Toward a paradigm shift from deficit-based to proactive speech and language treatment: Randomized pilot trial of the Babble Boot Camp in infants with classic galactosemia

Participants

The current participants are 14 children with CG and their parents. Here, we report on a subset of the children, the five oldest children with the longest participation record, for whom a nearly complete dataset is available through age 21 months. This pilot treatment cohort consists of four children, two girls (codes CG1, CG2) and two boys (CG4, CG5). Note that CG1 only participated in the study up to age 18 months, due to personal circumstances. One additional boy with CG was randomly selected to serve as a control who did not participate in the BBC treatment program. All families participated in the close monitoring components of the study, described further below. In the near future, this parallel design will be built out by recruiting more children into the treatment and control cohorts using randomization and blinding, the latter of which can only be applied to research team members who analyze the data.

In- and exclusionary criteria are identical for the treatment and control children with CG and are designed to evaluate the effects of the treatment while keeping all other factors the same. Inclusionary criteria are the following: Age at entry into the study is approximately 2 to 4 months. All infants are required to have a newborn diagnosis of CG. Boys and girls of any racial/ethnic background are equally eligible to participate, but given the highest CG prevalence rate among Caucasians, proportionally high numbers of Caucasians are expected. At least one parent or caregiver must enroll as a participant because we also collect quality of life information from the adults. The adults who enroll can be biological parents, adoptive parents, foster parents, or regular caregivers who are not related to the child as long as they provide care to the child on a regular basis. Primary language in the home must be English and at least one parent or caregiver must have at least an 8 ^th grade education. Because the intervention is implemented via telepractice software, any family whose primary language is English can participate, regardless of country of residence. The cohort as a whole currently includes families in the US and the UK. Exclusionary criteria are the following: Galactosemia forms other than CG; medical or sensory diagnosis that could introduce confounding, e.g., Trisomy 21 and deafness. Note that one child with CG, enrolled into the BBC as an infant, met the original criteria but went on to develop chronic ear infections requiring surgical insertion of pressure equalizing tubes at age 17 months; at the same time, she also underwent a frenectomy to address a tongue tie. Due to concerns regarding her hearing acuity and restricted tongue movement prior to these surgeries, her data are excluded from this report.

Regarding the five children described here, all live at home with both biological parents and are cared for during the day by their mothers while their fathers are at work. In all five families, parental levels of education, an estimate of socio-economic status, include at least some college. Consistent with the high CG prevalence rates among Caucasians worldwide, all five children are Caucasian, and all reside in the US. Although additional interventions beyond the BBC, where available, are allowed, none of the children described here were receiving any additional services.

Materials and procedures

The BBC is implemented via parent training by a speech-language pathologist (SLP) with expertise in early childhood. This SLP implements the program in all families in the treatment cohort, ensuring consistency and fidelity in the parent training. She uses a HIPAA-compliant telepractice computer interface to connect with the families. Parents learn about the typical milestones of prespeech, speech, and language development, potential red flags for delays, and, importantly, specific activities that support typical development for all stages of the program and development beyond.

The program is built around 17 activities and routines designed to foster relevant communication skills for children ages 2 to 24 months. Activities are components of the program that take place for at least 5 minutes per day, whereas routines are designed to become daily habits in the parent-child interactions. Examples of activities are stimulating and reinforcing babble by showing the child videos of babbling babies and enriching the child’s linguistic environment with joint book reading (Storkel et al., 2017). Examples of routines are saying the names of objects that the child points to (Dimitrova et al., 2016), and expanding child utterances to provide slightly more complex model sentences (Hassink & Leonard, 2010). Activities and routines are modeled on typical developmental milestones for ages 2 to 24 months reported in the scientific literature (Chapman, 2000; Gordon-Brannan & Weiss, 2007; MacLeod, 2013; Paul & Norbury, 2012; Stoel-Gammon, 1983; Stoel-Gammon, 2011) Note that there is considerable variability regarding these milestones, for instance onset of canonical babble among typically developing children (Oller et al., 1999) as well as children with various types of challenges such as hearing impairment with early amplification (von Hapsburg & Davis, 2006). Therefore, while the developmental milestones are the same for all children, children in the BBC treatment cohort progress through these milestones not based on their chronological age but on their present levels of ability. Also, activities may be individualized based on a child’s present levels; for instance, one child may need to learn to babble “dada” via shaping the [d] from a raspberry whereas another child might acquire that sound on her/his own or by imitating a model.

