title: Self-rated health in a longitudinal perspective: a 9-year follow-up twin study.
abstract: OBJECTIVE
  This study first considers age and cohort explanations for age-related changes in mean values and variance in self-rated health. Second, it evaluates the contributions of genes and environments to self-rated health measured longitudinally.
  
  
  METHODS
  Subjects were participants in the Swedish Adoption/Twin Study of Aging. Self-rated health assessments were collected in four waves over a 9-year follow-up period, from one or both members of 788 twin pairs. Linear mixed effect models were used to test for differences in means and variances. Structural equation modeling provided estimates of genetic and environmental components of variance and contributions to stability.
  
  
  RESULTS
  Changes in means and variance within cohorts seem to reflect illness. Earlier-born cohorts are more variable and have lower self-rated health. These cohort differences were not explained by childhood socioeconomic status. Correlations between time points reflect both environmental and genetic factors.
  
  
  CONCLUSIONS
  Both genes and environments contribute to self-rated health longitudinally, and both age and cohort effects are seen. Age-related changes in self-rated health can be attributed to illness. Cohort differences are most likely attributable to socially mediated and individual-specific environmental factors.
authors.affiliation: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Box 281, SE-171 77 Stockholm, Sweden. pia.svedberg@meb.ki.se
authors.forename: Pia
authors.initials: P
authors.lastname: Svedberg
authors.forename: Margaret
authors.initials: M
authors.lastname: Gatz
authors.forename: Paul
authors.initials: P
authors.lastname: Lichtenstein
authors.forename: Sven
authors.initials: S
authors.lastname: Sandin
authors.forename: Nancy L
authors.initials: NL
authors.lastname: Pedersen
mesh_terms: D000300:Adoption; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000235:genetics* / Q000523:psychology; D000704:Analysis of Variance; D001294:Attitude to Health; D002908:Chronic Disease; D004200:Diseases in Twins / Q000235:genetics* / Q000523:psychology; D005260:Female; D005500:Follow-Up Studies; D015577:Geriatric Assessment; D006304:Health Status; D006801:Humans; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D012042:Registries; D012931:Social Environment; D013548:Sweden; D014429:Twins, Dizygotic / Q000235:genetics / Q000523:psychology; D014430:Twins, Monozygotic / Q000235:genetics / Q000523:psychology