title: Cortical ¹¹C-PIB uptake is associated with age, APOE genotype, and gender in "healthy aging".
abstract: OBJECTIVE
  Our aim was to elucidate factors that contribute to amyloid-β (Aβ) accumulation in the brains of the seemingly healthy elderly population, and whether there is interplay between those factors.
  
  
  METHODS
  We conducted a cross-sectional positron emission tomography (PET) study with the amyloid tracer 11C-PIB, in 64 cognitively healthy subjects (54-89 years). In addition to PET, magnetic resonance imaging, neuropsychological testing, and APOE genotyping was performed. The results were assessed with a statistical general linear model as well as with Statistical Parametric Mapping (SPM).
  
  
  RESULTS
  The effects of age (p < 0.001), APOE ε4 carrier status (p = 0.003), and gender (p = 0.001) on composite cortical 11C-PIB uptake were all significant. The effect of educational level was non-significant (p = 0.37). No significant interactions were found between any of the factors. Cortical 11C-PIB uptake increased, on the average, by 0.015 cortex/cerebellar cortical ratio unit, with every year of age. APOE ε4 positive subjects exhibited higher cortical 11C-PIB uptake than APOE ε4 negative subjects (unadjusted means 1.49 ± 0.34 versus 1.29 ± 0.26) and males had higher uptake than females (1.49 ± 0.39 versus 1.29 ± 0.22), irrespective of age. The results of the voxel-based (SPM) analysis were similar. In addition, SPM analysis showed that lower CERAD score was associated with higher 11C-PIB uptake in the frontal cortex.
  
  
  CONCLUSIONS
  Age and APOE ε4 genotype were associated with higher 11C-PIB uptake. In this sample of cognitively healthy elderly individuals, men exhibited higher 11C-PIB uptake than women. Possible gender differences in Aβ accumulation have not been addressed in detail in previous studies, and deeper evaluation in the future is warranted.
authors.affiliation: Turku PET Centre, University of Turku and Turku University Hospital, Finland.
authors.forename: Noora M
authors.initials: NM
authors.lastname: Scheinin
authors.affiliation: Turku PET Centre, University of Turku and Turku University Hospital, Finland.
authors.forename: Kristina
authors.initials: K
authors.lastname: Wikman
authors.affiliation: National Institute for Health and Welfare (THL), Turku, Finland.
authors.forename: Antti
authors.initials: A
authors.lastname: Jula
authors.affiliation: National Institute for Health and Welfare (THL), Helsinki, Finland.
authors.forename: Markus
authors.initials: M
authors.lastname: Perola
authors.affiliation: Department of Biostatistics, University of Turku, Finland.
authors.forename: Tero
authors.initials: T
authors.lastname: Vahlberg
authors.affiliation: Turku PET Centre, University of Turku and Turku University Hospital, Finland.
authors.forename: Johanna
authors.initials: J
authors.lastname: Rokka
authors.affiliation: Department of Nuclear Medicine, PET and Cyclotron Unit, Odense University Hospital, Denmark.
authors.forename: Kjell
authors.initials: K
authors.lastname: Någren
authors.affiliation: Turku City Hospital, Turku, Finland Clinical Geriatrics, Karolinska Institutet, Karolinska University Hospital, Huddinge, Sweden.
authors.forename: Matti
authors.initials: M
authors.lastname: Viitanen
authors.affiliation: Turku PET Centre, University of Turku and Turku University Hospital, Finland Department of Neurology, Turku University Hospital, Turku, Finland.
authors.forename: Juha O
authors.initials: JO
authors.lastname: Rinne
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000235:genetics / Q000502:physiology*; D000682:Amyloid / Q000378:metabolism*; D000814:Aniline Compounds; D053327:Apolipoprotein E4 / Q000235:genetics; D001057:Apolipoproteins E / Q000235:genetics*; D052160:Benzothiazoles; D001921:Brain / Q000000981:diagnostic imaging* / Q000502:physiology*; D003430:Cross-Sectional Studies; D004522:Educational Status; D005260:Female; D005838:Genotype; D060005:Genotyping Techniques; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals; D012727:Sex Characteristics; D013844:Thiazoles
chemical_list: C475519:2-(4'-(methylamino)phenyl)-6-hydroxybenzothiazole; D000682:Amyloid; D000814:Aniline Compounds; D053327:Apolipoprotein E4; D001057:Apolipoproteins E; D052160:Benzothiazoles; D019275:Radiopharmaceuticals; D013844:Thiazoles
keywords: APOE; Aging; PET; PIB; amyloid; gender; positron emission tomography