ADHD symptoms, executive attention, and electrophysiological activity in post-institutionalized children.

Abstract

Prior research indicates children who experience early deprivation in institutional care have increased rates of attentional problems (e.g., ADHD) years after adoption. Limited and conflicting evidence suggests post-institutionalized (PI) children may demonstrate behavioral deficits on measures of attentional control, response inhibition, and conflict monitoring and resolution, capacities broadly referred to as executive attention. Previous research has documented increased concentration of electroencephalogram (EEG) relative power in low frequency (e.g., theta) bands in PI children, compared to never institutionalized children. Similar patterns of low frequency EEG power have been observed in individuals with ADHD, suggesting a potentially shared neurobiological correlate. The current study examined both behavioral and electrophysiological correlates of attention in PI children. Parent reported ADHD symptoms, behavioral performance on two computerized executive attention measures, and resting EEG power were collected in a sample of 5 ½-year-old internationally adopted PI children (n = 25) and compared to same age non-adopted (NA) children (n = 33). Resting EEG collected when the children were 18 months of age was examined in longitudinal analyses. Consistent with prior research, PI children had increased levels of ADHD symptoms, although most children's symptoms were below a clinical threshold. No group differences were found in behavioral performance on executive attention measures. Analysis of longitudinal EEG data indicated PI children demonstrated greater concentration of low frequency EEG power (e.g., theta) than NA children at 18 months of age, and this group difference remained at age 5 ½, despite the PI group having spent an average of 4 ½ years in adoptive care. Contrary to hypotheses, concentration of frontal relative EEG power in the theta band at age 5 ½ was associated for PI children with more accurate performance on an executive attention task. In addition, in PI children increased concentration of low frequency frontal relative EEG power at age 18 months was associated with lower ADHD symptoms at age 5 ½ years. Interpretation of these results is limited by small sample size, particularly for the EEG analyses. However, these findings suggest the importance of considering brain-behavior relationships in respect to developmental context (e.g., resource poor vs. resource rich environments).