What the Evidence Does (and Does Not) Show for the Centers for Disease Control and Prevention Child Development Milestones: An Illustrative Example Using Expressive Vocabulary.

PURPOSE: Child development milestones are a critical tool for pediatricians and caregivers to use for developmental surveillance. Following review and selection by a panel of subject matter experts, the Centers for Disease Control and Prevention (CDC) published a revised list of milestones across multiple domains of development. Using expressive vocabulary, a key indicator of language development, as an illustrative example, the purpose of this brief review is to evaluate the evidence used to establish the CDC developmental milestones and determine whether the samples used to establish these milestones are representative of U.S. children. METHOD: Authors reviewed the methods and evidence cited to determine the CDC milestones. First, authors identified each language/communication milestone that measured expressive vocabulary as number of words, followed by review of the sources cited in support of each extracted milestone. Then, data related to both milestones and sample characteristics were extracted and compiled as well as compared with data from a validated parent report measure of expressive vocabulary, the MacArthur-Bates Communication Development Inventories. RESULTS: Results indicated that evidence was conflicting, misaligned, or missing for the selected CDC expressive vocabulary milestones. This review also indicated that the samples used to determine the selected CDC expressive vocabulary milestones are not representative of U.S. children. CONCLUSION: The striking paucity of evidence supporting the new CDC milestones for expressive vocabulary illustrates the critical need for future research in this area to establish more accurate milestones for U.S. children, with a focus on culturally inclusive large-scale data.

Differences in speech articulatory timing and associations with pragmatic language ability in autism.

Background: Speech articulation difficulties have not traditionally been considered to be a feature of Autism Spectrum Disorder (ASD). In contrast, speech prosodic differences have been widely reported in ASD, and may even be expressed in subtle form among clinically unaffected first-degree relatives, representing the expression of underlying genetic liability. Some evidence has challenged this traditional dichotomy, suggesting that differences in speech articulatory mechanisms may be evident in ASD, and potentially related to perceived prosodic differences. Clinical measurement of articulatory skills has traditionally been phoneme-based, rather than by acoustic measurement of motor control. Subtle differences in articulatory/motor control, prosodic characteristics (acoustic), and pragmatic language ability (linguistic) may each be contributors to differences perceived by listeners, but the interrelationship is unclear. In this study, we examined the articulatory aspects of this relationship, in speech samples from individuals with ASD and their parents during narration. Method: Using Speechmark® analysis, we examined articulatory landmarks, fine-grained representations of articulatory timing as series of laryngeal and vocal-tract gestures pertaining to prosodic elements crucial for conveying pragmatic information. Results: Results revealed articulatory timing differences in individuals with ASD but not their parents, suggesting that although potentially not influenced by broader genetic liability to ASD, subtle articulatory differences may indeed be evident in ASD as the recent literature indicates. A follow-up path analysis detected associations between articulatory timing differences and prosody, and subsequently, pragmatic language ability. Conclusion: Together, results suggest a complex relationship where subtle differences in articulatory timing may result in atypical acoustic signals, and serve as a distal mechanistic contributor to pragmatic language ability ASD.