Pubdate: Tue, 20 Dec 2005 Source: Medical Post (Canada) Copyright: 2005 The Medical Post Contact: http://www.medicalpost.com/ Details: http://www.mapinc.org/media/3180 Author: Karen Birchard CANNABIS-INDUCED PSYCHOSIS LINKED TO SCHIZOPHRENIA: STUDY LONDON - A Danish study has found that almost half of all patients who are treated for cannabis-induced psychosis go on to develop some form of schizophrenia. Almost one-third go on to be diagnosed with paranoid schizophrenia. The researchers, writing in the British Journal of Psychiatry, said in the study, those who used cannabis showed schizophrenic symptoms earlier than those who were not users. The team from Aarhus University Hospital said there's been very little research carried out on people with schizophrenic symptoms who were known users of cannabis despite knowledge that cannabis has been linked to mental illness. This study is the first to show that temporary mental problems due to cannabis use are often followed by psychiatric illness. The researchers followed 535 patients for three years. All had been treated for cannabis-induced psychosis. They were compared with more than 2,700 people with schizophrenia-spectrum disorders who had no history of cannabis-induced illness. Forty-five per cent of the 535 went on to develop schizophrenic disorders. More than 72% went on to suffer from other mental illnesses such as depression. Only about 15% required no further psychiatric treatment after their initial cannabis-induced psychosis. The researchers then compared the ages when schizophrenic symptoms were noticed and found the drug users were much younger than those who hadn't used cannabis. The men showed symptoms, on average, at 24.6 years, compared with 30.7 years in the comparison group. For women, the age was 28.9 years for the drug users compared with 33.1 years.