VAGAL TONE REGULATION DURING SUSTAINED ATTENTION IN BOYS EXPOSED TO OPIATES IN-UTERO

Attention and learning problems among children exposed to opiates in u tero have been previously reported but are difficult to interpret due to imprecise measurement and inadequate control of postnatal factors. In this study, we used a behavior-based measure of attention (continuo us-performance tasks) and a physiological index of sustained attention (cardiac vagal tone) to measure more precisely the process of sustain ed attention. Boys, aged 7 to 12, exposed to opiates in utero, were co mpared to boys whose mothers began using illicit substances after the child's birth (environmental controls), and boys whose mothers were no n-drug users. This three-group design was intended to isolate in utero effects from postnatal environmental influences. Vagal tone, a measur e of heart-rate variability sensitive to vagal influences on the heart , was measured pre- and postbaseline and during the three tasks of the Gordon Diagnostic System (Delay, Vigilance, and Distractibility). Vag al tone has been found to be sensitive to changes in environmental dem and for sustained attention in infants, school-age children, and adult s. Results indicated that when distractors were added to the vigilance task (Distractibility task), opiate-exposed boys failed to suppress v agal tone compared to both control groups. However, both the opiate-ex posed boys and the environmental controls made fewer correct responses than non-drug-exposed controls on this task. These results indicate t hat normal physiological responses to increased attentional demand may be impaired in boys exposed in utero to opiates in this age range. Ho wever, the poor Distractibility scores of both the opiate-exposed and environmental controls suggests an important role of environmental inf luences on attentional performance.