General Anesthesia Can Make The Elderly 15% More Likely To Develop Alzheimer's Disease

Elderly People More Likely to Develop Dementia After General Anesthesia
Senior citizens may want to think twice about surgeries that require general anesthesia, as it can increase the risk of dementia. Elderly| Mental Health Hub

There's no denying that our bodies deteriorate as we age. First to go are usually joints, followed by vision and memory. And often, the elderly will undergo major surgeries on joints or organs to improve their quality of life.

But can the general anesthesia they're put under ultimately speed the decline of their brains and cognitive functions?

During anesthesia, drugs are administered to block surgery patients' pain receptors and dull their awareness to the point where they are reversible sedated. This ensures that patients will not experience discomfort during surgery. The general anesthetics tend to work mainly on the brain to allow for a reversible loss of consciousness. Local anesthetics may also be used; they do not act on the brain but rather the local pain receptors, such as one's arm or leg, to shut them off and stop uncomfortable sensations in the patient.

While anesthesia is reversible and harmless in most surgery patients, the elderly, whose bodies are deteriorating due to age, may have difficulty recovering afterward.

A new study has found that general anesthesia, when used on the elderly, can increase the risk of dementia and the development of neurodegenerative disorders like Parkinson's or Alzheimer's disease.

Researchers have identified an initial decline in cognitive function right after surgery, called postoperative cognitive dysfunction (POCD), that can lead to dementia. POCD is associated with promoting neuroinflammatory reactions within the brain. The reactions essentially make the brain sick and cause degeneration of its cells.

This degeneration at the cellular level is the cornerstone of dementia, or more importantly a decrease of cognitive function, which can cause forgetfulness, long-term memory loss, loss of language, poor judgment, and erratic behavior. Dementia tends to develop into diseases, such as Alzheimer's, as these diseases thrive when neurons are made vulnerable by the deterioration made apparent by dementia.

The study included 9,294 elderly people who had undergone surgery between 1999 and 2001. They were interviewed and given cognitive evaluations at post-surgery years 2, 4, 7 and 10. About nine percent of the participants developed dementia after eight years of anesthetic exposure and 15 percent were likely to develop Alzheimer's disease.

Notably, it was the patients who underwent general anesthesia that developed POCD and were in the group most likely to develop neurodegenerative disorders. Researchers have thus established that those who have general anesthesia face a greater risk of developing neurological issues than those who receive local anesthesia.

Previous studies have indicated that operation-related morbidity becomes more frequent after the age of 75. In this study, the average age of participants was 75 after the 10-year study was complete. Similarly, co-existing cardiovascular disorders, smoking habits, and history of stroke can contribute to the lethality of anesthesia and the development of dementia.

At 75, the brain's functions have declined enough on their own and, if POCD is added to that, development of a neurodegenerative disease is very likely. Alzheimer's disease, though based in brain function, or the lack thereof, can be an early cause of death in seniors aged 75 years and older. Patients can become so forgetful they wander away from their homes, thinking they are elsewhere, forget where they live, and starve or develop pneumonia.

Researchers have concluded that preoperative evaluations must be taken of the elderly to determine whether they should even have general anesthesia. And similarly, long-term follow-ups should be done post-surgery to ensure the recognition of POCD and dementia so that treatments can be sought immediately to prevent the onset of serious neurodegenerative disorders.

 

Source: Sztark F, Le Goff ML, Andre D, et al. Exposure to general anesthesia could increase the risk of dementia in the elderly. European Society of Anesthesiology. 2013.

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