RECENT ADVANCES IN MEDICAL KNOWLEDGE OF CAUSES OF MENTAL RETARDATION.

A steady reduction of mortality owing to advances in medicine has altered the patterns of disease, increasing the proportionate importance of certain types of disease in the very young and the very old.Neonatal and infant mortality rates in mongolism remain very high. The mortality has nevertheless fallen considerably and this may well be so for other diseases causing mental retardation.Despite dramatic advances in the fields of biochemistry and cytogenetics, revealing many new causes of mental retardation, a large proportion of mentally retarded patients are still undiagnosable in respect of etiology.Other principles of causation, not so often discussed in the medical literature, deserve consideration, e.g. isoimmunization due to other antigens than those of the blood groups and diseases due to deficiency of some trace element. Peculiarities of distribution, geographical, seasonal, occupational or social, merit examination, and recent research along these lines has led to significant results. Whole classes of causes may not have occurred to us, and it may prove fruitful in this respect to turn our minds toward less fashionable paths of thought.