Prenatal cocaine exposure effects on arousal-modulated attention during the neonatal period.

The organization of arousal and attention as a function of intrauterine cocaine exposure was investigated in 180 normal nursery infants prior to hospital discharge and at 1 month of age. This was done by studying visual looking preferences when infants were in three arousal conditions: less aroused (after feeding); more aroused-endogenous (before feeding); and more aroused-exogenous (after feeding but including 8-Hz visual stimulation prior to each visual preference trial). The stimuli were light panels illuminated at three temporal frequencies between 1 and 8 Hz presented in pairs using a balanced presentation series of trials. Infants not exposed to cocaine demonstrated strong arousal-modulated attention, preferring faster frequencies when less aroused and slower frequencies when more aroused in both endogenous and exogenous conditions. In contrast, cocaine-exposed infants showed a lack of arousal-modulated attention and preferred faster frequencies of stimulation regardless of arousal condition. Similar differences in arousal-modulated attention as a function of cocaine exposure were obtained at 1 month after birth, indicating that these effects lasted longer than would be reasonable to attribute to the active presence of cocaine or its metabolites. This form of stimulus-seeking behavior was shown to be independent of confounding factors associated with prenatal cocaine exposure such as the absence of prenatal care, alcohol use, minority status, or gender, as well as mediating factors associated with growth such as birthweight. A direct and more chronic effect of intrauterine cocaine exposure on arousal-modulated attention and presumably on the developing CNS therefore was supported.