Cannabis (drug)

:This article is about cannabis used as a drug. For other uses, see cannabis.

Long-term effects of human consumption

Main article: Health issues and the effects of cannabis

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There is little conclusive scientific evidence about the long-term effects of human cannabis consumption. The findings of earlier studies purporting to demonstrate the effects of the drug are unreliable, as the studies were flawed, with strong bias and poor methodology. The most significant confounding factor is the use of other drugs, including alcohol and tobacco, by test subjects in conjunction with cannabis. When subjects using only cannabis were combined in the same sample with subjects using other drugs as well, researchers could not reach a conclusion as to whether their findings were caused by cannabis, other drugs or the interaction between them.

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Tolerance, withdrawal and dreams

Although use may become habitual, the extent of physical dependence to cannabis is unknown. (DEA, 2004) Many animal and human studies conducted since the 1970s have revealed cannabis withdrawal symptoms in some people after abstinence from heavy use which is usually characterized by a period of anxiousness, sleeplessness, more vivid and memorable dreams, (REM rebound), irritability, and diminished appetite after cessation of use. Because cannabis is a psychedelic, unlike typical depressant or stimulant drugs, these persistent effects are typically not as severe as those normally associated with physical dependence.

Related Topics:
Physical dependence - DEA - 1970s - Sleeplessness - REM - Psychedelic - Depressant - Stimulant

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THC molecules break down quickly after ingestion, although some components can be detected for a period of up to a month after use. Although these components are not proven to have any ongoing physical or mental effects in themselves? users do not report getting "high" on residual THC metabolites? THC's long half-life, working its way out of the body slowly over many days, reduces the potential to cause severe physical withdrawal symptoms. (Markel 2002)

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Long-term effects on the mind and brain

There is a growing body of medical evidence to show a link in some people between cannabis use and psychosis, schizophrenia, and clinical depression. Some believe that cannabis may trigger latent conditions or be part of a complex coordination of causes, referred to as the diathesis-stress model in psychology. On the other hand, many people with pronounced psychological disorders, especially schizophrenia and depression, often self-medicate their illness with cannabis in place of potent main-stream drugs like antipsychotics, due to cannabis's relatively low side effects and calming physiological effects that alleviate symptoms. Though cannabis has been used for thousands of years, and has been increasingly popular in the west since the 1960s it is only since the 1990s that the link between cannabis and psychosis has been identified.

Related Topics:
Psychosis - Schizophrenia - Clinical depression - Diathesis-stress model - Psychology - Self-medicate - Antipsychotics

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One concern with research that identified correlation between cannabis use and psychotic illness has been that, where cannabis is thought to be helpful in treating medical conditions, a correlation may easily be drawn which does not imply causality attributable to cannabis. Recent research has addressed this concern by studying large groups free of mental illness, to examine the proportion of individuals that already use cannabis who go on to develop mental illnesseshttp://www.ukcia.org/research/CannabisUseInAdolescenceAndRiskForAdultPsychosis.pdf.

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Further evidence for causality was provided by a 2005 studyhttp://www.ukcia.org/research/COMTgene.pdf showing the existence of a genetic predisposition to cannabis related symptoms of psychosis, showing significant correlation between genetic factors, cannabis use and symptoms of psychotic illness. The study demonstrates that adolescent cannabis usage is a predictor for symptoms of adult psychosis in the estimated 25% of the population with these genotypeshttp://www.timesonline.co.uk/article/0,,3561-1565337,00.html. The study is adjusted for prior evidence of mental illness, and for several other alternative explanations. This argument is still hotly disputedhttp://www.cannabisireland.com/health_2.html http://www.alternet.org/drugreporter/21436/, and research is ongoing.

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Some claim that extended use of cannabis may help a human reach a higher level of mental consciousness and clarity, expanding the mind and helping individuals become more aware, insightful and intelligent.

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These claims may seem to be contradictory while indicating differing views of a common effect.

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Long-term physical effects of smoking

The combustion of any organic material creates irritants and carcinogens, and cannabis is no different. The long-term effects of smoking any substance depends on frequency of use, duration of inhalation, and composition of the smoke. This leads many to assume that the effects of cannabis can be directly compared to other well-known smoking materials such as tobacco. However, direct, volume-for-volume comparisons of the two are probably invalid because the chemical composition and methods of usage are not the same. Studies on the subject are inconclusive and have not isolated all the possible factors exacerbating or ameliorating the effects of cannabis user. Here are some of these factors:

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Possibly exacerbating factors:

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• Studies have pointed out that cannabis produces more tar and burns at a higher temperature than tobacco.
• Many cannabis smokers inhale the smoke more deeply and hold it in their lungs for a longer period of time.

Possibly ameliorating factors

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• Generally, even a chronic cannabis user does not inhale a daily volume of smoke equal to even a significant fraction of that of a tobacco smoker.
• Cannabis smoke does not tend to penetrate to the smaller, peripheral passageways of the lungs, concentrating rather on the larger, central passageways.
• Industrialized cultivation and preparation of tobacco introduces a variety of toxic and carcinogenic additives and congeners such as nitrosamines, arsenic, radium-226, and polonium-210. This problem does not pertain to cannabis, the vast majority of which is grown in wild, organic, or hydroponic conditions.
• There is evidence to suggest that cannabinoids present in cannabis may actually serve to protect against cancer. http://ehp.niehs.nih.gov/docs/2000/108-10/correspondence.html#thc

While some studies have claimed a positive correlation between cannabis use and lung cancer, this might primarily indicate only that cannabis use may correlate with tobacco use, and more objective scientific attention is needed to separate these and other factors in order to better understand the potential long-term physiological effects of cannabis use itself. Updated reports seem to suggest that when the data is properly analyzed, the correlation may in fact be negative.http://www.counterpunch.org/gardner07022005.html

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