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Plasma Aβ and PET PiB binding are inversely related in mild cognitive impairment

D P Devanand1, N Schupf, Y Stern

  • 1Divisions of Geriatric Psychiatry, New York State Psychiatric Institute, Columbia University, New York, NY 10032, USA. dpd3@columbia.edu

Neurology
|July 1, 2011
PubMed
Abstract

Insights

In mild cognitive impairment (MCI), lower plasma amyloid-beta (Aβ) 42/40 ratio correlates with increased brain amyloid plaque detected by Pittsburgh compound B (PiB-PET) imaging. This suggests plasma Aβ may serve as a biomarker for brain amyloidosis.

Area of Science:

  • Neuroscience
  • Biomarker Discovery
  • Alzheimer's Disease Research

Background:

  • Alzheimer's disease (AD) is characterized by amyloid-beta (Aβ) plaque accumulation in the brain.
  • Mild cognitive impairment (MCI) is a prodromal stage of AD, often associated with early Aβ pathology.
  • Positron emission tomography (PET) with Pittsburgh compound B (PiB-PET) is a key imaging technique for visualizing brain amyloid.

Purpose of the Study:

  • To investigate the relationship between amyloid imaging via PiB-PET and plasma Aβ levels in individuals with MCI and healthy controls.
  • To explore the potential of plasma Aβ as a peripheral biomarker reflecting central amyloid burden.

Main Methods:

  • A case-control study involving 20 MCI patients and 19 cognitively intact controls.
  • PiB-PET was used to quantify amyloid binding potential (BP(nd)) in specific brain regions and the total brain.
  • Plasma Aβ40 and Aβ42 levels were measured, and the Aβ42/Aβ40 ratio was calculated.

Main Results:

  • Patients with MCI showed a significantly decreased plasma Aβ42/Aβ40 ratio compared to controls.
  • PiB-PET revealed increased amyloid binding in MCI patients in the cingulate, parietal, and total brain regions.
  • A lower plasma Aβ42/Aβ40 ratio was significantly associated with higher PiB binding in the brain, particularly in MCI patients.

Conclusions:

  • The findings support the "sink" hypothesis, where increased brain Aβ is linked to reduced peripheral Aβ levels.
  • The plasma Aβ42/Aβ40 ratio shows promise as a potential biomarker for brain amyloidosis in MCI.
  • Combined use of plasma Aβ and PiB binding may offer a valuable risk biomarker for clinical applications.

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