Wednesday April 25, 01
By Will Dunham
WASHINGTON (Reuters) - Elevated levels of proteins in the blood at birth appear to foreshadow the development of autism and mental retardation later in childhood, researchers said on Wednesday in a finding that could lead to earlier diagnosis and better treatment.
Researchers studied archived neonatal blood samples from children born in four northern California counties from 1983 to 1985 who were later diagnosed with autism, mental retardation, cerebral palsy or developed normally.
They found that concentrations of proteins in the blood called neural growth factors were significantly elevated in children who later developed autism or mental retardation, but not in the other children. The findings appear in the journal Annals of Neurology.
Dr. Karin Nelson, who led the study, said the discovery of this early-warning indicator for the development of autism and mental retardation before the onset of symptoms could help doctors make earlier and more definitive diagnoses.
Nelson, who works at the National Institute of Neurological Disorders and Stroke, part of the US government's National Institutes of Health, said the research could point the way for developing drugs that could be used in children showing these early-warning signs to better treat and perhaps prevent the development of autism.
Nelson said despite the similarities in these early biological markers for autism and childhood mental retardation, there is no reason to think they are the same disorder.
Autism, a developmental disorder, affects up to one in 500 children. Diagnosis generally is not made until after symptoms surface at about age 2. The children are unresponsive to human contact and exhibit poor language development and bizarre behavior such as uncontrollable head banging and screaming fits.
A Poorly Understood Malady
``The basic biology (of autism) has been fundamentally not understood,"" Nelson said in an interview.
``These kids look normal, most of them, and they move normally. For a long time it was thought that this was a psychological disorder caused by defective parenting. Now it is pretty clear this is an organic disease of the brain.""
The study found that children who later developed autism or mental retardation had, on average, three times as much of certain brain growth factors in their blood as the other kids. The finding that these major regulators of brain development differ in autistic children in the first days of life helps in the understanding of the malady's biological basis, she said.
``Things are happening after birth that make one hopeful that there may be ways found to intervene,"" Nelson said. ``Many people think that the earlier you start treatment, the more favorable the outcome.""
Neural growth factors are important to the formation of the central nervous system during embryonic development. Previous research found that many of these proteins are crucial in the production of new brain cells and the organization of those cells into distinct networks.
The researchers said the abnormal abundance of these proteins in the autistic and retarded children may disrupt the normal process of cell migration, differentiation and programmed death during early nervous system development.
Animal studies have shown that an early shortage of one of these proteins leads to microcephaly (a brain defect marked by a small head and mental retardation) and other developmental problems.
Nelson said ``gorgeous foresight"" by the California Department of Health Services to save blood specimens from the state's newborn screening program made the findings possible.
The department's Judith Grether, a co-author of the study, said the archive provides ``a tremendously valuable resource for scientific study of a wide range of developmental disabilities and birth defects.""