Government-funded research at UCSD investigates marijuana's effects to
better understand how the drug can both help and hurt its users.
By Justin Gutierrez
Sunday, Apr. 27, 2008
Labs at UCSD and around San Diego are investigating the medicinal value and
addictive qualities of cannabis, the drug that, according to the United
Nations Office on Drugs and Crime, is used by approximately 162 million
people each year.
Like many other recreational drugs, marijuana binds to the brain's
receptors. Receptors are similar to keyholes, which release an effect
throughout the body when the correct link is made. However, unlike many of
the body's other compounds, the brain has receptors that respond
specifically to chemicals found in marijuana, called cannabinoid receptors.
These receptors trigger physical rewards in the body during exercise, in
what UCSD School of Medicine professor of anesthesiology Dr. Mark Wallace
likens to "the runner's high."
The most common cannabinoid in marijuana is tetrahydrocannabinol, or THC.
According to Wallace, there are over 450 compounds within the plant that
contribute to marijuana's effects.
Wallace's most recent study on cannabinoids involved 15 healthy individuals
who inhaled marijuana and endured pain from a forearm injection of
capsaicin, the compound that produces the spicy sensation in chili peppers.
Wallace found that if capsaicin was injected 45 minutes after a subject
smoked marijuana, there was a significant decrease in pain. However, if
capsaicin was administered five minutes after the subject smoked, there was
no significant decrease in pain. In addition, Wallace found that task
performance and motor skills in his study were not significantly impaired
with a dose of 4 percent THC marijuana.
"This study was conducted to put the debated pain-relieving quality of
cannabis to the test," Wallace said. "We were shown that there is a
potential benefit in using cannabis moderately to treat patients with
Wallace's study was funded by SB 847, a bill signed into effect by former
Gov. Gray Davis in 1999. The legislation allowed the University of
California to establish a California Medical Marijuana Research Program.
With this bill, as well as the 1996 State Proposition 215, the Center for
Medical Cannabis Research was established. Based in San Diego and affiliated
with UCSD, the center gathers researchers to answer the ultimate question
involving marijuana — is it genuinely therapeutic and effective enough for
"The ultimate goal for the CMCR is to test the safety and efficacy of using
cannabis and its compounds in medical treatment," CMCR representative
Heather Bentley said. "This goal holds particularly true in situations where
there are no other solutions for patients who suffer from chronic pain and
Bentley said cancer, AIDS, obsessive-compulsive disorder, diabetes,
multiple-sclerosis and depression have all been medically treated with the
use of marijuana with some success.
While UCSD heads many cannabis experiments, it receives all research
marijuana from one government-funded source — the University of Mississippi
— which is governed by the National Institute on Drug Abuse, the sole
American contractor that has been growing legal marijuana since 1974.
At the Scripps Research Institute, NIDA is supplying another project with
drastically different goals. SRI Professor Barbara Mason is heading a study
that will look at addiction as a reason for constant marijuana relapses.
Participants in Mason's study are required to be regular marijuana users and
are paid to not smoke. They are given a medication which abruptly blocks
cannabinoid receptors, creating a full-scale withdrawal from marijuana for
day. This allows Mason and her colleagues to study marijuana withdrawal
within a short period of time, whereas natural withdrawal usually lasts for
"Our study focuses on abuse and dependence on cannabis and how it affects
higher cognitive functioning, like reasoning, decision making and problem
solving," Mason said. "We are trying to characterize marijuana withdrawal."
Mason said one of the most prevalent symptoms of marijuana withdrawal is
sleep disturbances, characterized by strange dreams and interruptions that
can last months after a user quits smoking. Other symptoms include "violent
outbursts," such as aggressive behavior, anxiety attacks and difficulty
UCSD assistant professor of psychiatry Dr. Susan Tapert will create magnetic
resonance images of the brains of participants involved once the study moves
past its initial stages. The participants include some of UCSD's own
Tapert is particularly interested in how cannabis use affects long-term
development of the brain in adolescents and young adults.
"This matter is important to me because marijuana is so widely used," Tapert
said. "About 5 percent of high school seniors report using marijuana daily.
It is import to understand its neurological effects, so that young adults
are rightfully informed about the effects of marijuana use."
According to Mason, despite marijuana's widespread use, its effects on the
body and mind are hardly understood. Because marijuana's long-term effects
are still unknown, researchers like Tapert are focusing their attention on
teens and young adults, like undergraduates, whose learning abilities could
be affected by the substance.
"Like with any substance, overuse can bring undesired results," Wallace
said. "In the future, marijuana's place in medicine will hopefully be
understood, as well its adverse effects on the mind and body."
Readers can contact Justin Gutierrez at firstname.lastname@example.orgThis e-mail address
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