ROCHESTER, Minn., Jan. 20 (UPI) -- Surgical anesthesia was not linked to the development of mild cognitive impairment, or MCI, in patients over the age of 40, according to a new study by the Mayo Clinic.
Elderly patients can develop delirium after surgery, however it usually disappears within days or weeks and has not previously been associated with long-term impairments.
At least one study has shown a type of anesthetic can increase MCI risk, however a previous study by Mayo Clinic researchers found no link between anesthesia in patients under age 45 and increased risk for MCI.
While the new study did not find a strong association at any age, researchers remain concerned about the possibility that patients over age 65 could be at greater risk.
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The researchers also said children under the age of 2 who have had several surgeries could be at increased risk for MCI later in life, which is also currently being studied at Mayo Clinic. Scientists at the clinic previously found anesthetics increased ADHD rates among children.
"We looked at a group of patients who have been followed here in Olmsted County, where we have detailed information about their cognitive function as they age," said Dr. David Warner, an anesthesiologist at the Mayo Clinic, in a press release. "The bottom line of our study is that we did not find an association between exposure to anesthesia for surgery and the development of mild cognitive impairment in these patients."
In the study, published in Mayo Clinic Proceedings, researchers enrolled 1,731 residents of Olmsted County, Minn., between the ages of 70 and 89 who did not have MCD. The participants were asked to undergo evaluations for MCD, including a neurologic evaluation, neuropsychological testing, and others, with follow-up evaluations every 15 months.
During a mean follow-up time of 4.8 years, 31 percent of participants developed MCI, although 85 percent had some type of surgery that required anesthesia at least once since age 40. While exposure to anesthesia after age 40 was not associated with MCI, those who had surgery after age 60 may experience a higher risk.
The researchers said more research must be done on patients over age 60, especially those having vascular surgeries, in addition to issues that have been seen with learning and memory in children later in life.
"Because of the associations that we've seen, there is more concern in the young than the old, and it will require quite a bit more research to find out what is happening with the children, and if there is a problem, how we can best address it," Warner said. "But for the moment, there is little clinical evidence that anesthesia itself leads to cognitive decline in the elderly -- although more research is needed."
