Researchers are investigating the effects of marijuana use on the development of neurological disorders in HIV-infected youth.

With the aid of a $4.7-million grant from the National Institutes of Health, collaborating researchers from U. California-San Diego, U. Florida and U. South Florida hope to identify blood-based biomarkers — markers to track how substance abuse alters HIV function and progression from within the central nervous system.

By identifying biomarkers and how the combination of HIV and marijuana alter neurological pathways in young adults, the study hopes to find how marijuana use contributes to the behavioral decisions made by people, from age 18 to 24, infected with HIV.

HIV — a virus that destroys the immune system and eventually leads to AIDS — currently has no cure, but is thought to be affected by chemical components in marijuana.

According to UCSD pediatric neuropsychologist Sharon Nichols, marijuana is thought to play a role in suppressing immune function.

“It is … important to understand the effects of HIV in the brain in adolescents and emerging adults, partly because their brains are still developing and partly because they are likely to be living with HIV for a long time,” Nichols said. “Understanding the early effects of HIV and how to prevent future problems is especially critical. [The study] will help us at the basic level to lead to better treatments.”

Marijuana affects both mental and emotional control, according to Nichols — who researches cognitive reasoning in HIV-infected adolescents who undergo antiretroviral treatment.

“The big obstacle we face is that substance abuse can play a role in immune system and cognitive functioning,” Nichols said.

Though antiretroviral drugs exist to help alleviate the effects of HIV, those infected still experience problems with movement and cognition control — including dementia — and risk spending the rest of their lives with impaired cognitive abilities.

The team will study the main components of marijuana, THC and cannabinoids, to determine how it affects the nervous and immune systems.

So far, research found that 30 to 40 percent of HIV infected adolescents also are involved with substance abuse. Almost one-third of those infected use marijuana on a daily basis.

There is no current research that shows the effects of marijuana use on the behaviors of adolescents with HIV, even with the prevalence of marijuana use among them. To study the effects on a molecular level, researchers are using a multidisciplinary approach over the five years of the study.

Researchers hope that the three branches and their shared results will find overlapping data. Researchers at UCSD will study how HIV affects the brain by looking at cognitive processes. USF neurobiologists will study cannabinoids’ effects on the immune system. Virologists at UF will study both HIV-infected and HIV-free small blood cells capable of absorbing bacteria and small particles.

“This network approach involves universities, clinics, etc,” Nichols said. “We want to look all through the United States. People in California are different from New York — they could be using different substances across the country.”

The study will include four groups of 16- to 25-year-olds picked from 15 parts of the country.