Snore-associated sleep fragmentation in infancy: mental development effects and contribution of secondhand cigarette smoke exposure.

OBJECTIVE The link between sleep-disordered breathing and neurocognitive functioning in preschool and school-aged children now has been established clearly. Within these age groups, isolated studies have examined the potential effect of snoring without gas exchange abnormalities on aspects of cognitive competence. The goal of the study was to test the potential association between snoring and decrements in developmental performance among infants. METHODS Thirty-five healthy community infants (8.2 +/- 0.4 months) were administered the Bayley Scales of Infant Development, including the Mental Development Index (MDI), after standard, overnight research polysomnography. RESULTS The apnea-hypopnea index for all infants was 0. Respiratory arousal index was significantly correlated with MDI. Snoring-associated arousals accounted exclusively for this relationship; spontaneous arousals and those that were associated with central apnea and oxyhemoglobin desaturation episodes (> or =4%) were not significantly correlated with MDI. Living in a smoking household was not significantly associated with the presence of objectively recorded snoring but was associated with an increase in arousal frequency in snoring infants. CONCLUSIONS Infants with lower scores on a standardized mental development assessment had higher snoring-arousal indices. Because neither apnea nor hypopnea was present, these findings constitute additional evidence that snoring is not just an innocent noise during sleep in infants but may in fact represent the lower end of the disease spectrum associated with sleep-disordered breathing. Secondhand exposure to cigarette smoke may increase the deleterious effects of infant snoring.