The Biology of Disadvantage: Childhood Poverty,Health, and Achievement

Nicole HairUniversity of Wisconsin-Madison

Department of Economics and Institute for Research on Poverty

March 2, 2014

Talk Outline

I Stylized facts about “disadvantage” and inequality

I Consequences of childhood poverty for physical health,behavior, early achievement and educational attainment

I Theoretical framework for understanding how poverty mightaffect children and families

I Exploration of potential link between childhood poverty andbrain structure and development

I Programs and policy responses aimed at mitigating influenceof poverty on children

What is Poverty?

Having little or no money or means of financial support

I Federal government created a set of poverty thresholds in the1960s

I In 2012, the poverty threshold (FPL) for family of three was$19,090 and for a family of four it was $23,050

I US poverty rate 15% and WI poverty rate 11.4% in 2012

I Alternative poverty measures are increasingly recognized asimportant

I US Census Supplemental Poverty Measure (SPM) takes intoaccount government benefits and necessary expenses liketaxes that are not in the official measure

I 2012 SPM poverty rate 16% slightly higher than official rate

Consequences of Childhood Poverty

Income gradient in health

I Children (and Adults) in poorer households tend to havepoorer health

I Relationship holds across numerous dimensions or indicatorsof children’s health status

Case, Lubotsky & Paxson, Economic Status and Health in Childhood: The Origins of the Gradient, American Economic Review, vol. 92, iss. 5, pp. 1308-1334 (2002)

Case, Lubotsky & Paxson, Economic Status and Health in Childhood: The Origins of theGradient, American Economic Review, vol. 92, iss. 5, pp. 1308-1334 (2002)

Marginal Effects of Parental Income Level on Children(6 to 17 years) Reported Being in Fair or Poor Health

Marginal Effects of Household Income Level on Adults’ Health(Reported Being in Fair or Poor Health)

Currie and Lin, Chipping Away At Health: More On The Relationship Between Income And Child Health, Health Affairs(2007) vol. 26 no. 2: 331-344

Adapted from: Currie and Lin, Chipping Away At Health: More On The Relationship Between Income And Child Health, Health Affairs (2007) vol. 26 no. 2: 331-344

I Low-income children are in worse health than other childrenI Low-income children are more likely than other children to have chronic or

acute condition and are more likely to be limited by these conditions

Income Achievement Gap

I Socioeconomic disparities in cognitive outcomes and academicachievement have been well-documented

I Childhood poverty associated with lower scores onstandardized tests, poorer grades in school, & less educationalattainment(Brooks-Gunn, 1997; Haveman & Wolfe, 1995; Dahl & Lochner, 2012)

I Observed ability gaps across SES groups open up at early ages(Duncan et al., 1998; Cuhna et al., 2006)

Low income children enter school with higher levels of problembehavior and these differences persist

Low income children enter school with lower levels of academicskills and these differences persist

Bottom Line

I Observed income gradient in health: children in poorerhouseholds tend to have poorer health

I Disparities in cognitive outcomes and academic achievementalso well-documented

I Childhood poverty associated with lower scores onstandardized tests, poorer grades in school, & less educationalattainment

How does poverty lead to thesedisparities??

I Relatively little known about how early exposure to povertytranslated into deficits in cognition and achievement

I Recent research efforts involving biomarkers and brain scansattempt to gain insight into “black box” linking poverty topoor health and deficits in achievement

I Research on tie between poverty and anatomy of thebrain with Jamie Hanson, Seth Pollak, Barbara Wolfe and others

I Goal of project: bring insight into what “causes” income achievementgap

I Potential neurobiological channel - explore whether brain structure/development may serve as one bridge linking socioeconomic status toachievement

SES, Environment & Brain Plasticity

I Brain structure and development offer window into processeslinking poverty to deficits in cognition and academic achievement

I Childhood poverty associated with inequities in both physical andpsychological environments (Evans, 2004)

I ↑ levels of life stress (family instability, violence) and exposure toenvironmental toxins

I ↓ parental nurturance and cognitive stimulation in the home

I Research with animals shows strong link between environment and brainI Environmental stimulation or enrichment, parental nurturance,

early life stress all affect brain growth and functioning(Rosenzweig et al., 1978; Greenough et al., 1975, 1978; Zhang et al., 2004)

I Small studies with humans suggest alterations in structure or functioning(for review, Hackman & Hanson 2012)

I Developed to aid in understanding brain maturation in“healthy, typically-developing” infants, children, & adults

I Size and scope unprecedented

I Objective 1: children and adolescents 4 to 18 years823 observations from 389 unique children

I Objective 2: infants to age 4 years200 observations from 81 unique children

I Anatomic MRI scans, cognitive & behavioral assessments,demographic characteristics

I Scans “interpreted” using structural imaging techniques(voxel based morphometry)

FIGURE 1: This figure shows example axial slices from a typical subject scanned at birth (left column), 2 (middlecolumn), and 4 years old (right column). T1 MRI, T2 MRI, and segmented gray matter (green) and white matter(red) are provided.

