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Marijuana Linked to Earlier Onset of Psychosis

Manifesti_LotteriaTripoli_194_mMarijuana (cannabis), thanks to the powerful depressing action of its active ingredient tetrahydrocannabinol (THC), is one of the oldest and most widely used means of self-medication against acute and chronic stress. THC users report experiencing a pleasurable state of relaxation, with heightened sensory experiences of taste, sound and color. In addition to its psychological effects, THC produces alterations in motor behavior, perception, cognition, memory, learning, endocrine function, food intake, and regulation of body temperature. The common perception is that, of all illegal drugs, marijuana may be the safest and least addictive—despite significant evidence that it causes side effects of fatigue, paranoia, memory problems, depersonalization, mood alterations, urinary retention, constipation, decreased motor coordination, lethargy, slurred speech, and dizziness, in addition to increased tolerance and addiction.

Impaired health including lung damage, behavioral changes, and reproductive, cardiovascular and immunological effects have been associated with regular marijuana use. Regular and chronic marijuana smokers may have many of the same respiratory problems that tobacco smokers have (daily cough and phlegm, symptoms of chronic bronchitis), as the amount of tar inhaled and the level of carbon monoxide absorbed by marijuana smokers is 3 to 5 times greater than among tobacco smokers. Smoking marijuana while shooting up cocaine has the potential to cause severe increases in heart rate and blood pressure. – NHTSA Fact Sheet

New research suggests that marijuana use may play a direct causal role in the development of psychotic disorders, including schizophrenia. An extensive meta-analysis of more than 443 studies comparing the age at onset of schizophrenia in individuals who used marijuana with the age at onset of schizophrenia in non–users yielded most sobering results.

Investigators at Prince Wales Hospital and the School of Psychiatry at the University of New South Wales in Sydney, Australia, found that the mean age at illness onset was more than 2.7 years earlier for cannabis users compared with nonusers. The age of onset did not significantly differ between alcohol users and nonusers. These results were published in the February 2011 issue of the Archives of General Psychiatry.

The results support the hypothesis that cannabis use plays a causal role in the development of psychosis… (and) suggest the need for renewed warnings about the potentially harmful effects of cannabis. – Matthew Large

In presenting the findings, lead study author Matthew Large, MBBS, Department of Mental Health Services concluded that the meta-analysis provides strong evidence for a relationship between marijuana use and earlier onset of psychotic illness and of a direct causal role in the development of psychosis in some more vulnerable individuals.