Objective: To determine whether clinically nondemented elderly individuals
with pathologically confirmed preclinical AD are characterized by cognitive
decline as measured by psychometric tests before death. Methods: Psychomet
ric performance was examined retrospectively in 14 individuals who were non
demented at time of death and grouped in accordance with their neuropatholo
gic findings: 1) Healthy brain (n = 9) was characterized by the absence of
senile plaques or by only patchy neocortical deposits of plaques; 2) precli
nical AD (n = 5) was characterized by neuritic and diffuse plaques distribu
ted throughout the neocortex. All individuals showed neurofibrillary pathol
ogic change in medial temporal lobe structures. For comparison, we also eva
luated 10 individuals who died in the earliest symptomatic stage of dementi
a of the Alzheimer type (DAT). All individuals had been assessed by clinica
l and psychometric measures during life. The psychometric measures yielded
a standardized factor score that represented global cognitive performance.
Results: At the last assessment before death, individuals with very mild DA
T were impaired on the factor score and on individual psychometric measures
with respect to the nondemented individuals, Those nondemented individuals
with preclinical AD did not differ in performance from those with healthy
brains. For individuals with at least three psychometric assessments during
life, there was no decline in performance for either those with healthy br
ains (n = 5) or preclinical AD (n = 3), although decline was evident for ve
ry mild DAT individuals (n = 5). Conclusions: Pathologically confirmed prec
linical AD is not associated with cognitive impairment or decline, even on
measures shown to be sensitive to very mild DAT.