Longitudinal changes in cognitive and adaptive behavior in fragile X females: A prospective multicenter analysis

In prospective studies of young, fragile X [fra(X)] males with the full mut ation, cognitive abilities (IQ scores) and adaptive behavior levels (DQ sco res) declined in most subjects tested. Little is known about longitudinal c hanges in IQ and DQ scores in young fra(X) females, although one earlier re trospective study showed declines in IQ scores in 8 of 11 subjects. To exam ine fra(X) females prospectively, we tested and retested 13 females with th e full mutation, age 4 to 15 years. Nine were tested and retested in North America, and four were evaluated at the Catholic University in Leuven, Belg ium, Cognitive abilities of North American females were measured using the Stanford-Binet 4th Edition, Adaptive behavior levels were ascertained from the Vineland Adaptive Behavior Scales. For Belgians, test-retest scores fro m the Wechsler Intelligence Scales for Children-Revised were used. Subjects were subsequently separated into two age cohorts: those tested initially b efore age 7 years and those tested initially after age 7 years, Compared wi th young males with the full mutation and of the same age, females expected ly display a wider range of IQ scores. Test-retest IQ scores showed statist ically significant decreases (P < 0.03). Analysis of individual test-retest scores indicate that declines in eight females were statistically signific ant. Adaptive behavior scores were available only for North American female s. Five of nine (55%) showed significant declines in DQ. Like young males w ith the full mutation, all females with the full mutation attained higher a daptive behavior levels than cognitive scores, i.e., DQ > IQ. (C) 1999 Wile y-Liss, Inc.