ICU linked to mental ailments

A study underscores what doctors have long observed about such side effects from intensive care units.

Two-thirds of patients sick enough to land in a hospital intensive care unit come away from the experience with substantial mental deficits, a new study has found.

The research, which quantifies a phenomenon long observed by criticalcare physicians, found that three months after leaving the hospital, 4 in 10 patients continued to have cognitive problems on par with those seen in cases of moderate traumatic brain injury.

More than a quarter experienced a decline in mental function akin to that seen in patients with mild Alzheimer’s disease, the study says.

For 58% of ICU patients, those intellectual deficits were still there a year after they had been released from the hospital, the study found.

The latest research, published Wednesday in the New England Journal of Medicine, found that the sudden decline in mental function was as likely to affect young patients as older patients. And it was no more likely in patients who were ill before their hospitalization than it was in those who had been healthy.

Only one factor appeared to predict which patients would sustain mental deficits after an ICU stay: the length of time the patient experienced delirium, a common occurrence among the hospitalized with a critical illness.

The study tracked for a year 821 patients who landed in the ICU from a wide range of circumstances. Some were admitted after surgery; others had suffered a stroke or a sudden turn in an ongoing illness or injury.

The authors of the study, physicians at Vanderbilt University Medical Center and Thomas Hospital in Nashville, were cautious in explaining why ICU patients so often emerged with substantial cognitive impairment.

Although suspicion has long fallen on the widespread use of powerful painkillers and sedatives in the ICU, they found few clear links between a patient’s ICU medications and the patient’s subsequent cognitive health.

At the same time, the study authors observed a weak relationship between post-ICU mental decline and the use of benzodiazepines — anti-anxiety and sedative medications including diazepam (marketed as Valium).

While that link “should be interpreted cautiously,” the authors said, its weakness should not encourage physicians to minimize the use of such drugs where possible.

The researchers suggested that delirium itself may contribute to loss of mental function, given that it is also linked to inflammation and the death of brain cells, which may either start or signal a downward slide in brain health.