Study Links Word Acquisition With Walking Ability in Rett Syndrome

Children with Rett syndrome who can verbalize meaningful words are more likely to be able to walk past age 10, a study suggests.

The study, “Meaningful word acquisition is associated with walking ability over 10 years in Rett syndrome,” was published in the journal Brain & Development.

Rett syndrome can result in a variety of neurological symptoms, including problems with cognitive, sensory, emotional, and motor skills. Yet, the person-to-person variability in how the disorder manifests makes accurate prognoses difficult.

As such, early features that predict how Rett syndrome will progress are of interest to clinicians.

In this study researchers in Japan looked for predictors of walking ability in these patients.

“Walking ability is important for family counselling and planning for the provision of care for young children with RTT [Rett syndrome],” the researchers wrote.

They analyzed data from the Japanese Rett syndrome database, which included data for 100 female patients ranging in age from 1 to 43 years (mean age 14.5). Eighty-six people had typical (classic) Rett Syndrome and 14 had atypical Rett syndrome.

Among 92 people with available genetic information, 88 (95%) had mutations in the gene MECP2, which are the most common cause of Rett syndrome.

The scientists analyzed a variety of clinical factors, as well as motor and cognitive milestones, in relation to walking ability later in life.

Nearly half of the patients (49%) were unable to walk without support. The age of acquisition of walking ranged from 11 months to 6 years. Notably, 40 (40%) of the participants did not develop the ability to produce meaningful words, with the remaining 60 first being able to do so from 10 months to 6  years.

Being able to produce meaningful words was associated significantly with greater ability to start walking. In addition, significantly fewer of those with microcephaly (abnormally small head circumference, seen in 58 patients) developed the ability to walk, compared to those with normal head circumference.

Crawling and walking were achieved more often by individuals with mutations in MECP2 that have been reported previously to result in comparatively mild symptoms (namely the mutations (R306C, R133C, and R294X), compared to individuals with other mutations.

“Our study confirmed the importance of genotypes [genetic profiles] associated with severe and mild phenotypes [disease manifestations],” added the investigators.

Fifty-six participants were older than 10. Among this group, 31 were able to walk, and 26 were not — mostly because they had never been able to walk, or because they had lost the ability.

The scientists then conducted statistical analyses to look for predictive factors of walking ability after age 10. Untimately, the findings revealed that the only significant predictor was meaningful word acquisition.

According to the team, limitations of the study include the fairly small group of participants, as well as its cross-sectional design — that is, data were assessed at a single point in time, rather than following patients over time.

Overall, the identification of word acquisition as a predictive factor of walking ability may help in clinical decision-making for children with Rett syndrome.

“In conclusion, our findings may be useful for informing the development of early intervention methods, and the planning of comprehensive treatment for young infants with RTT,” the researchers concluded.