Longitudinal verbal fluency in normal aging, preclinical, and prevalent Alzheimer's disease.
BACKGROUND
Few longitudinal studies evaluate differences in patterns of change of category compared to letter fluency across the spectrum of cognitive impairment.


METHODS
We compared change in category (animal and supermarket) and letter (F, A, S) fluency among 239 participants in 3 groups: remained cognitively normal throughout follow-up (n = 96), developed Alzheimer's Disease (AD; preclinical AD, n = 21), and with AD at initial testing (prevalent AD, n = 122).


RESULTS
At baseline, prevalent and preclinical AD groups scored lower on animal than letter fluency. On all fluency measures, the prevalent AD declined faster than other groups (all P < .0001), and preclinical AD declined faster than unimpaired (all P <or= .02). Overall, animal fluency declined faster than letter fluency; animal fluency declined significantly faster than letter fluency among cognitively normal and prevalent AD participants.


CONCLUSIONS
Greater longitudinal declines in category compared to letter fluency are consistent with cross-sectional studies. Steeper declines on both fluency measures distinguish preclinical AD from cognitively unimpaired individuals.
Clark
Linda J
LJ
Alzheimer Disease Research Center, and Department of Neurology, University of Southern California, Los Angeles, California 90033, USA.
Gatz
Margaret
M
Zheng
Ling
L
Chen
Yu-Ling
YL
McCleary
Carol
C
Mack
Wendy J
WJ
D000368:Aged; D000369:Aged, 80 and over; D000375:Aging; D000544:Alzheimer Disease / Q000175:diagnosis* / Q000453:epidemiology*; D003071:Cognition; D003072:Cognition Disorders / Q000175:diagnosis / Q000453:epidemiology; D003937:Diagnosis, Differential; D018450:Disease Progression; D042241:Early Diagnosis; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008568:Memory; D015999:Multivariate Analysis; D009483:Neuropsychological Tests; D015995:Prevalence; D012660:Semantics; D013064:Speech Disorders / Q000175:diagnosis* / Q000453:epidemiology*