Scientists have identified blood markers that may be associated with the development of autism and mental retardation later in childhood. The new research, which will appear in the May issue of the Annals of Neurology, could lead to earlier, more accurate diagnoses and improved therapies for these disorders.

Karin B. Nelson of the National Institute of Neurological Disorders and Stroke and her colleagues studied archived neonatal blood samples from children who developed normally, as well as those who went on to develop autism, mental retardation or cerebral palsy. The team found that the blood of children who later developed autism or mental retardation contained significantly elevated levels of neural growth factors in contrast to the blood from the other two groups.

Neural growth factors play a key role in the formation of the central nervous system during embryonic development, producing and organizing brain cells, among other things. An overabundance of these proteins, the researchers propose, may thus disrupt the normal cycles the cells go through during early nervous system development. Many of the biological and genetic mechanisms underlying the development of disorders such as autism remain unknown, however. Nelson and her colleagues therefore plan to continue similar research in the future.