The trajectory of mathematics skills and working memory thresholds in girls with fragile X syndrome

Melissa M. Murphy, Michèle M.M. Mazzocco

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4 Scopus citations


Fragile X syndrome is a common genetic disorder associated with executive function deficits and poor mathematics achievement. In the present study, we examined changes in math performance during the elementary and middle school years in girls with fragile X syndrome, changes in the working memory loads under which children could complete a cognitive switching task, and the association between these two areas of function, in girls with fragile X syndrome relative to their peers. Our findings indicate that the trajectory of math and executive function skills of girls with fragile X differs from that of their peers and that these skills contribute to predicting math achievement and growth in math performance over time. Also, changes in math performance were associated with incremental increases in working memory demands, suggesting that girls with fragile X have a lower threshold for being able to perform under increasing task demands. Still, we found improvement in executive function performance between 10 and 12 years in girls with fragile X rather than a performance plateau as has been reported in other studies. The findings implicate the importance of early intervention in mathematics for girls with fragile X that addresses poor calculation skills, the supporting numerical skills, and deficits in executive functions, including working memory.

Original languageEnglish (US)
Pages (from-to)430-449
Number of pages20
JournalCognitive Development
Issue number4
StatePublished - 2009
Externally publishedYes

Bibliographical note

Funding Information:
This research was supported by NIH grant R01 HD-034061-01 to 09, awarded to Dr. Mazzocco. Additional support was provided by a National Fragile X Foundation Summer Rosen Fellowship awarded to Stacy Chung. The authors wish to thank the many people who contributed to this research, including the participants and their families, the faculty and staff at our participating schools in the Baltimore County Public School District, former research coordinator Gwen F. Myers, and former research assistants Stacy Chung and Anne Henry. The authors also acknowledge research assistant Munisa Bachu for assistance preparing figures.


  • Fragile X syndrome
  • Mathematical learning disability
  • Mathematics skills
  • Working memory


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