Carly S. Molloy

Contribution of brain size to IQ and educational underperformance in extremely preterm adolescents.

Objectives Extremely 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. Methods Longitudinal 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. Results Brain 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. Conclusions EP 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.

Visual Processing in Adolescents Born Extremely Low Birth Weight and/or Extremely Preterm

BACKGROUND AND OBJECTIVES Ocular growth and development differs between preterm and term-born infants and may cause long-term negative consequences for visual function, but contemporary data on long-term visual outcomes in representative samples of the highest risk extremely low birth weight (ELBW, <1000 g birth weight) or extremely preterm (EP, <28 weeks’ gestation) survivors are lacking. Our objective was to compare visual functioning between ELBW/EP and normal birth weight (NBW, >2499 g birth weight) control adolescents. METHODS: Geographically determined cohort study of 228 consecutive ELBW/EP survivors born in the state of Victoria in 1991 and 1992, and 166 randomly selected NBW controls assessed between 14 and 20 years of age. Visual acuity, stereopsis, convergence, color perception, and visual perception were assessed and contrasted between groups. RESULTS: ELBW/EP subjects had significantly worse visual acuity with habitual correction in both the left and right eyes, and for the best eye (P < .001). The ELBW/EP adolescents also exhibited poorer stereopsis, odds ratio (OR) 3.22 (95% confidence interval [CI] 1.78 to 5.84), and convergence, OR 2.76 (CI 1.32 to 5.75) than controls, and more problems with visual perception, OR 3.09 (CI 1.67 to 5.71) after habitual correction. CONCLUSIONS: Despite advances in medical care improving the survival rate of high-risk ELBW/EP infants, visual morbidity is still relatively high compared with controls in late adolescence.

Docosahexaenoic Acid and Visual Functioning in Preterm Infants: A Review

Preterm children are at risk for a number of visual impairments which can be important for a range of other more complex visuocognitive tasks reliant on visual information. Despite the relatively high incidence of visual impairments in this group there are no good predictors that would allow early identification of those at risk for adverse outcomes. Several lines of evidence suggest that docosahexaenoic acid (DHA) supplementation for preterm infants may improve outcomes in this area. For example, diets deficient in the long-chain polyunsaturated fatty acid DHA have been shown to reduce its concentration in the cerebral cortex and retina, which interferes with physiological processes important for cognition and visual functioning. Further, various studies with pregnant and lactating women, as well as formula-fed infants, have demonstrated a general trend that supplementation with dietary DHA is associated with better childhood outcomes on tests of visual and cognitive development over the first year of life. However, research to date has several methodological limitations, including concentrations of DHA supplementation that have been too low to emulate the in utero accretion of DHA, using single measures of visual acuity to make generalised assumptions about the entire visual system, and little attempt to match what we know about inadequate DHA and structural ramifications with how specific functions may be affected. The objective of this review is to consider the role of DHA in the context of visual processing with a specific emphasis on preterm infants and to illustrate how future research may benefit from marrying what we know about structural consequences to inadequate DHA with functional outcomes that likely have far-reaching ramifications. Factors worth considering for clinical neuropsychological evaluation are also discussed.

Long-term effect of high-dose supplementation with DHA on visual function at school age in children born at <33 wk gestational age: results from a follow-up of a randomized controlled trial

BACKGROUND Children born preterm are at risk of visual-processing impairments. Several lines of evidence have contributed to the rationale that docosahexaenoic acid (DHA) supplementation of preterm infants may improve outcomes in visual processing. OBJECTIVE The aim was to determine whether at 7 y of age children who were born very preterm and who received a high-DHA diet have better visual-processing outcomes than do infants fed a standard-DHA diet. DESIGN This was a follow-up study in a subgroup of children from a randomized controlled trial. Infants were randomly assigned to milk containing a higher concentration of DHA (1% of total fatty acids; high-DHA group) or a standard amount of DHA (0.2-0.3% of total fatty acids as DHA; control group). The randomization schedule was stratified by sex and birth weights of <1250 or ≥1250 g. A total of 104 (49 in the high-DHA group and 55 in the standard-DHA group) children aged 7 y were assessed on a range of visual-processing measures, including visual acuity, contrast sensitivity, vernier acuity, binocular stereopsis, and visual perception. RESULTS There was no evidence of differences between the high-DHA and standard-DHA groups in any of the visual-processing measures. In the majority (12 of 13) of variables assessed, the direction of effect favored the control group. The study was large enough to detect a moderate treatment effect, if one truly existed. CONCLUSION Supplementing human milk with DHA at a dose of ∼1% of total fatty acids given in the first months of life to very preterm infants does not appear to confer any long-term benefit for visual processing at school age. This trial was registered at anzctr.org/au as ACTRN12606000327583.

