Richard W. Hall, M.D.
Preterm delivery affects 8% of the total deliveries in the United States. Of the preterm deliveries, 1.5% (60,000) are Very Low Birth Weight (VLBW), weighing less than 1,500 gm. These neonates require prolonged intensive care and 51% of VLBW neonates suffer major disability later in life. Many of these Ex-Preterm children develop cognitive deficits and abnormal behaviors during childhood. Quantitative measures of pre-attentional, attentional and frontal lobe processes were compared to evaluate quantitative measures of these deficits in Ex-Preterm vs. Ex-Term adolescents. We compared 43 Ex-Preterm with 26 Ex-Term adolescents using the P50 auditory potential, the Psychomotor Vigilance Task (PVT), a reaction time (RT) test, and Near Infrared Spectroscopy (NIRS). The mean amplitude (+SE) of the P50 amplitude was similar in the Ex-Preterm (1.8+1.4 microV) vs. Ex-Term adolescents (1.8+0.6 microV), but the Ex-Preterm group showed a trimodal distribution in amplitude (High, 3.3+0.4 microV, p<0.01; Medium, 1.7+0.1 microV, p=0.53; Low, 0.7+0.1 microV, p<0.01) suggested by statistically significant variance between populations. Mean RT was longer in Ex-Preterm (250+8 msec) vs. Ex-Term subjects (200+5 ms, p<0.001). PVT lapses were increased in Ex-Preterm subjects, and varied inversely with P50 amplitude (Overall Mean 17+5 lapses, p<0.05; Low P50 amplitude, 25+10, p<0.01; Medium, 21+11, p<0.05; High, 6+2, p<0.01) vs. Ex-Term subjects (2+0.4 lapses, p<0.01). NIRS levels did not differ statistically, but tended to correlate with P50 amplitude in the Ex-Preterm group. These findings suggest differential pre-attentional, attentional and frontal lobe dysfunction in ex-preterm adolescents. These measures could provide a means to objectively assess differential dysregulation of arousal and attention in Ex-Preterm adolescents, allowing optimization of therapeutic designs.
