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Harmonization of Neuroticism and Extraversion phenotypes across inventories and cohorts in the Genetics of Personality Consortium: an application of Item Response Theory

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  • Stéphanie M van den Berg
  • Marleen H M de Moor
  • Matt McGue
  • Erik Pettersson
  • Antonio Terracciano
  • Karin J H Verweij
  • Najaf Amin
  • Jaime Derringer
  • Tõnu Esko
  • Gerard van Grootheest
  • Narelle K Hansell
  • Jennifer Huffman
  • Bettina Konte
  • Jari Lahti
  • Lindsay K Matteson
  • Alexander Viktorin
  • Jasper Wouda
  • Arpana Agrawal
  • Jüri Allik
  • Laura Bierut
  • Ulla Broms
  • George Davey Smith
  • Johan G Eriksson
  • Luigi Ferrucci
  • Barbera Franke
  • Jean-Paul Fox
  • Eco J C de Geus
  • Ina Giegling
  • Alan J Gow
  • Richard Grucza
  • Annette M Hartmann
  • Andrew C Heath
  • Kauko Heikkilä
  • William G Iacono
  • Joost Janzing
  • Markus Jokela
  • Lambertus Kiemeney
  • Terho Lehtimäki
  • Pamela A F Madden
  • Patrik K E Magnusson
  • Kate Northstone
  • Teresa Nutile
  • Klaasjan G Ouwens
  • Aarno Palotie
  • Alison Pattie
  • Anu-Katriina Pesonen
  • Lea Pulkkinen
  • Laura Pulkki-Råback
  • Olli T Raitakari
  • Anu Realo
  • Richard J Rose
  • Daniela Ruggiero
  • Ilkka Seppälä
  • Wendy S Slutske
  • David C Smyth
  • Rossella Sorice
  • Angelina R Sutin
  • Toshiko Tanaka
  • Josine Verhagen
  • Sita Vermeulen
  • Eero Vuoksimaa
  • Elisabeth Widen
  • Gonneke Willemsen
  • Margaret J Wright
  • Dan Rujescu
  • Andres Metspalu
  • Marina Ciullo
  • Katri Räikkönen
  • Alejandro Arias Vasquez
  • Paul T Costa
  • Liisa Keltikangas-Järvinen
  • Cornelia M van Duijn
  • Brenda W J H Penninx
  • Robert F Krueger
  • David M Evans
  • Jaakko Kaprio
  • Nancy L Pedersen
  • Nicholas G Martin
  • Dorret I Boomsma

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Original languageEnglish
Pages (from-to)295-313
Number of pages19
JournalBehavior Genetics
Issue number4
Early online date15 May 2014
Publication statusPublished - Jul 2014


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.

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