April 17, 2008

The Neuroscience of 420

Don’t be alarmed this coming Sunday if you notice a certain herbaceous aroma permeating campus. RELAX, because it’s simply a special day for some of our Knox contingent. That’s right, all those Birkenstock-wearing, grimy-faced, tie-dyeing, good-for-nothin’, recycling, NPR-listening, godless, community-gardening, dread-locked, Al-Gore-lovin’, nag-champa-stankin’, tofu-munchin’, hippie burnouts will be celebrating. Sunday, better known as “4/20,” is cannabis appreciation day, so we thought we’d provide some information about what goes on inside the heads of those planning to partake in the festivities for those who are curious.

Cannabis, a five- to seven-leaved highly-adaptable herb, has been smoked by humans for thousands of years for religious and recreational purposes. The best-known active compound in marijuana is the cannabinoid THC, though there are approximately 60-80 other known cannabinoids found in the plant. Common effects of using marijuana include euphoria, hunger, anxiety, production or relief, lethargy, and perceptual alterations. In fact, it was researchers in 1988 studying how these effects are produced who first identified a group of receptors in the nervous system that are activated by THC. The prevalence of these receptors (called CB receptors, or CBRs) in brain, fat, liver, intestinal, muscle, and bone tissues implicated the existence of a cannabinoid produced naturally within the body (an endocannabinoid). The search was on, and it wasn’t long before the first endocannabinoid, anandamide, was identified in 1992. These two discoveries sparked interest within the neuroscientific community and subsequent research uncovered a vast endocannabinoid system that has since been implicated in mediating aspects of pain, food intake, energy balance, and immune function.

As understanding of this system increases, more ground is getting covered on the medical marijuana front while novel drugs are being synthesized to modulate endocannabinoid transmission. Currently medical marijuana is prescribed for the clinical treatment of glaucoma, multiple sclerosis, chronic pain, wasting syndrome associated with cancer and AIDS treatment, boredom, anorexia, spastic disorders, and inflammatory bowel disease. Interestingly, grandmother’s old-timey favorite Tylenol is actually converted to a cannabinoid in order to achieve its effects. One pharmaceutical, Rimonabant, is prescribed for treating obesity because it blocks CBRs, playing upon their role in stimulating appetite. The natural distribution of CBRs throughout the brain reflects their contribution to psychological function. For example, there are large concentrations of CBRs in the cerebellum, a striated structure at the rear base of the brain that is critical for movement and coordination. Since activation of these receptors induces an inhibitory effect, this simple fact of density could explain why it requires a lot more motivation to get up off the couch after smoking a lot. Similarly, there is a significant contribution of CBRs to memory processes in the hippocampus, which suggests a reason for the notorious forgetfulness of some potheads (pronounced “po-theed” by those involved in the movement to “take the word back”).

Indeed, cannabis has many remarkable properties with no lethal overdose potential. However, this fact has contributed to a long-standing myth about marijuana: that it is not addictive. It is commonly stated that THC’s habit-forming effect is a function of psychological addiction, rather than the more serious physical addiction. Certainly, the dangers of marijuana are incomparable with those of “hard” drugs, which reasonably attains a safer reputation for weed. Unfortunately, this very fact is dangerous on its own, as countless individuals rationalize a lack of moderation with the misconception that their ability to stop is a simple matter of will. In reality, the dichotomy of psychological vs. physical addiction is a vestige of the outdated models for addiction. The current neurophysiological understanding of addiction sheds light on the strong connections between the circuitry affected by addiction and regions responsible for decision-making. It is important to realize that the human experience cannot be separated from the physiological condition of the brain.

All things considered, there is much to appreciate about cannabis, but its consumption must be considered seriously as a lifestyle-changing activity. So enjoy this coming Sunday in whatever way you see fit, and don’t mind the savory scent that may be floating about. Rest assured that those producing it are simply rejoicing in their own endocannabinoid systems, for better or worse… or just for laughs.

Andy Arnold

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