Autism's Earliest Symptoms Not Evident in Children Under 6 Months

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http://www.sciencedaily.com/releases/2010/02/100216091009.htm

Autism's Earliest Symptoms Not Evident in Children Under 6 Months

ScienceDaily (Feb. 16, 2010) — A study of the development of autism in infants,

comparing the behavior of the siblings of children diagnosed with autism to that

of babies developing normally, has found that the nascent symptoms of the

condition -- a lack of shared eye contact, smiling and communicative babbling --

are not present at 6 months, but emerge gradually and only become apparent

during the latter part of the first year of life.

Researchers conducted the study over five years by painstakingly counting each

instance of smiling, babbling and eye contact during examinations until the

children were 3. They found that by 12 months the two groups' development had

diverged significantly. Intentional social and communicative behavior among

children developing normally increased while among infants later diagnosed with

autism it decreased dramatically.

The study is published online early and will appear in the March issue of the

Journal of the American Academy of Child & Adolescent Psychiatry.

" This study provides an answer to when the first behavioral signs of autism

become evident, " said Sally Ozonoff, the study's lead author, a professor of

psychiatry and behavioral sciences and a researcher with the UC MIND

Institute. " Contrary to what we used to think, the behavioral signs of autism

appear later in the first year of life for most children with autism. Most

babies are born looking relatively normal in terms of their social abilities but

then, through a process of gradual decline in social responsiveness, the

symptoms of autism begin to emerge between 6 and 12 months of age. "

Autism is a pervasive developmental disorder of deficits in social skills and

communication, as well as in repetitive and restricted behaviors, with onset

occurring prior to age 3. Abnormal brain development, probably beginning

prenatally, is known to be fundamental to the behaviors that characterize

autism. Current estimates place the condition's incidence at between 1 in 100

and 1 in 110 children in the United States.

Children with a sibling already diagnosed with autism are known to be among

those at greatest risk of developing the disorder. The current study included 25

high-risk children who met criteria for autism at 3 years of age, matched with

25 low risk peers who were developing normally. It was conducted at the MIND

Institute and the University of California, Los Angeles. The sole inclusion

criterion for the high-risk group was having a sibling with autism; low-risk

participants had to have been born after 36 weeks gestation and have no autistic

family members.

The children's development was evaluated at 6, 12, 18, 24 and 36 months of age

using a series of widely implemented diagnostic tools, including the Autism

Diagnostic Observation Schedule (ADOS) and the Autism Diagnostic

Interview-Revised (ADI-R). Examiners were not told which babies were at high- or

low-risk when evaluating the participants' development.

The researchers found that there were few discernable differences between the

two groups at the outset but that after six months, 86 percent of the infants

who developed autism showed declines in social communication that were outside

the range for typical development. " After six months, " the study found, " the

autism spectrum disorder group showed a rapid decline in eye contact, social

smiling, and examiner-rated social responsiveness. " Group differences were

significant by 12 months in eye contact and social smiling and all other

measures by 18 months, the study found.

The study is notable because of the accuracy and precision of its prospective

methodology, assiduously recording exact numbers of social and communicative

behaviors during lab visits. Previously, researchers have constructed evidence

of autism's earliest manifestations by interviewing parents about when they

believed their children's symptoms first arose or by reviewing home movies for

clues to when children begin exhibiting symptoms of autism.

" Until now, research has relied on asking parents when their child reached

developmental milestones. But that can be really difficult to recall, and there

is a phenomenon called the " telescoping effect " where people usually say that

they remember something happening more recently than when it occurred, " Ozonoff

said. In addition parents frequently will turn off the video camera when their

children are behaving poorly -- precisely when autistic symptoms may appear.

Ozonoff said that the study provides a deeper understanding for parents,

caregivers and health-care providers and for future research of the

developmental trajectory for very young children with autism.

" We need to be careful about how we screen, and we need to know what we're

looking for, " Ozonoff said. " This study tells us that screening for autism early

in the first year of life probably is not going to be successful because there

isn't going to be anything to notice. It also tells us that we should be

focusing on social behaviors in our screening, since that is what declines early

in life. "

" This study also found that the loss of skills continues into the second and

third year of life, " she said. " So it may not be adequate, as the American

Academy of Pediatrics currently suggests, that providers screen for autism twice

before the end of the second year. Autism has a slow, gradual onset of symptoms,

rather than a very abrupt loss of skills. "

" Screening may need to continue into the third year of life, since symptom

emergence takes place over a long time. If a child starts exhibiting a declining

trajectory and a sustained reduction in social communication we want to refer

them into therapy, especially if they are at risk, " Ozonoff said, " even before

we might be able to make a definitive diagnosis. "

Ozonoff said that the study does not address the etiology of autism or

causality. In this study, the infants who participated were at high risk due to

having strong family histories of autism, suggesting that genetics play a major

role in the later autism diagnoses, despite the fact that their symptoms were

not apparent at birth.

Other study authors include Ana- Iosif, Fam Baguio, Ian C. Cook,

Hill, Beth Steinfeld, Sally J. , Sarabjit Sangha and S.

Young of UC and Ted Hutman, Agata Rozga and n Sigman of the

University of California, Los Angeles.

The study was funded by grants from the National Institute of Mental Health of

the National Institutes of Health.