lthough substantial progress
has beenachieved
in both the diagnosis and treatment of schizo-phrenia
and the understanding of its neurobiologicalsubstrates, a
full understanding of its origins and path-ogenic
mechanisms remains elusive. Understanding thedevelopment
of schizophrenia is critical for developingnew
treatment strategies, in part because early inter-ventions—ie, secondary
prevention—are associatedwith
better treatment outcomes. There is thus a grow-ing
emphasis on the accurate diagnosis of schizophre-nia
as soon as symptoms of psychosis are evident. Con-ceptually, of
course, the most effective treatment wouldinvolve
the prevention of psychosis altogether—ie, pri-mary prevention.Progress towards this goal, however, remains
in itsinfancy, in
part because we are only just learning toidentify
what the genetic liability to schizophrenia lookslike
before the onset of psychosis. In this paper, we dis-cuss recent progress in this area by
focusing on “schizo-taxia,” a
clinically meaningful condition that may reflectthe
liability for schizophrenia. We then consider
animportant
implication of identifying this condition: thepossibility
of treatment strategies for the primary pre-Conceptualization
of the liability for schizophrenia: clinical
implicationsMing
T. Tsuang, MD, PhD, DSc; FRCPsych; William S. Stone, PhD;Stephen
V. Faraone, PhDAuthor
affiliations: Harvard Medical School Department of Psychiatry
at the the Massachusetts Mental Health Center and Brockton / West Roxbury Veterans
Affairs Medical Center and Harvard Institute of Psychiatric Epidemiology and Genetics,
USA (Ming T. Tsuang; William S. Stone; Stephen V. Faraone); Department of Epidemiology,
Harvard School of Public Health, Boston, Massachu-setts, USA (Ming T. Tsuang);
Pediatric Psychopharmacology Unit, Psychiatry Service, Massachusetts General Hospital,
USA (Stephen V. Faraone) Address for correspondence:
Ming T. Tsuang, MD, PhD, Stanley Cobb Professor of Psychiatry and Head, Harvard
Medical School Department of Psychiatry at the Massachusetts Mental Health Center,
74 Fenwood Rd, Boston, MA 02115, USA 1
5 3Historically, the
Diagnostic and Statistical Manual of Mental Disorders (DSM)
diagnostic criteria for schizo-phrenia
have emphasized several features, including symptoms of psychosis, a dissociation
of symptomsfrom
their etiology, a reliance on clinical symptoms, and a categorical approach to
classifying the disorder.Although
these emphases are quite useful, they have limitations. We review these here,
and stress theimportance
of incorporating recent data on the genetic / biological and neurodevelopmental
origins ofschizophrenia
into current conceptions of the disorder. We also review “schizotaxia,”
which is a concept thatembodies
this point of view, occurs before the onset of psychosis, and is hypothesized
to represent the lia-bility
for schizophrenia. If our hypothesis on this point is correct, the identification
of schizotaxic individualswill
eventually facilitate the development of prevention strategies by identifying
a premorbid (but clinicallysignificant)
condition for schizophrenia. Moreover, the identification of biological or neuropsychologicalcomponents of schizotaxia will provide
more specific bases for developing novel treatment interventions.Our initial attempts to develop protocols
for the assessment and treatment of schizotaxia are encouraging,and will be reviewed. Keywords:
psychosis; schizophrenia; schizotaxia; classification; diagnosis; genetics; risperidone
AMing
T. TSUANGB a s i c
r e s e a r c h
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