Cannabis

New Genetics Evidence Should Help Quell “Reefer Madness”Mongering

A team of Australian and Dutch researchers (Gillespie et al), writing in the June 2019 issue of the British medical journal The Lancet, criticized a March 2019 study by British researchers (Di Forti et al) in the same journal that suggested variations in cannabis use and potency may be responsible for variations in psychotic disorders. Opponents of cannabis legalization have used the Di Forti study as evidence to support their position. 

The criticism rests on the fact that the authors of the March study “assume that cannabis causes psychosis or psychotic symptoms without acknowledging compelling, alternative hypotheses.” 

Gillespie and colleagues point out that most studies looking at associations between cannabis and psychosis don’t adjust for “confounding” that arises from correlated genetic and environmental individual differences. They point to their own findings as well as those of other researchers showing cannabis use may be higher among individuals with a genetic liability that predisposes them to both cannabis use and the development of psychotic disorders. 

To address the shortcomings of the March study, they specifically point to the results of their recent meta-analysis of the largest genome-wide association study of lifetime cannabis use to date. The study indicated that genetic risk factors for cannabis use and schizophrenia are positively correlated. The meta-analysis applied bidirectional randomization and found a “consistent pattern of evidence supporting a causal effect of schizophrenia risk on lifetime cannabis use.” The study “found little evidence for any causal effect of cannabis use on schizophrenia.” While conceding their analyses were not based on cannabis use frequency or potency but rather genetic risk factors, they felt confident making the following statement:

Nevertheless, our findings strongly suggested that associations between measures of cannabis use and psychosis or psychotic disorders are far more nuanced than Di Forti and colleagues assume. In addition to correlated genetic liabilities, indirect and bidirectional processes are likely to affect the associations between cannabis use, misuse, and psychotic disorders. By not acknowledging the alternative, compelling and plausible mechanisms, Di Forti and colleagues’ conclusion regarding the harmful effect of high-potency cannabis use on mental health is likely to be overestimated.

The Return of Reefer Madness

Alex Berenson’s recent attempt to generate panic at the prospect that marijuana use may become legalized and normalized, with his book Tell Your Children: The Truth About Marijuana, Mental Illness, and Violence, even borrows its title from the camp 1930s propaganda film Reefer Madness. While not nearly as over-the-top as the film, Berenson certainly exaggerates suggestions that marijuana can cause psychosis.

The Beginning of the End for Cannabis Prohibition?

The Boston Globe reports Colorado Senator Cory Gardner is crafting a bill that would prevent the federal government from interfering with states that have voted to legalize cannabis for recreational or medicinal purposes. The Senator is busy recruiting several co-sponsors for the bill, and he has received assurances from President Trump that he would sign such a bill into law.

This would be a step in the right direction and would alleviate concerns in many states that the Department of Justice, under new guidance from Attorney General Sessions, might enforce federal marijuana prohibition.

Unfortunately, as long as the Drug Enforcement Administration continues to classify cannabis as a Schedule 1 drug, quality clinical research on the potential medical applications of cannabis will remain significantly inhibited. By definition, a Schedule 1 drug has “no currently accepted medical treatment use.” Recent studies have shown that chronic pain patients have been able to reduce their opioid dosage and consumption by adding cannabis to their pain management regimen. A study of Medicare Part D patients from the University of Georgia published in JAMA earlier this month demonstrated this effect in states where medicinal marijuana has been legal. Another study published the same week from the University of Kentucky showed this effect was even greater in states where marijuana is legal for recreational use. And another recent study from the Minnesota Department of Health earlier this year found 63 percent of patients taking medical marijuana for their chronic pain were able to reduce or eliminate their opioid use within 6 months.

Yet Another Study Points to The Potential of Cannabis for Reducing Opioid Use

The Minnesota Department of Health reported today that 42 percent of the more than 2,000 first-time medicinal marijuana users with intractable pain enrolled in its research study obtained significant pain relief. In announcing the results, the Minnesota Health Commissioner said, “We need additional and more rigorous study, but these results are clinically significant and promising for both pain treatment and reducing opioid dependence.”

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