Monday, May 20, 2019
Distortion 1: Drug Use After Prohibition Ends
Distortion 2: Drug Use Estimates
Distortion 3: Needle Exchange
Distortion 4: Harm Reduction
Distortion 5: Methadone Treatment
Distortion 6: Emergency Room Visits
Distortion 7: Gateway
Distortion 8: Ecstasy
Distortion 9: Cannabis As Medicine
Distortion10: Young People and Drugs
Distortion 11: Marijuana Potency
Distortion 12: Cannabis and Driving
Distortion 13: US Crime Rates
Distortion 14: Cannabis and Drug Treatment
Distortion 15: People Only Smoke Pot To Get High, Whereas They Drink Alcohol To Be Sociable
Distortion 16: ONDCP's 'Open Letter on Marijuana' & the AntiDrug Media Campaign
Distortion 17: Cannabis and Drug Treatment Part II
Distortion 18: Cannabis and Mental Illness
Special: NORML's Truth Report 2005, An Analysis & Response To The Drug Czar's Open Letter About Marijuana
Special: Debunking The Myths Chronic Pain & Opiods, by Frank Fisher, MD
Distortion 19: Estimating the Size of the Illicit Drug Market
Distortion 20: Methamphetamines
Distortion 21: US Crime Rates & Arrest Rates
Distortion 22: Marijuana & Violence
Search using CSDP's own search tool or use
In March 2005, several reports appeared in the news media regarding a causal link between cannabis and psychosis. The National Post of Canada reported on March 10, 2005 ( "Study Links Pot-Smoking, Psychosis") that "Daily marijuana users are 1.6 to 1.8 times more likely to develop psychosis compared to non-users, a group of New Zealand scientists reported after following the health and development of 1,200 men and women born in 1977 for 25 years. The findings, published in the March edition of the journal Addiction, make it increasingly difficult for pot advocates to dismiss a growing body of evidence linking regular cannabis use with increased risks of psychosis, an outcome mental health experts have long suspected. 'This makes it more definitive,' says Harold Kalant, a professor of pharmacology at the University of Toronto. 'Most people accept that the link has been established beyond anyone's ability to dismiss it.'"
As is often the case, there is less here than meets the eye. The article, "Tests of Causal Linkages Between Cannabis Use and Psychotic Symptoms," by David M. Fergusson, L. John Horwood and Elizabeth M. Ridder, though important, has flaws which bring its findings into question.
The first point that needs to be noted is that the researchers
did not perform or review actual diagnoses of these subjects
nor did they report on actual cases of mental illness. The
study looked only at self-reports of possible symptoms.
Indeed, the authors in their Addiction article were
much less hyperbolic in their conclusion:
Yet, are even these cautious conclusions justified by the data?
The number of symptoms being reported was actually rather low: non-users reported on average a maximum of 0.69 symptoms, while the daily users reported on average a maximum of 1.95 symptoms. What also went unreported by the news media was the fact that other user groups in the study, including the weekly users, showed a decline in the number of reported symptoms over time. Data from the report is printed below.
The researchers relied on a psychological screening instrument called the Symptom Checklist-90 to measure these symptoms. (The full checklist and the psychological constructs represented by the different problems/complaints can be viewed at the Medical Algorithms Project.) The symptoms examined by the researchers were:
As noted by Bruce Mirken and Mitch Earleywine in their article
"Psychosis, Hype and Baloney"
(AlterNet, March 7, 2005):