Mental retardation is not a medical diagnosis, but serious cognitive limitation is a neurologic symptom that requires medical assessment. Severe mental retardation is medically equivalent to brain damage or brain dysfunction. The new American Association on Mental Retardation definition of mental retardation is not compatible with a biomedical approach. There exist no generally accepted clinical practice guidelines for the medical assessment of mental retardation and developmental delay. The physician who is participating in the assessment needs to investigate developmental processes and possible medical etiologies. Attempts should be made to assess language and nonverbal problem-solving abilities separately, even in infancy and early childhood. A number of factors from the history (e.g., fetal hypoactivity) and physical examination (e.g., minor dysmorphic features) can be quite useful components of the assessment. More problems and unanswered clinical questions occur at the boundary between mild mental retardation and developmental delay (development that is slow but not quite slow enough to qualify for a formal diagnosis of mental retardation). Current medical research is fragmenting mental retardation into diverse and quite specific syndromes.
1998 Wiley-Liss, Inc.