Plasma amyloid beta42 and amyloid beta40 levels are associated with early cognitive dysfunction after cardiac surgery.
BACKGROUND
Decreased cognitive function associated with coronary artery bypass graft surgery is common. These deficits may be similar to the cognitive dysfunction seen in the spectrum of mild cognitive impairment to Alzheimer's disease, which are believed to result from the accumulation of amyloid beta (Abeta) peptide in the brain. We measured cognition both before and after coronary artery bypass graft surgery and assayed Abeta levels to investigate whether the cognitive dysfunction of cardiac surgery was associated with Abeta levels.


METHODS
The plasma of 332 patients, who had undergone neuropsychological testing before and 3 and 12 months after coronary artery bypass graft surgery, was analyzed for Abeta(42) and Abeta(40). Patients were classified as having preexisting cognitive impairment if cognitive function was decreased in two or more tests compared with a healthy control group, and postoperative cognitive dysfunction was defined as a decline in two or more tests compared with the group mean baseline score.


RESULTS
Preexisting cognitive impairment was present in 117 patients (35.2%), and postoperative cognitive dysfunction was present in 40 (12%) at 3 months and 41 (13%) at 12 months after surgery. Both plasma Abeta(42) and Abeta(40) levels assessed before the surgery were significantly lower in patients who later had postoperative cognitive dysfunction at 3 months.


CONCLUSIONS
Decreased preoperative plasma levels of Abeta(42) and Abeta(40) in patients who exhibit postoperative cognitive dysfunction at 3 months suggest that postoperative cognitive dysfunction at this time may share a common mechanism with mild cognitive impairment and Alzheimer's disease. This process may be exacerbated by anesthesia.
Evered
Lisbeth A
LA
Centre for Anaesthesia and Cognitive Function, Department of Anaesthesia, St. Vincent's Hospital, University of Melbourne, Melbourne, Victoria, Australia.
Silbert
Brendan S
BS
Scott
David A
DA
Maruff
Paul
P
Laughton
Katrina M
KM
Volitakis
Irene
I
Cowie
Tiffany
T
Cherny
Robert A
RA
Masters
Colin L
CL
Li
Qiao-Xin
QX
D000368:Aged; D016229:Amyloid beta-Peptides / Q000097:blood*; D003072:Cognition Disorders / Q000097:blood* / Q000175:diagnosis / Q000209:etiology*; D001026:Coronary Artery Bypass / Q000009:adverse effects*; D005260:Female; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests; D010446:Peptide Fragments / Q000097:blood*; D013997:Time Factors
D016229:Amyloid beta-Peptides; D010446:Peptide Fragments; C078592:amyloid beta-protein (1-40); C075222:amyloid beta-protein (1-42)