Misclassification of "probable senile dementia--Alzheimer's type" in the Baltimore Longitudinal Study of Aging.

Several papers in the literature refer to 27 men in the Baltimore Longitudinal Study as "probable Senile Dementia--Alzheimer's Type." The method used to identify these presumed cases was based on a retrospective review of archival records. An examination of the cognitive performance data of these 27 men is described in this report. Of the 27 presumed cases of SDAT, 15 had cognitive performance measures concurrent with (or later than) the latest historical records available for case identification; the cognitive data for 12 of those 15 men were inconsistent with SDAT. Conclusions based on the number and characteristics of these presumed cases of SDAT must be viewed with skepticism.