Evidence that age-associated memory impairment is not a normal variant of aging.
The concept of age-associated memory impairment (AAMI) suggests that clinically recognized memory dysfunction can be a feature of normal aging. To determine whether AAMI represents a variant of normal aging, we longitudinally studied individuals meeting AAMI criteria for development of dementia. Two hundred two community-living individuals (mean age, 77 years) with or without mild memory impairment were assessed annually for an average of 3 years at the Washington University Alzheimer's Disease Research Center. At baseline, no individual was unequivocally demented, as defined by a Clinical Dementia Rating (CDR) score of 1 or greater. Modified National Institute of Mental Health criteria were used to identify individuals with AAMI who otherwise met a criterion for cognitive normality. The Short Blessed Test (SBT) was used as a measure of general cognitive function; conservative (SBT = 5) and permissive (SBT = 10) cutoff scores were used as indicators of cognitive normality. With the more permissive measure of cognitive normality, 59 (29%) of the 202 individuals met AAMI criteria. Progression to dementia by 3 years occurred in 42% of AAMI individuals versus 16% of the individuals who did not meet AAMI criteria. With the more restrictive SBT cutoff of 5, 22% of individuals met AAMI criteria; progression to dementia occurred in 31% of these individuals versus 9% of the individuals without AAMI. Survival times to dementia differed significantly between AAMI and non-AAMI groups defined by either cutoff score. Our findings indicate that individuals with AAMI have a three-fold greater risk for development of dementia than individuals who do not meet AAMI criteria. Hence, AAMI may represent a dementia prodrome rather than a benign variant of aging.
Goldman
W P
WP
Department of Neurology, and the Alzheimer's Disease Research Center, Washington University, St. Louis, Missouri 63108, USA.
Morris
J C
JC
D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000175:diagnosis* / Q000523:psychology; D000647:Amnesia / Q000175:diagnosis* / Q000523:psychology; D005260:Female; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests; D011594:Psychometrics; D012016:Reference Values