What is it about?
We investigate a new hypothesis about why Hispanics develop dementia at a younger age and how ethnicity interacts with another risk factor, neuropsychiatric symptoms (NPSs), to increase the risk of incident mild cognitive impairment (an at-risk stage for Alzheimer's disease). This study discovered that Hispanic participants had an 11-fold higher risk of developing mild cognitive impairment (MCI) compared to non-Hispanic participants. Hispanic ethnicity and neuropsychiatric symptoms jointly increased the risk of MCI, suggesting a potential risk group for Alzheimer’s disease progression.
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Why is it important?
In previous work by our group, we described and presented early evidence of differences in the prevalence and presentation of NPSs in different racial and ethnic groups. Also known as neuropsychiatric symptoms (NPS), NPS are core features of Alzheimer`s disease and related dementias. Once thought to emerge primarily in people with late-stage disease, these symptoms like anxiety, depression, psychosis, and apathy, are currently known to manifest commonly in very early disease and in prodromal phases, such as mild cognitive impairment. We discovered that these same psychiatric symptoms appear in asymptomatic, cognitively unimpaired community-dwelling older adults; however, the presence of one or more NPS in the Hispanic sample carried the highest risk, nearly equaling the impact of the Apolipoprotein E (APOE) 4 gene, a genetic configuration that increases a person's risk of developing Alzheimer's disease by 12 times in people with two copies of the gene. Finally, our findings add to the evidence and will guide ambitious national research initiatives aimed at disentangling the genetic underpinnings of NPS in Alzheimer's disease, such as the Alzheimer's Disease Sequencing Project (ADSP).
Perspectives
This seminal paper is one of five original research contributions comparing two homogeneous populations along the largest U.S./Mexico American border: Hispanic Mexican Americans and non-Hispanic Whites, using the Texas Alzheimer Research and Care Consortium (TARCC)'s curated database from the Texas Harris Alzheimer's Research Study on Cognitive Aging. All consenting TARCC subjects' blood samples were deposited in the National Institute on Aging Genetics of Alzheimer's Disease Data Storage Site (NIAGADS), a national data repository that allows qualified investigators to access genetic data for the study of Alzheimer's disease and Alzheimer's disease-related dementias. TARCC samples have been used in major publications on genetic risks, immune response variants, and the effects of brain protein and lipid processing. Most important to me is the ongoing analysis of ancestry self-report data against genetics to better understand variations in risk factors based on race and ethnicity. In this sense, I can be identified as the "rabbit" who took the "short" and unusual road or the "turtle" who took the longest road to arrive at a pivotal finding in the relationship between brain, behavior, and Alzheimer's. I am pleased to have taken the less traveled path as a geriatric psychiatrist and to pay tribute to Alois Alzheimer and his first patient, Auguste Deter, who displayed paranoia as the first symptom of Alzheimer's and considered this an elemental fact that sparked my interest in Alzheimer's disease psychopathology research.
Ricardo Salazar
Harvard University
Read the Original
This page is a summary of: An 11-Fold Higher Risk of Incident Mild Cognitive Impairment With Hispanic Ethnicity and Baseline Neuropsychiatric Symptoms, Journal of Neuropsychiatry, August 2024, American Psychiatric Association,
DOI: 10.1176/appi.neuropsych.20230180.
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