FRIDAY, Aug. 24, 2007 (HealthDay News) -- Elderly people with the apolipoprotein E (APOE) e4 gene variant -- associated with an increased risk of late-onset Alzheimer's disease and other types of dementia -- are more likely to develop postoperative delirium after major surgery than those without the gene variant, a U.S. study finds.
Researchers at the University of California, San Francisco, analyzed 190 elderly patients, average age 72.5.
They found that about 28 percent of those with APOE e4 developed postoperative delirium, compared with 11 percent of those without APOE e4.
After adjusting for a number of factors -- including older age and previous central nervous system disorders -- the researchers concluded that patients with the APOE e4 gene variant were nearly four times more likely to develop postoperative delirium.
Overall, about 15 percent of the patients developed postoperative delirium on the first and second days after surgery.
Postoperative delirium has been linked with increased rates of in-hospital death and nursing home placement, the researchers noted.
"Despite this prevalence and clinical importance, no specific causative factor has been identified," study author Dr. Jacqueline M. Leung said in a prepared statement.
"Our results suggest that genetic predisposition plays a role and may interact with anesthetic/surgical factors contributing to the development of early postoperative delirium," said Leung.
The findings were published in the September issue of the journal Anesthesiology.
Leung said more studies are needed to further investigate the APOE e4-postoperative delirium link and to explore whether people with APOE e4 who develop postoperative delirium are at increased risk for later cognitive impairment.
The U.S. National Institute on Aging has more about Alzheimer's disease genetics.