Prevalence of Dementia Before Age 65 Much Higher Than Expected

Megan Brooks

July 20, 2021

The global prevalence of young-onset dementia (YOD) is significantly higher than previously thought.

Results of a large meta-analysis show that currently, 3.9 million individuals are living with YOD. Among these patients, symptoms of the memory-robbing disease start before age 65.

Recent global YOD estimates have ranged from 42.3 to 54.0 per 100,000 population, the researchers note. However, the new study, which included 74 global studies with 2.7 million participants, shows that the global age-standardized prevalence of YOD is 119.00 per 100,000 among individuals aged 30 to 64 years; there was little difference in prevalence between men and women. On the basis of the latest population estimates, these new prevalence data imply that there are approximately 175,000 persons with YOD in the United States.

Although the new global estimate of YOD is higher than previously thought, "it is still probably an underestimation owing to lack of high-quality data. This should raise awareness for policy makers and health care professionals to organize more and better care for this subgroup of individuals with dementia," the investigators, with first author Stevie Hendriks, MSc, Maastricht University, the Netherlands, and the Young-Onset Dementia Epidemiology Study Group, write.

The study was published online July 19 in JAMA Neurology.

"Essential" Data

YOD is exceedingly rare in those aged 30 to 63 (1.1 per 100,000) but is more prevalent at age 60 to 64 years (77.4 per 100,000), they note.

"Our findings fit the general observation that prevalence of dementia increases exponentially from 60 years of age onward," they write.

The prevalence of YOD was similar in men and women, lower in the United States than in Europe, highest in upper-middle-income countries, and highest for Alzheimer's disease, followed by vascular dementia and frontotemporal dementia.

Monitoring the prevalence of YOD is "essential" to adequately plan and organize health services, the investigators note.

In addition, to ensure more accurate prevalence estimates in the future, "efforts should be made to conduct more cohort studies and to standardize procedures and reporting of prevalence studies. In addition, more data are needed from low-income countries as well as studies that include younger age ranges," they add.

New Insights

In an accompanying editorial, David S. Knopman, MD, Department of Neurology, Mayo Clinic, Rochester, Minnesota, notes that the study provides new insights into an "underappreciated problem."

YOD is a "particularly disheartening diagnosis because it affects individuals in their prime years, in the midst of their careers, and while raising families," Knopman writes.

"Most dementia care is geared for older patients, and as a consequence, services are rarely available to address the needs of someone diagnosed with dementia in their 50s who has dependent children at home and a spouse who must continue working. Understanding the prevalence and incidence of YOD is a first step in addressing this challenge," Knopman writes.

He notes that the authors of this analysis have "done a service to the dementia community by collecting and analyzing the dozens of individual studies of YOD.

"The product, a rationally derived estimate of dementia prevalence across the population aged 30 to 64 years, provides a basis for initiating more efforts to improve methods for timely diagnosis and to address the unique needs of patients with YOD," Knopman concludes.

JAMA Neurol. Published online July 19, 2021. Abstract, Editorial

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