Marijuana & Alcohol Legal but Dangerous

As legalization spreads, more Americans are becoming heavy users of cannabis, despite its links to violence and mental illness. The best data concerning the scope and effects marijuana & alcohol use come from the National Survey on Drug Use and Health.

The surveys ask about problems users believe they have experienced because of their use. The Substance Abuse and Mental Health Services Administration (SAMHSA) consolidates the answers to estimate how many would meet the clinical criteria for dependence (2.8 million) or abuse (an additional 1.4 million) set down by the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders (commonly referred to as the DSM-IV). SAMHSA makes these calculations for all substances in an effort to estimate the nationwide need for treatment for each substance.

It turns out that 137 million people self-report current alcohol use, and 17.3 million describe enough problems to meet the criteria for alcohol abuse or dependence, equivalent to one instance of alcohol abuse or dependence per 7.9 current users, or 13% of current users — significantly lower than the corresponding ratio for marijuana.

In 2012 the Treatment Episode Data Set recorded 681,374 treatment admissions for which the primary substance of abuse was alcohol and 305,560 for which it was marijuana or hashish. That works out to 15 admissions for every 1,000 current marijuana users versus only 5 for every 1,000 alcohol users.

What is clear is that, in individual cases, marijuana can cause psychosis, and psychosis is a high risk factor for violence. What’s more, much of that violence occurs when psychotic people are using drugs or alcohol. The drug they are most likely to use is cannabis. The most obvious way that cannabis fuels violence in psychotic people is through its tendency to cause paranoia. People with psychotic disorders, paranoia can fuel extreme violence.

A 2012 paper in the Journal of Interpersonal Violence, examining a federal survey of more than 9,000 adolescents, found that marijuana use was associated with a doubling of domestic violence in the U.S. A 2017 paper in the journal Social Psychiatry and Psychiatric Epidemiology, examining drivers of violence among 6,000 British and Chinese men, found that drug use was linked to a fivefold increase in violence, and the drug used was nearly always cannabis.