Epidemiology, Historical Changes in

Epidemiology is the study of the occurrence, distribution, and causal factors of diseases, disorders, or other health-related states. The field of epidemiology uses this information to control, prevent, and plan for the treatment of diseases or conditions. Although this definition of epidemiology may be appropriate for many physical conditions, diseases, and disorders, the epidemiology of intellectual disabilities and developmental disorders (ID/DD) cannot be limited to this traditional, deficit-focused definition. Instead, the study of ID/DD in the United States (and arguably worldwide) has undergone several historical changes over the past 200 years. The epidemiology of specific ID/DD may have been estimated at any given time, but these estimates must be viewed in the context of prevailing models of disability, which have evolved historically in response to ...