A type of brain scan used to inform physicians’ diagnoses of Alzheimer’s disease is less likely to give Black, Hispanic, and Asian individuals a positive result compared to white people, according to new research. The test, known as a positron emission tomography (PET) scan, helps track a patient’s disease progression and can even qualify them for certain treatments, meaning that racial disparities in the tool’s helpfulness can impact care negatively for nonwhite patients.
In a new study published on Monday in JAMA Neurology, American researchers analyzed PET scan positivity in a group of over 17,000 adults aged 65 and older who had been diagnosed with either mild cognitive impairment or dementia. PET scans measure the amount of beta-amyloid plaques in the brain—these plaques build up for Alzheimer’s patients and disrupt the function of cells. And while a positive PET scan is not enough on its own to make a diagnosis, the test can inform an otherwise uncertain diagnosis, and a patient must show evidence of amyloid in the brain for them to be prescribed aducanamab, a recently approved drug.
The problem thus far, according to the researchers behind the new study, is a common one across clinical trials: PET scans “have largely been studied in individuals identified as White, with minimal inclusion of racially and ethnically diverse groups,” they wrote.
In contrast, their trial represented a collaboration among universities across the country and a sample that included 321 Asian, 635 Black, and 829 Hispanic participants—making this one of the largest nonwhite samples studied. Even though Black and Hispanic populations have higher rates of Alzheimer’s and dementia diagnoses than whites do, all three nonwhite groups had lower odds of their PET scans coming back positive. Black individuals were 29 percent less likely to have a positive PET scan than white people, Hispanic people were 32 percent less likely, and Asian individuals were 53 percent less likely.
According to the researchers, these differences may mean that the causes or symptoms of Alzheimer’s and dementia vary across the populations—Black and Hispanic individuals, for instance, have higher rates of hypertension and diabetes than white people do, in part due to structural inequities and other social determinants of health. These conditions are associated with specific presentations and progressions of Alzheimer’s. The researchers were quick to point out, too, that race itself is a categorization based largely on social factors, and that it often serves “as a proxy for social determinants of health, structural racism, and cultural and linguistic factors” rather than biology or genetics.
Worryingly, these results could indicate that Alzheimer’s therapies that, like aducanamab, require the presence of amyloid or others that work by reducing amyloid plaques may not be equally beneficial for all patient populations. Further research and clinical trials should emphasize representation in their recruitment; otherwise, these new therapies may worsen existing health care disparities, the researchers wrote.
“If diverse groups are less likely to benefit from amyloid-directed therapies and likely to experience considerable financial hardship from the associated cost, there is a risk these novel treatment options may exacerbate existing racial and ethnic disparities in dementia care,” they wrote.
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