Study reverses negative effects of adolescent marijuana use

Sept. 12 (UPI) -- Researchers at the University of Western Ontario have developed a method to use pharmaceuticals to reverse the negative psychiatric effects of THC in marijuana.

Chronic marijuana use during adolescence has been linked to the development of psychiatric diseases such as schizophrenia in adulthood.

The study, published today in Scientific Reports, found that adolescent THC exposure modulates the activity of a neurotransmitter known as GABA in the prefrontal cortex region of the brain.

"What is important about this study is that not only have we identified a specific mechanism in the prefrontal cortex for some of the mental health risks associated with adolescent marijuana use, but we have also identified a mechanism to reverse those risks," Steven Laviolette, professor at Western Ontario's Schulich School of Medicine & Dentistry, said in a news release.

Researchers found that the reduction of GABA as a result of THC exposure in adolescence caused the neurons in adulthood to be hyperactive in the prefrontal cortex but also out of sync with each other showing abnormal oscillations called gamma waves.

"GABA is an inhibitory neurotransmitter and plays a crucial role in regulating the excitatory activity in the frontal cortex, so if you have less GABA, your neuronal systems become hyperactive leading to behavioral changes consistent with schizophrenia," Justine Renard, post doctoral fellow at the University of Western Ontario, said.

The loss of GABA in the cortex lead to a corresponding hyperactive state in the brain's dopamine system, which is commonly seen in patients with schizophrenia.

Researchers found that by using drugs to activate GABA in a rat model of schizophrenia, they were able to reverse the neuronal and behavioral effects of THC and halt schizophrenia symptoms.

"What this could mean is that if you are going to be using marijuana, in a recreational or medicinal way, you can potentially combine it with compounds that boost GABA to block the negative effects of THC," Laviolette said.