Affiliations: [a] Turku PET Centre, University of Turku and Turku University Hospital, Finland | [b] National Institute for Health and Welfare (THL), Turku, Finland | [c] National Institute for Health and Welfare (THL), Helsinki, Finland | [d] Department of Biostatistics, University of Turku, Finland | [e] Department of Nuclear Medicine, PET and Cyclotron Unit, Odense University Hospital, Denmark | [f] Turku City Hospital, Turku, Finland | [g] Clinical Geriatrics, Karolinska Institutet, Karolinska University Hospital, Huddinge, Sweden | [h] Department of Neurology, Turku University Hospital, Turku, Finland
Correspondence:
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Correspondence to: Juha O. Rinne, Turku PET Centre, University of Turku and Turku University Hospital, Kiinamyllynkatu 4-8, 20520 Turku, Finland. Tel.: +358 2 3131866; Fax: +358 2 2318191; E-mail: juha.rinne@tyks.fi.
Abstract: Background/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.
