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Delirium linked to long-term cognitive decline in Alzheimer's patients

Patients with Alzheimer’s disease who had developed delirium during their hospital stay experienced increased rates of cognitive deterioration for up to 5 years, according to study results.

“Identification of modifiable risk factors for cognitive deterioration in [Alzheimer’s disease] is a top national priority to develop preventive strategies for slowing the progression of [Alzheimer’s disease] severity and reducing morbidity,” the researchers wrote.

Approximately 4.5 million older adults in the United States have Alzheimer’s disease, according to the Department of Health and Human Services. Delirium affects more than 20% of all hospitalized adults aged at least 65 years, and the prevalence of delirium increases to 60% to 89% of patients with Alzheimer’s disease.

Alden L. Gross, PhD, MHS, a postdoctoral researcher at the Institute for Aging Research at Hebrew SeniorLife in Boston, and colleagues studied data on 263 hospitalized patients with Alzheimer’s disease who were part of the the Massachusetts Alzheimer Disease Research Center patient registry.

Cognitive function was measured by the information–memory–concentration (IMC) section of the Blessed Dementia Rating Scale, and researchers identified delirium by examining hospital records.

Fifty-six percent of patients with Alzheimer’s disease had developed delirium during hospitalization. There was no significant difference in the rate of cognitive deterioration between those who had developed delirium and those who did not before hospitalization (P=.24), according to the researchers. Adjusting for dementia severity, comorbidity and demographics, Gross and colleagues found that patients who had developed delirium during their hospital stay experienced greater cognitive deterioration in the year after hospitalization (3.1 IMC points per year; 95% CI, 2.1-4.1) vs. patients who had not developed delirium (1.4; 95% CI, 0.2-2.6).

“The ratio of these changes suggests that cognitive deterioration following delirium proceeds at twice the rate in the year after hospitalization,” the researchers wrote.
Patients who experienced delirium maintained a more rapid rate of cognitive deterioration up to 5 years.

Gross and colleagues said delirium prevention programs could help reduce delirium for at least 27% of patients with Alzheimer’s disease, representing 1.2 million people in the United States and 4 million worldwide.

“Given that the national costs of delirium are estimated to be $40 (billion) to $150 billion annually, strategies that affect even a fraction of these costs have the potential for far-reaching cost savings for our health care system, greatly exceeding the costs of current pharmacological treatments for [Alzheimer’s disease].”

Disclosure: The researchers report no relevant financial disclosures.