Mental Retardation (DSM-IV-TR)

Source:  Mental Retardation (DSM-IV-TR)    Tag:  mild mental retardation characteristics
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, 3rd Edition; Stanford-Binet, 4th Edition; Kaufman Assessment Battery for Child ren). 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., a 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 sociocultural 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 will more accurately reflect the person's learning abilities. When there is a marked discrepancy across verbal and performance scores, averaging to obtain a hill-scale IQ score 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, sociocultural background, and corrununity 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 lQ which tends to remain a more stable attribute.

Degrees and Severity of Mental Retardation :
  1. Mild Mental Retardation: IQ level 50-55 to approximately 70
  2. Moderate Retardation: IQ level 35-40 to 50-55
  3. Severe Mental Retardation: IQ level 20-25 to 35-40
  4. Profound Mental Retardation: IQ level below 20 or 25

Source: DSM-IV-TR