Health issues and the effects of cannabis

For other articles on health aspects of cannabis please see Medical Marijuana and Cannabis (drug). For other aspects please see cannabis.

Despite the controversy surrounding the effects of cannabis (marijuana), some of the medical effects are not disputed.

Contents

1 Smoking

2 THC

3 Physiological effects

4 Cannabis and driving

5 Effect on mental health

6 External links

Smoking

Cannabis smoking is assumed often to be capable of causing several of the same health problems as tobacco smoking, such as bronchitis and bronchial asthma. The effects of cannabis on the lungs can be however very different: it may actually relieve symptoms of bronchitis, asthma, and strep throat. Also there is some evidence that cannabis may serve a harm-reduction function in relation to tobacco addiction, by enabling lungs to clear themselves of tar deposits, and it should be noted that while a habitual tobacco smoker may consume twenty to forty cigarettes (one to two packs) in a day, a habitual marijuana cigarette (joint) smoker consumes far fewer. It should also be noted, however, both that marijuana burns at a higher temperature than tobacco, and that marijuana users usually inhale much deeper breaths (hits) and hold them in for much longer in order to absorb as much of the tetrahydrocannabinol (THC) in the smoke as possible.

Many marijuana users wishing to minimize risks of lung damage instead choose to either eat their dosages or use water pipes or vaporizers, which are known to considerably reduce and perhaps, in the case of vaporizers, eliminate lung damage. Although very limited research has been conducted on the effects of cannabis when consumed orally, it is commonly theorized that its harm is negligible, undoubtedly far less harmful than oral consumption of alcohol. Water pipes, while they do filter out many impurities, may also reduce the concentration of THC, necessitating inhalation of a greater quantity of smoke in order to receive the same amount of THC as that in an unfiltered marijuana cigarette; this may lead to a greater amount of lung damage. Inhalation of any amount of smoke is widely considered to be unhealthy, as smoke nearly always contains known toxins. A 2000 study conducted by NORML and MAPS found that the unfiltered joint outperformed all devices except the vaporizers, with a ratio of about 1 part cannabinoids to 13 parts tar. This ratio is still rather low; according to the report, "This disturbingly poor ratio may be explained by low potency (2.3%) of the NIDA-supplied marijuana used in the study"[1] (http://www.growkind.com/vaporizer-study.html).

THC

The THC molecule and related compounds are usually detectable in drug tests for approximately one month after using cannabis. This detection is possible because THC metabolites are stored for long periods of time in fat cells and THC has an extremely low water solubility, although the harmfulness of that phenomenon has not yet been well-researched. The long-term metabolites are nonidentical to THC, and are not considered psychoactive.

Physiological effects

Some of the effects of marijuana use include increased heart rate, dryness of the mouth, reddening of the eyes, impaired motor skills and concentration, and frequently hunger which is often accompanied by greater enjoyment of food's taste and aroma.

Cannabis and driving

One highly controversial aspect of cannabis use is its effect on one's ability to drive an automobile. Studies on the subject have been limited, and generally have not taken into account relevant factors such as age and alcohol intoxication. Most studies that have taken these factors into account have concluded that cannabis' effect on driving ability is negligible, and may be more positive than negative, due to the tendency of intoxicated individuals to drive slower and more cautiously.

The United Kingdom's Transit Research Laboratory (TRL) concluded in a 2001 study that cannabis intoxication plays a relatively insignificant role in vehicular accidents. Specifically, intoxicated individuals had a lowered "tracking time" (ability to control the steering wheel) but were otherwise normal and, unlike alcohol (which reduces activity in the part of the brain that recognizes and responds to risks), participants were aware of the effects and compensated by driving more slowly and cautiously.

Similar conclusions have been reached by studies maintained by the federal governments of Australia, United Kingdom, New Zealand and the United States (see here (http://www.scotland.gov.uk/cru/kd01/blue/druguse-15.htm) for a list of studies). Those studies that have concluded that cannabis has a significant negative effect on driving ability generally involve the use of roadside sobriety tests as an indicator of reduced ability. For example, see this NIDA report (http://www.nida.nih.gov/NIDA_Notes/NNVol11N1/marijuana.html). However, in most of these studies, the majority of subjects who tested positive for THC also tested positive for alcohol, making it difficult to single out THC's effect on driving.

Effect on mental health

There is no hard evidence that cannabis causes a deterioration in mental health; however, there are many studies that show a strong correlation between mental health problems and cannabis usage. This could be a causal relationship, or it could be that people who are susceptible to mental problems tend to smoke cannabis, or it couild be connected to the criminalization of cannabis. There has not currently been enough scientific study of the drug's effects to come to a definite conclusion.

A recent Dutch study of 4,000 people in the general population showed that those who admitted taking large amounts of cannabis were almost seven times more likely to have psychotic symptoms three years later.

Another landmark study, in 1987, of 50,000 Swedish Army conscripts, found that those who admitted at age 18 to having taken cannabis on more than 50 occasions, were six times more likely to develop schizophrenia in the following 15 years. However, critics state that this study was hampered by the fact that the psychosis cases were restricted to patients requiring a hospital admission, and a lack of information on drug use over the follow-up period. Furthermore, these findings have not been replicated in another population based sample. Template:Journal reference

There is a classification of psychosis within the DSM-IV called 'cannabis psychosis' which is very rare. In susceptible individuals ingestion of sufficient quantities of the drug can trigger a psychotic event. This will recede if the drug is removed. Studies into potential effects on psychosis and schizophrenia have not been conclusively demonstrated.

However a recent review of the evidence by Louise Arsenault, et al 2004 (http://bjp.rcpsych.org/cgi/content/full/184/2/110) reports that on an individual level, cannabis use confers an overall twofold increase in the relative risk for later schizophrenia. Cannabis use appears to be neither a sufficient nor a necessary cause for psychosis. It is a component cause, part of a complex constellation of factors leading to psychosis.