Because in young infants, communication skills do not develop in isolation but, rather, in the context of fine and gross motor, cognitive, social-emotional, and adaptive skills, the SLP discusses developmental milestones of the baby as a whole with the parents. An example is a play activity at age 11 to 12 months where parent and child take turns putting balls into a bucket. Each time, the parent says, “Ball,” and the child imitates, producing an approximation of the word. This activity builds social-cognitive skills (following directions, imitating, turn-taking), speech and language abilities, and fine and gross motor skills. Learning to greet by waving bye-bye is another example of growth involving social communication and gross motor skill. In the context of the BBC, the SLP makes observations and suggestions regarding those skills most relevant to the communication process, including balance/equilibrium when seated or standing in front of the parent, reaching for objects, and grasping and giving objects.

Following an orientation to the program, the SLP meets with each family once per week for approximately 15 minutes to train and consult on the relevant activities given the child’s current skill status. Three sources of information are discussed in each meeting: (1) Parents send the SLP up to three home videos up to 2 minutes in length and the SLP reviews these prior to the meeting; (2) During the meeting, parents report on progress with a given skill that was the focus during that week and on their amount and level of engagement with the child on the skill of interest; and (3) The SLP makes direct observations of the baby and the parent-child interactions during the meeting. In this way, the SLP’s training model includes the following steps: (1) describing the activity/routine, (2) modeling it, (3) giving feedback as parents practice it during the meeting, (4) providing feedback on the home video, (5) evaluating it in the following week’s meeting with the parents by discussing the child’s present skills, and (6) discussing ways to build on these skills towards the next target with the parents. Each week, the SLP makes recommendations for no more than two activities/routines to implement that support the child’s current skills and build toward the next developmental step. The SLP assesses parent fidelity in carrying out the activities/routines that had been agreed upon in the previous session, by asking the parents how frequently they engaged in the activities/routines during the preceding week. If parents have questions during the week, they may email the SLP and receive a written explanation. Altogether, the SLP spends 20 to 30 minutes per child per week reviewing the home video, meeting online with the child and parent(s), charting present levels and next goals, and billing.

One key principle underlying all activities is the zone of proximal development or scaffolding in which parents provide speech and language models that bridge what the child can already do and what is slightly beyond the child’s skill set: the model is in the zone of skills that the child can do with help (Vygotsky, 1979). One key skill that is targeted throughout the program is imitation.

Outcome measures

Because the BBC is designed to beneficially influence speech and language development, the primary outcome variables are speech sound production in babble and speech and expressive language ability. Secondary areas of interests are cognitive and motor development and quality of life, but these are only partially addressed in this report. During the active BBC phase, we monitor all of these areas as well as a range of other enrichment variables including volubility of child vocalizations, environmental influences, and demographic factors. Quantitative measures of these enrichment variables will be analyzed and described in future reports.

