"The postnatal environment that children experience has a tremendous impact on children's cognitive status and attentional regulation skills," explained Julie A. Kable, assistant professor at Emory University School of Medicine and first author of the study. "Children of women who consume large amounts of alcohol during pregnancy and/or are substance abusers often experience family environments that do not support optimal development. As a result, when you examine older children it is often difficult to partition out the impact of the prenatal exposure with the impact of the postnatal environment. Assessments conducted closer in time to the insult provide a more accurate picture of the teratogenic effect."
"From a clinical point of view," added Sandra W. Jacobson, a professor in the department of psychiatry and behavioral neurosciences at Wayne State University School of Medicine, "tests such as the ones used in this study are important since it is critical to identify affected children as early in infancy as possible. Interventions are more likely to prove effective when implemented early in development and when specific core deficits are identified and can be targeted."
Research participants were recruited from the larger Atlanta-based Fetal Growth and Development Study, a project designed to estimate the prevalence of Fetal Alcohol Syndrome. Researchers used structured interviews to gather demographic, pregnancy-related, and alcohol and other drug-use information from the mothers; their infants were given an extensive physical examination; and medical records of the pregnancy and delivery were also collected. Based on the reported drinking habits of the mothers, infants were divided into two groups: high risk and low risk. While sitting in a car seat, each infant was presented with both auditory (400 and 1,000 hertz pure tones) and visual stimuli (chromatic Caucasian faces), and his/her cardiac responses were recorded.
"One of the most important cognitive processes is learning to regulate arousal level in order to appropriately take in new information or learn from the world around you," said Kable. "This study found that prenatal alcohol exposure resulted in disruption of this fundamental cognitive process."
Specifically, infants identified as "high risk" had significantly higher levels of arousal yet responded more slowly to stimuli than did infants identified as "low risk." Higher levels of behavioral arousal, coupled with lower neurophysiological responses involved in encoding environmental stimuli and initiating attention, suggest that "high risk" infants have difficulties with regulating interactions between arousal levels and the attentional system that processes environmental events.
"[These results] provide evidence of less efficient neurophysiological encoding of information in infants in the high-risk alcohol and drug exposure group," noted Jacobson. "These infants were more likely to have specific deficits in processing speed … which is consistent with our previous reports of slower processing speed in infants. These infant findings confirm the data reported for older children, namely, that sustained attention by alcohol exposure is not affected while processing speed is. Furthermore, the deficit in this high-risk group is associated with both visual and auditory attention, while the previous studies had only examined visual responses. More research will be needed to determine whether the auditory deficit is attributable to the alcohol or smoking exposure."
"The long-term implications of these findings are impairments in cognitive and later attentional regulation skills," added Kable. "If one does not maximize learning efficiency then he or she experiences a cumulative deficit over time. The cognitive deficits will result in lowered IQ scores and difficulties with learning basic functional and academic skills. The arousal difficulties may result in behavioral disturbances and meltdowns from being over-aroused and not being able to appropriately calm down when needed."
