In the first worldwide study of its kind, scientists from Toronto's Centre for Addiction and Mental Health (CAMH) found evidence that heavy methamphetamine users might have a higher risk of developing schizophrenia. This finding was based on a large study comparing the risk among methamphetamine users not only to a group that did not use drugs, but also to heavy users of other drugs.
The report will be published online on Nov. 8, 2011, at AJP in Advance, the advance edition of the American Journal of Psychiatry, the official journal of the American Psychiatric Association.
Methamphetamine and other amphetamine-type stimulants are the second most common type of illicit drug used worldwide.
"We found that people hospitalized for methamphetamine dependence who did not have a diagnosis of schizophrenia or psychotic symptoms at the start of our study period had an approximately 1.5 to 3.0-fold risk of subsequently being diagnosed with schizophrenia, compared with groups of patients who used cocaine, alcohol or opioid drugs," says Dr. Russ Callaghan, the CAMH scientist who led the study. Dr. Callaghan also found that the increased risk of schizophrenia in methamphetamine users was similar to that of heavy users of cannabis.
To establish this association, the researchers examined California hospital records of patients admitted between 1990 and 2000 with diagnosis of dependence or abuse for several major abused drugs: methamphetamine, cannabis, alcohol, cocaine or opioids. They also included a control group of patients with appendicitis and no drug use. The methamphetamine group had 42,412 cases, while cannabis had 23,335.
Records were excluded if patients were dependent on more than one drug or had a diagnosis of schizophrenia or drug-induced psychosis during their initial hospitalization. Readmission records within California hospitals were analyzed for up to 10 years after the initial admission. The researchers then identified patients who were readmitted with a schizophrenia diagnosis in each drug group.
There has been a longstanding debate as to whether there is a connection between methamphetamine use and schizophrenia. Many Japanese clinicians have long believed that methamphetamine might cause a schizophrenia-like illness, based on their observations of high rates of psychosis among methamphetamine users admitted to psychiatric hospitals. However, they lacked long-term follow-up studies of methamphetamine users initially free of psychosis. In North America, this link has mostly been discounted, as psychiatrists believed that the psychosis was already present and undiagnosed in these methamphetamine users.
"We really do not understand how these drugs might increase schizophrenia risk," says Dr. Stephen Kish, senior scientist and head of CAMH's Human Brain Laboratory. "Perhaps repeated use of methamphetamine and cannabis in some susceptible individuals can trigger latent schizophrenia by sensitizing the brain to dopamine, a brain chemical thought to be associated with psychosis." Dr. Kish also cautions that the findings do not apply to patients who take much lower and controlled doses of amphetamines or cannabis for medical purposes.
Since this is the first such study showing this potential link, the researchers emphasize that the results need to be confirmed in additional research involving long-term follow-up studies of methamphetamine users.
"We hope that understanding the nature of the drug addiction-schizophrenia relationship will help in developing better therapies for both conditions," says Dr. Callaghan.
In an earlier study using California hospital records, the researchers found evidence for a possible association between heavy methamphetamine use and Parkinson's disease.
Media Contact: Michael Torres, Media Relations, CAMH; 416-595-6015
The Centre for Addiction and Mental Health (CAMH) is Canada's largest mental health and addiction teaching hospital, as well as one of the world's leading research centres in the area of addiction and mental health. CAMH combines clinical care, research, education, policy development and health promotion to help transform the lives of people affected by mental health and addiction issues.
CAMH is fully affiliated with the University of Toronto, and is a Pan American Health Organization/World Health Organization Collaborating Centre.
Michael Torres | EurekAlert!
Multi-year study finds 'hotspots' of ammonia over world's major agricultural areas
17.03.2017 | University of Maryland
Diabetes Drug May Improve Bone Fat-induced Defects of Fracture Healing
17.03.2017 | Deutsches Institut für Ernährungsforschung Potsdam-Rehbrücke
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...
20.03.2017 | Event News
14.03.2017 | Event News
07.03.2017 | Event News
24.03.2017 | Materials Sciences
24.03.2017 | Physics and Astronomy
24.03.2017 | Physics and Astronomy