Developmental effects on mental health disorders in persons with developmental disabilities

A variety of factors likely contribute to errors in psychiatric dianostic assessment of persons with developmental disabilities including such problems as diagnostic overshadowing congitive disintegration, psychosocial masking, intellectual distortion, and baseline exaggeration. One reason that these clincial errors might occur is that surface manifestations of mental health disorders may differ in different groups. While dianostic classification schemes reflect the "normative" phenomenology (what the disorder typically looks like an adult with average IQ). Clinicians may misdiagnose or miss mental health diagnoses when they apply these adults norms to their assessment of individuals who have significant developmental delays. Understanding how developmental level impacts on the clinical features of a mental health disorder can greatly improve accuracy in diagnostic assessment.Literature addressing the impact of developmental factors on the phenomenology of several major psychiatric disorders is reviewed. Parallels between research describing "age effects" on the presentation of depression and anxiety in children. And behavioural symptoms seen in these disorders in persons with mental retardation are discussed. The ways in which a developmental perspective may help to improve differential diagnosis of psychiatric disorders when assessing individuals with mental retardation are described. [AJ].