study of marijuana.

The legal manifestation of this fear is the continued classification of marijuana as a Schedule I drug, a category shared by heroin and other drugs that are banned from medical use because of their dangerous, addictive qualities. While only 11 states have formally decriminalized possession of small amounts of marijuana, 45 states distinguish between marijuana and other Schedule I drugs for law-enforcement and sentencing purposes.

Until the 1980s, technological limitations obstructed scientific understanding of the neuropharmacology of THC, of how the active ingredient in marijuana actually affects brain functions. Observations and conclusions about this subject, though based on some biological studies, were largely influenced by observations of behavior. This has allowed cultural prejudice to sustain the faith that marijuana is somehow related to heroin, and that research will eventually prove this hypothesis. Actually, the discovery of the THC receptor site and the subsequent research and observations it has inspired conclusively refute the hypothesis that marijuana is dope.

Many important brain functions which affect human behavior involve the neurotransmitter dopamine. Serious drugs of abuse, such as heroin and cocaine, interfere with the brain’s use of dopamine in manners that can seriously alter an individual’s behavior. A drug’s ability to affect the neural systems related to dopamine production has now become the defining characteristic of drugs with serious abuse potential.

According to the congressional Office of Technology Assessment, research over the last 10 years has proved that marijuana has no effect on dopamine-related brain systems – unless you are an inbred Lewis rat (see below), in which case abstention is recommended.

The discovery of a previously unknown system of cannabinoid neural transmitters is profound. While century-old questions, such as why marijuana is nontoxic, are finally being answered, new, fascinating questions are emerging – as in the case of all great discoveries. In the words of Israeli researcher Raphael Mechoulam, the man who first isolated the structure of THC, “Why do we have cannabinoid receptors?”

Mechoulam’s theory will resonate well with marijuana smokers in the United States. He observes that “Cannabis is used by man not for its actions on memory of movement or movement coordination, but for its actions on memory and emotions, “and asks, “Is it possible that the main task of cannabinoid receptors . . . (is) to modify our emotions, to serve as the links which transmit or transform or translate objective or subjective events into perceptions and emotions?” At a 1990 conference on cannabinoid research in Crete, Mechoulam concluded his remarks by saying, “Let us hope, however, that through better understanding of cannabis chemistry in the brain, we may also approach the chemistry of emotions.”


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