New study explores the relationship between preterm birth and autism spectrum disorder
(29 January 2009: VIDYYA MEDICAL NEWS SERVICE) -- Recent studies have suggested that autism spectrum disorder (ASD) may be more prevalent among children born very prematurely. The early symptoms of ASD are also associated with other conditions related to preterm births, such as cerebral palsy, which can make it difficult to correctly screen children for ASD. Because of this, researchers have begun to explore the relationship between preterm birth, cognitive and developmental impairments, and ASD. Two articles soon to be published in The Journal of Pediatrics explore this possible correlation between preterm birth and ASD.
Dr. Karl Kuban and colleagues from Boston University, Wake Forest University, and Harvard University studied 988 children born between 2002 and 2004 who participated in the ELGAN (Extremely Low Gestational Age Newborn) study, a large, multi-center study that enrolled more than 1500 infants born at least three months prematurely. They wanted to explore whether children born preterm are more likely to screen positive on the Modified Checklist for Autism in Toddlers (M-CHAT), a survey administered to a caregiver regarding a child's behavior. Pediatricians typically wait to formally diagnose ASD until after a child's third birthday. In this study, however, the caregivers of the infants completed the M-CHAT when the children were 24 months of age. The researchers found that 21% of the preterm children screened positive for ASD.
Dr. Kuban and his colleagues were also interested in learning whether a child born prematurely who had motor, visual, hearing, or cognitive impairments was more likely to screen positive on the M-CHAT. Of the 988 children, 26% had cognitive impairments, 11% had cerebral palsy, 3% had visual impairments, and 2% had hearing impairments. They also observed that nearly half of the children with cerebral palsy and more than two-thirds of the children with visual or hearing impairments screened positive. According to Dr. Kuban, "Children who are born more than three months premature appear to be twice as likely to screen positive on the M-CHAT." He notes, however, that the percentage of children who screened positive for ASD dropped to 10% when the variables of cognitive, visual, hearing, and motor impairments were removed.
In a related editorial, Dr. Neil Marlow and Dr. Samantha Johnson of University College London stress that because early identification leads to early treatment of children with ASD, screening tests are designed to over-identify children at risk. They suggest that useful knowledge may be gained by following the children as they mature to determine how many of those who initially screened positive actually develop ASD. Dr. Marlow notes that the study is valuable because "it raises our awareness of the difficulties in interpreting screening results." He cautions that further research is needed before conclusions can be drawn about the direct correlation between preterm birth and ASD.
The study is reported in "Positive Screening on the Modified Checklist for Autism in Toddlers (M-CHAT) in Extremely Low Gestational Age Newborns" by Karl C. K. Kuban, MD, SM, Epi, T. Michael O'Shea, MD, MPH, Elizabeth N. Alfred, MS, Helen Tager-Flusberg, PhD, Donald J. Goldstein, PhD, Alan Leviton, M, DOI: 10.1016/j.jpeds.2008.10.011.
The accompanying editorial is "Positive Screening Results on the Modified Checklist for Autism in Toddlers: Implications for Very Preterm Populations" by Neil Marlow, MD, and Samantha Johnson, PhD, DOI: 10.1016/j.jpeds.2008.11.028.
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