DURHAM, N.C. -- Physicians at Duke University Medical Center have found that patients who experience mental impairment after open heart surgery are more likely to carry the gene that predisposes people to Alzheimer's disease.
While up to three-quarters of all heart surgery patients experience some
degree of cognitive impairment following surgery using heart-lung bypass
machines, patients with the Alzheimer's- related gene apoliprotein E-4 (APOE-4),
are more susceptible to this damage, a preliminary study of 65 patients
Since normal APOE is involved in nerve cell repair, they believe the variant APOE-4 is unable to make such repairs efficiently, as evidenced in patients with Alzheimer's disease. The study findings were published Tuesday in the September issue of the Annals of Thoracic Surgery. The study was supported by grants from the National Institutes of Health, National Institute on Aging, the American Heart Association and the Anesthesia Patient Safety Foundation.
"We noticed that after major heart surgery, the neurologic deficits of many patients -- attention, concentration and memory problems -- were very much like the early symptoms of Alzheimer's disease," said Duke's Dr. Mark Newman, chief of cardiothoracic anesthesiology and the study leader. "After controlling for other characteristics, we found a statistically significant correlation between patients with the APOE variant and neurological damage after surgery.
"Patients with the APOE variant were more susceptible to neurological damage than the other patients," Newman said. "The fact that this association was found in such a small study population leads us to believe the results will be borne out in larger studies."
Physicians say that while they can do nothing now to offset this susceptibility, it may be possible to develop drugs or other strategies to protect brain cells in these patients.