UCI receives $9 million grant to find long-term impact of cannabis exposure on adolescent brain

The National Institute on Drug Abuse (NIDA), part of the National Institutes of Health (NIH), has awarded the University of California, Irvine School of Medicine, a 4-year, $9 million grant aimed at determining the long-term impact of cannabis exposure on the adolescent brain.

Led by Daniele Piomelli, PhD, professor of anatomy and neurobiology at UCI School of Medicine, and director of the newly created UCI Center for the Study of Cannabis, the grant will fund a systematic series of preclinical studies to determine whether cannabis' active ingredient, delta-9-tetrahydrocannabinol (THC), during adolescence causes persistent changes in endocannabinoid (ECB) signaling, synaptic plasticity and behavior. The research will be conducted by a group of principal investigators from UCI including Marcelo Wood, PhD, Christine Gall, PhD, Gary Lynch, PhD, and Stephen Mahler, PhD. The grant is UCI's only NIDA Center of Excellence.

The ECBs are cannabis-like molecules produced by the brain, which are involved in a variety of physiological and psychological processes, such as emotion, learning and memory.

"The ECB system is the main point of entry of THC into the brain. Now that cannabis is legal in many states, it's very important to understand whether excessive activation of this signaling system during adolescence can produce alterations in cognition and motivated behavior that last into adulthood," said Piomelli.

Referred to as ICAL (Impact of Cannabinoids Across the Lifespan), the Center will seek to answer two specific questions:

• What are the long-term effects of adolescent exposure to THC on brain function and behavior?
• What are the molecular mechanisms underlying such effects?

"Studies suggest that adolescents who are exposed to cannabis are at risk for development of various neuropsychiatric disorders later in life, but there is much research still needed," said Piomelli. "It is especially important to understand at what times in life and at what dosages cannabis may become dangerous, and to develop preventive and therapeutic strategies to manage this risk. This grant will allow us to take great strides toward gaining a solid understanding of the true benefits and dangers of cannabis and may lead to better ways to prevent cannabis dependence. It may also guide solid, evidence-based public policy decisions concerning medicinal and recreational uses of cannabis, as well as inform the development of medications aimed at treating harmful diseases."

According to study published in JAMA Psychiatry in 2015, the prevalence of cannabis use in the adult population of the US has climbed from 4.1 percent in 2001-2002 to 9.5 percent in 2012-2013, while the total number of Americans diagnosed with cannabis use disorder (abuse or dependence) has now reached 6.8 million. As with other psychoactive drugs, cannabis use typically starts in early teenage years and progressively increases throughout adolescence ¬- according to national survey sponsored by NIDA at NIH, in 2013, 11.7 percent of 8th graders and 35.1 percent of 12th graders used the drug at least once. Teenage boys and girls experiment with cannabis more than any other recreational substance and a substantial percentage of them (5.8 percent of 12th graders in 2013) also tried synthetic cannabis substitutes such as Spice and K2. Though striking, these numbers are likely to grow in the near future as risk perception of cannabis's potential consequences continues to decrease. Furthermore, the accelerating diffusion of medicinal cannabis-derived products is exposing new groups of young people to the drug. These trends are of particular concern within a social context in which changes to legislation and broadening acceptance fuel financial interests that can potentially override public health and safety concerns.