A new study from researchers at Washington University School of Medicine in St. Louis questions long held assumptions that older adults may experience memory loss and other cognitive problems following surgery. In fact, the researchers were not able to detect any long-term cognitive declines attributable to surgery in patients they studied. Past cognitive studies tested surgery patients just before an operation and then retested them several months later. So if a patient was just beginning to suffer declines at the time of the first test, it might be assumed that further declines at follow-up were caused by their operation when, in fact, they already were underway. To get better initial screenings, Michael S. Avidan, MD, associate professor of anesthesiology and surgery, and fellow investigator Alex S. Evers, MD, examined data from Washington University's Alzheimer's Disease Research Center (ADRC). The ADRC tests cognitive function in volunteers annually, beginning at the age of 50. Having years of cognitive data on hand made it easier to map a person's cognitive trajectory before and after surgery or illness and see whether either had any long-term impact on cognitive performance. The 575 patients they studied had been tested annually at the ADRC and include those with Alzheimer's-type dementia. At the start of the study, 361 people had mild to moderate dementia, and 214 were dementia-free. Those patients were divided into three groups: those who had surgery, those with illness, and a third group with neither. "We were able to use patients as their own controls before and after surgery and to compare groups of patients over time, and we did not detect any evidence of a long-term cognitive decline," Evers says. "Our findings suggest that if older people physically recover from surgery, they should expect that within six months or a year, they will return to their previous level of cognitive ability, too." "This is an important finding for persons with Alzheimer's and their families who may worry that a pending operation could adversely affect the patient's cognitive status" says John C. Morris MD, director of the ADRC. "There has been a widespread belief that the memory and thinking abilities of patients with early Alzheimer's disease may worsen as a consequence of surgery, but the evidence from this study does not support that belief." The investigators say their study, published in the November issue of the journal Anesthesiology, is not the final word on the relationship between surgery and cognitive declines: Some patients may be more vulnerable for genetic reasons or because of how their brains react to surgery or anesthesia. But in general the findings should be a relief for older people facing surgery. Says Avidan, "If you need surgery and you're elderly, even if you already have some cognitive impairment, whether you decide to have surgery or not should depend on surgical risks and benefits, and not the possibility of cognitive problems."