A nationwide study finds that Black and Latinx adults with cognitive impairment are less likely to have Alzheimer’s-linked amyloid buildup, even as they face higher rates of dementia, raising urgent questions about diagnosis, treatment access, and the future of dementia care.
Study: Differences in amyloid PET positivity based on ethnoracial group and social determinants of health: The new IDEAS study. Image credit: PeopleImages/Shutterstock.com
A study published in the journal Alzheimer’s and Dementia reveals ethnoracial variations in amyloid positron emission tomography (PET) positivity among older adults with cognitive impairment.
Investigating Alzheimer’s biomarkers in diverse populations
The global prevalence of Alzheimer's disease and related dementia (ADRD) is rapidly increasing, with more than 10 million new dementia cases occurring each year worldwide. The prevalence is particularly high in developing countries, where about 60 % of people living with dementia currently reside, and this percentage is expected to reach 70 % by 2050.
Early detection of these neurodegenerative diseases is essential for appropriate disease management and improved patient care. However, minoritized individuals, including Black and Latinx older adults, often face unique challenges, such as interpersonal racial discrimination and structural racism, which can potentially delay disease diagnosis and worsen outcomes.
Social determinants of health (SDOH) such as education and socioeconomic background significantly contribute to the ethnoracial differences in dementia risk. Existing evidence indicates that Black and Latinx older adults are at 1.5–2 times greater risk of clinical ADRD.
The accumulation of amyloid plaques in the brain is a major pathological hallmark of Alzheimer’s disease, which is detected through positron emission tomography (PET). Existing evidence indicates that the rate of amyloid PET positivity varies between different ethnic and racial groups.
The current study aimed to characterize rates of amyloid PET positivity across ethnoracial groups in relation to SDOH in a highly diverse cohort of older adults with mild cognitive impairment or dementia.
The study included a total of 5757 participants: 1248 Black, African American, or African; 1166 Hispanic, Latino, or Spanish (Latinx); and 3343 the all-other races and ethnicities. About 63 % of participants had mild cognitive impairment, and 37 % had dementia.
Amyloid-positive scans were less common in minorities
The study analysis revealed that participants belonging to the all-other races and ethnicities had significantly higher rates of amyloid PET positivity than Black and Latinx participants.
Four categories of SDOH including gender, type of Medicare coverage, education attainment, and Area Deprivation Index (ADI) were examined for associations with rates of amyloid PET positivity. ADI is a scientifically validated measure of neighborhood-level social disadvantage.
Participants in the comfortable and distressed ADI groups showed a higher possibility of having amyloid PET positivity than those in the prosperous ADI group. Participants in the mid-tier and at-risk ADI groups did not show a significantly different likelihood of amyloid PET positivity compared to the prosperous group. Specifically, the prosperous group participants had the lowest risk for amyloid PET positivity, and the distressed group participants had the highest risk.
Among other SDOH categories, educational attainment was not significantly associated with amyloid PET positivity in the primary analyses, although fully adjusted models suggested higher rates of amyloid positivity with increasing educational attainment.
Regarding clinical outcomes, the study revealed that the rate of dementia diagnosis and the possibility of enrollment in a Medicare Advantage plan were higher among Black and Latinx participants compared to those belonging to the all-other races and ethnicities.
No significant ethnoracial differences in Alzheimer’s disease medication use prior to PET were observed in the primary analyses, although fully adjusted models suggested a lower likelihood of medication use among Black and Latinx participants compared to all-other race and ethnic group participants.
Equity concerns in Alzheimer’s care
The study finds strong ethnoracial differences in amyloid PET positivity rates in cognitively impaired older adults from across the United States. However, the social determinants of health measured in this study do not appear to have a significant impact on the observed ethnoracial differences.
The study replicated prior related findings in a more diverse cohort by increasing the representation of minoritized groups, including Black (22 %) and Latinx (20 %). According to the study findings, Black and Latinx groups have significantly lower amyloid positivity rates, despite cognitive impairment. Notably, Black and Latinx participants were more likely to be diagnosed with dementia and had lower cognitive test scores despite having lower amyloid positivity rates.
The absence of biomarker positivity is a major contributor to the disproportionate exclusion of these groups from clinical trials investigating the efficacy of novel anti-amyloid treatments. Such underrepresentation can potentially limit their eligibility for these novel treatments, highlighting the need for non-amyloid interventions for cognitive decline.
The observed ethnoracial differences in amyloid PET positivity may suggest a higher prevalence of non-Alzheimer’s disease causes of cognitive impairment, including non-amyloid dementias in Black and Latinx populations, such as vascular dementia. This suggests that amyloid-targeted interventions alone may provide less overall benefit in populations where a greater proportion of cognitive impairment is driven by non-amyloid causes and highlights the need for considering alternative interventions, such as lifestyle interventions, which can effectively control vascular risk factors such as hypertension and diabetes.
Although SDOH are known to influence health outcomes, the study found no significant impact of the tested components on ethnoracial differences in amyloid positivity. This may be due to the absence of life course or individual-level data.
Overall, the study highlights the need for developing diagnostic tools and treatments for dementias to offer equitable care to all cognitively impaired people with diverse ethnoracial backgrounds.
The study did not consider important genetic factors in the analysis, such as apolipoprotein E (APOE) genotype, which may vary across ethnoracial groups. The researchers are planning to explore in the future how genetic factors influence amyloid PET positivity rates.
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