Bayonet-shaped language development in autism with regression: a retrospective study

Area of Science:

• Neurodevelopmental disorders
• Developmental psychology
• Speech and language pathology

Background:

• Language delay is a key factor in autism spectrum disorder (ASD) evaluations.
• Early language regression (ELR) is reported in 10-50% of cases, but its long-term impact is unclear.
• Understanding ELR's predictive value is crucial for addressing parental concerns post-diagnosis.

Purpose of the Study:

• To determine the predictive value of early language regression (ELR) on language development and socio-communicative outcomes in autism spectrum disorder (ASD).
• To guide clinicians in managing parental concerns regarding language prognosis at the time of ASD diagnosis.

Main Methods:

• Utilized data from 2,047 participants with ASD (ages 4-18) from the Simons Simplex Collection.
• Employed Cox proportional hazard and logistic regression models to assess ELR's effect on language milestones and complex language use.
• Used linear models to examine the relationship between ELR, non-verbal IQ, and socio-communicative/language levels.

Main Results:

• Early language regression (ELR) is linked to earlier language milestones but delayed attainment of fluent, complex language.
• Non-verbal IQ, rather than ELR, significantly influences the ultimate language and socio-communicative levels in autistic individuals without intellectual disability.
• Language and socio-communicative skills, as measured by Vineland and ADOS, were not impacted by ELR in participants with flexible language.

Conclusions:

• Autistic individuals with ELR and normal non-verbal intelligence exhibit a "bayonet shape" language trajectory: regression, plateau, then catch-up.
• Language development in ASD is primarily influenced by non-verbal IQ, with ELR not being a significant predictor of long-term outcomes.
• ELR does not negatively affect the flexible language abilities or socio-communicative levels in the long term.