Serum amyloid p component as a biomarker in mild cognitive impairment and Alzheimer's disease.
BACKGROUND
Serum amyloid P component (SAP), present in amyloid-beta (Abeta) plaques in Alzheimer's disease (AD), may protect Abeta deposits against proteolysis, thereby promoting plaque formation. The aim was to investigate if SAP levels in cerebrospinal fluid (CSF) and serum can be used to discriminate controls, AD and mild cognitive impairment (MCI) patients, and to identify incipient AD among MCI patients.


METHODS
SAP levels in CSF and serum were determined in 30 controls, 67 MCI and 144 AD patients. At follow-up, 39 MCI patients had progressed to dementia, while 25 had remained stable (mean follow-up time: 2.6 +/- 1.0 and 2.1 +/- 0.8 years).


RESULTS
Cross-sectionally no differences were found in SAP levels in CSF and serum between the groups. MCI patients that had progressed to dementia at follow-up had lower CSF SAP levels (13 microgram/l, range 3.3-199.3 microgram/l) than MCI nonprogressors (20.2 microgram/l, range 7.0-127.7 microgram/l; p < 0.05) [corrected]. A low CSF SAP level was associated with a 2-fold increased risk of progression to AD (hazard ratio = 2.2; 95% confidence interval = 0.9-5.4).


CONCLUSIONS
Our data suggest that measurement of CSF SAP levels can aid in the identification of incipient AD among MCI patients.
Verwey
Nicolaas A
NA
Department of Neurology, Alzheimer Center, VU University Medical Center, Amsterdam, The Netherlands. n.verwey@vumc.nl
Schuitemaker
Alie
A
van der Flier
Wiesje M
WM
Mulder
Sandra D
SD
Mulder
Cees
C
Hack
C Erik
CE
Scheltens
Philip
P
Blankenstein
Marinus A
MA
Veerhuis
Robert
R
D000368:Aged; D000544:Alzheimer Disease / Q000097:blood* / Q000134:cerebrospinal fluid; D016229:Amyloid beta-Peptides / Q000097:blood / Q000134:cerebrospinal fluid; D015415:Biomarkers; D003072:Cognition Disorders / Q000097:blood* / Q000134:cerebrospinal fluid; D003430:Cross-Sectional Studies; D003937:Diagnosis, Differential; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D010446:Peptide Fragments / Q000097:blood / Q000134:cerebrospinal fluid; D012307:Risk Factors; D000683:Serum Amyloid P-Component / Q000134:cerebrospinal fluid / Q000378:metabolism*
D016229:Amyloid beta-Peptides; D015415:Biomarkers; D010446:Peptide Fragments; D000683:Serum Amyloid P-Component; C075222:amyloid beta-protein (1-42)