Behavioral manifestations of autism in the first year of life

Abstract

In the interest of more systematically documenting the early signs of autism, and of testing specific hypotheses regarding their underlying neurodevelopmental substrates, we have initiated a longitudinal study of high-risk infants, all of whom have an older sibling diagnosed with an autistic spectrum disorder. Our sample currently includes 150 infant siblings, including 65 who have been followed to age 24 months, who are the focus of this paper. We have also followed a comparison group of low-risk infants. Our measures include a novel observational scale (the first, to our knowledge, that is designed to assess autism-specific behavior in infants), a computerized visual orienting task, and standardized measures of temperament, cognitive and language development. Our preliminary results indicate that by 12 months of age, siblings who are later diagnosed with autism may be distinguished from other siblings and low-risk controls on the basis of: (1) several specific behavioral markers, including atypicalities in eye contact, visual tracking, disengagement of visual attention, orienting to name, imitation, social smiling, reactivity, social interest and affect, and sensory-oriented behaviors; (2) prolonged latency to disengage visual attention; (3) a characteristic pattern of early temperament, with marked passivity and decreased activity level at 6 months, followed by extreme distress reactions, a tendency to fixate on particular objects in the environment, and decreased expression of positive affect by 12 months; and (4) delayed expressive and receptive language. We discuss these findings in the context of various neural networks thought to underlie neurodevelopmental abnormalities in autism, including poor visual orienting. Over time, as we are able to prospectively study larger numbers and to examine interrelationships among both early-developing behaviors and biological indices of interest, we hope this work will advance current understanding of the neurodevelopmental origins of autism.

Variation in Vocal-Motor Development in Infant Siblings of Children with Autism

“…This result is not surprising in light of the prevalence of delayed reduplicated babble in the group and the fact that delayed babble has been shown to relate to delayed language (e.g., Oller, Eilers, Neal, & Schwartz, 1999;Stoel-Gammon, 1989). It is also very much in line with other recent studies of Infant Siblings in the second and third years that have reported delays in language using both standardized and parent report measures (Mitchell et al, 2006;Yirmiya et al, 2006a;Yirmiya et al, 2006b;Zwaigenbaum et al, 2005). Whether the Infant Siblings as a group will continue to be characterized by delay at later ages is an open question (and there is some indication that they will not; Pilowsky, Yirmiya, Shalev, & Gross-Tsur, 2003; but see Bailey, Palferman, Leavey, & Le Couteur, 1998).…”

“…Using the Mullen Scales of Early Learning, Landa and Garrett-Meyer (2006) have reported that at 6 months of age, Infant Siblings of children with autism who themselves later go on to develop ASD show no significant communicative delays. By contrast, however, Zwaigenbaum et al (2005) found that at 12 months of age, Infant Siblings later diagnosed with ASD scored significantly lower on both the expressive and receptive language subscales of the Mullen; and in a study of Infant Siblings carried out by Yirmiya and colleagues (Yirmiya et al, 2006a;Yirmiya, Gamliel, Shaked, & Sigman, 2006b), 2 of 3 infants who scored 2 or 3 on the CHAT at 36 months had significant language delays.…”

“…Our focus is on the later-born infant siblings of children diagnosed with autism. These infant siblings are themselves at especially high risk for an autism or ASD diagnosis (e.g., Zwaigenbaum et al, 2005; see also Zwaigenbaum et al, 2006). The larger ongoing study observes infants prospectively at monthly intervals from the ages of 5-14 months with follow-up at 3-month intervals from 18 to 36 months.…”

Gross Motor Development, Movement Abnormalities, and Early Identification of Autism

“…phenotype of autism suggest that symptoms emerge between 9 and 18 months of life in most children, with even early social-communicative behaviors looking largely intact before the first birthday in most infants later diagnosed with autism (Bryson et al 2007;Yirmiya et al 2006;Yirmiya and Ozonoff 2007;Zwaigenbaum et al 2005). Studies using prospective samples have not found differences in motor behavior, assessed with standardized instruments, at 4 months (Yirmiya et al 2006), 6 months (Landa and Garrett-Mayer 2006), 12 months (Zwaigenbaum et al 2005), or 14 months (Yirmiya et al 2006) of age.…”

Imitation Assessment and Its Utility to the Diagnosis of Autism: Evidence from Consecutive Clinical Preschool Referrals for Suspected Autism

“…There is some evidence that imitation problems in infancy, together with several other indicators, proceed and predict the diagnosis of autism (Zwaigenbaum et al 2005).…”