Jt. Becker et al., THE NATURAL-HISTORY OF ALZHEIMERS-DISEASE - DESCRIPTION OF STUDY COHORT AND ACCURACY OF DIAGNOSIS, Archives of neurology, 51(6), 1994, pp. 585-594
Objective: We describe the sampling, initial evaluation, and final dia
gnostic classification of subjects enrolled in a natural history study
of Alzheimer's disease (AD). Design: Volunteer cohort study. Setting:
Multidisciplinary behavioral neurology research clinic. Patients or O
ther Participants: Three-hundred nineteen individuals were enrolled in
the Alzheimer Research Program between March 1983 and March 1988. Of
these, 204 were originally classified with AD, 102 were normal elderly
control subjects, and 13 were considered special cases. Main Outcome
Measures: Final consensus clinical diagnosis, final neuropathologic di
agnosis, and death. Results: Of the 204 patients enrolled in the study
, re-review after as many as 5 years of follow-up resulted in a final
clinical classification of 188 with probable AD. Seven patients were b
elieved to have a significant vascular component to the dementia, thre
e were found to have developed depression, and six were excluded on ot
her clinical grounds. Neuropathologic examination of 50 brains indicat
ed definite AD in 43. After removing these seven misdiagnosed patients
, the final group of probable/definite AD totaled 181 individuals. Acc
uracy of the baseline clinical diagnosis relative to neuropathology wa
s 86%, and when follow-up clinical data were considered, 91.4%. Detail
ed neuropsychological testing yielded high sensitivity (0.988) and spe
cificity (0.983) to dementia. Analyses of survival time from study ent
ry until death revealed that older patients were significantly more li
kely to die during follow-up, but neither sex, years of education, nor
pattern of cognitive impairment were related to survival. Conclusions
: These data provide the descriptive basis for future studies of this
cohort. They indicate that longitudinal follow-up of demented cases in
creases accuracy of diagnosis, and that detailed cognitive testing aid
s in early classification.