Those complications, according to the researchers, include mental decline, being put in a nursing home and even death.

The study, however, cannot say whether the combination of delirium and a hospital stay caused those outcomes - just that together, they're a risk factor.

Delirium - a sudden change in a person's state of mind that results in severe confusion - can be a result of several complications, including illness, a stroke or brain injury, a reaction to a medication or drug addiction.

Dr. Tamara Fong, the study's lead author from the Beth Israel Deaconess Medical Center in Boston, told Reuters Health in an email that delirium can complicate hospital stays for Alzheimer's patients and make their health decline faster.

"We found that while hospitalization alone resulted in poor outcomes for patients with (Alzheimer's disease) ... the combination of hospitalization and delirium resulted in an even greater risk for developing a poor outcome," wrote Fong.

For the study, researchers combined information from patients at the Massachusetts Alzheimer's Disease Research Center between 1991 and 2006 with information from the federal government to see what happened within the year following their hospital stay.

Overall, 367 of the 771 participants were hospitalized, and 194 of those were diagnosed with delirium. About 43 percent went on to be put in a nursing home or other care facility after their hospital stay and about 15 percent died - whether or not they went to a nursing home.

The researchers, who published their findings in the Annals of Internal Medicine, said that works out to about one in 16 dying, one is seven being put in a nursing home and one in five suffering a mental decline within one year of getting out of the hospital.

Those who never went to the hospital and those who went to the hospital but didn't have delirium did better.

"If we can show that delirium prevention can delay cognitive decline and improve the outcomes for patients with (Alzheimer's disease), this may be a far more effective treatment than the current drug treatments that are available," wrote Fong.

CAUSES UNCLEAR

Dr. Liana Apostolova, of the University of California, Los Angeles, told Reuters Health the study is powerful and well thought out, but the results could be because delirium occurs in people with a more severe and aggressive form of Alzheimer's. Another possibility is that people who go to the hospital are generally sicker to begin with.

But Apostolova, who works at the Mary S. Easton Center for Alzheimer's Disease Research and was not involved with the new study, said there are two important messages from these findings.

"One of the messages is that we have to prevent hospitalizations and delirium in patients with Alzheimer's disease." The other, she said, is that doctors can prepare families of hospitalized Alzheimer's patients with delirium that their relative may be at a higher risk for one of the complications.

She told Reuters Health that anyone with a cognitive impairment whose routine is suddenly changed can end up with delirium.

Typically, keeping an Alzheimer's patient in a routine and making sure they're always in a place with at least soft lighting and music may help, said Apostolova.

"We hope that this study will bring attention to how bad delirium can be for persons with Alzheimer's disease," wrote Fong.

SOURCE: bit.ly/Mnaens Annals of Internal Medicine, online June 18, 2012.

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