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Persistent Cognitive Deficits Common in ICU Patients with Delirium

Samson, Kurt

doi: 10.1097/
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Investigators reported in a new study that almost three out of four patients developed delirium in the ICU and more than 50 percent developed measurable symptoms of cognitive impairment three and 12 months after discharge.

Many surgical and intensive care unit patients who experience episodes of delirium while hospitalized have measureable cognitive deficits for at least one year after being discharged, similar to those in individuals with traumatic brain injuries and Alzheimer disease, according to researchers at Vanderbilt University's ICU Delirium and Cognitive Impairment Group in Nashville, TN.

The investigators looked at a group of 821 adult patients who had experienced episodes of delirium while in intensive care units (ICU) for respiratory failure, cardiogenic or septic shock. Although only 6 percent had cognitive deficits at baseline, almost three out of four patients developed delirium in the ICU and more than 50 percent developed measurable symptoms of cognitive impairment three and 12 months after discharge.

The Bringing to Light the Risk Factors and Incidence of Neuropsychological Dysfunction in ICU Survivors (BRAIN-ICU) study, conducted at Vanderbilt University Medical Center and Saint Thomas Hospital, also in Nashville, found that 35 percent had global cognition scores similar to patients with moderate traumatic brain injuries (TBI), and approximately 25 percent had scores similar to those in Alzheimer disease (AD) patients 3–12 months post-discharge.

The findings were reported in the Oct. 3 issue of the New England Journal of Medicine.

Lead author Pratik Pandharipande, MD, professor of anesthesiology and critical care, told Neurology Today that the persistent cognitive deficits, as measured by standardized testing, were independent of the use of sedatives or analgesics while patients were hospitalized, and that global cognitive function scores were lower among those who experienced the longest periods of delirium while hospitalized.



Due to continued improvements in medical care, patients today are surviving critical illness more often, he noted. However, most medical professionals are unaware that these patients are at significant risk of cognitive issues after they are released from the hospital, and many primary physicians do not think to ask these patients about their mental status. At the same time, patients may be unwilling to bring it up with their doctors.

“If patients are surviving critical illnesses with disabling forms of cognitive impairment, we need to be aware of it. Just surviving is no longer good enough,” he said. “Regardless of why a patient is admitted into an ICU, they have to know that some are likely to suffer cognitively in ways similar to a TBI patient or an AD patient on the back end of their critical care.”

Careful delirium-monitoring and management techniques, including earlier attempts to wean patients off sedatives, improving sleep and, importantly, increasing patient mobility as soon as possible, might help reduce the problem, according to Dr. Pandharipande, who added that pilot studies are also under way to test whether cognitive therapy might also benefit such patients.

In addition, he said, physicians should routinely ask their patients, as well as family members, to be alert to any memory problems, agitation, hallucination, depressive systems, or signs of dissociation, the patients may be experiencing after discharge from the ICU.

The BRAIN-ICU study was funded in part by the National Institutes of Health.

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William Ehlenbach, MD, an assistant professor of pulmonary and critical care at the University of Wisconsin School of Medicine and Public Health in Madison, underscored the importance of raising awareness of potential problems after patients come home from the ICU. He has studied long-term cognitive problems in critical care patients. In a 2010 study published in the Journal of the American Medical Association, he and his colleagues reported that among a cohort of 2,929 individuals who were 65 years old or older, none of whom had dementia, those who experienced acute care hospitalization had a significantly greater likelihood of cognitive decline afterwards than did those who had not been hospitalized.



“This paper advances our understanding of the risk of long-term cognitive problems in these patients,” he told Neurology Today. “This is something that other studies have also reported, but this is an important contribution for several reasons. First, they were able to study this in a larger group of such patients. They also used standardized methods for assessing delirium and later cognitive decline, and carried out the research with the highest quality standards we have. I think that this is as good as it gets.”

“After being discharged, these patients often have multiple [health] complaints, and cognitive dysfunction is often missed — not only by the patients but by their primary providers. Often they are not going to come right out and often patients do not associate their cognitive problems with their hospitalization. Remember, not just memory can be impaired, but also executive functions such as those involving planning and decision-making. Many patients find it difficult discussing these.”

It is also unclear which specific critical illness syndromes may contribute most to later decline, he said, though evidence suggests that septic shock in particular can have serious effects on the brain.

Nonetheless, Dr. Ehlenbach told Neurology Today that he feels there is now enough evidence that patients with such acute illnesses who experience delirium can experience significant cognitive deficits for long periods after being discharged.

“I think that, over time, we should probably move toward more formal screening of cognition in these patients. The next stage is investigating what types of therapy might help reduce or prevent these cognitive problems, perhaps specific physical or cognitive rehabilitation approaches.”

There is also a need to develop formalized cognitive assessment tests for such patients that can be performed efficiently in routine clinical practice, he said, noting that similar tests already exist for both traumatic brain injury and stroke patients.

“I think we are moving in this direction, and something may be developed within the next five to ten years.”

Another problem is that not all hospitals clearly communicate that a patient who has experienced delirium might need cognitive evaluation once they return to their primary care doctor, he said.

“Is delirium highlighted in the hospital discharge summary that is sent to primary care doctors? Normally, the answer is no.”

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•. Pandharipande PP, Girard TD, Jackson JC, et al. Long-term cognitive impairment after critical illness. N Engl J Med 2013;369:1306–1316.
    •. Jackson J, Hart R, Gordon S, et al. Six-month neuropsychological outcome of medical intensive care unit patients. Crit Care Med 2003;31:1226–34.
      •. Ehlenbach WJ, Hough CL, Crane PK, et al. Association between acute care and critical illness hospitalization and cognitive function in older adults. JAMA 2010;303:763–70.
        •. Iwashyna T, Ely E, Smith D, Langa K. Long-term cognitive impairment and functional disability among survivors of severe sepsis. JAMA 2010;304:1787–94.
          •. The BRAINS-ICU Study:
            © 2013 American Academy of Neurology