title: [Formula: see text]Practice effects and longitudinal cognitive change in clinically normal older adults differ by Alzheimer imaging biomarker status.
abstract: The objective of this study was to examine practice effects and longitudinal cognitive change in 190 clinically normal elderly classified according to a two-feature biomarker model for Alzheimer's disease.
  
  
  
  All participants completed neuropsychological testing, MRI, FDG-PET, and PiB-PET at their baseline evaluation. We divided participants into four groups based on neuroimaging measures of amyloid (A+ or A-) and neurodegeneration (N+ or N-) and reexamined cognition at 15- and 30-month intervals.
  
  
  
  The A-N- group showed significant improvements in the memory and global scores. The A+N- group also showed significant improvements in the memory and global scores as well as attention. The A-N+ group showed a significant decline in attention at 30 months. The A+N+ group showed significant improvements in memory and the global score at 15 months followed by a significant decline in the global score at 30 months.
  
  
  
  Amyloidosis in the absence of neurodegeneration did not have an adverse impact on practice effects or the 30-month cognitive trajectories. In contrast, participants with neurodegeneration (either A-N+ or A+N+) had worse performance at the 30-month follow-up. Our results show that neurodegeneration has a more deleterious effect on cognition than amyloidosis in clinically normal individuals.
authors.affiliation: Division of Neurocognitive Disorders, Department of Psychiatry and Psychology.
authors.forename: Mary M
authors.initials: MM
authors.lastname: Machulda
authors.affiliation: Division of Biomedical Statistics and Informatics, Department of Health Sciences Research.
authors.forename: Clint E
authors.initials: CE
authors.lastname: Hagen
authors.affiliation: Division of Biomedical Statistics and Informatics, Department of Health Sciences Research.
authors.forename: Heather J
authors.initials: HJ
authors.lastname: Wiste
authors.affiliation: Division of Epidemiology, Department of Health Sciences Research.|Department of Neurology, College of Medicine, Mayo Clinic, 200 1 Street SW, Rochester, MN 55905.
authors.forename: Michelle M
authors.initials: MM
authors.lastname: Mielke
authors.affiliation: Department of Neurology, College of Medicine, Mayo Clinic, 200 1 Street SW, Rochester, MN 55905.
authors.forename: David S
authors.initials: DS
authors.lastname: Knopman
authors.affiliation: Division of Epidemiology, Department of Health Sciences Research.|Department of Neurology, College of Medicine, Mayo Clinic, 200 1 Street SW, Rochester, MN 55905.
authors.forename: Rosebud O
authors.initials: RO
authors.lastname: Roberts
authors.affiliation: Department of Radiology, College of Medicine, Mayo Clinic, 200 1 Street SW, Rochester, MN 55905.
authors.forename: Prashanthi
authors.initials: P
authors.lastname: Vemuri
authors.affiliation: Department of Radiology, College of Medicine, Mayo Clinic, 200 1 Street SW, Rochester, MN 55905.
authors.forename: Val J
authors.initials: VJ
authors.lastname: Lowe
authors.affiliation: Department of Radiology, College of Medicine, Mayo Clinic, 200 1 Street SW, Rochester, MN 55905.
authors.forename: Clifford R
authors.initials: CR
authors.lastname: Jack
authors.affiliation: Department of Neurology, College of Medicine, Mayo Clinic, 200 1 Street SW, Rochester, MN 55905.
authors.forename: Ronald C
authors.initials: RC
authors.lastname: Petersen
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000523:psychology; D000682:Amyloid / Q000378:metabolism; D058070:Asymptomatic Diseases; D015415:Biomarkers / Q000378:metabolism; D003071:Cognition; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging; D008297:Male; D008568:Memory; D059906:Neuroimaging; D009483:Neuropsychological Tests; D049268:Positron-Emission Tomography
chemical_list: D000682:Amyloid; D015415:Biomarkers
keywords: Cognition; FDG-PET; PiB-PET; amyloid; neurodegeneration; practice effects; preclinical Alzheimer’s disease