Cognitively unimpaired HIV-positive subjects do not have increased 11C-PiB: a case-control study.
OBJECTIVE
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.
Department of Neurology, Washington University, St Louis, MO 63110, USA. bances@wustl.edu
B M
BM
Ances
J J
JJ
Christensen
M
M
Teshome
J
J
Taylor
C
C
Xiong
P
P
Aldea
A M
AM
Fagan
D M
DM
Holtzman
J C
JC
Morris
M A
MA
Mintun
D B
DB
Clifford
D000328:Adult; D016229:Amyloid beta-Peptides / Q000378:metabolism*; D000704:Analysis of Variance; D000814:Aniline Compounds; D052160:Benzothiazoles / Q000378:metabolism*; D001921:Brain / Q000000981:diagnostic imaging / Q000378:metabolism*; D001931:Brain Mapping; D002250:Carbon Radioisotopes; D016022:Case-Control Studies; D016009:Chi-Square Distribution; D003072:Cognition Disorders / Q000000981:diagnostic imaging / Q000378:metabolism*; D005260:Female; D006678:HIV; D015658:HIV Infections / Q000000981:diagnostic imaging / Q000378:metabolism*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D011877:Radionuclide Imaging; D013844:Thiazoles
C475519:2-(4'-(methylamino)phenyl)-6-hydroxybenzothiazole; D016229:Amyloid beta-Peptides; D000814:Aniline Compounds; D052160:Benzothiazoles; D002250:Carbon Radioisotopes; D013844:Thiazoles