Marijuana Threat Assessment, Part One: Recent Evidence for Health Risks of Marijuana Use (Hudson Institute)

David W. Murray, Brian Blake & John P. Walters
Summary:
Thanks to advances in science, we have never known so much about the effects marijuana use has on the human body, particularly, the fragile brain. Yet, in a political era when scientific research is regularly marshalled to end public policy debates, the powerful, growing scholarship on marijuana has largely been ignored or dismissed. Indeed, marijuana use seems to be one of the glaring areas in modern life where wishful thinking reigns over rationality.

Yet, as the lesson of tobacco demonstrates, when Americans are given the scientific facts about serious threats to their health, they adjust their behavior and insist on measures to safeguard their communities. In the instance of marijuana, the public can be forgiven for not knowing the true threat. With the assistance of a sympathetic media, marijuana legalization advocates, many seeking to profit off the drug, continue to sell romantic falsehoods and outright lies. They casually dismiss the growing list of serious concerns about marijuana emerging from scientific scholarship and survey research, or just cry “reefer madness” without examining the evidence.

Amidst the current marijuana public policy discussion, more than ever, concerned citizens, community leaders, lawmakers, educators, and parents need to better understand the growing body of research about this drug. What follows is a compilation and discussion of the latest research, including reports that are beginning to come in on the effects legalization has had in Colorado and neighboring states—including increased criminal activity even with legalization. While all research has limitations, what we do know is becoming clearer by the day, and it will make many question what they thought they knew about this drug of abuse.

Key Recent Findings:

  • Journal of the American Medical Association: “There is little doubt about the existence of an association between substance use and psychotic illness…studies suggest that the association between cannabis use and later psychosis might be causal, a conclusion supported by studies showing that cannabis use is associated with an earlier age at onset of psychotic disorders, particularly schizophrenia.”
  • Society for the Study of Addiction: “Regular cannabis use in adolescence approximately doubles the risks of early school-leaving and of cognitive impairment and psychoses in adulthood. Regular cannabis use in adolescence is also associated strongly with the use of other illicit drugs.”
  • World Psychiatric Association: “Evidence that THC is a component cause of psychosis is now sufficient for public health messages outlining the risk, especially of regular use of high-potency cannabis and synthetic cannabinoids.”
  • American Academy of Pediatrics: “The adverse effects of marijuana have been well documented” and include “impaired short-term memory, decreased concentration, attention span, and problem solving” which “interfere[s] with learning.”
  • American Psychological Association: “Heavy marijuana use in adolescence or early adulthood has been associated with a dismal set of life outcomes including poor school performance, higher dropout rates, increased welfare dependence, greater unemployment and lower life satisfaction.”
  • Proceedings of the National Academy of Sciences: “Persistent adolescent-onset cannabis users” showed “an average 8-point IQ decline from childhood to adulthood.”
  • Clinical Psychological Science Journal: Duke University and UC Davis researchers “found that those dependent on cannabis experienced more financial difficulties, such as paying for basic living expenses and food, than those who were alcohol dependent.”
  • Journal of Drug and Alcohol Dependence: States that have legalized “medical” marijuana find an association with higher 12th grade drop-out rates, lessened college attainment, and increases in daily smoking. Further, there is a dose/response relationship between adverse impact and years of increased exposure under legalization.
  • U.S. Department of Health and Human Services, SAMHSA: Since legalizing marijuana, Colorado climbed to number one among states for both youth (12-17) and college age adults (18-25) marijuana use.

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