Objective-To examine prospectively the emergence of behavioral signs of autism in the first years of life in infants at low and high risk for autism.Method-A prospective longitudinal design was used to compare 25 infants later diagnosed with an autism spectrum disorder (ASD) with 25 gender-matched low-risk children later determined to have typical development. Participants were evaluated at 6, 12, 18, 24, and 36 months of age.Correspondence to: Dr. Ozonoff, M.I.N.D. Institute, University of California Davis Health System, 2825 50 th Street, Sacramento CA 95817; sally.ozonoff@ucdmc.ucdavis.edu. Disclosure: Drs. Ozonoff, Iosif, Cook, Hutman, Rogers, Rozga, Sigman, Steinfeld, and Young, and Mr. Baguio, Ms. Hill, and Ms. Sangha report no biomedical financial interests or potential conflicts of interest.Editorial support for the preparation of this article was provided by Diane Larzelere, UC Davis. NIH Public AccessAuthor Manuscript J Am Acad Child Adolesc Psychiatry. Author manuscript; available in PMC 2010 August 17. NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author ManuscriptFrequencies of gaze to faces, social smiles, and directed vocalizations were coded from video and rated by examiners.Results-The frequency of gaze to faces, shared smiles, and vocalizations to others were highly comparable between groups at 6 months of age, but significantly declining trajectories over time were apparent in the group later diagnosed with ASD. Group differences were significant by 12 months of age on most variables. Although repeated evaluation documented loss of skills in most infants with ASD, most parents did not report a regression in their child's development.Conclusions-These results suggest that behavioral signs of autism are not present at birth, as once suggested by Kanner, but emerge over time through a process of diminishment of key social communication behaviors. More children may present with a regressive course than previously thought, but parent report methods do not capture this phenomenon well. Implications for onset classification systems and clinical screening are also discussed. KeywordsAutism; Onset; Infancy; Regression This study examined when and how behavioral signs of autism spectrum disorders (ASD) emerge in the first years of life. Most previous investigations of this topic have been retrospective, relying on parent report of earlier development or analysis of home videotape of infants later diagnosed with ASD. The existing literature suggests that behavioral signs of autism emerge in two different patterns, an early onset and a regressive course.Retrospective studies have demonstrated that children with early-onset ASD differ from agematched children with delayed and typical development in orienting to name, gaze to faces, joint attention, and affect sharing. [1][2][3][4][5][6] Differences are most evident in the second year of life 7 but some studies have detected signs of ASD before the first birthday. 1,5,8 This early onset pattern is thought to occur in the majority of indiv...

Objective This study had three goals, to examine: 1) the frequency of atypical development, consistent with the broader autism phenotype, in high-risk infant siblings of children with ASD, 2) the age at which atypical development is first evident, and 3) which developmental domains are affected. Method A prospective longitudinal design was used to compare 294 high-risk infants and 116 low-risk infants. Participants were tested at 6, 12, 18, 24, and 36 months of age. At the final visit, outcome was classified as ASD, Typical Development (TD), or Non-TD (defined as elevated ADOS score, low Mullen scores, or both). Results 28% of the high-risk group was classified as Non-TD at 36 months of age. Growth curve models demonstrated that the Non-TD group could not be distinguished from the other groups at 6 months of age, but differed significantly from the Low-Risk TD group by 12 months on multiple measures. The Non-TD group demonstrated atypical development in cognitive, motor, language, and social domains, with differences particularly prominent in social-communication. Conclusions These results demonstrate that features of atypical development, consistent with the broader autism phenotype, are detectable by the first birthday and affect development in multiple domains. This highlights the necessity for close developmental surveillance of infant siblings of children with ASD, along with implementation of appropriate interventions as needed.

