Early Progress and Findings from a
Genetically Informative Investigation
of the PROSPER Prevention Project
H. Harrington Cleveland
Human Development Family Studies
The Pennsylvania State University
Overview
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Issues in candidate gene research
The PROSPER Study
How gPROSPER leverages PROSPER for G x E
Data collection Progress
Cleaning and analyzing gPROSPER
Early Findings
Issues with Candidate G X E Research
• Candidate Gene Research – especially G x E research
(e.g. Caspi et. al., 2003) – has been aggressively
criticized.
• Some (e.g. meta-analysis by Risch et.al., 2009) claim
that findings are consistent with chance.
• Others say that Risch et. al. (2009) is incorrect due to
inclusion of weak studies (see Uher & McGuffin,
2010, and Rutter et al., 2010).
• Common problems with adding candidate
genes to existing studies
– Poor measurement – few items, single reporters
– Retrospective data – recall bias
– Passive large scale data sets are vulnerable to rGE:
• reducing exposure to full range of environments across
genotypes (reduces power)
• undercutting interpretation of findings
More about rGE confounds
The problem: Families, peers, experiences are all genetically influenced
The result: G x E “effects” might be due to genetic selection of
environments/experiences
Minimum controls: investigate associations between genes and presumptive
“environmental moderator”
Better solutions:
Random assignment
Quasi-experimental solutions
- school level interventions (e.g., PROSPER)
- regression discontinuity designs
- state level differences in welfare policies
Another Problem: Population Stratification
A 3rd variable confound:
1. Samples may be made up of distinct genetic groups or they have been
genetic mixing of groups in recent past (i.e., racial admixture).
2. Groups may differ in allelic distributions and outcomes
3. Creating spurious associations between alleles and outcomes
4. Classic Study: Knowler et al.
General Finding – Gm haplotype of negatively associated with Type 2 diabetes in Amer
Ind./euro sample.
But: Gm haplotype more common among European descent cases
Analyses within Am. Indian and Euro groups found no association
Citations: Kwowler, et al. (1988).GM and Type 2 Diabetis Mellitus: An Association in American Indians with Racial Admixture. American Journal of Human Genetics. 43. 520526.
Cardon & Palmer (2003). Population stratification and spurious allelic association. Lancet, 361, 598-604
The PROSPER Parent Study
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Prospective Adolescent data collections: From 2002 through 2009, over 8,000 took part in 8 annual
data collections. Average participation rate was 89% across waves. In-school data collections provide
primary measures of family and peer environment and substance use outcomes for grant aims.
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Randomized community design: PROSPER is organized around 28 rural communities in Iowa and
Pennsylvania randomized into 14 control and 14 intervention units.
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Interventions: Communities chose one of three similar school-based program: Life Skills Training Program
(Botvin, 2000), All Stars Program (McNeal et al., 2004), and Project Alert (Ellickson et al., 2003). All programs
target social norms, personal goal setting, decision-making, and peer group affiliation. Interventions were
implemented during required 7th grade health classes.
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Social network data: Social network data collected across adolescence provide intricate measures of peer
micro-environments from 6th through 12th grade. Fully coded forgrades 6 to 9, rhese measures allow
investigation of if and how peer experiences mediate and moderate genetic influences on substance use
outcomes.
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In-Home sub-sample: Detailed parent and child reports of family processes, including video-taped
interactions (n=600 with genotyped DNA): 5 waves of measures for family environment, parenting practices,
relationships, from beginning of 6th grade to end of 9th grade.
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Early adult data collection: A follow-up sample is currently participating in two annual telephone/webbased surveys, at ages 19 and 20. These data collections oversample high-risk participants.
Primary Environmental Measures
Community Environments
Community intervention status
Community crime
Community alcohol and tobacco availability
SES and community disorganization
Peer Environments
Peer substance use
Unsupervised time w/ substance using peers
Substance use by clique
Degree of social isolation
Family Environments
Parent-child affective quality
Parent-child joint activities
Parental monitoring
Parental discipline
Substance Use and Abuse Measures
Adolescent Measures.
Set 1: Ever Used, Past Month, and Past Year: Alcohol, Cigarettes, Other Drugs
(depending on time frame: marijuana, inhalants, methamphetamine, ecstasy,
other people‘s prescription drugs, and prescription pain killers).
Early Adult Measures. Over 45 items across a broad range of substances.
