International Meeting for Autism Research: Case Report: Event Related Potentials in An Adolescent with Autism Prior to Onset of Schizophrenia

Case Report: Event Related Potentials in An Adolescent with Autism Prior to Onset of Schizophrenia

Friday, May 21, 2010
Franklin Hall B Level 4 (Philadelphia Marriott Downtown)
1:00 PM
L. L. Sears , Pediatrics, University of Louisville, Louisville, KY
E. M. Sokhadze , Psychiatry and Behavioral Sciences, University of Louisville, Louisville, KY
G. Mathai , Pediatrics, University of Louisville, Louisville, KY
T. Erwin , Pediatrics, University of Louisville, Louisville, KY
Background: Although identification of schizophrenia in persons with autism can be difficult, several research studies have suggested a link between these disorders based on genetic and biologic evidence.   Of note is the high prevalence of pervasive developmental disorders in subjects who later display features of schizophrenia  (Rapoport et al., JAACAP, 2009, 48:10-18).  Since it is unclear what may predispose certain individuals with autism to develop schizophrenia, further study is needed including identification of potential neurobiologic markers (Toal et al., BJP, 2009, 194:418-425).  Establishing predictive measures will enhance our understanding of the etiology of psychosis in autism and impact treatment and intervention for subjects with autism and co-morbid psychiatric disorders.
Objectives: To identify potential biologic markers for schizophrenia risk in autism we retrospectively evaluated event related potentials (ERPs) on a novelty oddball task completed prior to a subject with high-functioning autism (HFA) developing clinical features of schizophrenia.  The individual displayed onset of delusions, disorganized behavior and worsening adaptive skills with diminished motivation and blunted affect several months after completing the ERP study.  No medical conditions were identified that may have produced the psychosis.
Methods: We collected ERPs from the18-year-old male subject with HFA during a novelty oddball task and compared findings for the same task with 11 subjects with HFA but no positive symptoms of a psychotic disorder.  All subjects met Autism Diagnostic Interview-Revised criteria for autism. 
Results: The subject with autism who developed schizophrenia had increased amplitude of P3a, P3b and N170 waves for both novel and target stimuli compared to subjects with autism without positive symptoms of schizophrenia.   Locations where differences were found on the novelty oddball task include frontal, centro-parietal, and parieto-occipital brain regions.
Conclusions: Increased amplitude in ERPs during a novelty-processing task suggests differences in cognitive processing and brain function in a subject with HFA who later developed schizophrenia compared to HFA subjects without positive symptoms of psychosis.   While the negative signs found in schizophrenia are common in autism this ERP finding may be relevant for understanding the onset of the positive symptoms of a psychotic disorder such as delusions and hallucinations.  Further study of neuropsychological and biologic differences in persons with autism developing psychosis is needed to better address the complexity of these individuals for differential diagnosis and to better understand the etiology and treatment of both disorders.
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