Hanson JL, Hair N, Shen DG, Shi F, Gilmore JH, et al. (2013) Family Poverty Affects the Rate of Human InfantBrain Growth. PLoS ONE 8(12)

A Bit of BackgroundAnatomy of the Brain

Brain can be divided into 2 hemispheres - right and left

3 types of materials or tissue

I Gray matter - what fires in brain

I White matter - wires of brain

I Cerebrospinal fluid - jello like substance absorbs impact

Four lobes

I Occipital - visual regions

I Parietal - sensation and perception

I Temporal - memory, emotion, auditory

I Frontal - executive functions

Selecting Brain Regions of Interest

Cognitive neuroscience guides selection of brain regions of interest

Selection Criteria:

1. Critical for sustained attention, planning, & cognitive flexibilityImplications for learning and academic functioning

2. Protracted period of post-natal developmentMore likely to be vulnerable to environmental experience

3. Focus on gray matter tissueLess heritable than other brain tissues (Gilmore et al., 2010)

Brain Regions of Interest

I Total gray matterprocessing information, execution of actions

I Frontal lobeproblem solving, attentional control, complex learning

I Temporal lobememory, language comprehension

(word identification, relation of heard sounds to letters of alphabet, attachment

of meaning to words)

I Hippocampuslearning, long-term memory (portion of temporal lobe)

RESULTS: Infants

1. Infants from low-income families show delayedtrajectories of brain developmentUsed our estimated parameters to project total gray mattervolume trajectories for infants of varying economicbackgrounds based on the federal poverty level: 100

2. Results specific to gray matter critical for processing ofinformation and execution of actionsInfants from low-income families had lower volumes of graymatter AND slower trajectories of growth during infancy andearly childhood

3. Delays tied to emergence of disruptive behavioralproblems among impoverished childrenUse Child Behavior Checklist (CBCL); focus on childrensinternalizing and externalizing behaviors

Hanson JL, Hair N, Shen DG, Shi F, Gilmore JH, et al. (2013) Family Poverty Affectsthe Rate of Human Infant Brain Growth. PLoS ONE 8(12)

Hanson JL, Hair N, Shen DG, Shi F, Gilmore JH, et al. (2013) Family Poverty Affectsthe Rate of Human Infant Brain Growth. PLoS ONE 8(12)

Hanson JL, Hair N, Shen DG, Shi F, Gilmore JH, et al. (2013) Family Poverty Affectsthe Rate of Human Infant Brain Growth. PLoS ONE 8(12)

RESULTS: Children and Adolescents

1. Examine potential neurobiological link between betweenpoverty and deficits in cognitive and achievementoutcomes

I Establish a reference for normative brain developmentI Examine influence of poverty on regions of the brain critical for

scholastic achievement, adjusting for developmental norms

2. Childhood poverty associated with atypical developmentin total gray matter, the frontal lobe, the temporal lobe,and the hippocampusChildren from poor households display a maturational lag:Regional volumes 5 to 8 percentage points belowdevelopmental norms

3. Tie regions of the brain to performance on standardizedtests

Wechsler Abbreviated Scale of Intelligence (WASI)

Woodcock-Johnson III Tests of Achievement (WJ-III)

Normative Developmental Curve: Temporal Lobe Gray Matter

Normative Developmental Curve: Hippocampus Gray Matter

80

85

90

95

100

105

Re

gio

na

l Vo

lum

e a

s P

erc

en

tage

of

Age

-a

nd

Se

x-

Spe

cifi

c N

orm

Socioeconomic Status and Anatomic Brain Development

Low Income (<$25,000)

60

65

70

75

Total Gray Matter Frontal Lobe Temporal Lobe Hippocampus

Re

gio

na

l Vo

lum

e a

s P

erc

en

tage

of

Age

Spe

cifi

c N

orm

I Express regional volumes as percentage of sex- and age-specific norm

I Examine deviations from norm among low income children

I Define household as low income or “poor” if reported household incomebelow $25,000 (approximately 133% of FPL for family of four over oursample period)

80

85

90

95

100

105

Re

gio

na

l Vo

lum

e a

s P

erc

en

tage

of

Sex-

an

d A

ge-

Spe

cifi

c N

orm

Socioeconomic Status and Anatomic Brain Development

Poor <$25,000 Near Poor $25,000-$35,000 High Income >$35,000

60

65

70

75

Total Gray Matter Frontal Lobe Temporal Lobe HippocampusRe

gio

na

l Vo

lum

e a

s P

erc

en

tage

of

Sex

Spe

cifi

c N

orm

Takeaways: Childhood Poverty and the Brain

I Poverty associated with atypical developmentI Concentrated among poorest children (below 133% FPL)I Regional volumes 5 to 8 percentage points below normsI Maturational lag begins to emerge in infancy

I Each region tied to performance on indices of academic abilityand/or childhood disruptive behaviors

I Consequences of atypical development for scholastic successI Skills important determinants for range of adult outcomesI Without interventions to mitigate influence of poverty,

children’s potential limited at young ages by this tie

Programs and Policy Responses

I What works to lessen poverty’s influence on children?

I Extended development of critical brain regions establishesboth greater vulnerability and opportunity

I Development highly sensitive to changes in the environmentand nurturance - both negative and positive

I Suggests interventions to remediate early environments mayhave some success in altering link between poverty anddeficits in achievement

Income Support Programs

I Earned Income Tax Credit

Significant increases in math and reading test scores amongchildren whose families qualified for the credit (Dahl and Lochner, 2012)

I Casino revenues to American Indian familiesPositive effects of income disbursements on high schoolgraduation and educational attainment (Akee et al, 2012)

I Can we generalize to other types of programs?Child tax credit, Supplemental Nutrition Assistance Program(SNAP) increase families economic resources in similar ways.

Early Childhood Education (3 to 5 year olds)

I Consistent evidence of short-run effects non-experimentalevidence of long-run benefits from several program models

I i.e., Perry Preschool and Abecedarian

I Shown to increase long-term school attainment and earningsas well as reduce crime and the risk of adult poverty(Duncan, Ludwig, and Magnuson, 2010)

Innovations and Uncertainty

I Home visiting programsMuch to learn about how to promote positive parent-childinteractions

I Approaches in very early childhood (birth-3)How to balance income support and employment

I Combining approachesWhere should building parents human capital fit in?