Comparison of whole blood serotonin and platelet MAO in children with schizophrenia and major depressive disorder.

Whole blood serotonin and platelet monoamine oxidase (MAO) activity in boys with schizophrenia, schizotypal personality disorder, or major depressive disorder was compared with that of boys serving as controls. Boys with schizophrenia and schizotypal personality disorder had significantly higher platelet MAO than boys with major depressive disorder or controls. Boys with major depressive disorder had lower whole blood serotonin than boys with schizophrenia or schizotypal personality disorder.