Harmonization of Neuroticism and Extraversion phenotypes across inventories and cohorts in the Genetics of Personality Consortium: an application of Item Response Theory.
Mega- or meta-analytic studies (e.g. genome-wide association studies) are increasingly used in behavior genetics. An issue in such studies is that phenotypes are often measured by different instruments across study cohorts, requiring harmonization of measures so that more powerful fixed effect meta-analyses can be employed. Within the Genetics of Personality Consortium, we demonstrate for two clinically relevant personality traits, Neuroticism and Extraversion, how Item-Response Theory (IRT) can be applied to map item data from different inventories to the same underlying constructs. Personality item data were analyzed in >160,000 individuals from 23 cohorts across Europe, USA and Australia in which Neuroticism and Extraversion were assessed by nine different personality inventories. Results showed that harmonization was very successful for most personality inventories and moderately successful for some. Neuroticism and Extraversion inventories were largely measurement invariant across cohorts, in particular when comparing cohorts from countries where the same language is spoken. The IRT-based scores for Neuroticism and Extraversion were heritable (48 and 49 %, respectively, based on a meta-analysis of six twin cohorts, total N = 29,496 and 29,501 twin pairs, respectively) with a significant part of the heritability due to non-additive genetic factors. For Extraversion, these genetic factors qualitatively differ across sexes. We showed that our IRT method can lead to a large increase in sample size and therefore statistical power. The IRT approach may be applied to any mega- or meta-analytic study in which item-based behavioral measures need to be harmonized.
Department of Research Methodology, Measurement and Data-Analysis, University of Twente, Enschede, The Netherlands, stephanie.vandenberg@utwente.nl.
Stéphanie M
SM
van den Berg
Marleen H M
MH
de Moor
Matt
M
McGue
Erik
E
Pettersson
Antonio
A
Terracciano
Karin J H
KJ
Verweij
Najaf
N
Amin
Jaime
J
Derringer
Tõnu
T
Esko
Gerard
G
van Grootheest
Narelle K
NK
Hansell
Jennifer
J
Huffman
Bettina
B
Konte
Jari
J
Lahti
Michelle
M
Luciano
Lindsay K
LK
Matteson
Alexander
A
Viktorin
Jasper
J
Wouda
Arpana
A
Agrawal
Jüri
J
Allik
Laura
L
Bierut
Ulla
U
Broms
Harry
H
Campbell
George Davey
GD
Smith
Johan G
JG
Eriksson
Luigi
L
Ferrucci
Barbera
B
Franke
Jean-Paul
JP
Fox
Eco J C
EJ
de Geus
Ina
I
Giegling
Alan J
AJ
Gow
Richard
R
Grucza
Annette M
AM
Hartmann
Andrew C
AC
Heath
Kauko
K
Heikkilä
William G
WG
Iacono
Joost
J
Janzing
Markus
M
Jokela
Lambertus
L
Kiemeney
Terho
T
Lehtimäki
Pamela A F
PA
Madden
Patrik K E
PK
Magnusson
Kate
K
Northstone
Teresa
T
Nutile
Klaasjan G
KG
Ouwens
Aarno
A
Palotie
Alison
A
Pattie
Anu-Katriina
AK
Pesonen
Ozren
O
Polasek
Lea
L
Pulkkinen
Laura
L
Pulkki-Råback
Olli T
OT
Raitakari
Anu
A
Realo
Richard J
RJ
Rose
Daniela
D
Ruggiero
Ilkka
I
Seppälä
Wendy S
WS
Slutske
David C
DC
Smyth
Rossella
R
Sorice
John M
JM
Starr
Angelina R
AR
Sutin
Toshiko
T
Tanaka
Josine
J
Verhagen
Sita
S
Vermeulen
Eero
E
Vuoksimaa
Elisabeth
E
Widen
Gonneke
G
Willemsen
Margaret J
MJ
Wright
Lina
L
Zgaga
Dan
D
Rujescu
Andres
A
Metspalu
James F
JF
Wilson
Marina
M
Ciullo
Caroline
C
Hayward
Igor
I
Rudan
Ian J
IJ
Deary
Katri
K
Räikkönen
Alejandro
A
Arias Vasquez
Paul T
PT
Costa
Liisa
L
Keltikangas-Järvinen
Cornelia M
CM
van Duijn
Brenda W J H
BW
Penninx
Robert F
RF
Krueger
David M
DM
Evans
Jaakko
J
Kaprio
Nancy L
NL
Pedersen
Nicholas G
NG
Martin
Dorret I
DI
Boomsma
D001008:Anxiety Disorders / Q000235:genetics; D005120:Extraversion, Psychological; D055106:Genome-Wide Association Study; D006801:Humans; D015233:Models, Statistical; D000075384:Neuroticism; D010551:Personality / Q000235:genetics*; D010552:Personality Assessment; D010641:Phenotype