More on POT

In the Johns Hopkins study, head and neck tumors caused by the human papillomavirus (HPV), a common sexually transmitted virus, were most often linked to certain sexual behaviors and marijuana use, rather than tobacco and alcohol. The Johns Hopkins scientists also found that people with the viral-linked cancer were younger, more likely to be white, married, college-educated and have an annual income of $50,000 or higher.

Overall, the researchers detected HPV16 in 92 cancer patients. They found that HPV-positive cancers were associated with several measures of sexual behavior and exposure to marijuana but not with tobacco or alcohol use, or with poor oral hygiene. These associations became stronger with increasing numbers of oral sex partners, and with longer or more intense use of marijuana. In fact, among nonsmokers of tobacco, participants who smoked marijuana for at least five years were 11 times more likely to develop HPV-positive cancers.

Some reports show that chemicals in marijuana called cannabinoids could affect the immune system's ability to clear a viral infection,

This research was supported by the Damon Runyon Cancer Research Foundation, the State of Maryland Cigarette Restitution Fund, and the National Institute of Dental and Craniofacial Research.

Coauthors were Gypsyamber D'Souza, Ph.D.; William Westra, M.D.; Elizabeth Sugar, Ph.D.; Weihong Xiao, M.D.; Shahnaz Begum, M.D., Ph.D.; and Raphael Viscidi, M.D.

http://www.sciencedaily.com/releases/2008/03/080311165905.htm

many people in the community, as well as cannabis users themselves, believe that cannabis is relatively harmless and should be legally available . ScienceDaily (June 3, 2008) — Long-term, heavy cannabis use may be associated with structural abnormalities in areas of the brain known as the hippocampus and amygdala, The hippocampus, thought to regulate emotion and memory, and the amygdala, involved with fear and aggression Cannabis use also was associated with sub-threshold symptoms of psychotic disorders. "Although cannabis users performed significantly worse than controls on verbal learning.

The research study matches historic trends in cannabis use and exposure from a national population survey against estimates of new occurrences of schizophrenia in three English cities (Nottingham, Bristol and the London Borough of Southwark).

Exposure to cannabis grew fourfold over the thirty years to 2002, and its use among under-18s by 18-fold, say the researchers. If cannabis use causes schizophrenia, these increases in its use would lead to increases in overall schizophrenia incidence and prevalence of 29 per cent and 12 per cent respectively, between 1990 and 2010. (Incidence is defined as the frequency of new occurrences; and prevalence is the percentage of the population affected by the disease.)

Model projections suggest that if the association is confined to heavy cannabis users only, then approximately 10 per cent of schizophrenia cases may be due to cannabis by 2010.