Along with well-defined categories in classification systems (e.g., autistic disorders and attention-deficit/hyperactivity disorder (ADHD)), practitioners are confronted with many children showing mixed forms of developmental psychopathology. These clusters of symptoms are on the borderlines of more defined categories. The late Donald Cohen proposed heuristic criteria to study a group defined by impaired social sensitivity, impaired regulation of affect, and thinking disorders under the name multiple complex developmental disorders (MCDD). Although these children meet criteria for pervasive developmental disorder--not otherwise specified (PDD-NOS), they have additional important clinical features, such as thought disorder. After highlighting similarities and differences between MCDD and comparable groups (e.g., multidimensionally impaired children), this paper presents the findings of a study comparing formal thought disorder scores in children with MCDD to children with autism spectrum diagnoses, such as autistic disorder (AD), and to children with nonspectrum diagnoses, such as ADHD and anxiety disorders.
Methods: Videotaped speech samples of four groups of high-functioning, latency-aged children with MCDD, AD, ADHD, and anxiety disorders were compared to a control group of normal children using the Kiddie Formal Thought Disorder Rating Scale (K-FTDS).
Results: High formal thought disorder scores were found both in the AD and MCDD groups, low rates in the ADHD groups, and no thought disorder in the anxiety disorder and normal control groups. The severity of formal thought disorder was related to verbal IQ scores within the AD and MCDD groups.
Conclusion: High formal thought scores in children with complex developmental disorders, such as AD and MCDD, appear to reflect impaired communication skills rather than early signs of psychosis.