Comorbid Down's syndrome, Tourette syndrome and intellectual disability: registry prevalence and developmental course.

Doctors checked a national registry for kids who had both Down syndrome and Tourette syndrome. They found five cases and watched how each child developed over time.

This was the first head-count of TS inside the DS population, so numbers were small.

Only 2% of registered TS patients also had Down syndrome. When the two conditions did meet, the kids hit milestones later and showed more learning problems.

In short, TS plus DS was rare but signaled a tougher developmental road.

Freeman et al. (2015) fills in the picture: within DS, weaker motor skills track with weaker executive function. The 2000 paper warns us that adding TS makes this slope steeper.

Day et al. (2021) and Moya et al. (2022) later showed that poor executive function in DS feeds externalizing behavior and slows daily-living skills. Their surveys line up with the poorer outcome the registry noticed.

O'Reilly et al. (2000) looked at any severe ID that same year and found half of students had extra behavior disorders. The TS+DS duo is simply one rare slice of that wider pattern.

If you serve clients with Down syndrome, screen for tics. Spotting TS early lets you add habit-reversal or anxiety plans before problem behavior snowballs. Also test motor and executive skills; the later studies show these are the levers that lift communication, social, and daily-living gains. A quick tic checklist plus a simple fine-motor or working-memory probe can change your whole treatment plan.