Babbling, speech and language in children with neurological disabilities : development, validity of measures and effect of intervention

Sammanfattning: Children with neurological disabilities (ND) such as cerebral palsy, Down syndrome or other genetic syndromes often have speech and language disorder. In Sweden, children with ND often receive team-based habilitation services – with teams including speech and language pathologists – from an early age, but even so, many things are still unknown when it comes to the expected development of speech and language abilities. Furthermore, service delivery for speech and language difficulties has rarely been studied in the Swedish context and even internationally there is a lack of studies examining the effects of intervention. Babbling is an important precursor to speech and has been studied in many groups of children at risk of speech and language disorder. Thus, it shows promise as a field of study for children with neurological disabilies as well. One commonly studied babbling milestone is the onset of canonical babbling, when children produce speech-like syllables consisting of consonants and vowels. However, the most frequently used canonical babbling measure – the canonical babbling ratio (CBR) – has not been thoroughly validated. This thesis aimed to validate the CBR measure, to examine babbling, speech and language in a group of children with ND and to evaluate an intervention for young children with ND, specifically cerebral palsy. The thesis consists of five studies. In study I and II, a new and simplified version of the CBR measure (CBRUTTER ) was validated. It was found to be valid compared to other versions of the CBR and to babbling observation, suggesting it as an alternative to more laborious measures. Study II also evaluated the CBR criterion for the canonical babbling stage. A child is commonly considered to be in the canonical babbling stage when 15% or more of their babbling is canonical, that is a CBR of ≥ 0.15. Study II suggests that 0.14 may be a more appropriate criterion and emphasizes the need for proper discussion among babbling researchers on criteria for having entered the canonical babbling stage. In study I, III and IV, babbling, speech and language were examined at ages 1, 5 and 7 in a group of 18 children with neurological disabilities who received habilitation services from an early age. Compared to data from typically developing children, babbling milestones were delayed in the group of children with ND. At 5 and 7 years of age, speech and language disorder was very common, with only one participant presenting with results at age level on all measures. The severity of speech and language disorder was very varied, but a majority of participants had severe communication activity limitations. Despite this, parents rated the frequency of received SLP services as low. The results accentuate the need to closely follow speech and language development in children with ND, and to provide intervention as needed. In study V, a parent-implemented intervention for speech/language disorder was examined in young children with cerebral palsy. In a single case A-B study, four children received an intervention aimed at improving expressive vocabulary using a focused stimulation technique. Two children clearly improved their expressive vocabulary following the intervention, one showed less clear gains and one did not improve. Focused stimulation may thus be successful in children with cerebral palsy and speech/language difficulties and could be a valuable addition when it comes to SLP intervention options in children with neurological disabilities. In summary, this thesis presents new insights on the validity of the CBR measure, emphasizes the need to assess speech and language in children with neurological disability, and suggests an intervention for young children with cerebral palsy.