Visual Memory and Learning in Extremely Low-Birth-Weight/Extremely Preterm Adolescents Compared With Controls: A Geographic Study

BACKGROUND Contemporary data on visual memory and learning in survivors born extremely preterm (EP; <28 weeks gestation) or with extremely low birth weight (ELBW; <1,000 g) are lacking. METHODS Geographically determined cohort study of 298 consecutive EP/ELBW survivors born in 1991 and 1992, and 262 randomly selected normal-birth-weight controls. RESULTS Visual learning and memory data were available for 221 (74.2%) EP/ELBW subjects and 159 (60.7%) controls. EP/ELBW adolescents exhibited significantly poorer performance across visual memory and learning variables compared with controls. Visual learning and delayed visual memory were particularly problematic and remained so after controlling for visual-motor integration and visual perception and excluding adolescents with neurosensory disability, and/or IQ <70. Male EP/ELBW adolescents or those treated with corticosteroids had poorer outcomes. CONCLUSION EP/ELBW adolescents have poorer visual memory and learning outcomes compared with controls, which cannot be entirely explained by poor visual perceptual or visual constructional skills or intellectual impairment.

School-Age Outcomes of Early Intervention for Preterm Infants and Their Parents: A Randomized Trial

OBJECTIVE: To examine the child and parental outcomes at school age of a randomized controlled trial of a home-based early preventative care program for infants born very preterm and their caregivers. METHODS: At term-equivalent age, 120 infants born at a gestational age of <30 weeks were randomly allocated to intervention (n = 61) or standard care (n = 59) groups. The intervention included 9 home visits over the first year of life focusing on infant development, parental mental health, and the parent–infant relationship. At 8 years’ corrected age, children’s cognitive, behavioral, and motor functioning and parental mental health were assessed. Analysis was by intention to treat. RESULTS: One hundred children, including 13 sets of twins, attended follow-up (85% follow-up of survivors). Children in the intervention group were less likely to have mathematics difficulties (odds ratio, 0.42; 95% confidence interval [CI], 0.18 to 0.98; P = .045) than children in the standard care group, but there was no evidence of an effect on other developmental outcomes. Parents in the intervention group reported fewer symptoms of depression (mean difference, –2.7; 95% CI, –4.0 to –1.4; P < .001) and had reduced odds for mild to severe depression (odds ratio, 0.14; 95% CI, 0.03 to 0.68; P = .0152) than parents in the standard care group. CONCLUSIONS: An early preventive care program for very preterm infants and their parents had minimal long-term effects on child neurodevelopmental outcomes at the 8-year follow-up, whereas primary caregivers in the intervention group reported less depression.

The contribution of visual processing to academic achievement in adolescents born extremely preterm or extremely low birth weight

ABSTRACT Children born extremely preterm (EP, <28 weeks) and/or extremely low birth weight (ELBW, <1000 g) have more academic deficiencies than their term-born peers, which may be due to problems with visual processing. The aim of this study is to determine (1) if visual processing is related to poor academic outcomes in EP/ELBW adolescents, and (2) how much of the variance in academic achievement in EP/ELBW adolescents is explained by visual processing ability after controlling for perinatal risk factors and other known contributors to academic performance, particularly attention and working memory. A geographically determined cohort of 228 surviving EP/ELBW adolescents (mean age 17 years) was studied. The relationships between measures of visual processing (visual acuity, binocular stereopsis, eye convergence, and visual perception) and academic achievement were explored within the EP/ELBW group. Analyses were repeated controlling for perinatal and social risk, and measures of attention and working memory. It was found that visual acuity, convergence and visual perception are related to scores for academic achievement on univariable regression analyses. After controlling for potential confounds (perinatal and social risk, working memory and attention), visual acuity, convergence and visual perception remained associated with reading and math computation, but only convergence and visual perception are related to spelling. The additional variance explained by visual processing is up to 6.6% for reading, 2.7% for spelling, and 2.2% for math computation. None of the visual processing variables or visual motor integration are associated with handwriting on multivariable analysis. Working memory is generally a stronger predictor of reading, spelling, and math computation than visual processing. It was concluded that visual processing difficulties are significantly related to academic outcomes in EP/ELBW adolescents; therefore, specific attention should be paid to academic remediation strategies incorporating the management of working memory and visual processing in EP/ELBW children.