The Evolving Frontier of Medical Cannabis (aka Marijuana)

Last week I had the opportunity to give a talk on medical cannabis to members of the Montgomery County Medical Society. What struck me about the physicians in attendance was their high level of interest, as well as their concern about how little information they had received about this topic in their medical training. On the other hand, one physician spoke enthusiastically and confidently about all of the patients who she was treating with cannabis for conditions that had been refractory to other medications. She was not deterred by the absence of evidence for this practice in the medical research literature.

This discrepancy exists largely because of both the persistent refusal of the Drug Enforcement Administration to lower the barriers restricting legitimate research into this complex substance along with the inability of the U.S. Congress to pass remedial legislation to resolve the issue. As a result of this deadlock, many U.S. citizens have voted to legalize medical cannabis on state-by-state basis, thus creating a confusing inconsistency between Federal and State laws. Since the voters of California made medical cannabis legal in that state 22 years ago, almost every other state has followed suit in some way – currently, all but 4 states allow some form of medical cannabis. Unfortunately, except for some funds having been created in California, medical research has not benefited from these legal initiatives.

We are, nevertheless, gaining new information from research that is being done in this country despite the barriers, as well as in Europe where the barriers are lower. Some interesting findings of practical importance are coming from Ryan Vandrey at Johns Hopkins. His laboratory studies on humans document that, while cannabis can clearly cause both cognitive and psychomotor impairment, there is no correlation between THC blood level and impairment. This means that impaired driving due to cannabis cannot be managed in the same way as it has been with alcohol, for which reliable correlations do exist. Even more serious is his finding that impairment can be detected at THC blood levels below 5 nanograms, which is the legal limit that has been set in Montana and Washington. Currently, Maryland and DC have no laws in place addressing impaired driving due to “marijuana.”

Impaired driving is one of the corollary issues that arises when a physician recommends medical cannabis. Future medical research will continue to address that issue, as well as fundamental medical questions such as which conditions respond to cannabis and what doses are optimal. The pace of those discoveries, however, rests to a large extent in the hands of lawmakers and law enforcement agencies while the general public and the medical profession look on with interest and impatience.