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Experts explore issues, controversies around medical marijuana use


 

I live and work in Maryland, where medical marijuana dispensaries are just beginning to open. So far, my patients have been content to smoke illegal marijuana, even after my admonishments. Last week, however, a patient who suffers from chronic pain told me that one of her doctors suggested she try medical marijuana. What did I think? The patient is in her 70s, and she has not tolerated opiates. She lives an active life, and she drives. I didn’t know what to think and was left to tell her that I had no experience and would not object if she wanted to try it. The timing was right for “Issues and Controversies Around Marijuana Use: What’s the Buzz?” at the American Psychiatric Association’s annual meeting in New York this week.

Dr. Godfrey Pearlson

Dr. Godfrey Pearlson

The symposium was chaired by Godfrey Pearlson, MD, director of the Olin Neuropsychiatry Research Center, New Haven, Conn., and five speakers gave a comprehensive overview of the research on different aspects of cannabis use. Let me share the take-home message that each speaker made.

William Iacono, PhD, a professor of psychiatry at the University of Minnesota, Minneapolis, started with a session called “Does Adolescent Marijuana Use Cause Cognitive Decline?” Dr. Iacono and all the speakers who followed him pointed out how difficult it is to research these issues. The research is largely retrospective, and the questions are complex. The degree of use is determined by self-report, and there are questions about acute versus chronic use, whether cognitive decline is temporary or permanent, whether the age of initiating drug use is important, and finally, which tests are used to measure cognitive abilities. Dr. Iacono noted that results are inconsistent and mentioned a large population study done in Dunedin, New Zealand, which measured a decrease in verbal IQ and vocabulary measures at age 38 years if the user began smoking cannabis as an adolescent. Dr. Iacono’s twin studies showed that marijuana users scored lower on these measures in childhood, well before they began smoking, and poor academic performance predisposes to marijuana use.

“Adolescents who use cannabis are not the same as those who don’t,” Dr. Iacono said, “and heavy or daily use does not cause cognitive decline in those who begin smoking as adults.”

Dr. Pearlson introduced the second speaker by saying, “It’s easier to get funding to show the ill effects of cannabis than to show medicinal effects.” Sue Sisley, MD, director of Midtown Roots, a medical marijuana dispensary in Phoenix, conducts cannabis trials for the treatment of PTSD in veterans and noted that she has had a long and difficult road with marijuana research, and hers is the only controlled trial on cannabis for PTSD. When her Schedule I license was approved by the Food and Drug Administration, she was able to receive marijuana from the National Institute on Drug Abuse that was grown by the University of Mississippi in Oxford – the only federal growing facility. The marijuana was delivered by FedEx, and the drug was the consistency of talcum powder. It was a challenge to find a lab that could verify the components of the test drug, and when she did, she found the tetrahydrocannabinol content was considerably lower than marijuana sold on the black market. Also, the product contained both mold and lead. “As a physician, how do you hand out mold weed to our veterans?”

Her trials are still in progress, and more veterans are needed. Anecdotally, she says, a decrease has been seen in the use of both opiates and Viagra by the research subjects.

Michael Stevens, PhD, adjunct professor of psychiatry at Yale University, New Haven, Conn., discussed the risk of motor vehicle accidents in marijuana smokers and the logistical issues enforcement poses for law enforcement officials. “There is evidence that marijuana increases the risk for accidents.” Dr. Stevens went on to say that the elevated risk is notably less than that associated with the use of alcohol or stimulants. Studying the effects of marijuana on driving is difficult, as driving simulators do not necessarily reflect on-road experiences, and cognitive testing does not always translate into impairment. “We can’t give marijuana to teens and test them, and you can’t tell people who smoke every day that you’ll check in with them in a few years and check their driving records.”

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