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Dementia, including Alzheimer's disease, is one of the most devastating conditions of older age. Currently affecting nearly 7 million individuals in the U.S. and 24 million worldwide, dementia leads to total loss of memory and the ability to function independently - making it one of people's greatest fears of aging.
Delirium is an acute confusional state, a common and serious complication in older individuals that often follows surgery or serious illness. Sometimes accompanied by disorientation, paranoia and hallucinations, delirium develops in 14 to 56 percent of all hospitalized seniors, complicating hospital stays for over 2.5 million older individuals in the U.S. each year.
For the most part, dementia and delirium have been viewed as separate and distinct conditions. But researchers now are exploring whether delirium itself leads to the development of a cognitive disorder and wondering if delirium and dementia represent opposite ends of the same spectrum of disease, rather than two separate conditions (The Journal of Gerontology: Medical Sciences, January 2007).
"I have been studying delirium for 20 years," says Sharon Inouye, MD, MPH, a geriatrician at Beth Israel Deaconess Medical Center and Director of the Aging Brain Center at the Institute for Aging Research, Hebrew SeniorLife. "And the more cases I encounter, the more linkages I see with dementia. For a large proportion of older patients, the problem [of delirium] is never resolved. I routinely hear from patients' families, 'They went into the hospital, they became very confused, and they never recovered.'"
Dr. Inouye, a professor of medicine at Harvard Medical School, together with Luigi Ferrucci, MD, PhD, Chief of the Longitudinal Studies Section of the National Institute on Aging and Editor-in-Chief of the journal, which is published by the Gerontological Society of America, examined the relationship between these two widespread conditions during the "Aging Brain Center Scientific Symposium: The Interface of Delirium and Dementia," held last spring.
"Better understanding of delirium may represent a new window of opportunity for the prevention of dementia," explained Dr. Ferrucci.
Delirium is a tremendous expense to the country's medical system, amounting to more than $7 billion per year in hospital expenses and more than $100 billion a year when rehabilitation, institutionalization and long-term care is factored in.
In a 1999 study in The New England Journal of Medicine, Dr. Inouye demonstrated that delirium can be decreased by 40 percent by implementing a number of straightforward interventions while patients are hospitalized. These include making sure that patients are oriented and hydrated, that they are up and walking, that they are using their hearing aids and vision aids, and that they avoid the use of sleep medications.
"Our goal now is to better understand the fundamental changes that cause delirium and determine whether they result in permanent injury to the brain, in order to better devise ways to intervene and prevent this injury," he explained. "Knowing that our population is rapidly aging, these figures are only going to increase unless we do something now. We hope to eventually be able to identify at-risk individuals before they develop delirium, so that we can intervene before it escalates to a chronic condition."
Funding for the studies was provided, in part, by grants from the National Institute on Aging, the National Institute of Neurological Disorders and Stroke, the National Institute of Mental Health, the Alzheimer's Association and the Donaghue Medical Research Foundation.
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