Chapter 49: Other Disorders of Infancy, Childhood, & Adolescence

Reactive attachment disorder represents a severe disruption in the child's capacity to form secure emotional bonds, manifesting as emotional withdrawal, minimal social responsiveness, and a fundamental inability to seek comfort from caregivers. This condition emerges specifically in contexts of profound neglect, frequent caregiver transitions, or prolonged institutional placement during critical periods of development. Disinhibited social engagement disorder presents as the opposite presentation, characterized by indiscriminate sociability, absence of typical stranger anxiety, and socially inappropriate approach behaviors that persist despite improvements in the caregiving environment. Both conditions are rooted in early relational trauma and deprivation, with landmark longitudinal research including the English-Romanian Adoptee Study and the Bucharest Early Intervention Project demonstrating how institutional deprivation alters developmental trajectories and producing measurable neurobiological changes. Neuroimaging investigations reveal significant alterations in brain structure and function, including diminished white matter integrity, aberrant electroencephalographic patterns, and structural differences in limbic regions, establishing the biological consequences of early neglect on neural development. The chapter also addresses stereotypic movement disorder, characterized by repetitive, non-functional motor behaviors including rhythmic rocking, hand stereotypies, head-banging, and self-injurious movements. While some repetitive behaviors are developmentally typical, pathological presentation involves persistence, functional impairment, or tissue damage. The etiology encompasses genetic vulnerability, neurochemical imbalances particularly involving dopamine signaling, concurrent intellectual disability, and association with autism spectrum presentations. Treatment approaches integrate behavioral modification strategies, environmental enrichment, protective equipment, and selective pharmacotherapy including antagonism of opioid receptors in specific cases. The chapter emphasizes the critical importance of early recognition, careful differentiation from autism spectrum disorder and attention-deficit hyperactivity disorder, and implementation of evidence-based interventions centered on caregiver coaching, dyadic psychotherapy, and systematic behavioral intervention programs.