Neurocognitive Correlates of Attention-Deficit Hyperactivity Disorder Symptoms in Children Born at Extremely Low Gestational Age

Abstract

Objective: Compared with children born near term, those born extremely preterm (EP) are at much higher risk for attention-deficit hyperactivity disorder (ADHD). Little information is available about differences in neuropsychological outcomes among EP children with and without ADHD. Our analyses aimed to evaluate the neuropsychological correlates of ADHD symptoms in extremely low gestational age newborns (ELGANs).

Methods: We obtained Child Symptom Inventory-4 reports from parents (n = 871) and teachers (n = 634) of 10-year-old children born before the 28th week of gestation. Participants completed standardized assessments of neurocognitive and academic functioning.

Results: In the total sample, children who screened positive for ADHD symptoms were at increased risk for neurocognitive limitations. These associations were weaker when the sample was limited to those with intelligence quotient (IQ) ≥70 or ≥85. Even those with IQ ≥85 who screened positive for ADHD symptoms were more likely than their peers to have deficits on the DAS-II Working Memory Cluster and the NEPSY-II Auditory Response subtest. The risks for impaired academic performance (Z ≤ -1) on components of the WIAT-III were 2-to-3 times higher in this group than among ELGANs not classified as having ADHD symptoms.

Conclusion: Among children born EP, those with ADHD symptoms are more likely to have global neurocognitive impairment. When IQ is within normal limits, ADHD symptoms are associated with deficits in executive functioning skills. These findings highlight a group at risk for executive functioning deficits and related academic difficulties, even in the absence of intellectual disability.

Figure 1

Box-and-whisker plots of each neurocognitive subtest by ADHD (defined as meeting criteria by 2 of the following: CSI-4 report by parent, CSI-4 report by teacher, or clinical diagnosis). All subtest Z-scores are adjusted to population norms. Key: dark gray is ADHD and light gray is Non-ADHD. The central line in the box indicates the median (50^th centile), while the top of the box indicates the 75^th centile and the bottom of the box indicates the 25^th centile. V=Verbal, NV=Nonverbal reasoning, WM=Working memory, LC=Listening comprehension, OE=Oral expression, WR=Word reading, PwD=Pseudoword decoding, Sp=Spelling, NO=Numerical operations, AA=Auditory attention, RS=Auditory response set, INI=Inhibition inhibition, INS=Inhibition switching, AS=Animal sorting, INN=Inhibition naming, AW=Arrows, GEO=Geometric puzzles, VP=Visuomotor precision.

Figure 2

Forest plots of odds ratios (ORs) and 95% confidence intervals of a Z-score ≤ –1 on each DAS-II, OWLS, WIAT-III, and NEPSY-II neurocognitive assessment at age 10 associated with ADHD (defined as meeting criteria by 2 of the following: CSI-4 report by parent, CSI-4 report by teacher, or clinical diagnosis). Odds ratios in the left panel are unadjusted, while those in the right panel are adjusted for mother’s identification as black, mother’s age < 21 years, mother eligibility for public insurance, male sex, gestational age 23–24 weeks and birth weight Z-score < –2. The top set of panels is for all children, while the middle set is for children with an IQ > 70, and the bottom set is for children with an IQ > 85. Large dark circles indicate ORs significantly different from 1.0 (p < 0.05) while smaller gray circles indicate non-significant ORs. The ends of the horizontal lines indicate the bounds of the 95% confidence interval.