What No One Wants to Know About Marijuana.

From The Natural Mind by Dr. Andrew Weil
(last half of chapter four pg. 86-97)

Because marijuana is such an unimpressive pharmacological agent, it is not a very interesting drug to study in a laboratory. Pharmacologists cannot get a handle on it with their methods, and because they cannot see the reality of the non-material state of consciousness that users experience, they are forced to design experimental situations very far removed from the real world in order to get measurable effects. There are three conditions under which marijuana can be shown to impair general psychological performance in laboratory subjects. They are:

1. by giving it to people who have never had it before;
2. by giving people very high doses that they are not used to
   (or giving it orally to people used to smoking it); and
3. by giving people very hard things to do, especially things that they have never had a chance to practice while under the influence of the drug.

Under any of these three conditions, pharmacologists can demonstrate that marijuana impairs performance. And if we look at the work being done by NIMH-funded researchers, all of it fulfills one or more of these conditions. In addition, the tests being used by these scientists are designed to look for impairments of functions that have nothing to do with why marijuana users put themselves in an altered state of consciousness. People who get high on marijuana do not spontaneously try to do arithmetic problems or test their fine coordination.

What pharmacologists cannot make sense of is that people who are high on marijuana cannot be shown, in objective terms, to be different from people who are not high. That is, if a marijuana user is allowed to smoke his usual doses and then to do things he has had a chance to practice while high, he does not appear to perform any differently from someone who is not high. Now, this pattern of users performing better than nonusers is a general phenomenon associated with all psychoactive drugs. For example, an alcoholic will vastly outperform a nondrinker on any test if the two are equally intoxicated; he has learned to compensate for the effects of the drug on his nervous system. But compensation can proceed only so far until it runs up against a ceiling imposed by the pharmacological action of the drug on lower brain centers. Again, since marijuana has no clinically significant action on lower brain centers, compensation can reach 100 percent with practice.

These considerations mean that there are no answers to questions like, What does marijuana do to driving ability? The only possible answer is, It depends. It depends on the person – whether he is a marijuana user, whether he has practiced driving while under the influence of marijuana. In speaking to legislative and medical groups, I have stated a personal reaction to this question in the form of the decision I would make if I were given the choice of riding with one of the following four drivers:

1. a person who had never smoked marijuana before and just had;
2. a marijuana smoker who had never driven while high and was just about to;
3. a high marijuana smoker who had practiced driving while high; and
4. a person with any amount of alcohol in him.

I would unhesitatingly take driver number three as the best possible risk.