There has been a recent trend throughout the U.S. to legalize recreational cannabis (marijuana). Our Hawaii state legislators have wisely, heretofore, decided to vote against the legalization of recreational cannabis in Hawaii.

According to the Canadian Paediatric Society, health professionals need to be aware of and communicate the health risks related to cannabis use.

Scientific studies have revealed significant central nervous system toxicity of the THC (tetrahydrocannabinol) component of recreational cannabis. THC is the chemical in cannabis responsible for the psychotropic effect (“high”) that is experienced by users of recreational cannabis. The THC component in recent recreational cannabis samples has risen to many times the level that was present many years ago.

THC has been found to increase neurotransmitters that flood parts of the brain, such as the frontal cortex, which is responsible for higher order thought, such as judgment and decision-making processes. When key parts of the brain are exposed to these chemicals, they function less efficiently and have been found to exhibit toxic changes in the neurons involved.

Brain development continues until the mid-20s, and the adolescent brain is particularly sensitive to the toxicity of THC. MRI studies in young persons who use cannabis regularly have demonstrated structural changes that include lower brain volume, thinning of the cortex and less neural connectivity.

In an additional study of youths who used cannabis before age 16, the principal investigator, Dr. Francesca Filbey, reported “Not only did the age of use impact brain changes, but the amount of cannabis used also influenced the extent of altered brain maturation.”

Furthermore, a 2019 study showed that there were structural changes in the brains of a group of 14-year-old children who used cannabis only once or twice. The latter finding reveals that it is not necessary for a young person to use the drug for many years to induce brain changes.

Researchers have found that the early use of cannabis significantly increases the risk of developing schizophrenia. The prevalence of schizophrenia in the adult population is about 1%, and the risk of developing this disease is doubled in heavy cannabis users.

Recreational cannabis has been associated with increased risk-taking and impaired judgement. Use of marijuana has long been suspected to be the gateway to the use of more toxic drugs in susceptible individuals.

Some studies have shown increased utilization of recreational cannabis by teenagers following legalization.

Furthermore, in our state, the use of medicinal cannabis is already legal, and there is no need for the legalization of recreational cannabis with its known toxic effects on youthful brains.

Malcolm R. Ing, M.D., F.A.C.S., is an ophthalmology specialist in Honolulu.