Specifically to assess speech sound development and language growth, we use a combination of several standardized tests and established clinical procedures. In the present pilot report, we quantify speech and language growth using several metrics. First, we focus on the complexity of the produced speech sounds during babble and early speech. Once per month per child starting at age 6 months, we compute the Mean Babbling Level (MBL) (Stoel-Gammon, 1989), a clinical measure of speech sound complexity for babbling. To compute the MBL, a set of at least 50 utterances is compiled and transcribed into the International Phonetic Alphabet using broad transcription. Noncanonical babble is excluded from the transcriptions. An expert rater assigns a score of 1, 2, or 3 to each utterance and computes the average; thus, MBL scores range from 1 to 3 for each child at any given time point. A score of 1 is assigned to simple utterances consisting of a vowel, a syllabic consonant, or a consonant-vowel (CV) or vowel-consonant (VC) sequence where the consonant is either a glide (“w”, “y”) or a glottal stop, defined as a brief silence interrupting a vowel; note that glottal stops and glides are not considered to be true consonants. Examples of level 1 utterances are “m” and “wawa”. A score of 2 is assigned to utterances containing at least one CV or VC sequence with a true consonant; if there are two or more syllables, the consonants may be the same ones or differ only in whether they are voiced or not. Examples are “bapa” and “dida”. A score of 3 is assigned to utterances containing at least two true consonants produced in different parts of the mouth and/or with different airflow characteristics. Examples are “gaba”, and “adap”. The three scores thus express the progression from motorically and linguistically simple to more complex skills. MBL scores in the BBC treatment and control cohort were compared to MBL scores in TD children at equivalent ages (Morris, 2010). Whereas the MBL is applied to babble, which does not convey lexical meaning, an equivalent measure called Syllable Structure Level (SSL) exists for meaningful speech (Paul & Jennings, 1992), and as for the MBL, we used this measure in tandem with typical norms (Morris, 2010).

The source materials for the MBL and SSL are daylong naturalistic audio recordings captured with a passive, wearable audio recorder (LENA Research Foundation, Boulder, CO). The recordings are obtained in the natural environment of the families and children. The recorder is returned to the research labs and processed offline to obtain the raw, daylong audio file, which provided the source for the present MBL and SSL scores. Other measures based on the recordings will be reported in the future, including estimates of child volubility such as syllables per hour and vocalizations per hour, speech production and discourse characteristics of the target child and other family members, and other variables known to be important for language and communication development in children. All measures collected in this way are objective and algorithm-driven. For purposes of the present work, we extracted multiple 5-minute audio segments with the highest occurrence of child utterances in order to broadly transcribe these utterances into the International Phonetic Alphabet and to compute MBL and SSL scores for each child and month. These segments are selected using a built-in LENA algorithm, independently of who else is in the acoustic recording environment, for instance one or both parents, siblings, or others.

Second, we use the MacArthur-Bates Communicative Development Inventories 2 (MBCDI-2) (Fenson et al., 2007) to capture early expressive and receptive vocabulary sizes as reported by the parents when filling out the MBCDI-2 protocol forms. MBCDI-2 questionnaires were collected from each family at regular intervals (ages 12, 15, 18, 21, and 24 months), and computed percentile scores were compared between the treated and untreated participants. Percentiles were based on the publisher’s norms, separately for boys and girls. Here, we focus on receptive vocabulary, available up to age 15 months, and expressive vocabulary, available for all reported ages but regarding our pilot sample, only through age 21 months.

Third, the Ages and Stages Questionnaires - 3 (ASQ3) parent questionnaires (Squires & Bricker, 2009) capture communication abilities and personal-social development of young children. The evaluation of communication abilities differs from the expressive and receptive vocabulary checks in the MBCDI-2 in that it samples broader communication abilities, as relevant for child age, such as comprehending phrases, using language to achieve a goal, and producing multi-word sentences. The personal-social development component queries skills in activities of daily living such as feeding and dressing oneself and social interactions, both verbal and nonverbal, such as giving/receiving objects, asking for help, and role-play, as relevant for age. The ASQ3 is considered valid and reliable for purposes of tracking typical development in these and three other areas (gross motor, fine motor, and problem solving) and for identifying areas of concern, where the problem solving component is an estimate of cognitive ability (Schonhaut et al., 2013). All five questionnaire topics are applicable to children with CG because of the known risks for deficits in each of these areas (Antshel et al., 2004; Karadag et al., 2013; Potter et al., 2013). Each component is scored by summing the raw scores, then assigning one of three categories, based on the provided norms: Above cutoff (“On schedule”), close to cutoff (“Provide learning activities and monitor”), or below cutoff (“Assess further”). The ASQ3 questionnaires are available in 21 separate, age-appropriate and age-normed sets from ages 2 to 60 months. We administer this tool in 6-months intervals and report here on ages 12 and 18 months.

