A new study from the Infant Brain Imaging Network, which includes researchers at the Center for Autism Research at The Children’s Hospital of Philadelphia (CHOP), found significant differences in brain development starting at age 6 months in high-risk infants who later develop autism, compared to high-risk infants who did not develop autism.

“It’s a tremendously exciting finding,” said Sarah Paterson, PhD, director of the Infant Neuroimaging Lab at CHOP’s Center for Autism Research. “We found that the brains of the children who developed autism were markedly different even prior to the onset of behavioral symptoms of autism. Thus, our findings, while requiring replication, are a very important first step towards identifying a biomarker for autism risk. This would enable specialists to diagnose autism much earlier than what is currently possible through behavioral observations.”

The study also suggests that autism does not appear suddenly in young children but instead develops over time during infancy, note the authors. Intensive early intervention has been shown to improve outcomes in children with developmental delays and autism.

“This research raises the possibility that we might be able to intervene even before a child is 6 months old, to blunt or prevent the development of some autism symptoms,” said Paterson.

Participants in the study were 92 infants considered to be at high risk for ASD, because they all have older siblings with autism. Each infant had diffusion tensor imaging (DTI) — a type of magnetic resonance imaging (MRI) — at 6 months and behavioral assessments at 24 months. Most of the children also had additional brain imaging scans at either or both 12 and 24 months.

At 24 months, 28 infants (30 percent) met criteria for ASDs while 64 infants (70 percent) did not. The two groups differed in white matter fiber tract development — pathways that connect brain regions — as measured by fractional anisotropy (FA). FA measures white matter organization and development, based on the movement of water molecules through brain tissue.

This study examined 15 separate fiber tracts, and found significant differences in FA growth trajectories in 12 of the 15 tracts between infants who did develop autism versus infants who did not. Infants who later developed autism had elevated FA at six months but then experienced slower development over time. By 24 months of age, infants with autism had lower FA values than infants without autism.

The findings come on the heels of a recent study from London published in Current Biology, which found that infants at high risk for autism who were later diagnosed with the condition showed different brain responses from low-risk babies, or from high-risk babies that did not develop autism when shown images of faces looking at or away from the baby. Paterson said that the two findings strengthen one another and are encouraging evidence that scientists are on the right track towards finding markers for identifying autism much earlier than is currently possible.

mage of white matter pathways extracted from diffusion tensor imaging data for infants at-risk for autism. Warmer colors represent higher fractional anisotropy

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Autism researchers at the University of Pennsylvania School of Nursing have found a link between low birth weight and children diagnosed with autism, reporting premature infants are five times more likely to have autism than children born at normal weight.

The children, some born as small as about a pound, were followed for 21 years making this study, published in the journal Pediatrics, one of the most remarkable of its kind. The infants were born between September 1984 through July 1987 in Middlesex, Monmouth, and Ocean counties in New Jersey at birth weights from 500 to 2000 grams or a maximum of about 4.4 pounds.

“As survival of the smallest and most immature babies improves, impaired survivors represent an increasing public health challenge,” wrote lead author Jennifer Pinto-Martin, MPH, PhD, director of the Center for Autism and Developmental Disabilities Research and Epidemiology (CADDRE) at Penn Nursing. “Emerging studies suggest that low birth weight may be a risk factor for autism spectrum disorders.”

Links between low birth weight and a range of motor and cognitive problems have been well established for some time, but this is the first study that establishes that these children are also at increased risk for autism spectrum disorders (ASD).

“Cognitive problems in these children may mask underlying autism,” said Dr. Pinto-Martin. “If there is suspicion of autism or a positive screening test for ASD, parents should seek an evaluation for an ASD. Early intervention improves long-term outcome and can help these children both at school and at home.”

In future studies, Penn researchers will investigate possible links between brain hemorrhage, a complication of premature birth, and autism by examining brain ultrasounds taken of these children as newborns.

The researchers, including a team at The Children’s Hospital of Philadelphia, followed 862 children from birth to young adulthood finding that five percent of the children were diagnosed with autism, compared to one percent of the general population in what researchers called “the first study to have estimated the prevalence of ASD . . . using research validated diagnostic instruments.”

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A new study shows that one in three children who have an older sibling with an Autism Spectrum Disorder (ASD) fall into a group characterized by higher levels of autism-related behaviors or lower levels of developmental progress.

The study will be presented at the International Meeting for Autism Research (IMFAR) in May, 2012. ASDs are developmental conditions characterized by problems with social interaction and communication.

Previously, an international consortium of researchers found that almost one in five of the younger siblings of children with an ASD themselves developed an ASD.

Department of Psychology professor Daniel Messinger, presenting author of the study, says, “It is clear that the younger siblings of a child with an ASD may face challenges even if they are not themselves identified with an ASD. This new work identifies classes of outcomes in these children. We found that the majority of these high-risk siblings appear to be developing normally. However, a higher than expected proportion of the children face challenges related to higher levels of autism-related behaviors or lower levels of verbal and nonverbal developmental functioning.”

The study reveals that difficulties faced by the younger siblings of children with ASD involve both lower levels of verbal and nonverbal functioning and higher levels of autism-related problems. Examples of a child’s autism-related problems ─ which are not as severe as those of children with an ASD ─ include lower levels of back-and-forth play with others and lower levels of pointing to express interest in what is going on around them.

Overall, the research says, the majority of high-risk siblings are developing typically at three years of age, but the development of a substantial minority is affected by subtler forms of ASD-related problems or lower levels of developmental functioning. Lower levels of developmental functioning and higher levels of autism-related problems in the at-risk siblings define what researchers refer to as the broad autism phenotype.

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