• From tobacco and alcohol to marijuana and other illegal drugs (e.g.,
cocaine, inhalants, methamphetamine, ecstasy, hallucinogens, other
people‘s prescription drugs, and prescription pain killers).
• Alcohol use detail: including frequency, volume, getting drunk, and
different thresholds of binging.
• Alcohol abuse and dependency diagnostic criteria (DIS).
Peer substance use.
Peer Measures
Focus on reciprocated nominations (reciprocation rates are about 50%).
In addition: ‘Sent‘ and ‘received‘ networks, as well as best friends’ behaviors.
Unsupervised time with substance using friends.
Item: How often students “hang out (without adults around)” outside of school
with each nominated friend.
Allows indices of unsupervised and unstructured exposure to substance using
peers (Osgood et al., 1996; Osgood, 2010).
Clique substance use.
Cliques provide the proximate social context for information about group norms.
PROSPER network project (Osgood) provides clique substance use levels.
Degree of social isolation.
Core clique members: 77%
Peripheral clique members: 16%
Non-group members (including isolates): 7%
Family Measures
Parent-child affective quality.
Parental Affective Quality toward Child and Child’s Affective Quality toward Parents.
Across the 8 waves of in-school assessment, Alphas range from .86-.95 (mother
subscale) and .91-.96 (father subscale).
Parent-child joint activities.
The amount of time and range of activities shared by parents and adolescents is
assessed with 6 items, such as “work on homework or a school project together”.
Alphas range from .87 to.88.
Parental monitoring.
Assessed with 5 items measuring parents’ knowledge of adolescent’s whereabouts
and activities. Contributing items include “During the day, my parents know where I
am.” Alphas for this scale ranged from .78 to .88.
Parental discipline.
Parents‘ consistent discipline was measured with four items, including “My parents
discipline me for something some times, and then other times don‘t discipline me
for same thing.”‖Alphas range from .71 to .82.
Community Measures
Community intervention status.
14 coded as intervention.
14 coded as comparison communities.
Community crime.
Community violent crime (Alpha = .79; murder, rape, robbery, and aggravated
assault), property crime (Alpha = .96; arson, burglary, larceny, and motor theft),
and narcotic-related crime.
Community alcohol and tobacco availability.
Number of outlets each community; Number divided by community size; Distance
from school.
SES and community disorganization.
Percentage students receiving free and reduced lunches, ranging from 11% to
53%; percentage of households in poverty; residential instability (ranging from
25.4 -45.5%); and percent single female-headed households.
gPROSPER Overview
Implications of Genetic Variance for Substance Use Interventions in
Adolescence
Funding Source NIDA
Bo Cleveland, The Pennsylvania State University: M-PI
David Vandenbergh, The Pennsylvania State University: M-PI
Mark Feinberg, The Pennsylvania State University: Co-Principal Investigator
Mark Greenberg, The Pennsylvania State University: Co-Investigator
Jenae Neiderhiser, The Pennsylvania State University: Co-Investigator
Richard Spoth, Iowa State University: Consortium PD/PI
Particular strengths of PROSPER for GxE work
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Detailed measurement of environment and outcomes:
Developed to assess early adolescent interventions designed to operate through family and peer
contexts, a primary focus of PROSPER is measuring processes within these environmental domains.
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Randomized prevention trial design:
Community-level randomized of interventions removes person-level selection –both general and
rGE– of intervention-related experiences.
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Prospective cohort design:
Reduces perception-related rGE by not using long-term retrospective report of environmental factors
(Jaffe & Price, 2007).
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Large sample size:
1,500-1,800 for adolescent and young adult analyses
1,800-2,200 for adolescent-only analyses
Opportunity for self-replication by splitting sample into exploratory and confirmatory subsamples
600 with hyper-measured family relationship data
Conceptual model: How genes may influence substance use and
transact with intervention, family, and peer factors
gPROSPER Aims
Specific Aim 1: Examine impact of specific genetic risk on modifying the effects of
preventive interventions on the development of substance use behaviors.
Specific Aim 2: Characterize the interplay between proximal environmental measures
(parent-child relationship quality, parental monitoring, peer micro-environments) and
specific genes on substance use and abuse during adolescence and early adulthood.
