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Childhood-Onset Schizophrenia: Research Update Sanjiv Kumra, MD, FRCPC1, Maryanne Shaw, CPT, PhD2, Patricia Merka, RN, BscN, Dip TCPP3, Emilie Nakayama, MA4, Rachel Augustin, BA5 | ||
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This review is a research update of recent literature related to childhood-onset schizophrenia (onset of psychotic symptoms by age 12 years). This subgroup of patients has attracted considerable research interest because patients with a childhood onset may represent a more homogeneous patient population in which to search for risk or etiologic factors. We examine data indicating that childhood-onset schizophrenia (COS) shares the same clinical and neurobiologic features as later-onset forms of the disorder. Compared with adults with schizophrenia, however, this subgroup of patients appears to have more severe premorbid neurodevelopmental abnormalties, more cytogenetic anomalies, and potentially greater family histories of schizophrenia and associated spectrum disorders. While preliminary, these data indicate that a greater genetic vulnerability may be one of the underpinnings of COS. Future studies of this subgroup may provide important clues as to the genetic basis for schizophrenia and how gene products influence certain features of the disease, such as age of onset and mode of inheritance. (Can J Psychiatry 2001;46:923–930) Key Words: schizophrenia, children, neuroimaging, genetics, review, research |
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Across medicine, the study of phenotypic extremes with an early-onset has been an important approach to the understanding of disease (1). The combination of greater severity, relative treatment resistance, greater heritability, and earlier age of onset has been observed in multiple medical illnesses (2). Further, important molecular genetic discoveries in breast cancer (3) and Alzheimer’s disease (4) have occurred in subpopulations with an earlier age of illness onset. The possibility that patients with childhood-onset of schizophrenia (COS) (onset of psychotic symptoms by age 12 years) may represent a more homogeneous and enriched population in which to search for etiologic factors predisposing to schizophrenia has increased research interest in this form of the disorder. Although COS is quite rare, the incidence of schizophrenia rises sharply during adolescence, and there is an even larger proportion of at-risk adolescents with schizophrenia-like symptoms who present to psychiatrists for diagnostic and treatment evaluations.
Manuscript received and accepted June 2001. |
Biological studies of early-onset schizophrenia may also have application importance for designing early-intervention studies for at-risk adolescents. This review will focus primarily on recent research findings (that is, the past 5 years). It updates a previous review (5) of patients with COS studied at the National Institute of Mental Health (NIMH) and the University of California Neurospychiatric Institute. The NIMH COS cohort, which is frequently cited in this article, consists of treatment-resistant subjects who were referred for an inpatient treatment trial of clozapine. This patient group resembles poor-outcome adults with schizophrenia and appears to represent patients with COS overall. Is Childhood-Onset Schizophrenia Continuous With Adult-Onset Schizophrenia? Examination of the phenomenology, neuropsychology, and biology of patients with COS suggests that it shares basic pathophysiologic features with later-onset forms of the disorder. Phenomenology and Differential Diagnosis Several studies have demonstrated that schizophrenia can be reliably diagnosed in children using unmodified adult criteria (6–10) and that it can be clearly differentiated from the pervasive developmental disorders (PDDs).
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