Psychiatrists and critical care specialists at Johns Hopkins have begun a quest to reveal what it is about a stay in an intensive care unit (ICU) that leads many patients to report depression after they return home.

The Hopkins researchers note several factors predicted symptoms of depression 6-months after hospitalization among very sick ICU patients in a study reported online April 10 in Critical Care Medicine.

Although Bienvenu says physicians have long theorized that a health problem devastating enough to send someone to an ICU might trigger depression, the research team wondered whether the root causes might be more complex because only some patients become depressed.

“The hope is that as we learn more about the effect of variations in ICU care, we’ll be able to predict which patients are most susceptible to depression, prevent some depression by changing ICU practices, and make sure patients receive adequate mental health monitoring after discharge,” says O. Joseph Bienvenu, MD, PhD, an associate professor in the Department of Psychiatry at the Johns Hopkins University School of Medicine.

“Historically, the only goal for critical care physicians, understandably, was to keep people alive, but now there is interest in longer-term outcomes, such as patients’ mental health and wellbeing,” says Bienvenu in a release from Johns Hopkins. “So we asked ourselves, could certain aspects of critical illness and ICU care swing patients toward depression?”

The researchers evaluated patients recently admitted to one of 13 ICUs located at four teaching hospitals in Baltimore, Md. Each patient was treated for acute lung injury (ALI).
Bienvenu and his colleagues followed 160 patients who had survived at least 6-months after their ALI diagnosis. The researchers took note of a variety of features of each patient’s status and care while in the ICU, such as severity of organ failure, their blood sugar levels and other lab work, and the amount and type of sedative they received. The researchers also administered a questionnaire to patients that measured depressive symptoms ranging from none to possible or probable clinical depression.

Of the 160 patients, 26% scored above the threshold for possible depression. Compared to other ALI survivors, the depressed patients were more likely to have suffered greater severity of organ failure and to have received 75 mg or more of a benzodiazepine sedative daily.

Bienvenu says that because more severe organ failure may lead to a longer physical recovery period after ICU discharge, patients’ depression may be explained, in part, by a slow recovery. However, the researchers are not sure how to explain the association between depression and ICU benzodiazepine dose.

According to the researchers, one possibility could be that the amount of this drug received reflects how agitated patients were in the ICU, with very distressed individuals getting higher doses. Because this relationship has not been seen with other types of sedatives commonly prescribed in the ICU, it is possible that high doses of benzodiazepine alone may somehow cause depressive symptoms.

“This is clearly a question that needs further study,” says Bienvenu.