Schizophrenia Bulletin Advance Access originally published online on September 16, 2008
Schizophrenia Bulletin 2008 34(6):1033-1034; doi:10.1093/schbul/sbn122
© The Author 2008. Published by Oxford University Press on behalf of the Maryland Psychiatric Research Center. All rights reserved. For permissions, please email: journals.permissions@oxfordjournals.org.
Using Clinical Data Bases to Study Schizophrenia
Mark Weiser1 and
Michael Davidson
Department of Psychiatry, Sheba Medical Center, Tel Hashomer, Ramat Gan, and Dept of Psychiatry, Sackler Medical School, Tel Aviv University, Ramat Aviv, Israel
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Abstract
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Studying psycho-pathology using clinical registries enables
a birds-eye view of all mental illness, and allows researchers
to look at each illness in the context of other mental illnesses.
The papers presented in this issue indicate that at least some
of the symptoms commonly present in schizophrenia are actually
present in other mental disorders and may even be present in
individuals without diagnosed psychiatric disorders. Although
there are some disadvantages to research based on clinical registries,
this method enables study designs not be possible with conventional
research paradigms.
Keywords: mental illness / schizophrenia / clinical registries
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Introduction
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For pragmatic and scientific reasons, most researchers study
a specific illness. They identify patients who meet diagnostic
criteria, find matched controls, and test/measure their target
of interest. Studying illness using clinical registries enables
a birds-eye view of all mental illness and allows one to look
at each illness not only to itself but also in relation to other
mental illnesses. This is particularly relevant in psychiatry
where the mere concept of illness, the boundaries separating
between different illnesses, the syndrome status of many diagnostic
classes, and the boundaries separating between illness and variants
of normal behavior are a moving target. This special issue of
Schizophrenia Bulletin on clinical registries utilizes this
approach.
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Psychiatric Illness as a Continuum
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The paper by David et al, addresses the issue of cognitive impairment,
a domain of impairment considered a core pathology in schizophrenia.
The data, taken from a cross-section of recruits to the Swedish
military, show that cognitive impairment is present in all diagnostic
groups of mental illnesses and is not restricted to schizophrenia.
This in turn indicates that schizophrenia might be conceptualized
as lying on a continuum of psychiatric illnesses which have
in common cognitive impairment, with schizophrenia, perhaps,
being on the more severe end of the spectrum.
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Paternal age
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Over the past 8–9 years, a plethora of articles have reported
that advanced paternal age is a risk factor for schizophrenia.
Poor social abilities are also a "hallmark" of schizophrenia
and are considered an intermediate phenotype of the illness.
The article by Weiser et al addresses the relationship between
advanced paternal age and social functioning in persons without
mental illness. The article reports a small but significant
association between advanced paternal age and poorer social
functioning in the general population. This indicates that part
of the risk for schizophrenia inferred by advanced paternal
age might be mediated, at least partially, via the effect of
advanced paternal age on social functioning. Here again, this
"view from above" reveals interactions which would have been
missed in study designs which compare cases of schizophrenia
with controls. These findings are also significant regarding
future research, indicating that the study of the causes and
treatment of cognitive and social dysfunction is relevant to
all areas of psychopathology, not only to schizophrenia.
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Genetics
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So it seems that that at least some of the symptoms commonly
present in schizophrenia are actually present in other disorders
and, indeed, are present in individuals without diagnosed psychiatric
disorders. The next step might be to study the genetic underpinnings
of these phenomena, by studying the genetics of specific symptoms,
and not of clinical syndromes. An example of this approach is
utilized by DeRosse et al who examined the association between
genotype and individual symptoms of schizophrenia. They found
significant genetic risk factors for both reality distortion
and disorganized symptoms.
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Famine
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The article by Brown et al used clinical registries to examine
the effects of nutritional deficiencies in utero caused by famine
and confirmed an increased risk for schizophrenia in the off-springs.
This illustrates the power of discovery based on clinical registries
that would not be possible with conventional research designs.
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Disadvantages
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There are definite disadvantages to research based on clinical
registries. The design is predetermined and cannot be manipulated.
The large sample sizes encourage "fishing expeditions," which
often yield statistically significant findings, but have no
real meaning, and might even be misleading. The assessments
are clinical and are usually not done using validated research
instruments. Also, the data suggest pathophysiological mechanisms
but is never useful in elucidating mechanism. On the other hand,
if one looks at the research findings in the field over the
years, it is mainly the epidemiological findings that have been
replicated, whereas many of the more "biological" findings often
do not replicate. Most importantly, this approach does not address
the most important question which the field has yet to solve,
namely: what distinguishes the ill brain from the healthy brain.
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Conclusion
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It is probably most appropriate to conclude that, in the absence
of definitive neuropathology, clinical registries are vital
in providing decisive leads on etiology and insight on psychopathology.
The example of using registries to understand cardiovascular
risks (cholesterol, hypertension, life style) has been the impetus
to study and understand cardiovascular pathophysiology and ultimately
devise effective therapies. Research using clinical registries
provides direction toward the ultimate understanding of the
biology of behavior and of mental illness.
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Footnotes |
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1 To whom correspondence should be addressed; tel: +972-52-666-6575, fax: +972-3-6358599, e-mail: mweiser{at}netvision.net.il.
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Abstract
Introduction