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Race in the race against AD
SACRAMENTO, Calif.—In late July, the University of California (UC) was awarded a nearly $14.7-million multi-year grant from the National Institutes of Health to study contributors to dementia in the U.S. Latino population. The multicenter study will examine the biological underpinnings of stroke, mild cognitive impairment and Alzheimer’s disease among Latinos, and pursue new therapeutic directions to reduce brain health disparities.
The UC Davis campus and nine other institutions across the country will participate in the research. The investigators will draw from the more than 16,000-patient cohort of the ongoing Hispanic Community Health Study/Study of Latinos (HCHS/SOL), a multicenter epidemiologic study primarily focused on cardiovascular and pulmonary diseases. An ancillary study, the Study of Latinos-Investigation of Neurocognitive Aging (SOL-INCA), is examining genetic and cardiovascular disease risk factors for neurocognitive deficits, and will also provide important data for this research.
“This is the largest study of Latinos with cognitive impairment ever done,” said co-principal investigator Charles S. DeCarli, director of the UC Davis Alzheimer’s Disease Center. “Latinos are the fastest-growing minority population in our aging population, so cognitive impairment in this group is an important public health concern.” DeCarli, a UC Davis Health professor of neurology, noted that the Latino population is particularly important to study in the field of dementia because Latinos have a higher prevalence of diabetes, hypertension and obesity compared to non-Hispanic Caucasians, all of which are risk factors for stroke and dementia. Rates of Alzheimer’s disease are about 1.5 times higher than in white non-Hispanics.
According to a recent impact report titled “Latinos & Alzheimer’s Disease: New Numbers Behind the Crisis” and co-authored by researchers from the University of Southern California and Latinos Against Alzheimer’s, “Latino families are highly under-resourced in terms of income, retirement benefits and pension benefits. As the Latino population ages, a growing number of Latino communities, families and systems of care will be confronted by the growing crisis of Alzheimer’s disease (AD) with the fewest resources to manage it. [T]he Administration on Aging projects that between 2008 and 2030, the Latino population aged 65 years and older will increase by 224 percent compared to a 65-percent increase for the non-Latino white population in the same age category.”
“[T]his report projects a striking increase in the number of Latinos with AD through 2060. The number of Latinos with AD is expected to increase more than ninefold from 379,000 in 2012 to 1.1 million by 2030, and to 3.5 million by 2060—a growth of 832 percent—if a medical breakthrough is not discovered that cures or slows the progression of the disease. Total direct and indirect costs for Latinos with AD will reach approximately $105.5 billion by 2060 (in 2012 dollars). As the number of Latino families touched by AD increases over the coming decades—as individuals or as caregivers—the economic impact of AD on the Latino community will reach a cumulative $2.35 trillion (in 2012 dollars) by 2060, according to our projections,” says the impact report.
The UC Davis-led study will make use of leading-edge magnetic resonance imaging (MRI) techniques, which can help assess vascular brain injury and patterns of atrophy seen in Alzheimer’s disease. MRIs will be acquired at the partnering institutions and evaluated at UC Davis.
“Advanced neuroimaging techniques can help us better understand the relationship between brain structure and function with aging and disease,” said DeCarli, who directs the UC Davis Imaging of Dementia and Aging (IDeA) laboratory. “The information attained will help us to better design and monitor new therapies.”
Study investigators will also explore the role of genetics in Alzheimer’s disease. The E4 variant of the apoliprotein gene has been strongly implicated in increasing the risk of early-onset Alzheimer’s disease in non-Hispanic Caucasians. Paradoxically, some Hispanic ethnic groups have a very low frequency of this allele, despite high rates of dementia.
According to a study entitled “Earlier Onset of Alzheimer Disease Symptoms in Latino Individuals Compared With Anglo Individuals,” a retrospective database analysis “revealed that the mean age at symptom onset for 366 Latino patients with a clinical diagnosis of AD was 68.8 years, compared with 73.5 years for 2,823 Anglo patients. The reason for the 4.7-year difference did not vary between the East Coast (predominantly Caribbean) and West Coast (predominantly Mexican) sites.”
“In the second phase of the study, 119 Latino and 55 Anglo patients were prospectively evaluated using standardized assessment tools. There were no differences between the Latino and Anglo cohorts in sex distribution, the proportion with a diagnosis of probable vs. possible AD or the severity of cognitive impairment as measured by MMSE score at the time of enrollment,” the study continues. “After adjusting for center, sex and years of education, the mean age at onset for the first dementia symptom was 6.8 years (95-percent confidence interval [CI], 3.5–10.3 years) earlier in Latino compared with Anglo patients.”
“What else is going on, other than genetics? This grant will help us to advance this and many other interesting lines of research in this very ethnically and genetically diverse population group,” DeCarli commented.
The UC Davis-led study’s co-principal investigator is Hector M. Gonzalez, associate professor of epidemiology and biostatistics at Michigan State University. In addition to UC Davis and Michigan State, other study sites include the University of Illinois, Albert Einstein College of Medicine, University of Texas Science Center, Wayne State University, University of Washington, University of Miami, San Diego State University and University of North Carolina.