Abstract
IMPORTANCE: Young-onset dementia (YOD), which develops before age 65 years, can bring additional challenges to patients and their caregivers. The prevalence of YOD and its associated comorbidities across US racial and ethnic populations remain unclear. OBJECTIVE: To estimate the prevalence of YOD and examine associations between comorbidities and YOD among Medicare beneficiaries in various racial and ethnic groups. DESIGN, SETTING, AND PARTICIPANTS: This cross-sectional study used data from January 2022 to December 2022. Data were extracted from the Centers for Medicare & Medicaid Services 2022 Medicare Beneficiary Summary File (MBSF) for Medicare beneficiaries aged 45 to 64 years with almost-continuous fee-for-service coverage in 2022. The MBSF Research Triangle Institute race code was used to identify Hispanic, non-Hispanic American Indian and Alaska Native, non-Hispanic Asian, non-Hispanic Black, and non-Hispanic White populations. EXPOSURES: Comorbidities examined include diabetes, cardiovascular disease (CVD), hyperlipidemia, hypertension, depression, chronic kidney disease without end-stage kidney disease (ESKD), ESKD, liver disease, cancer, chronic obstructive pulmonary disease, traumatic brain injury (TBI), alcohol use disorder, drug use disorder, tobacco use disorder, and hearing loss. MAIN OUTCOMES AND MEASURES: The outcome was YOD, defined as Alzheimer disease and related dementias (ADRD) occurring in individuals aged 45 to 64 years. YOD was identified using end-of-year indicators of ADRD from the MBSF 30 Chronic Conditions Data file. The age-standardized prevalence of YOD in 2022 was calculated using the direct standardization method, with White adults in our sample as the standard population across age groups. RESULTS: In 2022, among a total of 2 189 231 Medicare beneficiaries aged 45 to 64 years, 71 092 (3.25%) received a diagnosis of YOD. Black adults had the highest age-standardized YOD prevalence (13 149 beneficiaries [3.76%]). Among beneficiaries aged 45 years and older with ADRD, the proportions of YOD were approximately 2 to 3 times higher among Black (13 149 beneficiaries [7.01%]), American Indian and Alaska Native (655 beneficiaries [6.49%]), and Hispanic (6090 beneficiaries [4.77%]) individuals compared with White (49 818 beneficiaries [2.89%]) and Asian (1380 beneficiaries [2.12%]) individuals. In addition, Black, Hispanic, and American Indian and Alaska Native adults had a higher prevalence of most examined comorbidities than White adults. Many comorbidities, such as TBI (odds ratio [OR] range, 8.80-14.77), depression (OR range, 4.19-5.12), and CVD (OR range, 3.54-5.49), were associated with YOD. CONCLUSIONS AND RELEVANCE: This cross-sectional study found that Medicare beneficiaries from minoritized racial and ethnic groups younger than 65 years experienced a higher burden of YOD. Improved early detection and enhanced care coordination may help address the needs of Medicare beneficiaries with YOD, especially those from minoritized racial and ethnic groups with multiple comorbidities.