For several decades there have been concerns about the dangers of cannabis, risks that were not recognised in the heady days of the 1960s, when 'weed' was all the rage.
The campaign to decriminalise it began in earnest then and reached its apogee in Holland when in the 1970s it was decided to tolerate the use of small amounts and allow the sale of this substance to those over the age of 18 in 'coffee shops', although its purchase anywhere else was prohibited.
However, in Holland restrictions have again been placed on the sale of cannabis with coffee houses now having to function as private clubs, since the sale of the substance is allowed only to their members.
The reason for these new regulations is to eliminate drug tourism and to limit the use of cannabis, which now has higher concentrations of tetrahydrocannabinol (THC) than previously, and is associated with higher toxicity than previously.
A further harbinger of a change in attitude was the changing position by a British newspaper, 'The Independent', which had vigorously campaigned for the decriminalisation of cannabis since 1997.
In 2007 it did a volte face and apologised saying "If only we had known then what we can reveal today . . ." This was prompted by new information on the dangers of cannabis due to the higher concentrations of THC -- these strains are sometimes referred to as 'skunk'.
Interest in the possibility of adverse reactions to cannabis is not new. More than 25 years ago a group of Swedish conscripts were studied and that study found that heavy cannabis use by the age of 18 increased the risk of schizophrenia six-fold, although it could not establish if this was because of pre-existing symptoms.
Then in 2000 and 2002 two papers were published on the Dunedin group of children, born in 1972 and now followed into their third decade. These studies took account of pre-existing symptoms and concluded that about one-tenth of those using cannabis by the age of 15 developed a schizophrenic type illness in comparison to 3pc of non-users.
The investigators concluded that certain young users were at increased risk of developing a psychotic illness if they misused cannabis regularly.
This same research group has now examined another aspect of cannabis use in the Dunedin cohort -- namely, whether it causes any change in intelligence over time. The follow-up of the original 1,000 subjects has now lasted for almost 40 years.
Their IQ was assessed as children -- before any had started using cannabis -- and then re-examined repeatedly. The team, now headed by Dr Madeline Meier of Duke University in North Carolina, published the results in US journal 'Proceedings of the National Academy of Sciences' last week.
Having taken into account other factors such as alcohol or tobacco dependency, other drug use and the number of years spent in education, they found that those who persistently used cannabis suffered a decline in their IQ.
Source: Irish Independent, 03/09/12
Safer Student Nights
eBulletin
Poll
