In a study comparing 140 patients who underwent bypass surgery and a second group of 92 coronary artery disease patients who did not have surgery, the Johns Hopkins team found no differences in cognitive abilities when patients were re-tested at three and 12 months. Results appear in the May 2003 issue of The Annals of Thoracic Surgery.
"Our study demonstrates that cognitive decline immediately after coronary artery bypass surgery is transient and reversible," says Ola Selnes, Ph.D., associate professor of neurology at Johns Hopkins and lead author of the study.
The researchers employed a number of neuropsychological tests to measure the memory and other cognitive abilities of the two groups of patients with coronary artery disease. The non-surgical group, Selnes says, made up the control group that helped determine the severity and duration of cognitive impairment in those who did have surgery.
"There have been a number of studies showing that bypass surgery causes cognitive decline, but without an appropriate control group we had no way of knowing how serious the defects were nor how long they lasted," says Selnes.
The neuropsychological tests included measures of attention, learning and memory, spatial abilities and speed of processing. All tests were given to patients when they were diagnosed with coronary artery disease to establish a baseline. The tests were given again at three months and 12 months after they were initially tested, and the results from the two groups were compared.
The researchers will continue to follow the study participants for three to five years to determine if coronary artery bypass surgery has long-term cognitive effects compared to those who did not have surgery.
The study was funded by the National Institute of Neurologic Disorders and Stroke and the Charles A. Dana Foundation. Other authors of the study are Maura Grega, M.S.N., Louis Borowics Jr., M.S., Richard Royall, Ph.D., Guy McKhann, M.D., and William Baumgartner, M.D.
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