Behavioral Inflexibility Across Two Neurogenetic Conditions: Down Syndrome and Fragile X Syndrome.

Harrop et al. (2021) asked caregivers to rate how rigid their kids act each day. They compared three groups: children with Down syndrome, fragile X only, and fragile X plus autism.

The survey was done online. Parents answered questions about trouble with change, repeating routines, and sticking to one topic.

Kids with fragile X plus autism scored highest on inflexibility. Kids with fragile X only landed in the middle. Kids with Down syndrome scored lowest.

Across all groups, higher rigidity went hand in hand with more anxiety and weaker social-communication skills.

Dixon et al. (2008) also used caregiver surveys and found Down syndrome children were more flexible than kids with non-specific ID or ASD. Harrop et al. (2021) adds fragile X groups and shows the same ladder: DS easiest, FXS middle, FXS+ASD hardest.

Lacroix et al. (2022) tested autistic adults with a computer task. They saw flexibility problems only when rule shifts were hidden and emotional. That lab result lines up with the parent reports here: hidden changes cause the most trouble.

Cregenzán-Royo et al. (2018) found that when moms show high expressed emotion, behavior problems rise in both FXS and DS. Clare’s team now links those problems to rigidity, giving you a second lever to watch.

If you serve kids with fragile X, screen for autism traits early. When both labels are present, build extra practice with schedule changes, choice boards, and priming. Track anxiety and social goals at the same time; gains in flexibility often pull those skills up with it.