title: Occupational characteristics and cognitive performance among elderly male twins.
abstract: OBJECTIVE
  To examine the effect of occupational characteristics on cognitive status change in members of the NAS-NRC Twins Registry of World War II veterans.
  
  
  METHODS
  Participants completed the modified Telephone Interview for Cognitive Status (TICS-m) on three occasions spanning a period of approximately 7 years. Based on factor analysis, occupational characteristics were interpreted as reflecting general intellectual demands (GI), human interaction and communication (HC), physical exertion (PE), and visual attention (VA).
  
  
  RESULTS
  Based on regression analysis of TICS-m change that was dependent on twin pairing and additionally covarying for education, age at each testing event, medical conditions, and initial TICS-m score, higher GI was associated with a modest longitudinal improvement in TICS-m performance, whereas higher PE and VA were both associated with a modest decline. Subsequent analysis revealed that these significant effects were present among dizygotic twins, but not among monozygotic twins.
  
  
  CONCLUSIONS
  Previous findings of a relationship between occupational characteristics and cognitive performance in later life may be partially explained by genetic factors; however, until these genes are identified, occupational characteristics may be useful markers.
authors.affiliation: Department of Psychiatry and Behavioral Sciences, Duke University Medical Center, Durham, NC, USA. guy.potter@duke.edu
authors.forename: G G
authors.initials: GG
authors.lastname: Potter
authors.forename: B L
authors.initials: BL
authors.lastname: Plassman
authors.forename: M J
authors.initials: MJ
authors.lastname: Helms
authors.forename: S M
authors.initials: SM
authors.lastname: Foster
authors.forename: N W
authors.initials: NW
authors.lastname: Edwards
mesh_terms: D000368:Aged; D001288:Attention; D003071:Cognition; D003142:Communication; D005163:Factor Analysis, Statistical; D006801:Humans; D007360:Intelligence; D007398:Interpersonal Relations; D007407:Interviews as Topic; D008137:Longitudinal Studies; D008297:Male; D008499:Medical Records; D008875:Middle Aged; D009790:Occupations; D005082:Physical Exertion; D012042:Registries; D012044:Regression Analysis; D014427:Twins / Q000523:psychology*; D014429:Twins, Dizygotic; D014430:Twins, Monozygotic; D014796:Visual Perception