Plasma beta-amyloid and white matter lesions in AD, MCI, and cerebral amyloid angiopathy.
BACKGROUND
Microvascular brain injury, typically measured by extent of white matter hyperintensity (WMH) on MRI, is an important contributor to cognitive impairment in the elderly. Recent studies suggest a role for circulating beta-amyloid peptide in microvascular dysfunction and white matter disease.


METHODS
The authors performed a cross-sectional study of clinical, biochemical, and genetic factors associated with WMH in 54 subjects with Alzheimer disease (AD) or mild cognitive impairment (AD/MCI) and an independent group of 42 subjects with cerebral amyloid angiopathy (CAA). Extent of WMH was determined by computer-assisted volumetric measurement normalized to intracranial size (nWMH). Biochemical measurements included plasma concentrations of the 40- and 42-amino acid species of beta-amyloid (Abeta40 and Abeta42) detected by specific enzyme-linked immunosorbent assays.


RESULTS
Plasma Abeta40 concentrations were associated with nWMH in both groups (correlation coefficient = 0.48 in AD/MCI, 0.42 in CAA, p < or = 0.005). Plasma Abeta40 remained independently associated with nWMH after adjustment for potential confounders among age, hypertension, diabetes, homocysteine, creatinine, folate, vitamin B12, and APOE genotype. The presence of lacunar infarctions was also associated with increased Abeta40 in both groups. nWMH was greater in CAA (19.8 cm3) than AD (11.1 cm3) or MCI (10.0 cm3; p < 0.05 for both comparisons).


CONCLUSIONS
Plasma beta-amyloid 40 concentration is independently associated with extent of white matter hyperintensity in subjects with Alzheimer disease, mild cognitive impairment, or cerebral amyloid angiopathy. If confirmed in longitudinal studies, these data would suggest circulating beta-amyloid peptide as a novel biomarker or risk factor for microvascular damage in these common diseases of the elderly.
Gurol
M E
ME
Department of Neurology, Massachusetts General Hospital, Boston, MA 02114, USA.
Irizarry
M C
MC
Smith
E E
EE
Raju
S
S
Diaz-Arrastia
R
R
Bottiglieri
T
T
Rosand
J
J
Growdon
J H
JH
Greenberg
S M
SM
D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000097:blood / Q000175:diagnosis* / Q000503:physiopathology; D016229:Amyloid beta-Peptides / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D001921:Brain / Q000098:blood supply / Q000473:pathology* / Q000503:physiopathology; D020520:Brain Infarction / Q000097:blood / Q000175:diagnosis / Q000503:physiopathology; D016657:Cerebral Amyloid Angiopathy / Q000097:blood / Q000175:diagnosis* / Q000503:physiopathology; D002536:Cerebral Arteries / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D002561:Cerebrovascular Disorders / Q000097:blood / Q000175:diagnosis / Q000503:physiopathology; D003072:Cognition Disorders / Q000097:blood / Q000175:diagnosis* / Q000503:physiopathology; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008833:Microcirculation / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D008875:Middle Aged; D009413:Nerve Fibers, Myelinated / Q000378:metabolism / Q000473:pathology*; D010446:Peptide Fragments / Q000097:blood*; D011237:Predictive Value of Tests; D011379:Prognosis
D016229:Amyloid beta-Peptides; D015415:Biomarkers; D010446:Peptide Fragments; C078592:amyloid beta-protein (1-40)