Objective: To identify aspects of a standardized clinical assessment that c
all predict which individuals within the category of "questionable" Alzheim
er disease (AD) have a high likelihood of converting to AD over time.
Design: Detailed semistructured interviews were performed at baseline and a
nnually for 3 years.
Setting: University-based gerontology research program.
Patients: The patient population consisted of 165 individuals 65 years and
older: 42 of the participants had a Clinical Dementia Rating (CDR) of norma
l cognition (CDR rating, 0.0) and 123 had a rating of questionable AD (CDR
rating, 0.5). After 3 years of follow-up, 23 of the 123 subjects with quest
ionable AD were diagnosed with probable AD
Main Outcome Measures: The interview was used to generate a summary measure
based on the sum of 6 CDR categories, known as the Total Box Score. The re
sponses to 32 selected questions from the interview also were examined.
Results: Likelihood of progression to AD during the follow-up period was st
rongly related to the Total Box Score. For example, more than 50% of indivi
duals with a Total Box Score of 2.0 or higher at baseline developed AD duri
ng the follow-up interval, whereas about 10% of individuals with a Total Bo
x Score of 1.0 or lower developed AD during this same period. Selected ques
tions from the standardized clinical interview also were highly predictive
of subsequent conversion to AD among the study population. Eight selected q
uestions from the clinical interview at baseline, combined with the CDR Tot
al Box Score, identified 88.6% of such individuals accurately (questionable
group, 82/91; converter group, 19/23).
Conclusions: A standardized clinical assessment can be used to identify the
subgroup of individuals within the category of questionable AD who have a
high likelihood of converting to AD over time. Subjects who met the criteri
a for questionable AD had a variety of trajectories during a 3-year follow-
up, suggesting that diverse factors may influence the functional changes ob
served in this population.