The German study compared the cognitive abilities of 52 patients prior to coronary artery bypass grafting surgery and five years afterward. None of the patients showed clinically significant cognitive decline when defined as a decline of 1 standard deviation or more in at least two of the seven-part Wilcoxon tests.

Other studies have reported late cognitive decline after bypass surgery. However, none of these long-term follow-up studies included a control group, as did the current study. Wolfgang Mullges, M.D., lead author, said "No individual patient showed a global decline at follow-up as compared to baseline. Seven patients (13 percent) had worse results in one single test."

The researchers also compared follow-up data with data obtained at discharge. In this comparison, only four patients (8 percent) showed a standard deviation of more than 1 percent in two of the tests. Sixteen patients (31 percent) had lower follow-up test scores in only one of the tests, and 46 (88 percent) had better results in at least one test.

The patients in this study may have had better outcomes through general medical care and by reducing vascular risk factors following surgery, said Mullges. "Many of the individuals had stopped smoking, many were prescribed statins, and many took steps to control their diabetes and hypertension," he noted.

One study limitation was a lack of data or incomplete data from a portion of the 92 original members of the patient group, and this may have introduced a bias toward a better outcome.

Mullges said physicians other than cardiologists should work with patients to provide care that reduces vascular risk for myocardial infarction, stroke, and vascular dementia. "Treatment of cardiac patients means more than surgery," he said.

The result could be a better quality of life for the growing elderly population. Active risk reduction may be even more strongly indicated for patients with preexistent cognitive or emotional problems.