Black and Latinx adults with cognitive impairment have lower amyloid accumulation associated with Alzheimer’s disease despite higher rates of dementia, a national study has found, raising urgent questions about diagnosis, access to treatment, and the future of dementia care.
Study: Differences in amyloid PET positivity based on ethnic groups and social determinants of health: a new IDEAS study. Image credit: PeopleImages/Shutterstock.com
Research published in journals Alzheimer’s disease and dementia We identified ethnoracial differences in amyloid positron emission tomography (PET) positivity rates in older adults with cognitive impairment.
Investigation of Alzheimer’s disease biomarkers in diverse populations
The global prevalence of Alzheimer’s disease and related dementias (ADRD) is rapidly increasing, with more than 10 million new cases of dementia occurring worldwide each year. Prevalence is particularly high in developing countries, where approximately 60% of people with dementia currently live, and this proportion is expected to reach 70% by 2050.
Early detection of these neurodegenerative diseases is essential for appropriate disease management and improved patient care. However, minority populations, including Black and Latinx older adults, often face unique challenges such as interpersonal and structural racism, which can lead to delayed disease diagnosis and worse outcomes.
Social determinants of health (SDOH), such as education and socio-economic background, significantly contribute to ethnic differences in dementia risk. Existing evidence indicates that Black and Latino older adults have a 1.5- to 2-fold increased risk of clinical ADRD.
The accumulation of amyloid plaques in the brain is a major pathological feature of Alzheimer’s disease and is detected by positron emission tomography (PET). Existing evidence indicates that amyloid PET positivity rates vary among different ethnic and racial groups.
The current study aims to characterize amyloid PET positivity rates across ethnic groups in the context of SDOH in a highly diverse cohort of older adults with mild cognitive impairment or dementia.
The study included a total of 5,757 participants, of whom 1,248 were Black, African American, or African. 1166 Hispanic, Latino, or Spanish (Latinx). 3343 All other races and ethnicities. Approximately 63% of participants had mild cognitive impairment and 37% had dementia.
Amyloid-positive scans were less common in minorities
Analysis of the study revealed that participants of all other races and ethnicities had significantly higher rates of amyloid PET positivity than Black and Latino participants.
Four categories of SDOH were examined for their association with amyloid PET positivity, including gender, type of Medicare coverage, educational background, and area deprivation index (ADI). The ADI is a scientifically validated measure of neighborhood-level social disadvantage.
Participants in the comfortable and distressed ADI groups were shown to be more likely to have a positive amyloid PET than those in the thriving ADI group. Participants in the intermediate and at-risk ADI groups showed no significant difference in the likelihood of positive amyloid PET compared to the flourishing group. Specifically, participants in the thriving group had the lowest risk of amyloid PET positivity, and participants in the deprived group had the highest risk.
Among other SDOH categories, educational background was not significantly associated with amyloid PET positivity in the primary analysis, but fully adjusted models suggested an increase in amyloid positivity with increasing education.
Regarding clinical outcomes, this study found that black and Latino participants had higher rates of dementia diagnosis and likelihood of enrollment in a Medicare Advantage plan compared with participants of all other races and ethnicities.
Although the primary analysis did not observe significant racial differences in pre-PET Alzheimer’s drug use, fully adjusted models suggested that Black and Latino participants were less likely to use drugs compared to participants of all other racial and ethnic groups.
Concerns about equity in Alzheimer’s disease treatment
This study found strong ethnic-racial differences in amyloid PET positivity among older adults with cognitive impairment 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.
This study replicated previous related findings in a more diverse cohort by increasing representation of minority groups such as Blacks (22%) and Latinos (20%). Study results showed that black and Latino groups had significantly lower rates of amyloid positivity despite cognitive impairment. Notably, Black and Latino participants were more likely to be diagnosed with dementia and had lower scores on cognitive tests, despite having lower rates of amyloid positivity.
The absence of biomarker positivity is a major reason for the disproportionate exclusion of these groups from clinical trials investigating the efficacy of novel anti-amyloid treatments. Such underestimation may limit patient eligibility for these novel treatments and highlights the need for non-amyloid interventions for cognitive decline.
The observed racial differences in amyloid PET positivity rates may suggest a higher prevalence of non-Alzheimer’s disease causes of cognitive impairment, including non-amyloid dementias such as vascular dementia, in black and Latino populations. This suggests that in populations where cognitive impairment is largely caused by non-amyloid causes, amyloid-targeted interventions alone may have limited overall benefit, highlighting the need to consider alternative interventions such as lifestyle interventions that can effectively control vascular risk factors such as hypertension and diabetes.
Although SDOH is known to influence health outcomes, this study did not find that the components tested significantly influenced ethnic differences in amyloid positivity rates. This may be due to the absence of life course or individual level data.
Overall, this study highlights the need to develop diagnostic tools and treatments for dementia to provide equitable care to all cognitively impaired people from diverse ethnic backgrounds.
This study did not take into account important genetic factors in the analysis, such as apolipoprotein E (APOE) genotype, which may differ between ethnic groups. In the future, the researchers plan to investigate how genetic factors influence amyloid PET positivity rates.
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