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

Jeanie L Y Cheong; Peter J Anderson; Gehan Roberts; Alice C Burnett; Katherine J Lee; Deanne K Thompson; Carly Molloy; Michelle Wilson-Ching; Alan Connelly; Marc L Seal; Stephen J Wood; Lex W Doyle

doi:10.1371/journal.pone.0077475

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

Jeanie L Y Cheong, Peter J Anderson, Gehan Roberts, Alice C Burnett, Katherine J Lee, Deanne K Thompson, Carly Molloy, Michelle Wilson-Ching, Alan Connelly, Marc L Seal, Stephen J Wood, Lex W Doyle

Psychology

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Abstract

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 (< 28 weeks) and term-born (≥ 37 weeks) 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.

Original language	English
Article number	e77475
Journal	PLoS ONE
Volume	8
Issue number	10
DOIs	https://doi.org/10.1371/journal.pone.0077475
Publication status	Published - 9 Oct 2013

Keywords

Adolescent
Brain
Cohort Studies
Female
Humans
Infant, Extremely Premature
Infant, Newborn
Intelligence
Intelligence Tests
Learning
Male
Organ Size

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Cheong_et_al_Contribution_of_brain_size_PLoS_ONE_2013
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@article{2860337df3af4254acb2ce31de2b7e78,

title = "Contribution of brain size to IQ and educational underperformance in extremely preterm adolescents",

abstract = "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 (< 28 weeks) and term-born (≥ 37 weeks) 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.",

keywords = "Adolescent, Brain, Cohort Studies, Female, Humans, Infant, Extremely Premature, Infant, Newborn, Intelligence, Intelligence Tests, Learning, Male, Organ Size",

author = "Cheong, {Jeanie L Y} and Anderson, {Peter J} and Gehan Roberts and Burnett, {Alice C} and Lee, {Katherine J} and Thompson, {Deanne K} and Carly Molloy and Michelle Wilson-Ching and Alan Connelly and Seal, {Marc L} and Wood, {Stephen J} and Doyle, {Lex W}",

year = "2013",

month = oct,

day = "9",

doi = "10.1371/journal.pone.0077475",

language = "English",

volume = "8",

journal = "PLoS ONE",

issn = "1932-6203",

publisher = "Public Library of Science (PLOS)",

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TY - JOUR

T1 - Contribution of brain size to IQ and educational underperformance in extremely preterm adolescents

AU - Cheong, Jeanie L Y

AU - Anderson, Peter J

AU - Roberts, Gehan

AU - Burnett, Alice C

AU - Lee, Katherine J

AU - Thompson, Deanne K

AU - Molloy, Carly

AU - Wilson-Ching, Michelle

AU - Connelly, Alan

AU - Seal, Marc L

AU - Wood, Stephen J

AU - Doyle, Lex W

PY - 2013/10/9

Y1 - 2013/10/9

N2 - 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 (< 28 weeks) and term-born (≥ 37 weeks) 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.

AB - 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 (< 28 weeks) and term-born (≥ 37 weeks) 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.

KW - Adolescent

KW - Brain

KW - Cohort Studies

KW - Female

KW - Humans

KW - Infant, Extremely Premature

KW - Infant, Newborn

KW - Intelligence

KW - Intelligence Tests

KW - Learning

KW - Male

KW - Organ Size

U2 - 10.1371/journal.pone.0077475

DO - 10.1371/journal.pone.0077475

M3 - Article

C2 - 24130887

SN - 1932-6203

VL - 8

JO - PLoS ONE

JF - PLoS ONE

IS - 10

M1 - e77475

ER -

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

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