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.