UC San Diego study examines effects of cannabis on driving
Published - 07/26/18 - 09:45 AM | 4753 views | 2 2 comments | 27 27 recommendations | email to a friend | print
Dr. Tom Marcotte observes as a subject operates the driving simulator.
Dr. Tom Marcotte observes as a subject operates the driving simulator.
Subjects smoke a joint, which is rolled at the facility, prior to their driving simulator sessions.
Subjects smoke a joint, which is rolled at the facility, prior to their driving simulator sessions.
With the Jan. 1 legalization of marijuana in California, cannabis users rejoiced in a final halting of past persecution.

Although the state has been at the forefront of the legal cannabis movement, often making pro-medical marijuana decisions, such as passing the Compassionate Use Act in 1996 (SB420), federally, the drug is still considered a Schedule I narcotic. That places it in the same class as heroin, LSD, ecstasy, methaqualone and peyote.

Now, users can simply go to a storefront dispensary, have their products delivered from a dispensary and even order off of the Internet.

This easy access has made determining cannabis inebriation a major concern of law enforcement and health officials throughout the state, however.

Unlike alcohol, researchers are yet to define marijuana intoxication quantitatively. For this reason, researchers at the University of California San Diego’s Center for Medical Cannabis Research (CMCR) are looking to answer two questions: “How does a particular dose of cannabis affect a driver?” and “What would that effect be several hours later?”

CMCR has been operational in Hillcrest since early 2000, one of the earliest federal research facilities of medical marijuana in the state and country.

Their study, titled “Impact of Repeated Cannabis Treatments on Driving Abilities,” has sought out the aid of 180 volunteers to participate in their one-day observations. Currently, CMCR has 100 participants involved in the study. They need 80 more to meet the predetermined participants required.

“Basically, we’re looking for healthy adults with cannabis exposure,” said Marcotte. “So far, we have got a nice age range. After legalization, dispensaries had voiced a resounding surprise at the number of senior citizens treating ailments. That’s what leads us to think, ‘Well, we could find out how this medication affects their driving abilities.’”

In March of 2017, sdnews.com ran a story about the San Diego Police Department’s mobile, saliva-screening device, Drager 5000, which tested for illicit drugs including cocaine, marijuana, amphetamines and prescription narcotics. Then- police chief Shelley Zimmerman said the two Drager mobile drug testers, which cost about $6,000 apiece, will be used mostly at DUI checkpoints initially.

With a cost like that, it would make it quite difficult to provide every officer in the field with one. Also, according to Marcotte, “What’s contaminated in your mouth does not come from your body. Ten to 20 hours later, it (THC) can still be there.”

That rules out being able the 100 percent probability of direct inebriation.

The study commences with selected participants arriving to CMCR’s facility in Hillcrest for blood tests, vitals, an interview and familiarization with the driving simulator. During their next session, they smoke a pre-rolled joint (grown at a NIDA facility) of either low-THC content cannabis flower (3 percent) or higher potency (16 to 20 percent and higher). Their blood and saliva are tested, and a consulting law enforcement officer conducts a typical field sobriety test.

On the road again

During the driving simulator, participants are subjected to typical judgment-based traffic scenarios, like turning left into oncoming traffic. As one could expect, typical reaction times are slowed, even with subjects that have “cannabis exposure.”

“In nearly all simulator sessions, it can be noted that people tend to brake much later and become much more distracted of a driver,” Marcotte said. “While smoking a joint can affect a driver nearly instantly, lasting for an hour or 1.5 hours, ingesting edibles can take up to two hours to take effect and last a few hours. Perhaps one frustrating aspect of the study, however, is that it is a traditional double-blind study. The only person who knows what pot the subject received (either a placebo low potency or high) is the pharmacist. So, it can be difficult to determine uniform indicators of intoxication.”

The harsh reality is that marijuana effects everyone differently. And with a vast array of tinctures, edibles, concentrates, etc. available to users, it makes it increasingly difficult to determine whether or not someone is high. Since THC is stored in fat cells, frequent users can have it present in their bloodstream from a time period lasting from 20 hours to more than a month.

Marcotte says that, among their other studies, they hope to study the effects of combining alcohol and marijuana.

He added that “Combining something like marijuana, which slows down your reaction time, with alcohol (which also does) that increases one’s risk-taking behavior, is of great concern for public health and safety in legalized states.”

They are also looking into the cumulative effects on older drivers as well.

Anyone over the age of 21, who has had some experience with cannabis and would like to be a paid participant in the study, visit jobs.ucsd.edu.
Comments-icon Post a Comment
B Decker
July 28, 2018
I am seventy-one years old,use NO drug,take no medicine other than THC which is ingested via vapor. My health is better than most people my age. I drive international and locally. Live in Bird Rock...close. I would love to participate in your study, Thanks Decker
July 30, 2018
Hi Decker,

You can also sign up for the study on CMCR's website, https://www.cmcr.ucsd.edu/.

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