Schizophrenia Rarer Than Previously Thought

More Common in Developed Countries, Say Researchers

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May 31, 2005 -- SchizophreniaSchizophrenia may be less common than experts previously thought.

Until now, the often-quoted statistic was that schizophrenia strikes about one in 100 people, say Australian researchers. That's an overestimate, they write in the Public Library of Science Medicine's May issue.

"If we wish to provide the general public with a measure of the likelihood that individuals will develop schizophrenia during their lifetime, then a more accurate statement would be that 'about seven to eight individuals per 1,000 will be affected,'" write the researchers, who included University of Queensland psychiatry professor John McGrath, MD, PhD.

About Schizophrenia

Schizophrenia is a severe, often disabling brain disease that can trigger hallucinations, delusions, paranoia, and a significant lack of motivation. It can affect a person's thoughts, emotions, and ability to interact appropriately with others.

Schizophrenia does not involve multiple or "split" personalities. The disease often starts in early adulthood and requires lifetime treatment. "Despite optimal treatment, approximately two-thirds of affected individuals have persistent or fluctuating symptoms," write researchers.

A World of Research

McGrath and colleagues reviewed 188 studies on schizophrenia. The studies came from 46 countries including Argentina, China, Iran, New Zealand, Russia, South Africa, and the U.S.

Among their findings:

  • Schizophrenia is more common in developed countries than in developing nations.
  • Similar rates of schizophrenia were seen among men and women, as well as urban and rural residents.
  • Schizophrenia rates were nearly twice as high for immigrants as for native-born people.

The findings about developed and developing countries should be viewed cautiously, say the researchers, since it's hard to sum up a country by a single economic variable.

McGrath and colleagues also say they were surprised to see similar rates for men and women and for people living in urban and rural areas. Their previous research had indicated higher rates for men and city dwellers.

Best-Case Scenario

More research about schizophrenia is needed, say the researchers. Even in a perfect world with unlimited funding, only a quarter of schizophrenia's burden could be avoided with current interventions, they write.

As for schizophrenia's frequency, there was "substantial variation" among the countries, say McGrath and colleagues. There was also significant difference based on what period of time was examined, from less than one month to a lifetime. Estimates ranged from 3.3 to 7.2 per 1,000 people with schizophrenia.

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SOURCES: Saha, S. Public Library of Science Medicine, May 2005; vol 2: pp 413-433. WebMD Medical Reference from Healthwise: "Schizophrenia: Topic Overview." WebMD Medical Reference from Healthwise: "Schizophrenia: Treatment Overview." News release, Public Library of Science.
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