RESEARCH SHATTERS MYTH THAT CANNABIS IS SAFE DRUG

FAR from being a relatively harmless "soft" drug, cannabis can drive people
temporarily insane, as well as harming the heart, lungs and immune system,
scientists said yesterday .

Studies showed that the drug can have serious effects on both mental and
physical health.

Dr Andrew Johns, from the Institute of Psychiatry in London, said regular
cannabis use led to acute psychological problems in a high proportion of
people.

One study found that 15 percent of cannabis users identified psychotic
symptoms, such as hearing voices or irrational feelings of persecution. And
a number of reports, reviewed by Dr Johns in the British Journal of
Psychiatry, suggested that the drug could induce psychosis in people with
no history of severe mental illness.

Heavy cannabis use could lead to a state resembling acute schizophrenia. In
this case, the drug was thought to trigger off an underlying illness.

Cannabis was also associated with high rates of other forms of mental
illness, such as adjustment disorder, and major depression.

It appeared to worsen the condition of people already suffering from
schizophrenia, with users experiencing more and earlier psychotic relapses.

Dr Johns wrote: "An appreciable proportion of cannabis users report
short-lived adverse effects, including psychotic states following heavy
consumption, and regular users are at risk of dependence. People with major
mental illnesses such as schizophrenia are especially vulnerable in that
cannabis generally provokes relapses and aggravates existing symptoms.

"Health workers need to recognise, and respond to, the adverse effects of
cannabis on mental health."

In another review published by the journal, Professor Heather Ashton, from
the University of Newcastle, pointed out that cannabis affected almost
every bodily system.

As well as producing severe anxiety, panic, paranoia and psychosis in high
doses, it also impaired memory and concentration, and had a number of
physical effects.

These included heart problems that might be serious for people with
preexisting cardiac disease, and suppression of the immune system.