American Board of Internal Medicine (ABIM) Certification Practice Exam

Which age group typically presents with sporadic Creutzfeldt-Jakob disease?

1. In infancy

2. In the seventh decade of life

3. In late adulthood

4. In early childhood

The correct answer is: In the seventh decade of life

Sporadic Creutzfeldt-Jakob disease (sCJD) predominantly affects individuals in the seventh decade of life, typically presenting between the ages of 60 and 70. This age-related prevalence is key in understanding the epidemiology of the disease, as sporadic cases arise without a known hereditary or infectious cause, differentiating them from genetic or acquired forms of prion diseases. The development of sCJD is associated with the accumulation of abnormal prion proteins in the brain, which leads to progressive neurological decline. Population studies indicate a peak incidence around this age, which is consistent with the understanding that neurodegenerative diseases are more common in older adults due to age-related biological changes. In contrast, other age groups presented in the question generally do not experience sCJD. Infancy and early childhood are not typical ages for this condition as it is virtually unheard of in these populations. Late adulthood, while it may encompass ages beyond 70, less frequently presents with the classic form of sporadic CJD, often yielding to different demographic patterns. Therefore, individuals in their seventh decade of life represent the typical demographic for sporadic Creutzfeldt-Jakob disease.