The individuals with mental retardation present an inferior intellectual development to normal and the difficulties of learning and social adaptation. Approximately 3% of the world-wide population present mental retardation. Second, PEACE (2002, P.23), ' ' We can consider the learning problem as a symptom, the direction of that not-learning does not configure a permanent picture, but enters a peculiar constellation of behaviors, in which if it detaches as signal of descompensao' '. Some authors who if dedicate to this subject use the terms problems or riots in indiscriminate way. Therefore to establish clearly the limits that separate to problems of learning of the calls learning riots is a task very complicated, that this subject also comes to be revealed by some specialists of some areas the professor, pedagogo, psicopedagogo, the fonoaudilogo and the psychologist. Intelligence is determined in such a way by the hereditary succession how much for the environment. In the majority of the cases of mental retardation, the cause is unknown.
However, some conditions during a gestation can cause or contribute for the mental retardation of the child. The common causes include the use of certain drugs, the extreme alcohol consumption, the x-ray, me the nutrition and certain infections you capsize (for former: rubola). Chromosomic anomalies (Syndrome of Down) are common causes of mental retardation. Diverse hereditary riots also can cause it. Some (p.ex., fenilcetonria and cretinismo, which had the tireoidiano hormone concentration low, can be corrected before the mental retardation occurs. The difficulties associates to the premature childbirth, the trauma skull-enceflico or the concentration very low of oxygen during the childbirth also can cause mental retardation. An occurred time the mental retardation, it is generally irreversible. The precocious diagnosis of the mental retardation becomes possible the therapeutical education and the planning in long stated period. Inferior intelligence to the normal one can be identified and be quantified through tests intelligence standard.