CANNABIS AND SCHIZOPHRENIA

Cannabis Is Causing Treatment-Resistant Forms of Schizophrenia

Sir: It is true that cannabis cannot "cause" schizophrenia, largely an
inherited condition (report, 21 July). What cannabis does is to increase the
risk of a first-episode psychosis in people genetically predisposed to
developing schizophrenia.

There is undoubtedly a trend for young people to be first exposed to
cannabis at an earlier age, in their early teens or before. First, it
brings forward the onset of schizophrenia in those predisposed
individuals, producing forms of the illness more likely to be
treatment-resistant. Second, the effect of cannabis on the still
developing brain is largely unknown.

There are two large categories of young people who develop psychosis,
distinct from schizophrenia: one, triggered directly by cannabis use,
is "drug-induced psychotic disorder", and in the other, "acute and
transient psychotic disorder", cannabis is often implicated.

Both conditions can be debilitating, with frightening symptoms lasting
months, and huge disruption to family and college life, often
requiring admission to in-patient mental health facilities.

The work of my team, which was set up to help young people (aged
between 15 and 35) suffering their first-episode psychosis would be
greatly reduced if cannabis did not exist. The"skunk" now plentiful in
Britain, three times the strength of the usual "home-grown" variety,
induces paranoia and hallucinations more frequently. It is similar to
the difference between knocking back two pints of ale and two pints of
wine.

Unless we are able to develop creative programmes for really engaging
young people with this issue in schools and colleges more youngsters'
careers will be blighted and more families will suffer the misery of
preventable mental illness.

Dr Charles Montgomery

Consultant Psychiatrist, Wonford House Hospital, Exeter