Cannabis Linked to Depression, Schizophrenia
LONDON (Reuters) –
Smoking cannabis increases the odds of suffering from depression and schizophrenia, doctors said on Friday.
The occasional joint may not be harmful, but people who start using cannabis in their teens have a higher risk of later being diagnosed with a psychiatric disorder and the severity of the illness is linked to the length of exposure to the drug.
"Very young adolescents who use cannabis have an increased risk for developing schizoprehenia as adults and the most at risk are the youngest users," Dr Louise Arseneault, of Kings College in London, told Reuters.
Doctors do not understand how cannabis increases the risk of schizophrenia and depression but they suspect it affects the dopamine system in the brain which is associated with pleasure.
It is thought the drug can trigger the onset or relapse of schizophrenia in people predisposed to the illness and may also exacerbate the symptoms.
In a study of 1,037 people born in New Zealand between 1972-73, Arseneault found that those who began using cannabis as teens were four times more likely to suffer from psychiatric problems as adults than adolescents who did not use the drug.
"The earlier you start, the more vulnerable you are," she said.
Her findings, which are reported in The British Medical Journal, are supported by two other studies in the magazine which found similar results.
Researchers at the Murdoch Children's Research Institute in Victoria, Australia found that teenage girls who frequently used the drug were more likely to suffer from depression and anxiety than other adolescents.
Another study of more than 50,000 Swedish enlisted men showed the use of cannabis increased the risk of schizophrenia by 30 percent.
"These results indicate a potentially serious risk to the mental health of people who use cannabis, particularly in the presence of other risk factors for schizophrenia," Stanley Zammit of the University of Wales College of Medicine in Cardiff who worked on the Swedish study, said in the report.
Schizophrenia is the most common form of severe mental illness. The cause of the disorder, which is characterized by unusual behavior, delusions and hallucinations is unknown but scientists say it affects chemicals in the brain.
It usually begins in the late teens and early 20s.
"The link between cannabis and psychosis is well established, and recent studies have found a link between marijuana and depression," Joseph Rey and Christopher Tennant, of the University of Sydney in Australia, said in a commentary in the journal.
I already rebutted this in http://www.freerepublic.com/focus/news/821802/posts?page=57#57, to which you did not reply; rather dishonest of you to repost it.
by ROSIE MESTEL, Los Angeles Times [11/22/00]
Excerpts: MENTALLY ILL TWICE AS LIKELY TO BE SMOKERS, STUDY FINDS; TOBACCO: SPECIAL PROGRAMS MAY BE NEEDED TO ENCOURAGE PATIENTS TO QUIT, GIVEN THEIR ISOLATION AND TENDENCY TO USE NICOTINE TO FIGHT DEPRESSION, EXPERTS SAY.
Nearly half of all cigarettes purchased in the United States are smoked by people who suffer from mental illnesses, according to Harvard Medical School research.
Mentally ill people are roughly twice as likely to smoke cigarettes as those without mental illnesses, according to the research, published in today's Journal of the American Medical Assn. Not only does the habit put them at greater risk for serious ailments such as heart disease and lung cancer, but in some cases it can interfere with the effectiveness of medications to treat their disorders.