Chronological age results in a lowering of scores at all ages for preterm-born subjects that is greater in the first few years and in those born at earlier gestational ages. Whether or not to correct for prematurity depends upon the context of the assessment.

ObjectivesExtremely preterm (EP) survivors have smaller brains, lower IQ, and worse educational achievement than their term-born peers. The contribution of smaller brain size to the IQ and educational disadvantages of EP is unknown. This study aimed (i) to compare brain volumes from multiple brain tissues and structures between EP-born (<28weeks) and term-born (≥37weeks) control adolescents, (ii) to explore the relationships of brain tissue volumes with IQ and basic educational skills and whether this differed by group, and (iii) to explore how much total brain tissue volume explains the underperformance of EP adolescents compared with controls.MethodsLongitudinal cohort study of 148 EP and 132 term controls born in Victoria, Australia in 1991-92. At age 18, magnetic resonance imaging-determined brain volumes of multiple tissues and structures were calculated. IQ and educational skills were measured using the Wechsler Abbreviated Scale of Intelligence (WASI) and the Wide Range Achievement Test(WRAT-4), respectively.ResultsBrain volumes were smaller in EP adolescents compared with controls (mean difference [95% confidence interval] of -5.9% [-8.0, -3.7%] for total brain tissue volume). The largest relative differences were noted in the thalamus and hippocampus. The EP group had lower IQs(-11.9 [-15.4, -8.5]), spelling(-8.0 [-11.5, -4.6]), math computation(-10.3 [-13.7, -6.9]) and word reading(-5.6 [-8.8, -2.4]) scores than controls; all p-values<0.001. Volumes of total brain tissue and other brain tissues and structures correlated positively with IQ and educational skills, a relationship that was similar for both the EP and controls. Total brain tissue volume explained between 20-40% of the IQ and educational outcome differences between EP and controls.ConclusionsEP adolescents had smaller brain volumes, lower IQs and poorer educational performance than controls. Brain volumes of multiple tissues and structures are related to IQ and educational outcomes. Smaller total brain tissue volume is an important contributor to the cognitive and educational underperformance of adolescents born EP.

The aim of this study was to evaluate attention difficulties in a contemporary geographic cohort of adolescents born extremely preterm (EP, <28 weeks' gestation) or extremely low birth weight (ELBW, birth weight <1000 g). The EP/ELBW group included 228 adolescents (mean age = 17.0 years) born in Victoria, Australia in 1991 and 1992. The control group were 166 adolescents (mean age = 17.4 years) born of normal birth weight (birth weight >2499 g) who were recruited in the newborn period and matched to the EP/ELBW group on date of birth, gender, language spoken and health insurance status. Participants were assessed on measures of selective, sustained, and executive (shift and divided) attention, and parents and participants completed behavioral reports. The EP/ELBW group performed more poorly across tests of selective and executive attention, had greater rates of clinically significant difficulties compared with the control group, and also had greater behavioral attention problems as reported by parents. Neonatal risk factors were weakly associated with attention outcomes. In conclusion, higher rates of attention impairments are observed in individuals born EP/ELBW well into adolescence and may have consequences for their transition to adulthood.

ADHD was more prevalent in EP/ELBW adolescents than controls, which is consistent with some, but not all, reports on preterm survivors born before the 1990s, and younger preterm children born in the 1990s. The high rates of anxiety and mood disorders were similar in both groups, and comparable with population-based estimates.