Data analysis

Results and trends are presented descriptively, supported with graphs. Because of the small sample size of this pilot study, statistical tests for group differences and other inferential statistical procedures were not possible here, but will be used in future reports of the study.

Quality control

Questionnaire data from the MBCDI-2 and ASQ3 were entered into the database by teams of at least two trained research assistants. The MBL and SSL scores were computed by three trained research assistants; 15% of their scores were double-scored by other team members to obtain inter-rater reliability, an amount of rescoring slightly larger than that in other studies of young children’s utterances (Hardin-Jones & Chapman, 2008; Stoel-Gammon, 1989), and differences of over 10% in a given child’s MBL score would be resolved by consensus; however, such a discrepancy has not occurred in the pilot data.

Mean Babbling Level (MBL)

MBL scores of the children with CG in the treatment cohort consistently exceeded those of the control child with CG and typical control children without CG (Figure 1). For the ages for which data were available for nearly all children (11 through 21 months), the average difference between the treatment cohort and the control child with CG was 1.01, indicating that the children with CG in the treatment cohort obtained substantially higher MBL scores than the children in the other two categories. For the ages for which data were available for the control child with CG and the typical control children without CG (12, 15, 16, 18, and 20 months, listed in Morris, 2010), the average difference was -0.04, indicating that the control child with CG obtained MBL scores roughly equivalent to the typical controls without CG, but note the declining trend for the control child at the most recent ages. The difference between the children in the treatment cohort and the typical children was -0.77, indicating that the children in the treatment cohort outpaced the typical children on average. Figure 1 shows MBL scores for all children and all available ages.

Figure 1. Mean Babbling Level (MBL) scores for the four children with CG in the treatment cohort (blue symbols), the control child with CG (green symbols), and typically developing children (black symbols).

Syllable Structure Level (SSL)

The SSL has similar scoring criteria as the MBL, but unlike the MBL, it is based on meaningful speech and required a minimum of 10 utterances. For one child in the treatment cohort, CG1, not enough meaningful utterances could be identified in any of the recording sessions up to 18 months, when the child left the study, to compute the SSL. Of the remaining children and for the available ages at 12, 13, 15, 19, and 20 months, the children in the treatment cohort with CG outperformed the control child with CG by 1.0. For ages 15 and 19 months, the only ages for which data were available for the treatment cohort and the typical children without CG, the children in the treatment group outperformed the typical children by 0.6. The control child with CG and the typical children without CG could not be compared directly because data at the same ages were not available, but at ages 20 and 21 months, his scores appear lower than the typical controls’ scores at age 19 and 22 months. Note that, with only one exception, the highest scores were obtained by CG2 and CG5. Figure 2 summarizes the SSL scores.

Figure 2. Syllable Structure Level (SSL) scores for the four children with CG in the treatment cohort (blue symbols), the control child with CG (green symbols), and typically developing children (black symbols).

Expressive and receptive vocabulary

Regarding expressive vocabulary size, the control child obtained one of the two or three lowest rankings for the ages for which data were available (Figure 3). Two children in the treatment cohort, CG2 and CG5, obtained the highest percentile rankings, which, at age 21 months, were 73 and 72, respectively. Two children, CG1 and CG4, obtained low expressive vocabulary scores, with CG1’s percentile score being 1.7 at 18 months and CG4, 4.0 at 21 months. The control child, similar to CG1 and CG4 in the treatment cohort, showed declining expressive vocabulary scores, below the 8^th percentile at 21 months. Note that not having any words at all at age 12 months, which was the case for CG1 and the control child, corresponds to the 25^th percentile for boys and the 20^th percentile for girls, but the ranking drops rapidly with age if the expressive vocabulary does not increase substantially.

