In the DSM-IV-TR, there are three criteria for an intellectual disability that a patient needs to meet. Criterion A stipulates that patients need to have “significantly subaverage intellectual functioning,” which is determined by the IQ score. A score of 70 or below fulfills Criterion A. About 87 percent of patients are only slightly slower than average in their learning skills, while 13 percent have an IQ of 50 or below, according to the National Dissemination Center for Children with Disabilities.
Criterion B for a diagnosis of an intellectual disability involves gaging the child's functional capacity. The clinician will look for impairments in the child's adaptive functioning. The American Association on Intellectual and Developmental Disabilities notes that adaptive behavior includes three types of skills: practical skills, conceptual skills and social skills. When assessing practical skills, the clinician will looks to see if the patient can take care of herself, use money or a telephone, and other daily activities. Conceptual skills include language, number concepts and self-direction. The social skills aspect of an assessment of an intellectual disability and functional capacity involves self-esteem, following rules and interpersonal skills. To assess these adaptive functioning skills, the clinician will use a different test than the one used to evaluate the patient's intelligence level.
Criterion C is the last of the criteria for an intellectual disability. For a patient to be diagnosed with an intellectual disability, these symptoms must have started before the patient was 18 years old.
