An integration of schizophrenia with schizotypy: identification of schizotaxia and implications for research on treatment and prevention.
The liability to schizophrenia (schizotaxia) is associated with deficits in a variety of domains, including negative symptoms and neuropsychological deficits, even in the absence of psychosis or pre-psychotic prodromal symptoms. Conceptually, this view of schizotaxia is similar to negative schizotypy (i.e., schizotypal personality disorder minus the positive symptoms). It is broader than DSM-IV schizotypal personality disorder (SPD), however, in that more relatives of patients with schizophrenia show core symptoms of schizotaxia than meet the diagnostic criteria for SPD. Three lines of evidence support the validity of schizotaxia. First, evidence of concurrent validation was obtained by showing that schizotaxic subjects were more impaired than non-schizotaxic subjects on a variety of independent clinical scales. Second, schizotaxic subjects showed higher levels of negative symptoms on the Structured Interview for Schizotypy than non-schizotaxic subjects, but did not differ on positive symptoms. Third, subjects who met predetermined criteria for schizotaxia (i.e., negative symptoms and neuropsychological deficits) showed positive effects following treatment with low doses of risperidone (0.25-2.0 mg). Thus, clinical deficits in schizotaxia may be identifiable, and to a significant extent, reversible. Implications for the conception of schizotypy and the prevention of schizophrenia will be discussed.
Tsuang
Ming T
MT
Department of Psychiatry, Harvard Medical School, Massachusetts Mental Health Center (MMHC), 74 Fenwood Road, Boston, MA 02115, USA. ming_tsuang@hms.harvard.edu
Stone
William S
WS
Tarbox
Sarah I
SI
Faraone
Stephen V
SV
D003072:Cognition Disorders / Q000175:diagnosis; D020022:Genetic Predisposition to Disease; D006801:Humans; D009483:Neuropsychological Tests; D011618:Psychotic Disorders / Q000175:diagnosis; D012559:Schizophrenia / Q000175:diagnosis / Q000235:genetics / Q000517:prevention & control; D012569:Schizotypal Personality Disorder / Q000175:diagnosis / Q000235:genetics / Q000517:prevention & control; D012720:Severity of Illness Index