Young Onset Dementia

August 11, 2021

A new systematic review and meta-analysis shows that young onset dementia (YOD) – namely dementia from ages 30 to 64 – is more common than previously thought. Alzheimer’s is the most prevalent form of early-onset dementia.

A new systematic review and meta-analysis shows that young-onset dementia (YOD) – that is dementia from ages 30 to 64 – is more common than previously thought, and that Alzheimer’s is the most prevalent form of early-onset dementia.

A team of Dutch researchers have investigated the global prevalence of young-onset dementia (YOD) and found that 3.9 million people aged 30 to 64 years are living with YOD in the world. Objective of their investigation – titled, “Global Prevalence of Young-Onset Dementia – A Systematic Review and Meta-analysis” and published in “JAMA Neurology” – was to answer the question “What is the global prevalence of young-onset dementia?”.

“In this systematic review,” authors write, “a total of 95 studies were included, of which 74 studies with 2,760,379 unique patients were included in the meta-analysis; the global age-standardized prevalence of young-onset dementia was 119.0 per 100 000 population aged 30 to 64 years. Estimates increased from 1.1 per 100 000 population aged 30 to 34 years to 77.4 per 100 000 population aged 60 to 64 years.”

“These prevalence estimates show the importance of young-onset dementia worldwide; policy makers could use this information to organize sufficient health care for young people living with dementia. … Databases were systematically searched for population-based studies on the prevalence of YOD published between January 1, 1990, and March 31, 2020.”

“A total of 95 unique studies were included in this systematic review, of which 74 with 2,760,379 unique patients were also included in 5-year age band meta-analyses. Studies were mostly conducted in Europe and in older groups in Asia, North America, and Oceania. Age-standardized prevalence estimates increased from 1.1 per 100 000 population in the group aged 30 to 34 years to 77.4 per 100 000 population in the group aged 60 to 64 years. This gives an overall global age-standardized prevalence of 119.0 per 100 000 population in the age range of 30 to 64 years, corresponding to 3.9 million people aged 30 to 64 years living with YOD in the world.”

“Subgroup analyses showed prevalence between men and women to be similar (crude estimates for men, 216.5 per 100 000 population; for women, 293.1 per 100 000 population), whereas prevalence was lower in high-income countries (crude estimate, 663.9 per 100 000 population) compared with upper–middle-income (crude estimate, 1873.6 per 100 000 population) and lower–middle-income (crude estimate, 764.2 per 100 000 population) countries.”

Researchers also found that age-standardized prevalence was highest for Alzheimer’s disease, followed by vascular dementia and frontotemporal dementia, and concluded: “To yield more accurate and comparable prevalence estimates in the future, efforts should be made to conduct more cohort studies and to standardize procedures and reporting of prevalence studies.”

New review and meta-analysis on young-onset dementia (YOD) was accompanied by an editorial entitled, “Young-Onset Dementia – New Insights for an Underappreciated Problem” by David Knopman, MD, Department of Neurology, Mayo Clinic, Rochester, Minnesota.

“At one time in the not-too-distant past, young-onset dementia was considered a disease, whereas later-onset dementia was considered the inevitable consequence of aging,” Knopman states. “We now reject such a formulation, but within that misguided dichotomy is a recognition of the dramatic differences in prevalence and incidence ofyoung-onset dementia compared with later-onset dementia.”

“Young-onset dementia is a particularly disheartening diagnosis because it affects individuals in their prime years, in the midst of their careers, and while raising families,” Knopman continues. “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.”

“The diminishing prevalence of dementia at younger ages means that epidemiological case finding almost always relies on passive surveillance methods,” Knopman explaines. “The acknowledged disadvantage of passive surveillance for dementia is the lack of control of diagnostic methods across numerous clinicians, raising the possibility of undercounting or overcounting cases owing to misdiagnosis (e.g., young-onset dementia as a psychiatric disorder or vice versa) or of noncontact by the young patient with dementia with the medical system. Milder cases are almost certainly likely to be undercounted; therefore, prevalence estimates in the meta-analysis could be higher if the full spectrum of symptomatic cognitive impairment was recognized.”

Full study “Global Prevalence of Young-Onset Dementia – A Systematic Review and Meta-analysis”
Editorial entitled, “Young-Onset Dementia – New Insights for an Underappreciated Problem”