Blood Poisoning’s Toll on the Brain

May 3, 2011

Every year, some 750,000 Americans suffer from sepsis, a life-threatening ailment that many have never heard of. The condition, sometimes called “blood poisoning” though no poison is involved, is an inflammatory response to serious infection that can cause damage to multiple tissues and organs. New findings show that the condition may lead to loss of memory and thinking skills that, when severe, may mimic the symptoms of Alzheimer’s disease.

Earlier this year, a study from the University of Washington in Seattle found that older men and women who receive critical care in the hospital are more likely to suffer from memory loss and cognitive decline than their peers who are not hospitalized and an earlier study, led by researchers at Beth Israel Deaconess Medical Center and Hebrew Senior Life in Boston, found that an episode of delirium, marked by agitation, confusion and hallucinations, rapidly accelerates cognitive decline and memory loss in Alzheimer’s patients.

In the current study, researchers at the University of Michigan Medical School in Ann Arbor sifted through data from more than 27,000 men and women over 50 who were part of the Health and Retirement Study, an ongoing national health survey of American residents. Among the study participants, nearly 1,200 had been hospitalized for severe sepsis, a critical condition that requires intensive medical care and that can damage the skin, kidneys, lungs and other organs.

The researchers followed the sepsis patients for up to eight years and found that the condition was not just bad for the body. Many of those who had severe sepsis showed thinking and memory problems that were similar to those of Alzheimer’s and other forms of dementia.

“An episode of severe sepsis, even when survived, may represent a sentinel event in the lives of patients and their families, resulting in new and often persistent disability, in some cases even resembling dementia,” the authors wrote.

The researchers found that the prevalence of moderate to severe cognitive impairment increased 10.6 percentage points among patients who survived severe sepsis. Their odds of acquiring moderate to severe cognitive impairment were more than three times higher than those who didn’t have sepsis, including those who were admitted to the hospital for other medical problems.

“Cognitive and functional declines of the magnitude seen after severe sepsis are associated with significant increases in caregiver time, nursing home admission, depression, and mortality,” the authors wrote. “These data argue that the burden of sepsis survivorship is a substantial, under-recognized public health problem with major implications for patients, families and the health care system.” The study was published in the Journal of the American Medical Association.

The authors added that given published dementia and sepsis incidence rates for those ages 65 years or older in the United Slates, their results suggest that nearly 20,000 new cases per year of moderate to severe cognitive impairment in the elderly may be attributable to sepsis.

Unlike Alzheimer’s, sepsis is a curable condition, though it remains a leading cause of death in hospitals. Symptoms include fever, chills, difficulty breathing and general weakness. The condition can rapidly worsen, making immediate hospitalization and prompt treatment with fluids and antibiotics critical.

The findings point to the need for prompt medical care for serious infections in those with or without Alzheimer’s disease. They also point to the need for long-term follow-up, since even if the infection is successfully treated, there may be long-term damage to the brain and body.

In an editorial accompanying the study, Dr. Derek Angus of the University of Pittsburgh School of Medicine noted that the findings “…can help physicians when assessing care options and discussing outcomes with patients and families.” Researchers aren’t sure why sepsis may contribute to cognitive decline, but by raising awareness of the issue, the hope is that doctors and family members will be more aware of the risk of thinking and memory problems during and after hospital stays.

A trip to the hospital, with its strange sights and sounds and change in routine, can lead to confusion and agitation in any patient. The problem may be especially challenging for someone with Alzheimer’s disease. If hospitalization is needed, experts recommend that family members and loved ones stick close by whenever possible to help ease the transition.

By ALZinfo.org, The Alzheimer’s Information Site. Reviewed by William J. Netzer, Ph.D., Fisher Center for Alzheimer’s Research Foundation at The Rockefeller University.


Theodore J. Iwashyna; E. Wesley Ely; Dylan M. Smith; et al.  “Long-term Cognitive Impairment and Functional Disability Among Survivors of Severe Sepsis.” Journal of the American Medical Association, Vol. 304(16), Oct. 27, 2010, pages 1787-1794.

Derek C. Angus: “The Lingering Consequences of Sepsis: A Hidden Public Health Disease?” Journal of the American Medical Association, Vol. 304(16), Oct. 27, 2010, pages 1833-1834.


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