Causes of Developmental Disorders
The first two chapters have emphasized the many factors associated with individual differences between handicapped children. Some general principles have been set out, and the main classes of developmental disorders of behaviors have been discussed. Missing in the discussion has been an emphasis on the causes or etiology of developmental disorders. In this chapter, we add a consideration of etiology because it is centrally important to later chapters on family processes and on treatment.
Interest in the etiology of behavioral orders of development comes from two sources. The first is the strong tendency among families of developmentally handicapped children to wish to attribute some cause to their child's handicap. The second interest in the study of causes of developmental disorders comes from the need to prevent handicapping conditions. Prevention is practical in many instances and perhaps is the ultimate treatment for disorders of development. For instance, recent advances in the understanding of the hereditary causes have lead to active family-planning programs involving genetic counseling. Lack of iodine was a major cause of mental retardation before the importance of a small amount of iodine in the diet was understood. Extreme forms of social deprivation during early postnatal development have been shown to have important effects on later adaptation. Understanding of the importance of social factors has led to social programs such as out-of-home adoption that have corrected abnormal early social environments.
The purpose of this chapter, then, is to review the topic of etiology of