title: Psychometric properties of the Icelandic NEO-FFI in a general population sample compared to a sample recruited for a study on the genetics of addiction.
abstract: Personality traits are major determinants of social behavior influencing various diseases including addiction. Twin and family studies suggest personality and addiction to be under genetic influence. Identification of DNA susceptibility variants relies on valid and reliable phenotyping approaches. We present results of psychometric testing of the Icelandic NEO-FFI in a population sample (N=657) and a sample recruited for a study on addiction genetics (N=3,804). The Icelandic NEO-FFI demonstrated internal consistency and temporal stability. Factor analyses supported the five-factor structure. Icelandic norms were compared to American norms and language translations selected for geographical and cultural proximity to Iceland. Multiple discriminant function analysis using NEO-FFI trait scores and gender as independent variables predicted membership in recruitment groups for 47.3% of addiction study cases (N=3,804), with accurate predictions made for 69.5% of individuals with treated addiction and 43.3% of their first-degree relatives. Correlations between NEO-FFI scores and the discriminant function suggested a combination of high neuroticism, low conscientiousness and low agreeableness predicted membership in theTreatedgroup.
authors.affiliation: deCODE Genetics/Amgen, Reykjavik, Iceland ; Public Health Sciences, University of Iceland.
authors.forename: Gyda
authors.initials: G
authors.lastname: Bjornsdottir
authors.affiliation: School of Health Sciences, Faculty of Psychology, University of Iceland.
authors.forename: Fridrik H
authors.initials: FH
authors.lastname: Jonsson
authors.affiliation: School of Health Sciences, Faculty of Psychology, University of Iceland ; SAA-National Center of Addiction Medicine, Reykjavik, Iceland.
authors.forename: Ingunn
authors.initials: I
authors.lastname: Hansdottir
authors.affiliation: Faculty of Pharmaceutical Sciences, School of Health Sciences, University of Iceland.
authors.forename: Anna B
authors.initials: AB
authors.lastname: Almarsdottir
authors.affiliation: Faculty of Medicine, School of Health Sciences, University of Iceland ; Landspitali University Hospital, Reykjavik, Iceland.
authors.forename: Maria
authors.initials: M
authors.lastname: Heimisdottir
authors.affiliation: SAA-National Center of Addiction Medicine, Reykjavik, Iceland.
authors.forename: Thorarinn
authors.initials: T
authors.lastname: Tyrfingsson
authors.affiliation: SAA-National Center of Addiction Medicine, Reykjavik, Iceland.
authors.forename: Valgerdur A
authors.initials: VA
authors.lastname: Runarsdottir
authors.affiliation: deCODE Genetics/Amgen, Reykjavik, Iceland.
authors.forename: Kristleifur
authors.initials: K
authors.lastname: Kristjansson
authors.affiliation: deCODE Genetics/Amgen, Reykjavik, Iceland.
authors.forename: Hreinn
authors.initials: H
authors.lastname: Stefansson
authors.affiliation: deCODE Genetics/Amgen, Reykjavik, Iceland.
authors.forename: Thorgeir E
authors.initials: TE
authors.lastname: Thorgeirsson
keywords: NEO-FFI; addiction; psychometrics