This most recent report by the British Advisory Council on the Misuse of Drugs provides a careful evaluation of cannabis. It recommends retaining the classification of cannabis as a Class C drug (along with valium, GHB and steroids) rather than upgrading it into Class B of more dangerous drugs such as amphetamines and barbiturates. Nevertheless it does describe cannabis use as a significant public health issue. With a few exceptions the report’s views coincide with my views on cannabis.
As a Class C drug a maximum prison sentence of 2 years is set for use while supply carries a maximum penalty of 14 years.
In Britain as in Australia cannabis use has decreased markedly (20-25%) over the past 5 years in all age groups.
Cannabis damages lungs but by less than cigarette smoking because less is smoked. Severe lung damage has been reported in heavy young users and there is the potential longer-term risk of lung cancer.
Cannabis damages the reproductive system in both males and females and causes low birth weights among pregnant women.
Cannabis can cause short-term psychotic effects - usually short-lived and responding to tranquilisers. A Danish study suggests half of those who contract a cannabis-induced psychosis experience repeat symptoms over 3 years although this may be due to continued cannabis use.
The incidence of cannabis psychoses has not been increasing.
Cannabis is the most common illicit drug found in the body fluids of those suffering motor vehicle injuries.
Dependence on cannabis is ‘unquestionably, a real phenomenon’. Significant numbers of young (under 18) and older cannabis users are dependent on cannabis.
Cannabis worsens the symptoms of schizophrenia and dealing with cannabis use (including dependence) is a major element of the treatment of many young males with this disorder.
The Council concluded that the evidence supports a causal link between use of cannabis in adolescence and the subsequent development of schizophrenia (page 18, para 8.10). Heavy users of cannabis have a 2-fold increase in the incidence of schizophrenia (page 19 para 8.10.1).
The Council was unclear whether cannabis use supported the ‘Gateway theory’ – that it led to use of more dangerous Class A drugs.
Cannabis impairs performance of tasks requiring sustained attention.
In preferred forms of cannabis (‘Sinsemilla’) THC concentration has doubled over the period 1995-2007.
The Council favours campaigns to drastically reduce cannabis use particularly among young people.