Cognition is an important function of the brain that enables us to acquire and process information, to enhance our understanding of thoughts, experiences, and our senses. Any condition that affects our ability to think, reason, memorize, or be attentive affects our cognitive ability. Some cognitive decline is a normal part of aging, but there are many things you can do to prevent or forestall cognitive changes as you age, including when planning for surgery.

Older adults are having more surgical procedures

As our population ages and medicine and healthcare advances, more older adults are likely to develop serious conditions (like heart problems) and undergo surgical procedures to treat or manage these conditions. Recent surveys suggest that progress in surgical techniques and control of anesthesia has increased surgical procedures in older people, with approximately 30% of all surgeries being conducted in people over the age of 70.

While advances in medicine may help people live longer, older adults are more likely to develop complications due to surgery. Some research suggests approximately one-quarter of those over 75 undergoing major surgery will develop significant cognitive decline, and about half of those people will suffer permanent brain damage.

Why do surgery and anesthesia cause problems with thinking for older adults?

There are degenerative changes in the brain with aging that predispose people to cognitive changes from surgery. Hence, age is a risk factor that needs to be considered when making decisions about surgery. Education level, mental health, and pre-existing medical conditions are also factors that affect an older person’s postsurgical cognitive functioning. People with higher levels of education tend to have more active brains due to regular mental stimulation. Mental and social activities promote brain health and decrease the risk of dementia and cognitive decline with normal aging.

Pre-existing medical conditions such as obesity, hypertension, coronary artery disease, diabetes, chronic kidney disease, stroke, and dementia predispose older adults undergoing surgery to more risk of postoperative cognitive decline. The reason these diseases cause cognitive decline is related to systemic inflammatory markers in the blood — proteins that are released into the bloodstream as a result of inflammation in the body. These markers enter the brain following a break in the blood-brain barrier (protective membrane) during the postoperative period, resulting in inflammation in the brain. This blood-brain barrier dysfunction is frequently seen in older people (even in the absence of surgery), and has been seen in approximately 50% of patients undergoing cardiac surgery.

Does the type of surgery and anesthesia matter?

Many surgical factors and techniques, blood pressure fluctuations during surgery, and longer time in surgery can adversely affect the cognitive function of older patients. Each factor affects cognitive functioning in a unique way. Younger patients tend to respond better to surgical stresses compared to older people.

Minor surgical procedures such as skin biopsies, excision of cysts, suturing of lacerations, and related procedures performed on an outpatient basis are unlikely to result in cognitive decline. However, as the complexity of a surgical procedure increases, with longer operative periods and greater exposure to more anesthesia medication, the likelihood of postoperative cognitive decline increases. This is especially true for cardiac surgery.

Studies suggest that incidence of postoperative cognitive decline is approximately 30% to 80% after cardiac surgery, while for noncardiac surgeries the prevalence is approximately 26%. While all major surgeries (such as orthopedic, abdominal, or gynecological) pose a risk for cognitive decline, cardiac surgeries have a much higher proportion of cognitive decline after surgery. The most common determinants of cognitive decline involving cardiac surgical procedures are the presence of pre-existing cognitive dysfunction and the use of bypass machines to replace the function of the heart and lungs during the surgery.

Anesthesia management before and during surgery affects what happens after surgery

The perioperative period refers to the time span of a surgical procedure, and includes three phases: preoperative, operative, and postoperative. Anesthesia management encompasses all three phases. The type and dose of anesthesia medication, the use of opioid analgesics, fluid, and glucose management can all influence a person’s cognitive function in the perioperative period. The use of multimodal anesthesia (where a combination of intravenous medications is used, instead of only inhaled agents) may protect against some cognitive dysfunction, as may using non-opioid analgesics for pain management in the postoperative period.

Are there strategies to avoid cognitive decline in the postoperative period?

Benjamin Franklin once said, “An ounce of prevention is worth a pound of cure.”  No other condition exemplifies this saying better than preventing postoperative cognitive decline.

The following are some strategies you and your caregivers can use to prepare for surgery.

Before surgery is scheduled:

  • Eat healthy, balanced meals. Foods rich in polyunsaturated fatty acids are protective for your brain health.
  • Exercise regularly, or as much as allowed by your cardiac conditions. Physical activity promotes brain health.
  • Maintain a healthy weight.
  • Remain socially active and connected.
  • Reduce stress. Meditation significantly reduces stress and promotes a sense of calm and overall well-being.
  • Practice good sleep habits and try to get six to eight hours of sleep a night.

When surgery is scheduled:

Schedule a comprehensive geriatric assessment. This enables your physician to diagnose reversible aspects of frailty preoperatively (if they exist) and take adequate measures in a timely manner, such as altering medications you may be taking, and/or postponing surgery if you are extremely frail, to improve nutrition and incorporate lifestyle changes.

Talk to your surgeon about the risks and complications of the procedure. If you are having heart surgery, ask if a cardiopulmonary bypass machine will be used, and whether it is important to your surgery.

Talk to your anesthesiologist about

  • The types of medications they plan to use, and if there are alternatives for those medications. Have a conversation about need for opioid analgesics, and if alternative non-opioid pain medication can be used to decrease the risk of postoperative cognitive decline.
  • The methods of measuring medications that can reduce your risk of cognitive changes. For example, use of EEG machines during surgical procedures enhances the anesthesiologist’s ability to monitor the depth of anesthesia. Anesthesia depth is the degree to which the central nervous system is depressed by an anesthetic medication. EEG monitoring will result in adequate usage of anesthetic agents, avoid overuse, and reduce risk for postoperative cognitive decline by reducing anesthesia exposure.
  • Gather relevant information on your perioperative management. Discuss which medications you currently take and should continue taking, and which ones should be avoided.

After surgery and during recovery:

Caregivers need to be informed about the need for keeping their loved one active and following physical rehab recommendations, and providing mental stimulation in the postoperative period. Puzzles, sudoku, board games, books, etc., will keep someone entertained while simultaneously providing them with some brain activity.

Finally, it is necessary to understand that although there is no cure for postoperative cognitive decline, preventive strategies and pre-planning with your team of surgeons, anesthesiologists, and geriatricians can help reduce the risks of cognitive problems that older adults often face following surgery.

References

Impact of frailty on outcomes in surgical patients: A systematic review and meta-analysis. The American Journal of Surgery, August 2019.

Postoperative cognitive dysfunction — current preventive strategies. Clinical Interventions in Aging, November 8, 2018.

Neurocognitive Function after Cardiac Surgery: From Phenotypes to Mechanisms. Anesthesiology, October 2018.

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