- NEW YORK (Reuters
Health) - Urban dwelling has never been known for its soothing effects,
but new research suggests that people living in large cities are more likely
than small-town residents to exhibit psychotic-like symptoms such as paranoia
and delusions.
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- In a study of more than 7,000 people in the Netherlands,
investigators found that both full-blown psychotic disorders and milder
psychosis-like symptoms were more common among those living in urbanized
areas. The link was most apparent among people born and raised in densely
populated areas, suggesting that childhood environment may create ``enduring
liabilities'' for adult psychiatric health, according to the researchers.
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- Dr. Jim van Os of Maastricht University and colleagues
report the findings in the July issue of the Archives of General Psychiatry.
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- The researchers divided the study participants into groups
living in one of five levels of urbanization, which were based on population
density. Through interviews, van Os and his colleagues determined that
the prevalence of psychiatric symptoms increased along with participants'
level of urbanization.
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- In the overall population, the prevalence of any type
of psychotic symptoms over a lifetime was about 4% to 17%, depending on
the definition of symptoms. The investigators looked at the number and
severity of symptoms such as feelings of persecution or auditory hallucinations.
Only about 1% suffered mental illnesses such as major depression, and even
fewer had been affected by schizophrenia-like disorders.
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- The fact that such symptoms were more common in urban
settings could be partly explained by symptomatic individuals having ``drifted''
to these areas, the authors note. However, they add, their previous research
has shown population stability in cities--that is, around 75% of city dwellers
were born there.
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- And a number of studies have demonstrated that psychotic
illness is more prevalent in urban settings than in rural areas, the report
indicates.
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- ``The high rates of psychotic illness in urban environments
may be the result of the influence of environmental factors,'' van Os and
colleagues write. ``As the urban effect appears to have its impact during
urban upbringing rather than during adult residence per se, developmental
mechanisms ought to be considered.''
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- The fact that in this study, psychosis-like symptoms
as well as full-blown illnesses were more common in cities suggests a greater
``psychosis proneness'' in urban settings, they add.
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- Why this potential connection exists is unclear, but
the researchers note that deprivation and social isolation in childhood
neighborhoods have been shown to affect mental health.
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- Another recent study in Denmark linked urban birth with
an increased of developing schizophrenia. While family history was a far
greater predictor of the risk, place of birth emerged as an environmental
factor. Those researchers speculated that people born in urban areas are
exposed to more infections during prenatal development and childhood. Some
experts believe early exposure to infections may affect the developing
brain in a way that makes it more vulnerable to schizophrenia.
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- SOURCE: Archives of General Psychiatry 2001;58:663-668.
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