Impaired cognition, a long-lasting consequence of the ICU

Impaired cognition after an ICU visit is common, often existing alongside physical debility and mental and emotional problems.


Millions of patients who leave ICUs every year probably feel the worst is behind them, but they may still face some major hurdles after discharge. James C. Jackson, PsyD, focused on a particularly common one, cognitive impairment, during his talk at the Society of Critical Care Medicine's annual meeting in Orlando, Fla., in February.

“When you talk to patients, you'll hear about so many struggles. … Chief among them for many would be the cognitive complaints that they endorse,” said Dr. Jackson, the director of long-term outcomes at the Critical Illness, Brain Dysfunction, and Survivorship Center at Vanderbilt University School of Medicine in Nashville, Tenn.

Cognitive impairment might be more problematic for younger and more active ICU survivors who would feel the impact of even mild effects Image by Martin Barraud
Cognitive impairment might be more problematic for younger and more active ICU survivors, who would feel the impact of even mild effects. Image by Martin Barraud

In a study by Dr. Jackson and colleagues published in the New England Journal of Medicine in 2013, more than a third of patients who left an ICU between March 2007 and May 2010 showed cognitive impairment three months after discharge. And most of them didn't get better during longer follow-up. “We found that it persisted up to one year,” he said.

The problem crosses ranges of age and baseline cognitive function. “It doesn't really matter necessarily how intact your brain is to start. That intact brain at a certain point can be overwhelmed by the burden and the magnitude of the insults it's receiving,” said Dr. Jackson.

In fact, cognitive impairment might be more problematic for younger and more active ICU survivors. “You could argue that the cognitive impairment in these younger ones is particularly important because their developmental trajectory in some ways hasn't been completed yet,” he said. “Younger folks, if they're working, are quite impacted often by even mild cognitive impairment. Our older retired patients don't want it either, but as a practical matter, it could be less disruptive to them.”

Although impairment is common, it also varies. “It exists against the backdrop of physical debility and against the backdrop of mental and emotional problems,” said Dr. Jackson.

Cognitive impairment may be both confused and combined with the mental health effects of an ICU stay, he explained. “Recently, for instance, we had a patient who had started attending a support group that we lead—delightful guy, very reliable reporter—talk very earnestly about the cognitive impairment that he had.” But a neuropsychology exam found that the patient was actually experiencing cognitive effects of depression and post-traumatic stress disorder rather than a brain injury as such.

Different trajectories

Among patients who do have cognitive impairment, there are different functional trajectories. “There are some patients who get a lot worse after the ICU, and they stay a lot worse. And there are some patients who get quite a lot worse after the ICU and then over time, they get even worse. … And some percentage of these patients are a bit worse after the ICU and they really improve until they plateau. So there are these three trajectories, probably more,” said Dr. Jackson.

Patients move along these trajectories within a fairly short time after an ICU stay. In their 2013 paper, Dr. Jackson and his colleagues considered patients with decreased cognition and function a year postdischarge to have long-term cognitive impairment. What happens to them after that has been relatively unknown. That may soon change, though.

“I'm very excited to say that we received some funding from the National Institute on Aging to reengage that cohort to try to figure out where all these patients are 13 years after the ICU, and I started visiting them just last month,” he said.

These visits have already been quite the educational experience, including one with a patient whose cognitive impairment was substantial enough to make him remarkably nonchalant about his intense bed bug infestation, Dr. Jackson reported. “We had our office space fumigated. But the main thing that was interesting to me was this gentleman that we had seen at three months and 12 months … and now at 13 years, he wasn't really any better than he had been. But he really wasn't any worse.”

Cognitive impairment does tend to improve in the immediate period after an ICU stay, Dr. Jackson said. Almost all patients are impaired at discharge, and he estimated that about half of those he sees in ICU follow-up clinic a few weeks later are still abnormal.

