title: Exercise and Alzheimer's disease biomarkers in cognitively normal older adults.
abstract: OBJECTIVE
  In addition to the increasingly recognized role of physical exercise in maintaining cognition, exercise may influence Alzheimer's disease (AD) pathology, as transgenic mouse studies show lowered levels of AD pathology in exercise groups. The objective of this study was to elucidate the association between exercise and AD pathology in humans using Pittsburgh compound-B (PIB), amyloid-beta (Abeta)(42), tau, and phosphorylated tau (ptau)(181) biomarkers.
  
  
  METHODS
  Sixty-nine older adults (17 males, 52 females) aged 55 to 88 years, were recruited and confirmed to be cognitively normal. A questionnaire on physical exercise levels over the past decade was administered to all. Cerebrospinal fluid samples were collected from 56 participants, and amyloid imaging with PIB was performed on 54 participants.
  
  
  RESULTS
  Participants were classified based on biomarker levels. Those with elevated PIB (p = 0.030), tau (p = 0.040), and ptau(181) (p = 0.044) had significantly lower exercise, with a nonsignificant trend for lower Abeta(42) (p = 0.135) to be associated with less exercise. Results were similar for PIB after controlling for covariates; tau (p = 0.115) and ptau(181) (p = 0.123) differences were reduced to nonsignificant trends. Additional analyses also demonstrated that active individuals who met the exercise guidelines set by the American Heart Association had significantly lower PIB binding and higher Abeta(42) levels with and without controlling for covariates (PIB: p = 0.006 and p = 0.001; Abeta(42): p = 0.042 and p = 0.046). Last, the associations between exercise engagement and PIB levels were more prominent in APOE epsilon 4 noncarriers.
  
  
  CONCLUSIONS
  Collectively, these results are supportive of an association between exercise engagement and AD biomarkers in cognitively normal older adults.
authors.affiliation: From the Program in Neuroscience, Division of Biology and Biomedical Sciences, Washington University, St. Louis, MO 63130, USA.
authors.forename: Kelvin Y
authors.initials: KY
authors.lastname: Liang
authors.forename: Mark A
authors.initials: MA
authors.lastname: Mintun
authors.forename: Anne M
authors.initials: AM
authors.lastname: Fagan
authors.forename: Alison M
authors.initials: AM
authors.lastname: Goate
authors.forename: Julie M
authors.initials: JM
authors.lastname: Bugg
authors.forename: David M
authors.initials: DM
authors.lastname: Holtzman
authors.forename: John C
authors.initials: JC
authors.lastname: Morris
authors.forename: Denise
authors.initials: D
authors.lastname: Head
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000134:cerebrospinal fluid* / Q000000981:diagnostic imaging / Q000235:genetics / Q000517:prevention & control*; D016229:Amyloid beta-Peptides / Q000134:cerebrospinal fluid*; D000814:Aniline Compounds; D001057:Apolipoproteins E / Q000235:genetics; D015444:Exercise / Q000502:physiology*; D005260:Female; D015577:Geriatric Assessment; D006801:Humans; D008297:Male; D008875:Middle Aged; D010446:Peptide Fragments / Q000134:cerebrospinal fluid*; D049268:Positron-Emission Tomography / Q000379:methods; D011569:Psychiatric Status Rating Scales; D012307:Risk Factors; D013844:Thiazoles; D016875:tau Proteins / Q000097:blood / Q000134:cerebrospinal fluid*
chemical_list: C475519:2-(4'-(methylamino)phenyl)-6-hydroxybenzothiazole; D016229:Amyloid beta-Peptides; D000814:Aniline Compounds; D001057:Apolipoproteins E; D010446:Peptide Fragments; D013844:Thiazoles; C075222:amyloid beta-protein (1-42); D016875:tau Proteins
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