Authors: Lauren V. Usher, Leann S. DaWalt, Jinkuk Hong, Jan S. Greenberg, and Marsha R. Mailick


Individuals with Fragile X syndrome (FXS) can have challenges with behaviors, functional skills, and co-occurring medical problems across their lifespan. While there have been some broad observations about aging in Fragile X syndrome, there is an opportunity to learn more about how Fragile X syndrome presents in adolescence and adulthood by looking at longitudinal data — or data that is collected long term, over multiple years — for large groups of people with Fragile X syndrome.

The study team at the University of Wisconsin-Madison Waisman Center↗ designed a study to do just that!

This study analyzed longitudinal data spanning nearly a decade examining trajectories of behavioral characteristics and health. Behavioral characteristics included daily living skills and behavior problems. Health characteristics included body mass index (BMI) and the number of health conditions experienced by adolescents and adults with Fragile X syndrome. The final data set included 134 individuals with Fragile X syndrome, ranging from age 19 to 49 years old, and included various ranges of ASD symptoms. Mothers provided data on their sons or daughters with Fragile X syndrome through self-administered questionnaires and telephone interviews at four time points, with individual families’ study participation spanning 7–9 years.

The study team found that although independence in daily living skills increased during adolescence and early adulthood, by the early 30s and beyond there was a plateau (leveling off) or a decline in independence. Similarly, after a decline in behavior problems during adolescence, individuals with Fragile X syndrome displayed a plateau or increase in behavior problems in adulthood. Body mass index also increased over time, with more adolescents and adults categorized as overweight or obese, and the number of health conditions that individuals experienced also increased over time. Lower levels of lifetime ASD symptoms were associated with greater independence in daily living skills and fewer behavior problems at study start. Sex was not a significant predictor of these outcomes.

Why This Matters

This study offers some of the first prospective quantitative analyses of behavioral and health trajectories in Fragile X syndrome. The patterns observed in both behavior and health trajectories indicate areas for support and intervention.

Adults with Fragile X syndrome can create a significant impact on families, caregivers, and the service system based on their more challenging behaviors and health concerns. Understanding how Fragile X syndrome presents throughout the lifespan and how both the system and family can plan for the adult’s future is imperative. This study shines a light on the need for better long-term support and care planning for individuals with Fragile X syndrome.

Next Steps

Utilizing long-term data can help researchers understand patterns in how conditions evolve. This work is integral to understanding how Fragile X syndrome changes and “shows up” in adolescence and adulthood. This research found patterns that may help families think through keeping their loved one with Fragile X active and learning as they age to support a happy, healthy life. Further longitudinal research is needed to inform treatment and support options for individuals with Fragile X syndrome and their families.

Acknowledgements and Funding

This work was supported by the National Institute of Child Health and Human Development to the IDDRC at the University of North Carolina↗ (P30 HD003100-S1) to support a Fragile X Research Center at three additional sites (Research Triangle Institute International, the University of Wisconsin-Madison and University of Kansas). The present analysis was based on data collected by the UW Madison Waisman Center site (M. Mailick, principal investigator). Additional support was provided by the National Institute of Child Health and Human Development (T32 HD07489 and R01 HD082110, M. Mailick, principal investigator) and the Waisman Center IDDRC (P30 HD03352 and U54 HD090256, A. Messing, principal investigator).

Usher, L.V., DaWalt, L.S., Hong, J. et al. Trajectories of Change in the Behavioral and Health Phenotype of Adolescents and Adults with Fragile X Syndrome and Intellectual Disability: Longitudinal Trends Over a Decade. J Autism Dev Disord 50, 2779–2792 (2020).↗

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Featured image by krzysztof-m↗ from Pixabay↗