Hall Scott S, Burns David D, Lightbody Amy A, Reiss Allan L
Department of Psychiatry and Behavioral Sciences, Stanford University, 401 Quarry Road, Stanford, CA 94305-5795, USA.
J Abnorm Child Psychol. 2008 Aug;36(6):927-39. doi: 10.1007/s10802-008-9223-y. Epub 2008 Mar 18.
Structural equation modeling (SEM) was used to examine the development of intellectual functioning in 145 school-age pairs of siblings. Each pair included one child with Fragile X syndrome (FXS) and one unaffected sibling. All pairs of children were evaluated on the Wechsler Intelligence Scale for Children-Third Edition (WISC-III) at time 1 and 80 pairs of children received a second evaluation at time 2 approximately 4 years later. Compared to their unaffected siblings, children with FXS obtained significantly lower percentage correct scores on all subtests of the WISC at both time points. During the time between the first and second assessments, the annual rate of intellectual development was approximately 2.2 times faster in the unaffected children compared to the children with FXS. Levels of the fragile X mental retardation protein (FMRP) were highly associated with intellectual ability scores of the children with FXS at both time points (r=0.55 and 0.64 respectively). However, when gender, age, and the time between assessments were included as covariates in the structural equation model, FMRP accounted for only 5% of the variance in intellectual ability scores at time 1 and 13% of the variance at time 2. The results of this study suggest that slower learning contributes to the low and declining standardized IQ scores observed in children with FXS.
采用结构方程模型（SEM）对145对学龄期兄弟姐妹的智力功能发展进行了研究。每对包括一名患有脆性X综合征（FXS）的儿童和一名未受影响的兄弟姐妹。所有儿童对在第1时间点接受了韦氏儿童智力量表第三版（WISC-III）评估，80对儿童在大约4年后的第2时间点接受了第二次评估。与未受影响的兄弟姐妹相比，患有FXS的儿童在两个时间点的WISC所有子测试中获得的正确得分百分比均显著较低。在第一次和第二次评估之间的时间段内，未受影响儿童的智力发展年增长率比患有FXS的儿童快约2.2倍。在两个时间点，脆性X智力低下蛋白（FMRP）水平均与患有FXS儿童的智力能力得分高度相关（分别为r=0.55和0.64）。然而，当将性别、年龄和评估间隔时间作为协变量纳入结构方程模型时，FMRP在第1时间点仅占智力能力得分方差的5%，在第2时间点占方差的13%。本研究结果表明，学习速度较慢导致了在患有FXS儿童中观察到的低且不断下降的标准化智商得分。
