14.2: Neurocognitive Disorders - Epidemiology

Learning Objectives

• Describe the epidemiology of neurocognitive disorders.

Delirium

The prevalence of delirium in the general community is relatively low at 1% to 2% based on data from the United States and Finland. For older individuals presenting to North American emergency departments, the rate is 8% to 17%. Prevalence rates for those admitted to the hospital range from 18% to 35%. For those in nursing homes or post-acute care settings prevalence is 20 to 22% and 88% for individuals with terminal illnesses at the end of life. Prevalence rates are lower for younger African Americans compared to White individuals of similar age.

Major and Mild NCD

Major and mild neurocognitive disorder prevalence rates vary widely depending on the etiological nature of the disorder and overall prevalence estimates are generally only available for older populations. Internationally, dementia occurs in 1-2% of individuals at age 65, and up to 30% of individuals by age 85. The female gender is associated with higher prevalence of dementia overall. Estimates for mild NCD among older individuals range from 2% to 10% at age 65 and 5% to 25% at age 85. In the U.S., incidence is highest in African Americans followed by American Indians/Alaska Natives, Latinx, Pacific Islanders, non-Latinx Whites, and Asian Americans.

Major and Mild NCD Subtypes

Alzheimer’s disease, the most commonly diagnosed neurocognitive disorder, is observed in nearly 5.5 million Americans (Alzheimer’s Association, 2017a), with 11% of those aged 65 and older and 32% older than 85 having dementia due to Alzheimer’s disease. It should also be noted that somewhere between 60-90% of dementias are attributable to Alzheimer’s disease, depending on the setting and diagnostic criteria. In terms of ethnoracial background in the U.S. the highest prevalence rates have been found among African Americans and Latinx of Caribbean origin (APA, 2022).

Over 2.87 million traumatic brain injuries (TBIs) happen each year within the United States, with men being 40% more likely to experience a TBI compared with women. The most common causes of TBI, in order of occurrence, are falls followed by collision with a moving or stationary object, automobile accidents, and assaults. It has also become increasingly recognized that concussion in sport causes mild TBI (APA, 2022).

Key Takeaways

You should have learned the following in this section:

• As individuals age, the rate of occurrence of delirium and dementia increases dramatically.
• Estimates for mild NCD among older individuals range from 2% to 10% at age 65 and 5% to 25% at age 85.
• As for Alzheimer’s disease, prevalence rates are 11% of those aged 65 and older and 32% of those older than 85.
• Men are more likely to experience a TBI than women.

Review Questions

1. What is the rate of occurrence of the neurocognitive disorders?