Mental performance in Down syndrome.

Psychological assessment, using standard psychometric tests, was carried out in 375 cases of clinically diagnosed Down syndrome to study the degree of mental handicap. There were 160 (42.7%) cases in the severely retarded group, while 43 (11.5%) were profoundly retarded, 124 (33.1%) were moderately retarded, 34 (9.1%) were mildly retarded and 7 (1.9%) belonged to the category of borderline intelligence.