DEAR DR. ROACH: I am a 67-year-old estate planning attorney. Last year I had back surgery and experienced substantial cognitive impairment immediately after. It has been over a year, and I have recovered perhaps 80% of my prior mental function. I would appreciate your thoughts on this issue, as many of my elderly clients have also experienced dementia symptoms following surgery and most have not fully recovered. — A.L.

ANSWER: Any kind of surgery can lead to a temporary decline in cognitive abilities. The umbrella term “perioperative neurocognitive disorders” is used to describe the spectrum of changes that can occur.

A sudden change in mental function is termed “delirium” when there is a fluctuation in mental status — that is, attention and/or awareness — in addition to changes in thinking. This is different from dementia, which is a slower, usually progressive, loss of cognitive abilities and usually other abilities, depending on the type of dementia.

Temporary loss of cognitive abilities is much more common in older people. While changes within the first 24 hours are extremely common, 12% of people were found to have post-operative cognitive dysfunction three months after surgery in a group where the average age was 68. Older age, lower baseline level of education and use of sedatives were found to be risk factors in an analysis of many studies. Your age and education did not put you at high risk. Further, prolonged symptoms past a year, such as you describe, are less common.

Having a degree of cognitive impairment, such as dementia, prior to surgery is a major risk factor as well. Many very high-functioning patients can develop some degree of dementia without their or their family’s realizing it, since their cognitive abilities are so superior that some loss is hard to notice.

Regardless of risk factors, some people never recover 100% of their function, and we have no good way of identifying who will have permanent problems. Although the published literature isn’t as bad as what you have seen with your clients, up to 40% of older people who develop post-operative delirium never recover to where they were before surgery. There are no known treatments for delayed recovery of the type you are describing.

Given how serious the diagnosis is, prevention strategies have been developed. The best measures are to avoid sedatives; get cognitive stimulation in a reassuring environment; maintain visual and auditory aids for sensory input (that means glasses and hearing aids); get moving early; and avoid becoming dehydrated. These are particularly important for people with risk factors for developing cognitive decline after surgery. So far, these expensive interventions have been done only in a handful of centers, but I hope that they will become more routine.

I honor your willingness to bring up this important issue, and I wish I had more optimistic news for you. For many surgeries, there is no choice involved. For elective surgeries, however, I would recommend that seniors keep the possibility of cognitive decline in mind when deciding whether to proceed.

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Dr. Roach regrets that he is unable to answer individual letters, but will incorporate them in the column whenever possible. Readers may email questions to ToYourGoodHealth@med.cornell.edu or send mail to 628 Virginia Dr., Orlando, FL 32803.