High Circulatory Titer of Platelet-Associated Autoantibodies in Childhood Onset Schizophrenia and Its Diagnostic Implications


Background: It has been suggested that the etiology of schizophrenia, in a distinct group of patients, originates from an autoimmune reaction against platelets. Previous studies have demonstrated significantly higher blood titers of platelet- associated autoantibodies (PAA) in adult schizophrenia patients as compared to normal healthy subjects. In addition, young adult schizophrenia patients at their early stages of the disorder displayed higher PAA titers than older patients with longer duration of the disorder. Aim: To assess the blood titers of PAA in children with schizophrenia as compared to matched control subjects without psychotic disorders, as a possible diagnostic parameter. Methods: Twenty-nine children with DSM-IV schizophrenia in the active psychotic state, with an age range of 6–12 years (mean ± SD: 9.6 ± 1.5 years), with average Positive and Negative Syndrome Scale scores of 108 ± 19.2, were assessed. The control group consisted of 25 children with DSM-IV conduct disorder in a similar age range of 5–12 years (mean ± SD: 9.5 ± 1.6 years). The blood titers of PAA were evaluated using an optimized ELISA test, expressed by a linear optical density (OD) scale. The blood samples of all participants were tested anonymously and were scored under a code number. A test recording above 1.4 OD units was predefined as positive. Results: The titers of PAA of children with schizophrenia (1.9 ± 0.5 OD units, range: 0.7–2.44 units) were significantly (p < 0.00001) higher than those of the control group (1.0 ± 0.4 OD units, range: 0.45–2.28 units). In 83% of the children with schizophrenia (24 out of the 29 patients) a positive test, i.e. OD >1.4, was detected. In contrast, in the control group, only 12% (3 of the 25 subjects) displayed a positive test, p < 0.00001. Conclusions: High titers of PAA in children with schizophrenia as compared with nonpsychotic controls may indicate an active autoimmune process in the early onset of schizophrenia. The PAA level may therefore provide a supportive diagnostic biomarker for childhood schizophrenia.