Cognitive and Functional Decline Often Follow Severe Sepsis

Seniors who survive an episode of severe sepsis may be left with substantial and enduring cognitive impairment and functional disability, according to a new study.

Researchers at the University of Michigan Medical School (Ann Arbor, USA) studied 516 individuals who survived hospitalization for severe sepsis and 4,517 who survived a nonsepsis hospitalization that were enrolled in the ongoing U.S. Health and Retirement Study, for whom they had detailed information on physical and neurocognitive function both before and after an episode of sepsis; the average age of survivors at hospitalization was 76.9 years.

The researchers found that following severe sepsis hospitalization--but not nonsepsis general hospitalization--there was a significant increase in the odds of developing both cognitive and physical dysfunction that persisted throughout the 8-year follow-up period. Moderate to severe cognitive impairment increased more than 3-fold, from 6.1% before sepsis to 16.7% afterward. In multiple regression analysis, the odds ratio for cognitive impairment in survivors of severe sepsis was 3.34. The researchers also observed a high rate of new functional limitations in the years following severe sepsis. Those with no functional limitations before sepsis developed a mean of 1.57 new limitations afterward, whereas those with mild to moderate limitations before sepsis developed a mean of 1.50 new limitations afterward. The researchers suspect that delirium, hypoperfusion, and inflammation may underlie the cognitive and physical decline seen after severe sepsis. The study was published in the October 27, 2010, issue of the Journal of the American Medical Association (JAMA).

"Delirium is a common part of sepsis, and untreated delirium accelerates Alzheimer's disease and is clearly associated with poor cognitive outcomes,” said first author Theodore Iwashyna, M.D., Ph.D. "Hypoperfusion, which is also a common part of sepsis, is clearly bad for the brain, and inflammation, which is another core part of sepsis, has been clearly associated with progression of cognitive decline, Alzheimer's, and vascular dementia.”

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