C-reactive protein is not a marker of cognitive impairment in patients with cardiovascular disease

Brendan Silbert¹, Lisbeth Evered¹, David Scott¹, Craig McCutcheon¹, Konrad Jamrozik²

¹Centre for Anaesthesia and Cognitive Function, Department of Anaesthesia, St Vincent’s Health, Melbourne, Australia
²School of Population Health and Clinical Practice (K.J.), University of Adelaide, Australia

Background: C-reactive protein (CRP) is recognised as a strong and independent risk factor for cardiovascular disease which may not only be a marker but also one of the participants of the inflammatory process associated with atherosclerosis. CRP has also been implicated as an independent risk factor for cognitive impairment in population studies.

Objectives: To investigate the association of CRP with cognition in patients presenting for elective coronary artery bypass graft (CABG) surgery.

Methods: Cognition was assessed in 264 patients using a standard battery of eight neuropsychological tests. The test battery consisted of the CERAD Auditory Verbal Learning test, Digit Symbol Substitution test, Trail Making test parts A and B, Controlled Oral Word Association Test (COWAT), Semantic Fluency test, and the Grooved Pegboard test (dominant and non-dominant hands). Patients were classified as having preoperative cognitive impairment by reference to a healthy control group or postoperative cognitive dysfunction by reference to baseline test scores.

Results: Preoperative cognitive impairment was present in 37.3% of patients and postoperative cognitive dysfunction present 18.3%, 12.1% and 13.6% of patients at one week, 3 months and 12 months postoperatively. On multivariable analysis CRP was not independently associated with cognition at any testing time but was strongly associated with age and left ventricular function.

Conclusion: Preoperative cognitive impairment and a postoperative cognitive dysfunction are present in a substantial proportion of patients undergoing CABG surgery but there is no independent association with baseline CRP levels. It is possible that cognitive impairment may result from the vascular disease rather than a direct association with CRP.