SCIENTISTS LIST MENTAL RISKS FROM SMOKING CANNABIS

Cannabis smoking - besides causing harm to heart, lungs and the immune
system - can lead to temporary bouts of mental illness.

Scientists report today in the British Journal of Psychiatry that
regular use may make things worse for people who have mental health
problems, and lead to panic attacks and anxiety in those who do not.

Andrew Johns of the Institute of Psychiatry at the Maudsley hospital
in south London surveyed a number of recent studies. One found that
15% of users identified psychotic symptoms or irrational feelings of
persecution. Other reports suggested the drug could induce psychosis
in people with no history of severe mental illness.

Those with mental illness - living in the community, and as likely as
anybody else to get hold of the drug - were even more at risk. "People
with major mental illnesses such as schizophrenia are especially
vulnerable, in that cannabis generally provokes relapses and
aggravates existing symptoms," Dr Johns said.

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

Researchers are testing cannabis as a potential medicinal drug - there
are claims that it can quell nausea during chemotherapy, relieve
glaucoma and stifle the pain of multiple sclerosis - but smoking
marijuana also imposes a price.

Last year US researchers showed that squirrel monkeys found the drug
addictive, and a Boston team reported that, an hour after inhaling,
the risk of heart attack increased fivefold.

Heather Ashton, of the University of Newcastle, reports in the same
journal that besides producing severe anxiety, panic, paranoia and
psychosis in high doses, cannabis impaired memory and
concentration.

There could be heart problems for people with pre-existing cardiac
disease, and the drug also suppressed the immune system. Cannabis
cigarettes could be as addictive as nicotine, and the tars from
cannabis cigarettes contained higher levels of some cancer-causing
chemicals than tobacco.

Smoking three or four reefers a day produced the same risk of
bronchitis or emphysema as 20 or more cigarettes.

Chronic use might also cause complications in pregnancy and
childbirth.