Sepsis Linked to Dementia in Elderly

“Older People Who Survive Sepsis Face Increased Risk for Developing Cognitive Problems”, Study Finds

Sepsis is a leading cause of death in hospital ICUs, and the elderly are particularly vulnerable to the life-threatening blood infection.

The thinking had been that once the crisis is over, older people who survive sepsis make full recoveries. But new research finds the opposite to be true.

Elderly people in the study had a threefold increase in life-altering mental declines after surviving sepsis. Study participants with no history of sepsis showed no increase in risk over the course of the study.

Three out of five sepsis survivors experienced serious physical and/or mental declines in the years following the event, says lead researcher Theodore J. Iwashyna, MD, PhD, of the University of  Michigan Medical School.

Based on the findings, the researchers estimate that sepsis may be responsible for 20,000 new cases of dementia among people aged 65 or older each year in the U.S. alone.

The study appears Wednesday in the Journal of the American Medical Association.

“The cognitive impairment we saw was often quite severe,” he tells WebMD. “Many people went from being relatively independent to being unable to do their own cooking or live on their own.”

Sepsis Common in Elderly

About 750,000 people in the United States develop sepsis each year. Known in lay terms as blood poisoning, sepsis occurs when the bloodstream is overwhelmed with bacteria, usually in response to the body’s attempt to fight severe infection.

People who become septic usually develop very low blood pressure, or shock. In very severe cases, small blood clots can also form, shutting down vital organs.

The overall death rate for people with sepsis is now about 25%, compared to 50% just two decades ago, Derek C. Angus, MD, tells WebMD.

Angus, who chairs the department of critical care medicine at the University of  Pittsburgh School of Medicine, has studied sepsis for many years. He was not involved with this research.

“Before the modern ICU, people with sepsis who developed organ failure usually died,” he says. “Today, many of these people are surviving. But this study confirms that they are not necessarily surviving with a clean bill of health.”

Long-Term Impact of Sepsis

The study included older people enrolled in a larger, nationally representative ongoing health study that included periodic assessment of mental functioning. About 1,500 episodes of severe sepsis occurred among the enrollees between 1998 and 2005, and about 40% of these episodes ended in death within 90 days.

Researchers compared outcomes among 516 people who survived sepsis to 4,517 people who survived a non-sepsis related hospitalization during about the same period. The average age of the survivors in both groups during hospitalization was 77.

Close to 60% of the hospitalizations for severe sepsis were associated with worsened mental and physical function, or both, in the years following the event.

Moderate to severe cognitive impairment almost tripled in the sepsis survivors, from 6% before sepsis to almost 17% after.

“Among people with no mental or physical limitations before sepsis, around 40% could not walk without assistance in the years after,” Iwashyna says.

Vaccination Prevents Sepsis

The findings highlight the importance of preventing sepsis in older patients, Iwashyna and Angus say.

One of the best strategies for doing this is to vaccinate vulnerable elderly populations against diseases like flu and  pneumonia.

Studies are also needed to determine if ICU practices contribute to the long-term problems identified in the study, Iwashyna says.

“We know that a core part of sepsis is delirium and that delirium is associated with progression of Alzheimer’s disease and cognitive decline,” he says. “It may be that preventing delirium in the ICU could have real benefits later on.”

Treatments designed to reduce inflammation may also affect long-term outcomes, Angus says.

“Inflammation has been implicated in all kinds of health issues, including cognitive decline, and it is a hallmark of severe sepsis,” he says. “Sepsis causes a huge inflammatory response, and we don’t know what the long-term impact is.”

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