title: Personality traits and the risk for Parkinson disease: a prospective study.
abstract: In this study, we explored the association between the personality traits, neuroticism and introversion, and risk of Parkinson disease (PD). A population-based cohort study was conducted using questionnaire data from the Swedish Twin Registry for twins born 1926-1958 (n > 29,000). Personality traits were assessed in 1973 by a short form of Eysenck's Personality Inventory. The cohort was followed from 1974 to 2012 through Swedish patient and cause of death registers for PD ascertainment. Cox proportional hazards regression was used to estimate subsequent risk of PD, adjusting for attained age, sex and smoking. A mediation analysis was performed to further explore the role of smoking in the relationship between personality trait and PD. Confounding by familial factors was explored using a within-pair analysis. During a mean follow-up time of 36.8 years, 197 incident PD cases were identified. Both neuroticism and introversion were associated with an increased risk of PD after adjustment. Smoking was a significant mediator in the relationship between personality traits and PD that partly accounted for the effect of introversion, whereas it acted as a suppressor for the effect of neuroticism on PD risk. In the within-pair analyses, associations for neuroticism and introversion were attenuated. In conclusion, our study provides evidence that neuroticism is associated with an increased risk of PD that is in part suppressed by smoking. There was a weak association between introversion and PD and this effect was at least partly mediated through smoking. The observed effects may partly be explained by familial factors shared by twins.
authors.affiliation: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Box 281, 171 77, Stockholm, Sweden. johanna.sieurin@ki.se.
authors.forename: Johanna
authors.initials: J
authors.lastname: Sieurin
authors.affiliation: Department of Clinical Neuroscience, Karolinska Institutet, Nobels väg 9, 171 65, Stockholm, Sweden.
authors.forename: Petter
authors.initials: P
authors.lastname: Gustavsson
authors.affiliation: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Box 281, 171 77, Stockholm, Sweden.
authors.forename: Caroline Elise
authors.initials: CE
authors.lastname: Weibull
authors.affiliation: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Box 281, 171 77, Stockholm, Sweden.|MRC Epidemiology Unit, University of Cambridge, Box 285, Cambridge Biomedical Campus, Cambridge, CB2 0QQ, UK.
authors.forename: Adina Leiah
authors.initials: AL
authors.lastname: Feldman
authors.affiliation: Department of Neurology, University of Southern California, 1333 San Pablo Street, MCA 243 9153 HSC, Los Angeles, CA, 90033, USA.
authors.forename: Giselle Maria
authors.initials: GM
authors.lastname: Petzinger
authors.affiliation: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Box 281, 171 77, Stockholm, Sweden.|Department of Psychology, University of Southern California, 3620 South McClintock Ave, Los Angeles, CA, 90089-1061, USA.
authors.forename: Margaret
authors.initials: M
authors.lastname: Gatz
authors.affiliation: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Box 281, 171 77, Stockholm, Sweden.|Department of Psychology, University of Southern California, 3620 South McClintock Ave, Los Angeles, CA, 90089-1061, USA.
authors.forename: Nancy Lee
authors.initials: NL
authors.lastname: Pedersen
authors.affiliation: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Box 281, 171 77, Stockholm, Sweden.|Department of Clinical Neuroscience, Karolinska Institutet, Nobels väg 9, 171 65, Stockholm, Sweden.
authors.forename: Karin
authors.initials: K
authors.lastname: Wirdefeldt
mesh_terms: D000328:Adult; D000368:Aged; D001008:Anxiety Disorders; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007439:Introversion, Psychological; D008297:Male; D008875:Middle Aged; D000075384:Neuroticism; D010300:Parkinson Disease / Q000453:epidemiology* / Q000209:etiology / Q000523:psychology; D010551:Personality; D010552:Personality Assessment; D010555:Personality Inventory / Q000706:statistics & numerical data; D011159:Population Surveillance / Q000379:methods*; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012042:Registries; D012307:Risk Factors; D011795:Surveys and Questionnaires; D014427:Twins
keywords: Cohort study; Introversion; Neuroticism; Parkinson disease; Personality