Cognitively Unimpaired HIV-positive Subjects Do Not Have Increased 11C-PiB: A Case-Control Study

Neurology. 2010 Jul 13;75(2):111-5. doi: 10.1212/WNL.0b013e3181e7b66e. Epub 2010 Jun 9.

Abstract

Objectives: Diagnostic challenges exist for differentiating HIV dementia from Alzheimer disease (AD) in older HIV-infected (HIV+) individuals. Similar abnormalities in brain amyloid-beta42 (Alphabeta42) metabolism may be involved in HIV-associated neuropathology and AD. We evaluated the amyloid-binding agent (11)C-Pittsburgh compound B ((11)C-PiB), a biomarker for Alphabeta42 deposition, in cognitively unimpaired HIV+ (n = 10) participants and matched community controls without dementia (n = 20).

Methods: In this case-control study, all participants had an (11)C-PiB scan within 2 years of concomitant CSF studies and neuropsychometric testing. Statistical differences between HIV+ and community controls for demographic and clinical values were assessed by chi(2) tests. Participants were further divided into either low (<500 pg/mL) or normal (>or=500 pg/mL) CSF Alphabeta42 groups with Student t tests performed to determine if regional differences in fibrillar amyloid plaque deposition varied with CSF Alphabeta42.

Results: Regardless of CSF Alphabeta42 level, none of the HIV+ participants had fibrillar amyloid plaques as assessed by increased (11)C-PiB mean cortical binding potential (MCBP) or binding potential within 4 cortical regions. In contrast, some community controls with low CSF Alphabeta42 (<500 pg/mL) had high (11)C-PiB MCBP with elevated binding potentials (>0.18 arbitrary units) within cortical regions.

Conclusions: Cognitively unimpaired HIV+ participants, even with low CSF Alphabeta42 (<500 pg/mL), do not have (11)C-PiB parameters suggesting brain fibrillar amyloid deposition. The dissimilarity between unimpaired HIV+ and preclinical AD may reflect differences in Abeta42 production and/or formation of diffuse plaques. Future longitudinal studies of HIV+ participants with low CSF Abeta42 and normal (11)C-PiB are required.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Amyloid beta-Peptides / metabolism*
  • Analysis of Variance
  • Benzothiazoles / metabolism*
  • Brain / diagnostic imaging
  • Brain / metabolism*
  • Brain Mapping
  • Carbon Radioisotopes
  • Case-Control Studies
  • Chi-Square Distribution
  • Cognition Disorders / diagnostic imaging
  • Cognition Disorders / metabolism*
  • Female
  • HIV
  • HIV Infections / diagnostic imaging
  • HIV Infections / metabolism*
  • Humans
  • Image Processing, Computer-Assisted
  • Male
  • Middle Aged
  • Neuropsychological Tests
  • Radionuclide Imaging

Substances

  • 2-(4'-(methylamino)phenyl)-6-hydroxybenzothiazole
  • Amyloid beta-Peptides
  • Benzothiazoles
  • Carbon Radioisotopes

Grant support