Thought disorder in childhood schizophrenia: replication and update of concept.

ABSTRACT Objectives To examine whether measures of thought disorder differentiated schizophrenic from normal children and to examine the relationship of these measures with developmental and cognitive factors. Method The speech samples of 88 schizophrenic and 190 normal children, aged 9 to 13 years, were coded with the Kiddie Formal Thought Disorder Rating Scale and Halliday and Hassan's analysis of cohesion. Results Above and beyond differences in mental age, gender, and neuroleptic status, the patients had significantly more formal thought disorder (FTD) and cohesive deficits than the normal children matched by mental age. The younger schizophrenic and normal children had significantly more thought disorder than the older children with these diagnoses. Combined FTD and cohesion scores correctly identified 76% of schizophrenic and 88% of normal children with little variability across mental age. The thought disorder measures generated 2 independent components: FTD and cohesion. Conclusions Thought disorder measures that include both FTD and cohesion provide a quantitative diagnostic tool of childhood-onset schizophrenia.