Cognitive Impairment after Critical Illness Can Be Severe

These steps may help reduce the mental toll in older adults.

A trip to the hospital, especially when it involves a stay in an intensive care unit (ICU), can trigger problems with mood and cognition in older patients. These problems—sometimes as serious as those associated with mild Alzheimer’s disease (AD)—are thought to be linked to a variety of factors, including the stress of hospitalization, drugs, pain, sleep deprivation, and delirium, or mental confusion. The good news is that there are ways medical staff, families and caretakers can help prevent or minimize these factors.

“Studies have shown that in older individuals, a serious illness increases the risk for delir-ium with subsequent cognitive issues, such as problems with memory, thinking, or planning,” says Maurizio Fava, MD, Executive Vice Chair of the Department of Psychiatry at MGH. “As many as 74 percent of older patients who spend time in the ICU develop delirium, and although most eventually recover, there can be serious and even permanent mood effects and cognitive changes in some patients. All of these mental effects can seriously affect the person’s health and ability to recover.”

A study of 24,000 ICU survivors found that they were 22 times as likely as comparable healthy individuals to be diagnosed with depression, anxiety disorders, or other psychiatric conditions over the three months following discharge from the hospital. Another 13 percent of study participants received a new prescription for a psychiatric medication in that time period, according to a report published Mar. 19, 2014 in the Journal of the American Medical Association (JAMA).


Experts have identified several measures that can help an older adult deal with the stresses of hospitalization, including:

  • Spend time with the patient, especially when he or she is experiencing delirium. Offer reassur-ance, and frequently remind the person that he or she is in the hospital.
  • Have clocks and calendars, pictures of loved ones, and familiar objects near the patient to minimize disorientation. Make sure the patient wears his or her glasses or hearing aid to minimize confusion.
  • Allow for as much uninterrupted sleep as possible, especially at night.
  • Get hospitalized or surgical patients out of bed and walking as soon as possible.
  • Avoid the use of unnecessary medications.

Inside the brain

The JAMA researchers theorized that psychological disorders associated with the ICU experience may be attributable to the effects of medications, delirium, or experiences such as being connected to a ventilator, among other factors. Patients become confused and frightened, and may form distorted memories of their experiences that are akin to distressing nightmares.

ICU-linked cognitive changes are also a serious problem. A study published Oct.3, 2013 in the New England Journal of Medicine found that one year after being discharged from the hospital, 24 percent had cognitive scores similar to those of individuals with mild AD. Longer periods of delirium predicted greater cognitive impairment, and measures of executive function—the ability to plan and make decisions—were significantly below those of comparable healthy indi-viduals.

Experts have proposed a number of theories about how the ICU experience might trigger cognitive changes. Symptoms might be related to underlying health problems, such as dehydration, infection, kidney or liver failure, or lack of oxygen. Delirium might be an indication of a disruption of brain circuits linked to acetylcholine, an important neurotransmitter, or of inflammatory processes that weaken the blood-brain barrier and allow harmful substances to enter and damage the brain, Still another hypothesis links chemicals used in general anesthesia to an increase in the production of toxic beta-amyloid proteins that are a hallmark of AD.

“Whatever the cause of these problems, there is clearly a need to address the negative effects of the ICU experience, especially in older patients, and to take steps to prevent delirium, which is often under-recognized in hospital situations,” Dr. Fava says. “Fortunately, we are learning ways to reduce the risk of these mental effects, and families and caretakers can join in this effort.”

Prevention possible

Awareness of the psychological aspects of the ICU experience, along with screening for mood and anxiety disorders in patients who are leaving the ICU, might help identify patients with mental health issues so that they can receive professional treatment.

Cognitive impairment can be addressed largely through prevention—an estimated 40 per-cent of delirium episodes are thought to be avoidable. Patients and their families might consider for-going elective surgeries when stress levels are very high or, if possible, relying on epidurals for sur-gical procedures rather than general anesthesia, which presents a greater risk for cognitive effects.


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