Trajectory of adaptive behavior in males with fragile X syndrome.

The team tracked adaptive behavior in boys and teens with fragile X syndrome. They tested the same group twice, first in early childhood and again in the teen years.

They used the Vineland Adaptive Behavior Scales. The goal was to see if skills kept growing or started to slide as the boys got older.

Skills rose from early childhood to mid-adolescence. After that, scores dropped in most areas for the older teens.

Daily living skills stayed the strongest. Social skills stayed the weakest. The dip showed up only in the second testing wave.

Ohan et al. (2015) followed men with fragile X into adulthood. They saw flat autism diagnosis rates, but small drops in verbal and repetitive behaviors. Together, the two studies draw a full arc: adaptive gains stall in adolescence, then autism traits edge downward in adult life.

Eussen et al. (2016) looked at preschool boys with fragile X. They found poor self-control and high activity years before the gains seen in the target study. This hints that early temperament issues can still give way to later adaptive growth.

Alaimo et al. (2015) studied adults with Down syndrome. They also saw fewer adaptive skills endorsed with age, not worse quality of skills. The pattern looks similar across the two genetic groups: aging trims the range of skills shown.

If you work with boys with fragile X, expect a sweet spot of growth until mid-teens. Plan re-evaluations around age 14–15. Shift goals to maintaining daily living and expanding social routines before scores slip. Use brief probes every few months to catch any downturn early.