Early Behaviors Linked to Later Autism Spectrum Disorders in NICU Infants

Background:

Infants with obstetric/neonatal complications such as those seen in neonatal intensive care units (NICUs) appear to have 3 to 4-fold risk for Autism Spectrum Disorders (ASDs). Our longitudinal studies with medically-at-risk NICU infants from birth follow development of regulatory influences on multiple domains including attention, motor skills, social communication, temperament, and cognition. We previously reported archival demographic, medical, neonatal neurobehavior (NB) and attention data on NICU infants later diagnosed with ASDs. This report further analyzes this set of data on additional tasks in later infancy to identify patterns in neurodevelopment specific to these infants.

Objectives:

To identify potential behavioral markers and precursors to ASD in early infancy.
To posit potential mechanisms underlying neurodevelopment of behaviors across ASD-specific domains.

Methods:

NICU infants were evaluated prior to hospital discharge and followed every few months from birth to 5 years. Data included information about medical conditions and demographics at birth, early neurological insult, and a variety of behaviors in multiple domains. This report compares NICU infants later diagnosed with ASD (n = 33; 19 by co-author ILC, 14 by other sources) to controls (n = 134; matched on gender (81% male), gestational age at birth (23-41 weeks) and year of birth (1994-2006)) from birth to 2 years. Behaviors include neonatal NB, arousal modulation of visual attention (AMA), focused attention and distractibility, exploration in a novel environment, and cognitive and motor performance.

Results:

In analyses controlling severity and maternal education, ASD infants exhibited behavioral deficits starting in the newborn period. Their neonatal NB showed more visual asymmetry, tone differences between arms and legs, and less decrease in number of abnormalities at 1 month (p's < .01). They had poorer AMA out to 4 months (p < .001), with more attention to faster stimuli (like younger or cocaine-exposed infants). They showed attention problems and less habituation to distractors during a focused attention task at 10 and 13 months; fewer referenced examiner (p < .07) or looked at toys (p < .003), and many spent most of the time looking at distractors (p < .10). Their behavior in a novel environment (13-25 months) appeared to indicate repetitive stereotypic movements, lack of toy play, and an atypically positive approach to a 2-ft robot. Their scores on BSID-II MDI and PDI declined as early as 7-10 months, which typically only occurs in infants with the most severe pathology.

Conclusions:

Infants later diagnosed with ASD may form a distinct sub-group within NICU babies, with atypical visual, motor, and regulatory development. They have a unique behavioral profile, with slower resolution of neonatal problems and development, atypical visual function, lack of toy play, and motor as well as cognitive involvement starting much earlier than expected. Studies of NICU infants should provide opportunities to observe and identify potential markers and precursor behaviors at much younger ages than symptoms are seen or ASD diagnosed. Earlier identification is important for earlier intervention potentially improving long-term outcome.