title: Heterogeneity of cognitive trajectories in diverse older persons.
abstract: This study examined trajectories of cognitive change in psychometrically matched measures of episodic memory, semantic memory, and executive function in an ethnically, demographically, and cognitively diverse sample of older persons. Individual rates of change showed considerable heterogeneity in each domain. Baseline clinical diagnosis predicted differential change in semantic memory and executive function, dementia > mild cognitive impairment (MCI) > normal, but average decline in verbal episodic memory was similar across all 3 diagnostic groups. There was substantial overlap of distributions of cognitive change across baseline diagnostic groups for all 3 measures. Cognitive change was strongly related to change in clinical diagnosis. Rapid and similar change was present for all 3 cognitive measures in patients with dementia and in those with normal cognition and those with MCI who progressed clinically. In cognitively normal patients, verbal episodic memory change was greater than change in the other two domains. Global status, measured by the Clinical Dementia Rating scale (Morris, 1993), predicted change in semantic memory and executive function, whereas APOE genotype predicted change in verbal episodic memory, and age had no effect on rates of change in any domain independent of global status and APOE. Results show important limitations in using cross-sectional diagnosis to predict prognosis and suggest that research to identify robust predictors of cognitive change across the full spectrum from normal to dementia is needed for better early identification of diseases that cause progressive decline.
authors.affiliation: Department of Neurology, School of Medicine, University of California, Sacramento, CA 95817, USA. dmmungas@ucdavis.edu
authors.forename: Dan
authors.initials: D
authors.lastname: Mungas
authors.forename: Laurel
authors.initials: L
authors.lastname: Beckett
authors.forename: Danielle
authors.initials: D
authors.lastname: Harvey
authors.forename: Sarah Tomaszewski
authors.initials: ST
authors.lastname: Farias
authors.forename: Bruce
authors.initials: B
authors.lastname: Reed
authors.forename: Owen
authors.initials: O
authors.lastname: Carmichael
authors.forename: John
authors.initials: J
authors.lastname: Olichney
authors.forename: Joshua
authors.initials: J
authors.lastname: Miller
authors.forename: Charles
authors.initials: C
authors.lastname: DeCarli
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology / Q000523:psychology*; D001057:Apolipoproteins E / Q000235:genetics; D003071:Cognition; D003072:Cognition Disorders / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology*; D003704:Dementia / Q000150:complications / Q000175:diagnosis / Q000503:physiopathology*; D004522:Educational Status; D056344:Executive Function; D005260:Female; D005838:Genotype; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008568:Memory; D008875:Middle Aged; D009483:Neuropsychological Tests; D011594:Psychometrics; D012720:Severity of Illness Index
chemical_list: D001057:Apolipoproteins E