Specific Aim 3: Examine how GxE and rGE processes involved in substance use
outcomes change from early adolescence to early adulthood and from initiation
through addictive use.
gPROSPER Data Collection Framework
PROSPER and Follow-up
Adolescent PROSPER
Adolescent In-School Surveys
N = 8,000
gPROSPER Supplement
DNA
collection
N = 1900
Supplemental
Early Adult
Interviews
N = 900
Follow-up Study
In-Home Sample
N = 538
gPROSPER Supplement
(in-home)
Sample w/ both DNA and
adolescent interviews N = 2,200
Analysis Data Sets
Follow-up
Early Adult
Interview
N =1,000 *
Adolescent and Early
Adult Interviews w/ DNA
N = 15,00-1,800
Data Collection Progress
• 530 pre-existing in-home DNA samples
• Years 1 and 2 adding 1200 more DNA samples
– From both follow-up and supplemental data
collections
• Year 3: Add 500 more DNA only participants
Candidate Genes
Initial list
Additions: Oxytocin and Vasopressin markers
Adopted approach (split sample approach):
• 600 In Home “richly phenotyped” samples
– 318k SNP array of coding exons
– Commonly studied VNTRs (e.g., DRD4, 5-httplr)
• 1400-1800 (early adult subsample)
– 30-35 candidate genes (approx 300-500 SNPs):
– Selected by function (e.g., dopamine related genes) and/or
subsample GWAS findings
Recruiting PROSPER participants into
GPROSPER
• Follow-up sample:
• DNA recruitment after completing survey
• Supplement (gPROSPER)
• Recruit into DNA and survey at outset
– Get DNA sample in lab, then do send survey
• Recruit into DNA-only data collection
• Sample Size Issues:
– Is 2,200 small?
• Depends on study design
– Passive correlational
– Assignment with manipulation/intervention
» See Brody Research
– Controlled environments (social psych experiments)
• Measurement Quality
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Retrospective Report vs. Prospective Design
Omnibus Study vs. Targeted Study
Single SNPs vs. Haplotypes
Single vs. Multi-Locus Constructions
Part 4: Early Findings
Based on 560 In Home cases
Preliminary work
- Dropped overly related individuals
- Developed racial stratification scheme
- Analyses were done:
1. On all cases
2. Controlling for dimensions of racial stratification
(PC1 and PC2)
3. Dropping all non-euros
Preliminary Cleaning: Finding and Dropping Related Individuals 319k
markers vs. 41k markers
Racial Stratification
in Prosper
Racial Stratification
in Prosper
1 sd from mean of
pc 1 among
self-identified
non-euros
Combined DRD4 by Intervention Effects on
Association between Maternal Activities with
Child at 6th grade and Child Alcohol Use by 9th
grade
DRD4: Dopamine related VNTR gene
• Coding: 7 repeats vs. others: DRD4 7+ vs. DRD4 7DRD4 7 +
linked to:
1. ADHD, substance use, addiction, novelty seeking
2. Developmental susceptibility to environment (linked to attentional
processes)
3. Experimental studies link drd4 7+ with:
- greater sensitivity to confederate drinking
- greater perception of social bonding when drinking
gPROSPER Early Findings
Based on 560 In-Home cases
1.
2.
Intervention Effects on Associations between
Maternal Activity and Alcohol Initiation among
DRD4 7+ Adolescents
Moderation of Maternal Closeness and
Resistance of Peer Pressure by DRD4
Population Stratification Checks:
1. Preliminary: Examine PC associations with DV &
environmental variable
2. Run full model
3. Repeat with PC as statistical controls
4. Repeat with dropping non-euros allelic distance
Predicting Wave 5 Alcohol Initiation by Wave I Mother Activity and Intervention Status
Three-way Int*MCA*D4
-.47(.21)*
Sensitivity Analysis
Intervention Effects of the Association between 6th grade Maternal Activities
and Alcohol Use Initiation by 9th Grade among DRD4 7+ Adolescents
Thanks to Gabriel Schlomer
Association between Maternal Closeness and Belief in Ability to Resist
Negative Peer Influence as a Function of DRD4
0.25
Resist Negative Peer Influence
0.2
0.15
0.1
0.05
0
-0.05
-0.1
-0.15
-0.2
-1SD
MEAN
+1SD
Closeness
DRD4 7-
0.045
-0.02
-0.085
DRD4 7+
-0.14
0.033
0.205
Note: Effect goes away with control for population stratification