Marijuana is not a gateway drug

Dr. Joseph Adams correctly notes that there is no credible scientific evidence that cannabis use is an effective treatment of opioid use disorder although cannabis may be useful in reducing chronic pain (“Marijuana unproven as help for opioid addiction,” Jan. 14). He also cites the strong evidence that medication-assisted treatment using buprenorphine or methadone in combination with counseling are evidence-based treatments for opioid use disorder.

Janice Vettel writes that "Marijuana is a gateway drug, always was and always will be,” (“You can't legalize marijuana when there is an opioid crisis,” Jan.9). Neither the National Institute on Drug Abuse nor the American Society of Addiction Medicine concurs with her belief. Although cannabis use may precede involvement with other drugs of abuse, there is no rigorous scientific evidence or known neurobiologic basis of a "gateway" effect. Her concerns about medication-assisted treatment do not reflect its demonstrated impact on reducing overdose death and increasing rates of long-term recovery.

There is ample evidence that cannabis use may lead to cannabis dependence and to a plethora of adverse reactions in the absence of dependence. Cannabis use is reported to be associated with earlier age of onset of schizophrenia and bipolar disorder when used in adolescence. Certainly its use may adversely effect the development of brain areas involved in judgement, executive function and impulse control.

My opinion is that the issue of legalization is less a medical issue than a legal and psychosocial issue. I agree with Ms. Vettel that the opinions of all stakeholders, including those of recovering persons with substance use disorders, are valuable.

Lawrence Adler

The writer is director and principal investigator at Clinical Insights Inc., a psychopharmacological research center.