Dementia risk continues to be higher in Black adults

Relative racial disparities in incident dementia were unchanged between Black and white older adults from 2000 to 2016, an analysis of Health and Retirement Study data showed.

“In the U.S., dementia risk is higher in non-Hispanic Black individuals than in non-Hispanic white individuals,” wrote Melinda Power, ScD, of George Washington University in Washington, D.C., and co-authors in JAMA Neurology.

“To evaluate progress toward reducing such disparities, tracking secular trends in racial disparities in dementia prevalence is essential,” they noted. “Although results suggest stable or declining dementia risk overall, there was no evidence suggesting change in relative racial disparities in dementia prevalence or incidence during follow-up.”

The Health and Retirement Study is a nationally representative study of adults 50 and older; participants are assessed every 2 years. Power and colleagues analyzed seven waves of participants (group sizes ranged from 6,322 to 7,579) to assess trends in dementia prevalence and created seven subcohorts to follow people for 4 years from baseline visits in 2000, 2002, 2004, 2006, 2008, 2010, and 2012 (group sizes ranged from 5,322 to 5,961) to assess incidence trends.

The ratio of Black-to-white incident dementia in each group did not change between 2000 and 2016 on 4-year follow-up. Prevalence ratios showed persistent increased risk for Black versus white participants and ranged from 1.5 to 1.9. Hazard ratios ranged from 1.4 to 1.8.

“Additional efforts to identify and mitigate factors contributing to these disparities are warranted,” Power and co-authors wrote. “Efforts to improve our capability to quantify and track dementia risk overall and by key socio-demographic groups are also needed. Such efforts would improve our ability to target interventions and track progress toward reducing both overall dementia risk and disparities in dementia risk.”

“Health equity can be achieved when all people have access to resources that help them to realize their full potential, despite socioeconomic position or socially determined circumstances,” noted Carl Hill, PhD, MPH, of the Alzheimer’s Association in Chicago, in an accompanying editorial. “Identifying those who are most at risk is a critical first step for pursuing equity in dementia science.”

“Similar to the work of Drs. Alzheimer and Carter Fuller that moved discussions of behavior from normal aging to biological changes in the brain, these results beg dementia science to move beyond individual risk factors like amyloid positivity and genetic risk to an exploration of determinants that may be more relevant for risk among Black individuals,” he added.

In the U.S., dementia prevalence declined for adults 65 or over from 11.6% in 2000 to 8.6% in 2012, despite concurrent increases in the prevalence of hypertension, diabetes, obesity, and cardiovascular risk.

Modifiable risk factors may delay or perhaps prevent onset of dementia, reducing personal and societal burdens. A recent report published by the Lancet Commission suggests 12 modifiable risk factors may account for about half of all global dementia: excessive alcohol consumption, head injury, and air pollution were newly added to established roles for education, hypertension, hearing impairment, smoking, obesity, depression, physical inactivity, diabetes, and infrequent social contact.

A 2018 study of National Health and Nutritional Examination Survey data for 2007-2014 found disparities in Black American rates of three cardiovascular risk conditions considered modifiable risk factors for dementia: diabetes, hypertension, and obesity.

In their study, Power and colleagues found the prevalence of self-reported, physician-diagnosed hypertension and diabetes increased between 2000 to 2016 for both Black and white participants. Hypertension increased 55% to 67% for white and 71% to 83% for Black persons; corresponding increases in diabetes were 15% to 24% for white and 23% to 42% for Black individuals.

For Black participants, mean age and percentage of males were 78.0 years and 37% in 2000, and 77.9 years and 38% in 2016. For white participants, mean age and percentage of males were 78.2 years and 40% in 2000, and 78.7 years and 44% in 2016.

Dementia was identified by several classification algorithms used in separate analyses that reached similar conclusions. The range of participants identified by the algorithms as having dementia across all years was 18 to 20%.

Increases in education over time were noted among Black participants. In 2000, 64% reported less than a high school education; in 2016, that figure was 33%.

“As dementia scientists look to identify determinants that are fundamental to the racial/ethnic disparities that Power and colleagues report, they should consider expanding scientific teams to include specialized expertise in understanding the phenomena of health disparities,” Hill wrote.

Limitations include algorithmic determination of dementia cases with possible misclassification. “We were unable to consider other racial/ethnic groups or consider effect modification by sex or other factors given concerns about statistical power,” the researchers pointed out.

“Our report focuses on the prevalence and incidence of the clinical syndrome of dementia,” they added. “Although this focus remains the most relevant outcome to patients and caregivers, the field has moved toward biomarker-based diagnoses of Alzheimer’s disease and other forms of dementia. As brain pathology burden and clinical symptoms do not always align, our findings may not reflect trends in disparities in prevalence and incidence of biomarker-based preclinical and clinical Alzheimer’s disease.”

  1. Relative racial disparities in incident dementia were unchanged between Black and white older adults between 2000 and 2016, an analysis of Health and Retirement Study data showed.

  2. Results suggested stable or declining dementia risk overall, but no evidence suggested either narrowing or widening of relative racial disparities in dementia prevalence or incidence.

Paul Smyth, MD, Contributing Writer, BreakingMED™

This work was supported by a grant from the National Institutes of Health. Health and Retirement Study data were supported by a grant from the National Institute on Aging; the study was conducted by the University of Michigan.

Power reported receiving grants from NIH.

Hill reported no conflicts.

Cat ID: 130

Topic ID: 82,130,130,33,361,192,925