Cannabis chronic effects

Cannabis sativa plants contain at least 400 different compounds, of which as many as 60 are structurally related to 5 -tetrahydrocannabinol (5 -THC), the primary psychoactive constituent of cannabis. When cannabis is smoked, hundreds of additional compounds are produced by pyrolysis, which may contribute to both acute and chronic effects (Abood and Martin, 1992). The central nervous system actions of canna-binoids are mediated primarily through the CBj receptor. A second type of cannabinoid receptor, termed the CB2 receptor, is distributed primarily in the periphery (Gifford et ah, 1999). Activation of central cannabinoid receptors modulates neurotransmitter release at... 

Bowman M, Pihl RO (1973) Cannabis psychological effects of chronic heavy use a controlled study of intellectual functioning in chronic users of high potency cannabis. Psychopharmacologia 29 159-190... 

Comparison between alcohol and marijuana. It can be difl cult to evaluate the relative danger of marijuana without a comparison to alcohol. When a summary of the dangers of marijuana is reviewed, the drug may sound very damaging. But, most people are not aware of all of the dangers of alcohol and a review of the results of alcohol abuse may (or may not) have an impact on a person s assessment of the danger of marijuana. Clearly, alcohol is l al for adults over 21 to use and marijuana is not. Therefore, marijuana is inherently more dangerous to possess than alcohol. However, this analysis, conducted in the Cannabis Book, involves the acute and chronic effects of these substances. 

There are pharmacological, social and legal issues to consider in this context of drug dependence and, of course, drug users and abusers vary enormously. A chronic alcoholic is very different from a weekend user of cannabis and any consideration of the topic has to consider legal and social issues as well as pharmacological effects of the drugs. 

Given the low incidence of severe withdrawal symptoms and the modest effects on the mesolimbic dopamine (reward) system, most investigators have found that cannabis has a low abuse or addiction potential. However, it has been argued that if cannabis is a non-addictive substance, why is its use so widespread and why are there so many longterm and heavy users Finally, contrary to the evidence that cannabis can produce chronic tolerance, some regular users report that they require less drug to achieve the same high, or sensitisation (Chapter 3). Three possible explanations may account for this. First, chronic users may focus on the effects that they wish to achieve. Second, the... 

Route of administration alters the effectiveness of cannabinoids. Orally administered THC has a slower and more erratic absorption. THC was found to be 45 times more effective for analgesia after intravenous than after subcutaneous administration (Martin 1985). The pharmacokinetics of different chemical constituents of cannabis vary (Consroe et al. 1991). The elimination half-life of cannabidiol is estimated to be about 2-5 days, with no differences between genders. Comparably, the elimination half-life of Al-THC is approximately 4 days, and may be prolonged in chronic users (Johansson et al. 1988, 1989). 

The effects of cannabis on cognition is a complicated issue. Numerous studies have been conducted to measure the mental effects of cannabis, but many of these are fraught with methodological problems. Several variables must be controlled in this type of research, including the dosage and potency of cannabis used, route of administration (e.g., smoking, oral, etc.), chronicity of dose, and the subject population (nonusers, occasional users, chronic users) employed (table 10.7). Population makeup has a large effect on outcome because there have been differences demonstrated between naive and experienced cannabis users (Murray 1986). 

A study of experienced cannabis smokers tested them on cognitive measures using two doses (1.75% or 3.55%) and placebo (Wilson et al. 1994). The functions most sensitive to the effects of THC were mental processing speed (digit-symbol substitution) and reaction time. When compared with cannabis nonusers, chronic users of cannabis—with a mean duration of use of 6.76 years and an average daily intake of 150 mg of THC—were found to have slower reactions on perceptuo-motor tasks, but no differences on intelligence or memory tests (Varma et al. 1988). 

The cognitive effects of cannabis are mild, and have many variables (dosage, chronicity of use, cognitive task employed, etc.). Of prime importance in such studies is the usage (or misusage) of the term impair-... 

Wert RC, Raulin ML. (1986). The chronic cerebral effects of cannabis use I. Methodological issues and neurological findings. Int J Addict. 21(6) 605-28. 

Tolerance develops to many of A -THC s effects in heavy marijuana users. Although chronic cannabis use does not result in severe withdrawal symptoms, numerous case reports attest to development of dependence in subjects taking high doses of THC for several weeks. The most prominent symptoms were irritability and restlessness others included insomnia, anorexia, increased sweating, and mild nausea. Cessation of mild or moderate use of marijuana, however, does not produce a withdrawal syndrome. 

Tumor-promoting effect. A 28-year-old man who abused alcohol, nicotine, and cannabis for several years was investigated. He suffered simultaneously from a squamous cell carcinoma of the hypopharynx with bilateral cervical metastases, an adenocarcinoma of the transverse colon and a primary hepatocellular carcinoma. There were occurrences of three separate malignant tumors with different histologies in the aerodigestive tract, which could be related to a chronic abuse of cannabis . 

GS025 Lukas, M. G., and D. M. Temple. Some effects of chronic cannabis treatment. 

CS174 Dixit, V. P., M. AryaandN. K. Lohiya. The effect of chronically administered cannabis extract on the female genital tract of mice and rats. Endokrinologie 1975 66 365-368. 

Vieira, J. E. V., G. S. G. Barros, M. C. Medeiros, F. J. A. Matos, M. P. Souza and M. J. Medeiros. Pharmacologic screening of plants from Northeast Brazil. II. Rev Brasil Farm 1968 49 67-75. Dixit, V. P., V. N. Sharma and N. K. Lohiya. The effect of chronically administered cannabis extract on the testicular function of mice. Eur J Pharmacol 1974 26 111-114. Pinheiro de Sousa, M. and M. Z. Rouquayrol. Molluscicidal activity of plants from Northeast Brazil. Rev Bras... 

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