Figure 3. Expressive vocabulary size for ages 12 through 21 months, shown as percentile rankings, for the four children with CG in the treatment cohort (blue symbols) and the control child with CG (green symbols).

Regarding receptive vocabulary, the control child obtained the second-lowest percentile ranking (Figure 4), but note that all children including the control child show typical receptive vocabulary scores at the two ages represented in the questionnaires. The lowest percentile score, 10.5, is considered low average; it was obtained by CG1 at age 12 months. All other scores are solidly within normal limits. Figure 3 and Figure 4 summarize expressive and receptive vocabulary percentiles, respectively.

Figure 4. Receptive vocabulary size for ages 12 and 15 months, shown as percentile rankings, for the four children with CG in the treatment cohort (blue symbols) and the control child with CG (green symbols).

Ages and Stages Questionnaires -3 (ASQ3)

The AGS3 questionnaires at 12 and 18 months indicated that three of the four children in the treatment cohort had communication and personal-social abilities as expected for age. One child in this cohort had communication abilities below expectation for age at 18 months, and personal-social abilities close to the cutoff for age expectations. The control child scored close to the cutoff for age expectation at 18 months for communication, and at 12 and 18 months for personal-social abilities.

Regarding problem solving, of the children in the treatment cohort, only CG1 and CG4 had scores that were not consistently in the range of scores expected for age, both at age 18 months, whereas the control child was close to the cutoff at both time points. Regarding fine and gross motor skills, CG1 was the only child in the treatment cohort with scores that were below (fine motor) or close to (gross motor) the cutoff, whereas the control child had scores close to the cutoff in both areas at one time point and, for gross motor, at both time points. Across all areas, mainly one child in the treatment cohort (CG1) and the control child did not show developmental skills on schedule. Table 1 summarizes the ASQ3 scores for all children in the five assessed areas.

Limitations and future directions

Because of the small sample size in this pilot study, generalizations to other children with CG are not possible. Direct measures of parent training outcomes are not yet available. Whereas the MBCDI-2 percentiles were based on sex-adjusted norms, the other measures were not, but note that the two children with the overall highest performance were a girl and a boy. It is not possible to identify which components of the BBC had the greatest impact, if any, on speech, language, cognitive, and motor development. Many other variables in the study, for instance volubility of child vocalizations and environmental factors such as quantity of child-directed speech, remain to be analyzed, not only in this pilot cohort but also in the full set of families in this study. Longer-term outcomes in the primary and secondary outcome variables will be evaluated as we follow the children until age 4 years and evaluate a more complete spectrum of outcome variables including speech, language, cognitive and motor development, and quality of life. Most importantly, the trends toward beneficial effects of the BBC on the primary outcome variables of speech sound production and expressive language warrant appropriately powered larger clinical trials. As mentioned, a fully powered clinical trial is currently in its initial stages.

Underlying data

Open Science Framework: Babble Boot Camp. https://doi.org/10.17605/OSF.IO/YZHT4 (Peter, 2019)

The project contains the following underlying data files:

The underlying data also include audio files recorded in the participants’ homes and hand-written questionnaires with identifiable information; therefore, these cannot be openly shared. De-identified questionnaire files can be made available to qualified researchers by contacting the first author at Beate.Peter@asu.edu.

Extended data

Open Science Framework: Babble Boot Camp. https://doi.org/10.17605/OSF.IO/YZHT4 (Peter, 2019)

The project contains the following extended data files:

Reporting guidelines

Open Science Framework: Babble Boot Camp. https://doi.org/10.17605/OSF.IO/YZHT4 (Peter, 2019)

The project contains the following reporting guidelines:

Data are available under the terms of the Creative Commons Attribution 4.0 International license (CC-BY 4.0).