title: Practice effects and longitudinal cognitive change in normal aging vs. incident mild cognitive impairment and dementia in the Mayo Clinic Study of Aging.
abstract: The objective of this study was to examine practice effects and longitudinal cognitive change in a population-based cohort classified as clinically normal at their initial evaluation. We examined 1390 individuals with a median age of 78.1 years and re-evaluated them up to four times at approximate 15-month intervals, with an average follow-up time of 5 years. Of the 1390 participants, 947 (69%) individuals remained cognitively normal, 397 (29%) progressed to mild cognitive impairment (MCI), and 46 (3%) to dementia. The stable normal group showed an initial practice effect in all domains which was sustained in memory and visuospatial reasoning. There was only a slight decline in attention and language after visit 3. We combined individuals with incident MCI and dementia to form one group representing those who declined. The incident MCI/dementia group showed an unexpected practice effect in memory from baseline to visit 2, with a significant decline thereafter. This group did not demonstrate practice effects in any other domain and showed a downward trajectory in all domains at each evaluation. Modeling cognitive change in an epidemiologic sample may serve as a useful benchmark for evaluating cognitive change in future intervention studies.
authors.affiliation: a Department of Psychiatry and Psychology , College of Medicine, Mayo Clinic , Rochester , MN , USA .
authors.forename: Mary M
authors.initials: MM
authors.lastname: Machulda
authors.forename: V Shane
authors.initials: VS
authors.lastname: Pankratz
authors.forename: Teresa J
authors.initials: TJ
authors.lastname: Christianson
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Ivnik
authors.forename: Michelle M
authors.initials: MM
authors.lastname: Mielke
authors.forename: Rosebud O
authors.initials: RO
authors.lastname: Roberts
authors.forename: David S
authors.initials: DS
authors.lastname: Knopman
authors.forename: Bradley F
authors.initials: BF
authors.lastname: Boeve
authors.forename: Ronald C
authors.initials: RC
authors.lastname: Petersen
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000523:psychology*; D000544:Alzheimer Disease / Q000175:diagnosis / Q000523:psychology; D003071:Cognition; D060825:Cognitive Dysfunction / Q000175:diagnosis* / Q000523:psychology*; D003704:Dementia / Q000175:diagnosis / Q000523:psychology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008568:Memory; D008910:Minnesota; D009483:Neuropsychological Tests; D011214:Practice, Psychological
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