Objective To examine prospectively the emergence of behavioral signs of autism in the first years of life in infants at low and high risk for autism. Method A prospective longitudinal design was used to compare 25 infants later diagnosed with an autism spectrum disorder (ASD) with 25 gender-matched low-risk children later determined to have typical development. Participants were evaluated at 6, 12, 18, 24, and 36 months of age. Frequencies of gaze to faces, social smiles, and directed vocalizations were coded from video and rated by examiners. Results The frequency of gaze to faces, shared smiles, and vocalizations to others were highly comparable between groups at 6 months of age, but significantly declining trajectories over time were apparent in the group later diagnosed with ASD. Group differences were significant by 12 months of age on most variables. Although repeated evaluation documented loss of skills in most infants with ASD, most parents did not report a regression in their child’s development. Conclusions These results suggest that behavioral signs of autism are not present at birth, as once suggested by Kanner, but emerge over time through a process of diminishment of key social communication behaviors. More children may present with a regressive course than previously thought, but parent report methods do not capture this phenomenon well. Implications for onset classification systems and clinical screening are also discussed.

Objective-To study the relationship between parent concerns about development in the first year and a half of life and later autism diagnostic outcomes.Method-Parent concerns about development were collected for infants at high and low risk for autism, using a prospective, longitudinal design. Parents were asked about developmental concerns at study intake and when their infant was 6, 12, and 18 months. Infants were then followed up until 36 months, when diagnostic status was determined.Results-By the time their child was 12 months, parents who have an older child with autism reported significantly more concerns in autism spectrum disorders-related areas than parents of children with typical outcomes. These concerns were significantly related to independent measures of developmental status and autism symptoms and helped predict which infants would later be diagnosed with autism or autism spectrum disorders. At 6 months, however, the concerns of parents who have an older child with autism do not predict outcome well.Conclusion-Explicitly probing for parent concerns about development is useful for identifying children in need of closer monitoring and surveillance, as recommended by the American Academy of Pediatrics.A fundamental component of pediatric practice is parent appraisal of child development. 1 Developmental history taking, including elicitation of parental concerns, is standard in most routine pediatric visits and is used to alert physicians to the possibility of conditions requiring further evaluation. As the incidence of and media attention to autism spectrum disorders (ASD) increase, concerns about the possibility of these conditions are increasingly being raised by parents. 2 Recently published guidelines from the American Academy of Pediatrics recommend that pediatricians ask parents about developmental concerns at each well-child visit and screen all children for autism twice by the second birthday. 3 If concerns are identified by parents, the American Academy of Pediatrics' surveillance and screening algorithm 3 recommends that an autism-specific screener should be administered and/or the child should be referred for a diagnostic evaluation, depending on the level of concern. Thus, parent report alone can trigger a referral for further evaluation.Retrospective studies indicate that parents recognize signs of autism far earlier than it is diagnosed. Although symptoms are typically present by the second birthday and one third of suggesting that it might be useful to screen for ASD as well. This finding was not replicated in a study screening 18-to 30-month old infants in primary care settings, 15 however, leading these authors to suggest that ASD-specific tools will be needed in the universal screening process. NIH Public AccessHowever, the importance of assessing the accuracy of parent reports of early development and their predictive validity for identifying autism is complicated in several ways. Several studies suggest that signs of autism emerge gradually over time and that the earlies...

Objective To examine longitudinal patterns of response to name from 6–24 months of age in infants at high and low risk for autism spectrum disorder (ASD). Study design A response to name task was tested at 6, 9, 12, 15, 18, and 24 months of age in 156 infant siblings of children with ASD (high-risk) or typical development (low-risk). At 36 months of age, participants were classified into 1 of 3 outcome groups: group with ASD (n = 20), high-risk group without ASD (n = 76), or low-risk group without ASD (n = 60). Differences in longitudinal performance were assessed using generalized estimating equations, and sensitivity and specificity for identifying ASD were calculated. Differences in age 36-month functioning were examined between infants who developed ASD and repeatedly vs infrequently failed to respond to name. Results At 9 months of age, infants developing ASD were more likely to fail to orient to their names, persisting through 24 months. Sensitivity/specificity for identifying ASD based on at least 1 failure between 12 and 24 months were estimated at .70 in this sample. One-half of the infants who developed ASD had repeated failures in this timeframe, and demonstrated lower age 36-month receptive language, and earlier diagnosis of ASD than infants with ASD who had infrequent failures. Conclusions In addition to recommended routine broad-based and ASD-specific screening, response to name should be regularly monitored in infants at risk for ASD. Infants who consistently fail to respond to their names in the second year of life may be at risk not only for ASD but also for greater impairment by age 3 years.