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Congenital Mental Deficiency: Certain types of feeble-mindedness tend to run in families. Low mentality occurs when some factor that ensures normal development is lacking in both parents. Difficulty arises in the diagnosis of true mental deficiency. There is no conclusive evidence that all cases of feeble-minded-ness are clearly hereditary. Some may be congenital, i.e., acquired during prenatal life. At birth severe lack of oxygen may cause brain damage. Other cases may be intensified by an impoverished social environment.
Certain diseases have particularly serious effects on the prenatal development of the child. By injuring the germ cells before fertilization, or by infecting the fetus before or at birth, the toxins of syphilis frequently cause stillbirth, miscarriage, congenital mental deficiency, blindness, or deafness. Gonorrhea is responsible for much sterility in men and women. In the past it has also been a common cause of blindness in the child. There is a simple preventative for this type of blindness: drops of a solution of silver nitrate are placed in each eye at birth. A small pamphlet
Mental deficiency is also associated with physical growth. The rate of physical growth of mentally deficient boys is slower than that of normal boys, depending upon the degree of the deficiency (45, 1936). Although subnormal boys continue to grow over a longer time than do normal and superior boys, their ultimate size, on the average, is below that of the private-school boys studied. They show retardation not only in height and weight but also in other developmental factors such ^s learning to walk, teething, and the onset of pubescence. Their mortality rate is nearly twice as high as that of the general population. |
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