title: Investigation of age and gender effects on positive orientation in Italian twins.
abstract: We investigated age and gender effects on "Positive Orientation" (POS)-an individual's tendency to view life with a positive outlook-using a genetically informed design. Study subjects were 1016 twins aged 22-75 from the Italian twin registry. We assessed POS by the recently developed P-scale. First, we used confirmatory factor analysis to investigate scale's measurement invariance by age and gender. Then, we applied biometric modelling to estimate genetic and environmental components of POS score. Overall, we found a satisfactory degree of measurement invariance by both age and gender. Results from these analyses further indicated an increasing mean level of POS across the lifespan. Additive genetic and unshared environmental factors explained respectively 58% and 42% of variance in POS score, with no significant gender differences; furthermore, the pattern of change of gene-environment architecture of POS over time was consistent with a greater plasticity of personality at older ages.
authors.affiliation: Genetic Epidemiology Unit, National Centre for Epidemiology, Surveillance and Health Promotion, Istituto Superiore di Sanità, Rome, Italy.
authors.forename: Corrado
authors.initials: C
authors.lastname: Fagnani
authors.forename: Emanuela
authors.initials: E
authors.lastname: Medda
authors.forename: Maria A
authors.initials: MA
authors.lastname: Stazi
authors.forename: Gian V
authors.initials: GV
authors.lastname: Caprara
authors.forename: Guido
authors.initials: G
authors.lastname: Alessandri
mesh_terms: D000328:Adult; D000339:Affect; D000367:Age Factors; D000368:Aged; D001699:Biometry; D004522:Educational Status; D005163:Factor Analysis, Statistical; D005260:Female; D059647:Gene-Environment Interaction; D005821:Genetic Techniques; D006801:Humans; D007558:Italy; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D010551:Personality; D011594:Psychometrics; D012737:Sex Factors; D012931:Social Environment; D014427:Twins / Q000523:psychology*; D014429:Twins, Dizygotic / Q000523:psychology; D014430:Twins, Monozygotic / Q000523:psychology
keywords: Heritability; Measurement Invariance; Positive Orientation; Positivity; Twins