What is the prevalence of delirium, dementia, and amnesia in the US?

Updated: Sep 19, 2018
  • Author: Richard D Shin, MD; Chief Editor: Gil Z Shlamovitz, MD, FACEP  more...
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Delirium accounts for or develops during 10–15% of all admissions to acute-care hospitals but is seen much more frequently in elderly persons (up to 75% of seriously ill and hospitalized), particularly following major surgery, trauma or prolonged ICU care. ICU delirium, with a prevalence estimated at 31.8%, is associated with increased ICU length of stay, longer mechanical ventilation duration, and increased mortality. [1]  Delirium is usually transient, but it can be persistent leading to a chronically dementing process in elderly patients.

The prevalence of dementia doubles every 5 years between ages 60 to about 90 years: 1% of persons aged 60–64 years up to 30–50% of those older than 85 years. Approximately 60% of nursing home beds are occupied by patients with dementia. In the ED, patients in nursing homes are more likely to present with delirium than other patients, even after adjusting for delirium risk factors. [2] Alzheimer disease (AD) accounts for most patients with dementia who are older than 55 years (50–90% of all cases). It is estimated that over 4 million people in the United States suffer from AD.

Although slowing of memory and word-finding are normal features of brain aging, approximately 10–15% of patients with mild cognitive impairment, a transitional state between normal functioning and dementia, progress to AD yearly.

For as yet unknown reasons, dementia rates in the United States have been declining over the past several years.

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