Mental Retardation and Head Growth Abnormalities1

To determine the association of head circumference and head breadth deficiency with mental retardation, 188 children with head growth abnor-malities were studied. Of those children with head growth abnormalities, 31.9 % were functioning above the mentally retarded range of intelligence. Those children with both head circumference and head breadth deficiencies had the highest incidence of mental retardation (85.7Wo). Microcephaly, a physical trait frequently associated with mental retarda-tion, is denned as head circumference falling more than 2 standard deviations below the mean on normative growth charts (Huttenlocher, 1979; Nellhaus, 1968). Some investigators have found that almost 100 % of microcephalic children are mentally retarded (O'Connell, Feldt, & Stickler, 1965; Pryor & Thelander, 1968). Others have found the figure to be closer to 90 % (Davies & Kirman, 1962). In a group of 202 children referred to an interdisciplinary center for developmental disabilities, Martin (1970) found that up to 13.5 % of microcephalic children were not retarded when cog-nitive assessments were performed. He concluded that the incidence of normal intelligence in microcephalic children is higher than previously indi-cated. Sells (1972), while examining 1,006 school age children, discovered that 1.9 % had head circumferences in the microcephalic range. He found no significant differences between the microcephalic and normocephalic children on individual tests of cognitive abilities. On that basis, he con-'A version of this paper was presented at the Region X Conference of the American Asso