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.