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Hinda and Arthur Marcus Institute for Aging Research Study Finds That Delirium Accelerates Memory Decline in Alzheimer’s Patients

Scientists have long suspected that delirium, an acute and relatively sudden confusional state, is linked to dementia. In fact, studies have shown that dementia patients are at increased risk of developing dementia. Now, researchers at the Marcus Institute of Hebrew SeniorLife have found that episodes of delirium rapidly accelerate cognitive decline and memory loss in Alzheimer’s disease patients. The study appeared in the May 5 issue of the journal Neurology.

“Our study suggests that over 12 months, Alzheimer’s disease patients who become delirious experience the equivalent of a 19-month decline in thinking and memory skills compared to those who do not experience delirium,” says lead author Tamara G. Fong, M.D., Ph.D., an associate scientist at the Marcus Institute’s Aging Brain Center and an instructor in neurology at Harvard Medical School.

Delirium is probably the single most common acute disorder affecting older adults. Between 14 percent and 56 percent of all hospitalized elderly patients suffer an episode of delirium, often following a medical disturbance, surgery or infection.

The researchers analyzed data gathered over a 15-year period from more than 400 Massachusetts Alzheimer’s Disease Research Center patients who were tested on memory, concentration and thinking skills. During the course of the study, 72 of the participants developed delirium.

Dr. Fong’s team found that among patients who developed delirium the average decline on cognitive tests was 2.5 points per year at the beginning of the study. This rate of decline nearly doubled, to 4.9 points per year, following an episode of delirium.

“Suppose an Alzheimer’s patient begins with mild symptoms, such as forgetting appointments or details of conversations, but over a period of the next 18 months loses the ability to identify relatives, becomes lost while driving familiar routes, or can no longer balance a checkbook or manage financial transactions,” says Dr. Fong. “This same patient, were he or she to experience an episode of delirium, might experience this rate of decline in only 12 months.”

Alzheimer’s disease, which affects as many as 4.5 million Americans, is an irreversible, progressive form of dementia that gradually destroys a person’s ability to carry out even the simplest tasks. On the other hand, says Dr. Fong, “delirium is a potentially preventable condition. Hopefully future studies can determine whether preventing delirium may improve or delay memory problems in Alzheimer’s disease patients.”

Institute researchers Sharon Inouye, M.D., Richard Jones, Sc.D., Doug Kiely, Peilin Shi, Ph.D., James Rudolph, and Frances Yang, Ph.D., also participated in the study, which was funded, in part by the Massachusetts Alzheimer’s Disease Research Center, the National Institute on Aging, the Alzheimer’s Association, and the VA Rehabilitation Career Development Award.

Scientists at the Marcus Institute, a research affiliate of Harvard Medical School, conduct rigorous medical and social studies, leading the way in developing strategies for maximizing individuals’ strength, vigor and physical well-being, as well as their cognitive and functional independence, in late life.