title: The importance of genetic and environmental effects for self-reported health symptoms: a 30-year follow-up considering survival and selection effects.
abstract: OBJECTIVE
  This study delineated the nature of individual differences in self-reported health status across a 30-year period.  Potential survival and selection effects on mean levels, variances, and genetic and environmental sources of variance were evaluated.
  
  
  METHODS
  Self-reported health status in 1963 was evaluated in 5,229 pairs of twins from the Swedish Twin Registry and in a subsample of 351 pairs surviving to the age of 80 years in 1993.  Structural equation modeling evaluated genetic and environmental contributions to total variance and change in variance.
  
  
  RESULTS
  For men but not women, the genetic and environmental influences on health symptoms differed between survivors and nonsurvivors.  Total variance increased, reflecting an increase in environmental variance, across the 30 years for both genders.  Genetic variance decreased longitudinally for men.
  
  
  CONCLUSIONS
  The increase in variation from the mid-50s to the mid-80s appears to be due to an accumulation in environmental variation.  There are gender differences that deserve further exploration.
authors.affiliation: Karolinska Institute, Sweden.
authors.forename: N L
authors.initials: NL
authors.lastname: Pedersen
authors.forename: B
authors.initials: B
authors.lastname: Steffensson
authors.forename: S
authors.initials: S
authors.lastname: Berg
authors.forename: B
authors.initials: B
authors.lastname: Johansson
authors.forename: G E
authors.initials: GE
authors.lastname: McClearn
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D004200:Diseases in Twins; D004777:Environment; D005260:Female; D005500:Follow-Up Studies; D006304:Health Status; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D011795:Surveys and Questionnaires; D016019:Survival Analysis; D013548:Sweden; D014427:Twins / Q000235:genetics / Q000706:statistics & numerical data; D014481:United States