Infants later diagnosed with autism have lower canonical babbling ratios in the first year of life.

BACKGROUND: Canonical babbling-producing syllables with a mature consonant, full vowel, and smooth transition-is an important developmental milestone that typically occurs in the first year of life. Some studies indicate delayed or reduced canonical babbling in infants at high familial likelihood for autism spectrum disorder (ASD) or who later receive an ASD diagnosis, but evidence is mixed. More refined characterization of babbling in the first year of life in infants with high likelihood for ASD is needed. METHODS: Vocalizations produced at 6 and 12 months by infants (n = 267) taking part in a longitudinal study were coded for canonical and non-canonical syllables. Infants were categorized as low familial likelihood (LL), high familial likelihood diagnosed with ASD at 24 months (HL-ASD) or not diagnosed (HL-Neg). Language delay was assessed based on 24-month expressive and receptive language scores. Canonical babble ratio (CBR) was calculated by dividing the number of canonical syllables by the number of total syllables. Generalized linear (mixed) models were used to assess the relationship between group membership and CBR, controlling for site, sex, and maternal education. Logistic regression was used to assess whether canonical babbling ratios at 6 and 12 months predict 24-month diagnostic outcome. RESULTS: No diagnostic group differences in CBR were detected at 6 months, but HL-ASD infants produced significantly lower CBR than both the HL-Neg and LL groups at 12 months. HL-Neg infants with language delay also showed reduced CBR at 12 months. Neither 6- nor 12-month CBR was significant predictors of 24-month diagnostic outcome (ASD versus no ASD) in logistic regression. LIMITATIONS: Small numbers of vocalizations produced by infants at 6 months may limit the reliability of CBR estimates. It is not known if results generalize to infants who are not at high familial likelihood, or infants from more diverse racial and socioeconomic backgrounds. CONCLUSIONS: Lower canonical babbling ratios are apparent by the end of the first year of life in ASD regardless of later language delay, but are also observed for infants with later language delay without ASD. Canonical babbling may lack specificity as an early marker when used on its own.

Brief report: an unusual manifestation of diagnostic overshadowing of pervasive developmental disorder--not otherwise specified: a five year longitudinal case study.

Children with communication disorders present with a range of comorbid conditions. Occasionally one of the comorbid conditions manifests so strongly that the primary condition goes unnoticed by the clinician. This tendency to overlook comorbid health problems in the presence of a disability is referred to as diagnostic overshadowing. This is a five-year follow up case study of a 9-year-old female child. The child was initially diagnosed to have Separation anxiety disorder (SAD), but during the course of follow up she began to exhibit features of pervasive developmental disorder-not otherwise specified (PDD-NOS). This case report throws light on the severity of SAD which overshadowed PDD-NOS. Importance of follow-up and the need for a multidisciplinary team to be sensitive to the phenomenon of diagnostic overshadowing is discussed.