Table 1

Summary statistics of sample, US Health and Retirement Study, 2006

VariablesMean (SD)%
 Cognitive function (range: 0–27)16.1 (4.3)
 High exposure to extreme heat*17.3
  Non-Hispanic white83.3
  Non-Hispanic black9.3
 Neighbourhood SES†
  Average neighbourhood70.5
  Disadvantaged neighbourhood11.6
  Affluent neighbourhood17.9
 Age in years (range: 52–104)65.0 (9.5)
 Female sex54.8
 Living alone, not married/partnered19.6
 ≥ Some college education49.2
 Household wealth$377K ($1099K)
 Years of follow-up (range: 2–12)9.3 (3.5)
  • *Exposure to extreme heat was measured as the average number of extreme heat days per year during the participant’s follow-up period, up to the year preceding their last cognitive assessment. High exposure was defined as a level that falls within the highest quintile, which corresponds to 13.1 or more days of extreme heat.

  • †Disadvantaged neighbourhoods refer to census tracts scoring 1 SD above the average on a composite index of area socioeconomic disadvantages (eg, % residents living in poverty). Affluent neighbourhoods are defined as census tracts scoring 1 SD above the mean on a composite index of socioeconomic advantages (eg, % residents with college education). Average neighbourhoods include all other census tracts not classified as either disadvantaged or affluent; all statistics were weighted.

  • SES, socioeconomic status.