Author: Mark Gold, MD

A continued effort to legalize the unrestricted access and use of marijuana in the U.S., primarily through voter initiatives, continues in spite of clinical trial evidence of lack of efficacy, increasing teen use, and reports of serious consequences from accidents to mental illness.

As marijuana is currently viewed by the public as “safe until proven dangerous” rather than dangerous until proven safe and effective, by way of randomized double blind clinical trials for a specific medical problem, we cannot make any claims regarding its medical benefit.

Risk of Psychosis

Little is known about the long-term effects of marijuana use as concern rises regarding the impact on the developing brains of young initiates. The effect of the psychoactive ingredient in cannabis, Δ9- tetrahydrocannabinol (THC) on subcortical neuronal connectivity and function is the most recent concern as increased prevalence of psychiatric morbidity have been reported in the medical literature— including depression, suicidality, panic, paranoia, amotivation, increased risk for psychosis and now, a six-fold increase in the risk of schizophrenia among the youngest initiates.

Why Does This Matter?

Although there is much to learn regarding the role of marijuana use and concurrent psychopathology, these findings support the hypothesis that prevention and early intervention for children and adolescents, young adults, and pregnant females is essential and a highly worthy goal. Bottom line is clear. Early onset and persistent, long-term marijuana use is associated with changes in resting-state brain function in the same dopaminergic nuclei and regions associated with brain reward, habit formulation and psychiatric illness, including psychosis.

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