“What I like to do is have them come back in about two to three months for a follow-up,” he said. “In that early, first eight weeks or so after the ICU, often people will improve quite dramatically. I think if the only time we see them is right after the ICU, we're going to form some conclusions about them that are potentially erroneous.”

Potential treatments

If patients are still impaired after a couple of months, they may be candidates for treatment. Dr. Jackson described some of the methods he and his colleagues have been using to help ICU survivors deal with cognitive impairment.

One is cognitive rehabilitation. “It's highlighting what your deficits are and trying to find workaround solutions. It's tapping into the strengths that you have and trying to maximize those,” he said, offering examples. “We teach them simple things like take nine hours at college if you can, as opposed to 15 on the heels of an ICU discharge,” he said. “In the workplace, … if you've got the benefit of an administrative person who can help you—I know you said you didn't lean on them before—let's lean on them now.”

Dr. Jackson has used a specific version of cognitive rehabilitation called Goal Management Training. “It is probably the best empirically validated approach for the improvement of executive functioning in particular,” he said. A major component of the training is reminding patients to stop and think in order to avoid absentminded mistakes, for example, stopping as they pass the hospital pharmacy to consider whether they need to pick up prescriptions.

“There are benefits and downsides to cognitive rehabilitation,” said Dr. Jackson. “It has a long history of effectiveness. It is often embraced by patients and offers frameworks that apply to many situations. But it requires experts to deliver.” The need for a trained expert, such as a social worker, to deliver the therapy makes it expensive, he noted.

An alternative is cognitive training. “Computerized cognitive training is quite different. It's promoting this notion that you can fundamentally improve your cognition. And it's really controversial,” said Dr. Jackson.

Experts strongly disagree about whether computerized training can improve cognitive function, he explained, citing two open letters signed by groups of researchers in 2014 and 2016, one that objected to the claims of cognitive training programs and one that concluded the evidence supports such claims.

Dr. Jackson and colleagues conducted a small study of one computerized cognitive training program in 24 ICU survivors. Their results, published as a research letter in Annals of the American Thoracic Society in 2018, found improvements in attention, processing speed, memory, and executive function with the program.

“I have moved from very skeptical to pretty open as I have seen patients benefit from them, admittedly, anecdotally,” he said. There are still a number of questions about the method, Dr. Jackson noted. “Does the benefit stop? Does it continue? Does it transfer? Or am I only going to get faster at pushing a button on a computer?”

Another challenge with the method is that patients must have some computer skills. “And even in 2020, especially in rural America, we shouldn't take for granted how limited some patients, especially our very elderly patients, are in this regard,” he said. “We had to say things like, ‘Yes, this is a computer right here.’”

Dr. Jackson sees clear benefits in cognitive rehabilitation but recognizes that it would be hard to make it widely available. “I think it's the right approach to use for many clinical conditions. But we need to figure out more effectively than we currently can who are the patients who are really at risk, who are the ones who are not so much at risk, and we really need to target the ones of the greatest need,” he said.

Computerized training, on the other hand, wouldn't require such targeting. “Here's why computerized cognitive training is attractive, though. It's easily scalable, and it's inexpensive. And for that reason, if it works, it would be something that our patients could embrace,” said Dr. Jackson.

In conclusion, he described a few other interventions he'd like physicians treating patients with cognitive impairment after the ICU to embrace. The first is exercise. “It's something that anyone could do, right? It isn't hugely expensive. And I think we should nudge people to do this,” he said. Even older, frail patients can often do some exercise if they can overcome the barrier of learned helplessness, Dr. Jackson suggested.

There should also be greater collaboration between clinicians treating cognitive impairment after critical illness and experts in brain injury. “People in the rehab world who work on brain injuries are not as familiar with this issue as they might be,” he said. “We haven't integrated as much as we might speech language pathologists, occupational therapists, physical medicine, and our physicians who work on brain injuries.”

His final recommendation was to help patients help each other. “Develop support groups that include an emphasis on issues of cognition, and functional ability secondary to cognition,” he said.