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Longitudinal PIB measures in control, MCI, and AD subjects

¹ University of Pittsburgh, Pittsburgh, Pennsylvania

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Objectives: Assess [C-11]Pittsburgh Compound-B (PIB) longitudinally in Alzheimer’s disease (AD), mild cognitive impairment (MCI), and control subjects.

Methods: Dynamic PIB PET studies were performed at baseline (BL) and yearly for up to 4 yr. Thirty-five subjects were studied (21 controls: 76±7 yr, 10 MCI: 72±7 yr and 4 mild-to-moderate AD: 68±10 yr). MRI was used to define regions (anterior cingulate, ACG; posterior cingulate, PCG; cerebellum, CER) and correct atrophy. PIB retention was assessed using the Logan distribution volume ratio (DVR=VT/VND), with CER as reference region.

Results: Seven controls had positive BL PIB retention for either (n=1) or both (n=6) ACG and PCG. Over subsequent years of follow-up, 4/7 PIB positive controls had increased levels of PIB retention. Remaining controls had negative (n=9) or intermediate (n=5) BL retention that did not become positive over subsequent years. The MCIs were either negative (n=3) or positive (n=7) at BL in both areas, and remained so over subsequent years. Only 2/7 PIB positive MCIs had increased levels of PIB retention upon follow-up. The 3 negative MCIs were amnestic single domain, while the PIB positive MCIs were amnestic with single (n=2) and multiple (n=3) domains and 2 others were non-amnestic single domain. All AD subjects were PIB positive in both areas at BL and remained so at 1 (n=3) and 2 (n=3) yr. Only 1 AD subject showed increased PIB retention beyond that measured at BL. One other AD, moderate at BL, became severe by yr 3, but PIB retention at yr 2 and 3 was similar to BL. These findings did not appear to be driven by changes in nonspecific cerebellar uptake.

Conclusions: Amyloid deposition in some PIB positive controls and MCIs increased longitudinally, while in ADs and most MCIs it appeared to plateau.

Research Support: NIA, NIMH, Dana Foundation, and Alzheimer's Assoc

This Article Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Mathis, C. Articles by DeKosky, S. PubMed Articles by Mathis, C. Articles by DeKosky, S.