Changes in everyday functioning and cognitive abilities are studied lo
ngitudinally in a representative sample of the oldest old. Respondents
were selected by using census records from all people aged 84, 86, 88
, and 90 years old living in an area of South Central Sweden, and then
were assessed at 2-year intervals. The findings show high base rates
for disabilities and high incidence of cognitive and functional defici
ts among survivors. Mortality is associated with higher rates of disab
ility at the previous time of assessment. Because of this increased mo
rtality rate among disabled individuals, prevalence does not rise as m
uch as would be expected from the high incidence. Instead, new cases o
f disabled are partly replacing disabled individuals who died since th
e previous evaluation.