"I'm really excited about the opportunity that this grant offers," says Mason. "It's time to get some clarity on how cannabis use impacts cognitive function, induces withdrawal symptoms, and affects the body's stress systems. This is important information. People are deciding every day whether to use or not to use marijuana, for medical purposes or otherwise, and there is little scientific information to advise this decision."
The NIDA grant will fund the startup of a new Translational Center on the Clinical Neurobiology of Cannabis Addiction, the first such center to be dedicated to studying the neurobiology of cannabis dependence. The ultimate goal of this research is to help develop novel approaches to the prevention, diagnosis, and treatment of marijuana addiction.
According to the Office of National Drug Control Policy, marijuana is the most commonly used illegal drug. The 2006 National Survey on Drug Use and Health (NSDUH) estimated 97.8 million Americans aged 12 or older had tried marijuana at least once in their lifetimes; 25.4 million had used marijuana in the past year.
Of those admitted to treatment programs for drug addition in 2005, marijuana was the primary drug for 292,250 people or 15.8 percent.
A New Center for Research
The issue of cannabis dependence first came to Mason's attention during her work on alcohol addiction. When recruiting patients for alcoholism clinical trials, she noticed that a number of candidates expressed the need of treatment for dependence on cannabis. She subsequently applied for an exploratory grant from NIDA to study the issue, which provided preliminary data for the foundation of the new center.
"While there are some people who have a problem with both alcohol and cannabis, many individuals are dependent on cannabis alone," she noted. "The estimate is that about four percent of those who use cannabis eventually become addicted to it."
The new center will pool the talent of several laboratories to learn more about addiction to cannabis and the consequences of withdrawal. In addition to Mason, who holds the Pearson Family Chair at Scripps Research, the center's principal investigators will include Scripps Research Associate Professor Michael Taffe, Scripps Research Associate Professor Loren Parsons, and University of California, San Diego, Associate Professor Susan Tapert.
The researchers and their teams will draw on complementary expertise in tissue analysis, imaging, animal models, and human clinical trials to understand the condition of marijuana addiction from a variety of perspectives. Techniques will include neuropsychological measures, biochemical analyses, and functional MRI.
Some of the center's initial projects will address questions such as the exact nature and duration of cognitive impairment caused by marijuana use; the role of development (for example, adolescence vs. young adulthood) on susceptibility to addiction; the effects of cannabis on the central nervous system; and the characteristics of withdrawal after long-term use.
The center will also contain a training component to mentor the next generation of researchers in the field.
"It's time we shed the light of science onto the topic of marijuana addiction," Masons says. "There is a lot we need to know in order to develop effective treatments.