Anxiety

[palmspringsbum]

Monday, September 25, 2006

Feeling paranoid

Is Weed the New Prozac?

by Jonah Lehrer
The New York Inquirer

Fifteen million Americans, or five percent of the population, are currently taking a drug that treats most of their anxiety symptoms. This drug isn’t addictive, can be delivered to your door in certain metropolitan areas, and is cheaper than most of its competitors. Its main side effect? The munchies.

I’m talking about marijuana, a.k.a. Cannabis sativa, and both scientists and pharmaceutical companies are looking to it as a possible cure for what may be our generation’s most pressing psychological affliction.

Perhaps it’s the War on Terror, or our stagnating incomes, or just the fact that Prozac is running out of fresh supplicants and Eli Lilly needs a new disease. Whatever the cause, the data is clear: Americans are growing more nervous, and we want something to take the edge off. Every generation needs a new pandemic, and anxiety is our new depression.

Despite the fact marijuana was first cultivated almost 10,000 years ago, modern medicine has yet to find a pharmaceutical equal. No other substance melts away our fears with such slick efficiency. But that may soon change. A cadre of neuroscientists is now using the natural potency of pot—its active ingredient is Tetrahydrocannabinol (THC)—as the possible basis for a next generation anti-anxiety pill.

Before you can understand why pot might be the next Prozac, you have to know a little bit about how marijuana works inside the brain. Our cortex contains a class of proteins called endocannabinoids. These compounds might sound illegal, but they are actually an essential ingredient of normal human brain function. For some mysterious reason, the active ingredient of a tropical shrub—THC—is able to perfectly mimic our natural endocannabinoids, and activate our neural receptors. Pot doesn’t infuse our brain with a foreign substance so much as it activates system that is already there. As Roger Nicoll, a neuroscientist at UCSF, puts it: “the brain makes its own marijuana.” Smoking a joint just helps you make more of it.

It wasn’t until 1984 that scientists even knew the endocannabinoid system existed. By the early 1990’s, researchers began to realize that this neural system was extremely important. For one thing, endocannabinoid receptors (CB1) proved to be one of the most abundant G-protein coupled receptors in the brain. Secondly, CB1 receptors were clustered where it counts, and seemed to populate many of our most important brain areas, like the cerebral cortex, hippocampus, and amygdala.

But scientists still couldn’t figure out what all these natural endocannabinoids did when we weren’t smoking pot. After all, our brains didn’t evolve so that we could get high; our CB1 receptors must also control some aspects of normal brain function. A tantalizing solution arrived in 2003, from Giovanni Marsicano of the Max Planck Institute of Psychiatry in Munich. After painstakingly dismantling their endocannabinoid system, he showed that mice lacking normal CB1 receptors could feel fear but couldn’t forget it. In other words, their anxiety is chronic. They are always nervous and twitchy.

Neuroscientists now believe that a faulty endocannabinoid system might play a large part in all sorts of anxiety syndromes from post-traumatic stress disorder to irrational phobias. Furthermore, they are using this knowledge to invent new drugs. The Holy Grail is a THC compound that is targeted to the parts of our brain—like the amygdala—that modulate our sense of fear. Such a pill would give us the anti-anxiety effects of pot, but without the giddiness, stupidity and hunger. While scientists still don’t know if such a site-specific pill is possible—can we just get our amygdala high?—experiments done in the next few years should help resolve the issue.

Needless to say, such a pill would raise all sorts of legal issues at the FDA. Although the FDA has already approved other types of synthetic THC—these drugs are used to treat the nausea brought on by chemotherapy and AIDS—it might be less prone to approve a pot inspired pill that is psychoactive, and deliberately imitates the effects of a fat spliff.

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<small>Jonah Lehrer is an editor-at-large for Seed Magazine. He blogs at scienceblogs.com/cortex. His first book, [i]Proust Was A Neuroscientist[/url], will be published by Houghton-Mifflin next year.</small>