Aim: To examine executive functioning in very preterm (gestational age ≤30 wks) children at 4 to 12 years of age.
Method: Two-hundred very preterm (106 males, 94 females; mean gestational age 28.1wks, SD 1.4; mean age 8y 2mo, SD 2y 6mo) and 230 term children (106 males, 124 females; mean gestational age 39.9wks, SD 1.2; mean age 8y 4mo, SD 2y 3mo) without severe disabilities, born between 1996 and 2004, were assessed on an executive function battery comprising response inhibition, interference control, switching, verbal fluency, verbal and spatial working memory, and planning. Multiple regression analyses examined group differences while adjusting for effects of parental education, age, sex, and speed indices.
Results: Relative to children born at term, very preterm children had significant (p(s) <0.02; where p(s) represents p-values) deficits in verbal fluency (0.5 standardized mean differences [SMD]), response inhibition (0.4 SMD), planning (0.4 SMD), and verbal and spatial working memory (0.3 SMD), independent of slow and highly fluctuating processing speed. A significant group by age interaction indicated that group differences for response inhibition decreased between 4 and 12 years.
Interpretation: Very preterm birth is associated with a profile of affected and non-affected executive functions independent of impaired speed. Deficits are of small to moderate magnitude and persist over time, except for response inhibition for which very preterm children catch up with peers.
© The Authors. Developmental Medicine & Child Neurology © 2011 Mac Keith Press.