New Research Links Gene to High Rates of Postoperative Delirium in the Elderly

Postoperative delirium is a very serious condition in the elderly, leading to the patient being sent to a nursing home, or even death in the hospital. Elderly patients who have a gene that has been associated with Alzheimer's disease also have a higher rate of postoperative delirium after a major surgery.

The gene responsible is the apolipoprotein E (APOE) e4 gene variant.

This study involved 190 patients with the average age of 72.5 who underwent major surgery, but not heart surgery. They used a standard assessment test to look for confusion and any other symptoms of delirium. They also took DNA samples in order to see if any of the patients were carriers of the gene.

It turns out the close to 15% of the patients did develop symptoms of postoperative delirium almost immediately after surgery, on the first and second days. Using the DNA analysis, it was determined that 24% of the 15% who developed the symptoms were carriers.

When they compared the patients with the gene to the ones who did not carry it, the carriers had an occurrence of postoperative delirium of about 28%, while those who do not carry the gene had a rate of 11%. After they made some adjustments to eliminate other risk factors as causes, things like older age, change in postoperative pain levels, and previous central nervous system disorders, the figures showed that the patients who had at least one copy of the APOE e4 variant gene had a four times greater chance to develop postoperative delirium.

Other population studies have shown that the APOE e4 gene variant is associated with dementia and the late-onset form of Alzheimer's disease, the form that is developed after age 65, and other forms of cognitive decline. There are other genes that have also been linked to a higher risk of early-onset Alzheimer's disease.

This is the first time a study like this was ever done and now they plan to go further and see if the gene has anything to do with any other similar diseases. Research also needs to focus on how to use this information. Is there a way to shut down the gene, making it ineffective? If so it would be a major breakthrough for patients with postoperative delirium, dementia, Alzheimer's disease and other forms of degenerative, mental disease. Research has only begun. There is no way to know how many of these types of diseases can be linked back to this one genetic defect.

The lead researcher in this project is Dr. Jacqueline M. Leung of University of California, San Francisco.

Source: American Society of Anesthesiologists (ASA) http://www.newswise.com/