Autism in a 15-month-old child.

Aut ism is a developmental disorder marked by severe deficits in reciprocal social interaction, communication, and imagination as well as repetitive and restricted patterns of interests and behaviors (1; DSM-IV-TR). Its early-onset symptom profile includes neuro-logical findings (2) and structural and functional brain abnormalities (3); these findings and the chronicity of autism strongly argue for a biological basis, including genetic liabilities (4). Epidemio-logic studies indicate rates of 16 children per 10,000 for more narrowly defined au-tism and up to 40 children per 10,000 for the more broadly defined group of conditions marked by substantial socialization deficits (5). Despite the presumed congenital nature of autism, its identification typically lags behind the onset of symptoms by several years (6–9). Epide-miologic studies currently place the mean age of diagnosis of autism at around 40 months (5). Early identification is very important (10–12) given the current consensus that the beneficial impact of intervention programs increases with earlier treatment (13–15). This is likely a function of early neuroplasticity and the importance of early experiences in shaping behavioral and brain development (16, 17). Over the past decade new information on autism as it appears in the second and third year of life has focused on social orientation and responsivity, communicative development (including both nonverbal communication and spoken language), imitation, and play and symbolic development (18–26) (see reference 27 for a review). However, specific knowledge of the crucial infancy period of development in individuals with autism is currently limited and includes a small number of retrospective studies based on parental report (6) as well as systematic analyses of home movies made by parents before the child was diagnosed (28–32). Despite methodological limitations, these studies have pointed to a series of converging findings. First, it is possible to differentiate infants who will be diagnosed as having autism from infants who will be diagnosed as having nonautistic global developmental delays and from typically developing children by the age of 12 months (28, 29, 31, 33) if not earlier (32). Second, a tendency to look at others less and to orient themselves less to people calling their names appears to be the most syndrome-specific deficit by the time children with autism are 1 year old (31, 32). Finally , there is some evidence that infants subsequently diagnosed with autism also display a series of sensory-processing and sensorimotor abnormalities (29) and use gestures and look at objects held by others less …