Cannabis, also known as grass, pot or marijuana, has spurred abundant controversy over the past century. In the UK this conflict reached a turning point in January 2004, when the British government downgraded cannabis from a class B drug to a class C drug, causing widespread concern among health care workers and the general public. In the light of the research on cannabis, the British government responded with a new initiative that reclassified it as a class B drug in January 2009. (1,2) However, not all EC countries share this view on cannabis legislation. In the Netherlands a softer approach is preferred, and possession of small amounts of cannabis is legal according specific regulations in particular locations called 'coffee shops'. The argument is that 'Coffee shops are tolerated in the attempt to keep young people, who experiment with cannabis, away from other much more dangerous drugs'. (3)
In the USA, a law passed in 1944 legally banned research on cannabis for medical purposes. This law was based on a committee report by the then New York mayor, Fiorello LaGuardia, (4) in which he stated that cannabis consumption leads to tolerance, resulting in a need for a higher dose to achieve the same effect. The law was introduced by Harry J Anslinger from the Federal Bureau of Narcotics and was amended in 1962 after his retirement. (5) The discussion of cannabis legalisation continues today. A recent event was the passing of the first marijuana decriminalisation law on 4 November 2008 in Massachusetts, USA, which reduced the legal consequences of possession of small amounts of cannabis. (6)
Cannabis is significant not only in terms of the conflict that rages over its legal status, but also because of its widespread use and the resulting legal and medical costs. Cannabis is estimated to be the world's third most popular recreational drug, following alcohol and tobacco, with an estimated 160 million people (4% of the world's population) using cannabis annually. (7) This widespread use is particularly worrying in the light of data that have established cannabis use as a non-genetic risk factor associated with schizophrenia. (10) Its ability to induce psychosis was first documented by the French psychiatrist Moreau de Tours in 1845. (11) Furthermore, patients with subclinical psychoses have poorer outcomes and require more clinical care when they are exposed to cannabis. (12)
In terms of years of potential life lost (YPLL), cannabis rated higher than cocaine in Australia for the period 1997-2004, (14) the YPLL for cannabis being 9.46 years and that for cocaine 6.91 years. Other recreational drugs, such as heroin (61.22 years) and alcohol (40.02 years), rated higher. In a study in Ohio, USA, conducted from 1998 to 2002, it was found that 59 cannabis users died during this time period, compared with 35 cocaine-related deaths. (15) Both these studies indicate that in terms of potential loss of life the cost of cannabis to societies is higher than that of cocaine.
In contrast to these harmful aspects of cannabis is its beneficial use as a medicinal drug. Cannabis exhibits analgesic properties that have been used in people with chronic pain, as well as to provide relief from spasticity in multiple sclerosis. (8) Cannabis (under the trade name Marinol) is currently available for medical use in the USA to relieve nausea and vomiting associated with chemotherapy in cancer patients, as well as to prevent loss of appetite associated with AIDS. (9)
The various aspects of cannabis have been described in numerous publications over the years. These aspects have never been scientometrically examined. The objective of this study was therefore to analyse trends in cannabis research from 1900 to 2008 in terms of publication date, countries of origin, main topics, and main research areas of the 10 most published authors. We were also interested in comparing cannabis with other harmful substances (alcohol, tobacco, cocaine and heroin) with regard to the number of publications relative to the number of respective users. …