55 Pa. Code 4210 app A
The following information is quoted from the Diagnostic and Statistical Manual (DSM) IV:
"The essential feature of Mental Retardation is significantly subaverage general intellectual functioning (Criterion A) that is accompanied by significant limitations in adaptive functioning in at least two of the following skill areas: communication, self-care, home living, social/interpersonal skills, use of community resources, self-direction, functional academic skills, work, leisure, health, and safety (Criterion B). The onset must occur before age 18 years (Criterion C). Mental Retardation has many different etiologies and may be seen as a final common pathway of various pathological processes that affect the functioning of the central nervous system.
General intellectual functioning is defined by the intelligence quotient (IQ or IQ-equivalent) obtained by assessment with one or more of the standardized, individually administered intelligence tests (e.g., Wechsler Intelligence Scales for Children-Revised, Stanford-Binet, Kaufman Assessment Battery for Children). Significantly subaverage intellectual functioning is defined as an IQ of about 70 or below (approximately 2 standard deviations below the mean). It should be noted that there is a measurement error of approximately 5 points in assessing IQ, although this may vary from instrument to instrument (e.g., Wechsler IQ of 70 is considered to represent a range of 65-75). Thus, it is possible to diagnose Mental Retardation in individuals with IQs between 70 and 75 who exhibit significant deficits in adaptive behavior. Conversely, Mental Retardation would not be diagnosed in an individual with an IQ lower than 70 if there are no significant deficits or impairments in adaptive functioning. The choice of testing instruments and interpretation of results should take into account factors that may limit test performance (e.g., the individual's socio-cultural background, native language, and associated communicative, motor, and sensory handicaps). When there is significant scatter in the subtest scores, the profile of strengths and weaknesses, rather than the mathematically derived full-scale IQ, may more accurately reflect the person's learning abilities. When there is a marked discrepancy across verbal and performance scores, averaging to obtain a full-scale IQ can be misleading.
Impairments in adaptive functioning, rather than a low IQ, are usually the presenting symptoms in individuals with Mental Retardation. Adaptive functioning refers to how effectively individuals cope with common life demands and how well they meet the standards of personal independence expected of someone in their particular age group, socio-cultural background, and community setting. Adaptive functioning may be influenced by various factors, including education, motivation, personality characteristics, social and vocational opportunities, and the mental disorders and general medical conditions that may coexist with Mental Retardation. Problems in adaptation are more likely to improve with remedial efforts than is the cognitive IQ, which tends to remain a more stable attribute.
It is useful to gather evidence for deficits in adaptive functioning from one or more reliable independent sources (e.g., teacher evaluation and educational, developmental, and medical history). Several scales have also been designed to measure adaptive functioning or behavior (e.g., the Vineland Adaptive Behavior Scales and the American Association on Mental Retardation Adaptive Behavior Scale). These scales generally provide a clinical cutoff score that is a composite of performance in a number of adaptive skill domains. It should be noted that scores for certain individual domains are not included in some of these instruments and that individual domain scores may vary considerably in reliability. As in the assessment of intellectual functioning, consideration should be given to the suitability of the instruments to the person's socio-cultural background, education, associated handicaps, motivation, and cooperation. For instance, the presence of significant handicaps invalidates many adaptive scale norms. In addition, behaviors that would normally be considered maladaptive (e.g., dependency, passivity) may be evidence of good adaptation in the context of a particular individual's life (e.g., in some institutional settings)."1
1 Reprinted with permission from the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision. Copyright 2000 American Psychiatric Association
55 Pa. Code 4210 app A