Mental Retardation, Dementia, and the Age of Majority

ABSTRACT

DSM-III-R, the standard psychological diagnostic manual, distinguishes between ‘mental retardation’ and ‘dementia’ solely on the basis of age of onset. A similar clinical picture arising before the age of three constitutes one condition, one arising between the ages of 3 and 18 both conditions, and one arising after the age of 18 the other condition. The other criteria for the two conditions have little in common and are in some aspects contradictory. The question arises whether a condition with such protean presentation can be said to constitute an entity, and it is suggested that the category of ‘mental retardation’ be discarded in favour of descriptors that are both more precise and do not attempt the function of a universal explanation for all behaviours.