Posted by SalArmy4me on August 28, 2001, at 2:59:28
In reply to Re: Bipolar II, Caffeine, Nicotine, THC » rosieshepherd, posted by Ron Hill on August 25, 2001, at 16:43:52
The British Journal of Psychiatry
© 2001 The Royal College of Psychiatrists
Volume 178 February 2001 pp 101-106
Pharmacology and effects of cannabis: a brief review†"There is considerable evidence, reviewed by Hall et al (1994), that performance in heavy, chronic cannabis users remains impaired even when they are not actually intoxicated. These impairments, especially of attention, memory and ability to process complex information, can last for many weeks, months or even years after cessation of cannabis use (Solowij, 1998). Whether or not there is permanent cognitive impairment in heavy long-term users is not clear.
Cannabinoids produce a dose-related tachycardia which may reach rates of up to 160 beats/minute or more, although tolerance develops with chronic use. There is also a widespread vasodilation and reddening of the conjunctivae, a characteristic sign of cannabis use (Paton & Pertwee, 1973). Postural hypotension and fainting may occur. These and other cardiovascular effects may carry a risk for individuals with preexisting cardiac disease, and several cases of acute and sometimes fatal cardiac incidents have been reported in young cannabis smokers.
Effects on the respiratory system
The smoke from herbal cannabis preparations contains all the same constituents (apart from nicotine) as tobacco smoke, including carbon monoxide, bronchial irritants, tumour initiators (mutagens), tumour promoters and carcinogens (British Medical Association, 1997). The tar from a cannabis cigarette contains higher concentrations of benzanthracenes and benzpyrenes, both of which are carcinogens, than tobacco smoke. It has been estimated that smoking a cannabis cigarette results in approximately a fivefold greater increase in carboxyhaemoglobin concentration, a three-fold greater amount of tar inhaled and retention in the respiratory tract of one-third more tar than smoking a tobacco cigarette (Wu et al, 1988; Benson & Bentley, 1995). This is mainly due to the way a cannabis joint is smoked, with deep and prolonged inhalation and no filter. In addition, cannabis has a higher combustion temperature than tobacco.Chronic cannabis smoking is associated with bronchitis and emphysema. It has been calculated that smoking 3-4 cannabis cigarettes a day is associated with the same evidence of acute and chronic bronchitis and the same degree of damage to the bronchial mucosa as 20 or more tobacco cigarettes a day (Benson & Bentley, 1995). Prospective studies of the long-term effects on the lungs of chronic cannabis smoking are lacking, but some authors suggest that chronic airways disease and bronchogenic carcinoma may be as great a risk as with tobacco smoking. In addition, there appears to be an increased incidence of rare forms of oropharyngeal cancer in young people who smoke cannabis chronically.
Effects on other systems
Cannabis also has immunosuppressant and endocrine effects although the clinical significance of these is still not clear. Chronic cannabis use appears to carry reproductive risks, both to the mother during pregnancy and childbirth and to the foetus and neonate, although these areas need further study. The full extent of long-term health risks of chronic cannabis use (if today's young smokers continue the habit) may require a latent period of 10-20 years to be revealed.CLINICAL IMPLICATIONS
* Cannabis use is associated with increased risk of road, rail and air traffic accidents.
* Chronic cannabis use can result in tolerance, dependence, withdrawal effects and possibly long-term cognitive impairment.
* Long-term cannabis use carries respiratory, cardiovascular and other health risks."
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thread:76104
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