Repetitive and stereotyped behaviours in pervasive developmental disorders

Area of Science:

• Neuroscience
• Psychiatry
• Developmental Psychology

Background:

• Repetitive and stereotyped behaviors are common in neuropsychiatric disorders, particularly Pervasive Developmental Disorders (PDD).
• The specific nature and autism specificity of these behaviors remain unclear.
• Understanding these behaviors is crucial for diagnosing and treating PDD.

Purpose of the Study:

• To investigate the distinct subgroups of repetitive behaviors in children with PDD.
• To examine the specificity of these behaviors to autism compared to mental retardation (MR).
• To explore the relationship between different types of repetitive behaviors and developmental factors.

Main Methods:

• A two-factor model was conceptualized, distinguishing between sensory/motor (lower-order) and cognitive rigidity (higher-order) behaviors.
• The model's fit was assessed in a clinical sample of children with PDD (with and without MR) and children with MR only.
• Statistical analysis was used to confirm the existence and independence of the proposed subgroups.

Main Results:

• Children with PDD exhibited higher rates of all repetitive behaviors than those with MR only.
• Two independent subgroups of repetitive behaviors were confirmed exclusively in the MR group.
• Lower-order behaviors correlated with global developmental issues, while higher-order behaviors were linked to rumination in the PDD group.

Conclusions:

• Sensory and motor repetitive behaviors appear less specific to autism and associated with lower developmental age.
• 'Higher-order' cognitive rigidity behaviors may be a more autism-specific characteristic.
• The co-occurrence of these behaviors in PDD might indicate altered neural networks, suggesting a specific feature of PDD.