Schizophrenia is just one of the disastrous effects of marijuana.  I have seen numerous cases in my own psychiatric practice.  The cause-effect research is very, very solid.  Marijuana is a very dangerous and destructive drug.

Schizophrenia Increased in US Army After Marijuana: Schizophrenia in US Army in Europe jumped from 1/1000 to 38/1000 over the 5-yr period from 1967-1971. Tennant & Groesbeck interpreted change as due to rapid growth cannabis use. Arch Gen Psyc 27:133-6, ’72

Dutch Prospective Study Finds Causal Link with Major Increase in Schizophrenia from Marijuana: A three year follow up of a Dutch cohort of 4045 people free of psychosis and 59 with a baseline diagnosis of psychotic disorder showed a strong association between use of cannabis and psychosis. Am J Epidemiol 2002; 156:319-327; Cannabis Use and Psychosis: A Longitudinal Population-based Study. J. van Os, M. Bak, M. Hanssen, R. V. Bijl, R. de Graaf and H. Verdoux; Baseline cannabis use predicted the presence at follow-up of any level of psychotic symptoms (OR = 2.76), as well as a severe level of psychotic symptoms (OR = 24.17), and clinician assessment of the need for care for psychotic symptoms (OR = 12.01). The effect of baseline cannabis use was stronger than the effect at 1-year and 3-year follow-up, and more than 50% of the psychosis diagnoses could be attributed to cannabis use. On the additive scale, the effect of cannabis use was much stronger in those with a baseline diagnosis of psychotic disorder (risk difference, 54.7%) than in those without (risk difference, 2.2%; p for interaction = 0.001). Results confirm previous suggestions that cannabis use increases the risk of both the incidence of psychosis in psychosis-free persons and a poor prognosis for those with an established vulnerability to psychotic disorder.

Schizophrenia Linked to Marijuana in Swedish Military: Schizophrenia is 2.4 times more likely in draftees with any marijuana use and 6 times more likely if used 50 times or more by age 20. There was no family history to explain the increased cases and they were typically of onset rapid often with paranoid features. Andreasson, Lancet ’88;i:592-3.

27 Year f/u of Swedish Military Study: BMJ 2002;325:1199 ( 23 November ); Virtually identical conclusions with further refinement of data. Finds marijuana the cause of 30% of schizophrenia developing in recruits which included 98% of Swede males. Stanley Zammit at the University of Cardiff, UK, evaluated data on over 50,000 men who had been Swedish military conscripts in 1969 and 1970. The new analysis revealed a dose-dependant relationship between the frequency of cannabis use and schizophrenia. This held true in men with no psychotic symptoms before they started using cannabis, suggesting they were not self-medicating.

Prospective New Zealand Study Proves Schizophrenia Causation: A birth cohort of 1037 individuals born in Dunedin, New Zealand, in 1972-3. Started measuring for psychosis age 11, drug use ages 15 and 18. 26 year f/u. First prospective study proving causation. divided the sample into three groups based on cannabis use at ages 15 and 18. The 494 controls (65.1% of the sample) had reported using cannabis "never" or "once or twice" at both ages; cannabis users by age 18 (236; 31.1%) first reported using cannabis "three times or more" at age 18; and cannabis users by age 15 (29; 3.8%) had reported using cannabis "three times or more" at age 15 (all of whom continued to use cannabis at age 18). Cannabis use is associated with an increased risk of experiencing schizophrenia symptoms, even after psychotic symptoms preceding the onset of cannabis use are controlled for, indicating that cannabis use is not secondary to a pre-existing psychosis. Secondly, early cannabis use (by age 15) confers greater risk for schizophrenia outcomes than later cannabis use (by age 18). The youngest cannabis users may be most at risk because their cannabis use becomes longstanding. risk was specific to cannabis use, as opposed to use of other drugs, and early cannabis use did not predict later depression. A tenth of the cannabis users by age 15 in our sample (3/29) developed schizophreniform disorder by age 26 compared with 3% of the remaining cohort (22/730). Our findings suggest that cannabis use among psychologically vulnerable adolescents should be strongly discouraged by parents, teachers, and health practitioners. Policy makers and law makers should concentrate on delaying onset of cannabis use. BMJ 2002;325:1212-1213 ( 23 November ); Cannabis use in adolescence and risk for adult psychosis: longitudinal prospective study; Louise Arseneault, Mary Cannon, Richie Poulton, Robin Murray, Avshalom Caspi, Terrie E Moffitt. While age 15 marijuana use was not related to later depression, young people who had used cannabis three times or more by age 18 were more likely to have a depressive disorder at age 26, even after use of other drugs was controlled for.

Schizophrenic Use Marijuana More Often Than Other Patients with Other Diagnosis: Lifetime prevalence cannabis higher in schizophrenia than with other psych Dx. Weller, Lancet, ’88;i:997.

Genetics Important in Abuse & Dependence: Ken Kendler of U Virginia in 335 female twin pairs says genetics moderate impact on probability of ever using and strong impact on risk of heavy use, abuse, and dependence with family and social environment playing big role in ever using but little role in developing heavy use or abuse. Am J Psychiatry ’98;155:1016-22

Marijuana Receptors: Cannabinoid receptor CB1 in brain neurons coupled via G proteins modulating adenylate cyclase and ion channels. CB@ in immune system inhibits adenylate cyclase. SR141716A a selective antagonist reduces alcohol intake in rats. Cannabinoids may also work through 5-HT receptors and regulate mesolimbic dopamine transmission. Which is a final common pathway for many drugs of abuse. Tolerance to cannabinoids is well established. The antagonist precipitate clear withdrawal symptoms. In mice which have been chronically exposed to THC. This reinforces already existing evidence that marijuana is addictive. With physical dependence. CB2 cannabinoid effects inhibit T-cell-dependent humoral immune responses. Anandamide a ethanolamide fatty acid which may be neurotransmitters. It activates CB1 similar to synthetic agonist CP55-940.n Stephen Stahl UCSD J Clin Psychiatry 11/98 59:566-7

Marijuana Linked to Schizotypal Personality: Higher scores on the Schizotypal Personality Questionnaire and the Magical Ideation Scale characterized the regular and past or occasional users compared with those who had never used cannabis. The co-occurrence of cannabis use and schizotypal traits appeared to be independent of anxiety and depression. 232 healthy 18-25yo studied. Lyon France. Psychiatry Res 2002 Jan 31;109(1):27-35

Thomas E. Radecki, M.D., J.D.

modern-psychiatry.com

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