Most dementia and Alzheimer’s disease epidemiology research has focused on people in developed countries, e.g., the United States, Canada, Australia, Japan, Taiwan, and Europe. However, in many low- and middle-income countries, life expectancy is rising, and by 2050, it is estimated that most of the world’s elderly will live in developing nations (Shetty, 2012). With an aging population comes an increase in people with dementia, making diagnosis, management, and treatment of these diseases a pressing concern.
- By 2050, most of the world’s elderly will live in developing countries.
- With that comes a rise in the incidence of dementia, yet many people in those nations lack access to quality health care.
- Fluid biomarkers are being touted as an accurate and practical way to diagnose dementia worldwide.
At the virtual AD/PD conference held last month, the pharmaceutical and diagnostics company Roche sponsored a symposium on AD perspectives from around the world, where clinicians presented case studies, local challenges, and best practices in their cities or countries. One hope is that connecting dementia leaders in this way will improve diagnoses and help people and families suffering from AD across the globe. Another hope on the part of the sponsor might be to develop market interest in such countries for diagnostic blood tests this company and others anticipate selling before too long.
The Lancet Commission's most recent report on dementia prevention, intervention, and care stated that, globally, low- and middle-income countries are home to about two-thirds of all people with dementia. It named 12 modifiable risk factors that increase the risk of dementia in both developed and developing nations (Aug 2020 conference news).
Many patients in developing nations lack access to adequate health care, including dementia treatment. In Nigeria, for example, an estimated 4.9 percent of people age 60 and older have dementia (Adeloye et al., 2019). However, people in rural areas live far away from the nation's few centers with necessary diagnostic tools like neuroimaging, said Adesola Ogunniyi from University College Hospital in Ibadan, Nigeria.
In Brazil, a 2013 study projected that country's prevalence to be around 7.9 percent by 2020 among people 65 years and older, which would place Brazil among the highest age-standardized population prevalences of AD and other dementias in the world (Burlá et al., 2013; Feter, Leite, and Rombaldi, 2020). Its residents face a similar problem in that PET scans and cerebrospinal fluid (CSF) biomarker tests are only available in large cities and are not covered by the public health system or private medical insurance, according to Paulo Caramelli from the Federal University of Minas Gerais, Belo Horizonte, Brazil. Amyloid PET scans exist in only two academic medical centers across this country of 211 million people. In both Nigeria and Brazil, older women, widows, and people with few years of education, or who are socially isolated, are at a higher risk of dementia.
In China, around 5.6 percent of people age 65 and older have dementia; indeed, the country fields roughly 25 percent of all dementia patients worldwide (Jia et al., 2020). Yet there is little public awareness of the disease, and 70 to 80 percent of all dementia patients receive no formal treatment, said Jiong Shi from the Cleveland Clinic. Shi has disclosed a relationship with Roche in a recent scientific paper.
Are fluid tests the way forward? Fluid biomarkers may offer an affordable, easy-to-use tool to help diagnose dementia across large populations. Henrik Zetterberg, University of Gothenburg, and other clinicians in Sweden have been using fluid biomarkers in clinical neurology practice for some time. CSF Aβ42, for example, has been shown to differentiate healthy people from those with AD, and NfL is useful in diagnosing a range of neurodegenerative conditions (Mar 2015 news; Jun 2019 news). Research on plasma biomarkers—raising hope for simple blood tests—has made tremendous strides in the past year alone (Apr 2021 conference news). For a meta-analysis survey of fluid biomarker research in Alzheimer's disease, see AlzBiomarker database.
By adopting plasma markers in particular, physicians in developing nations will be able to offer a more precise approach to AD diagnosis. But there are challenges. For one, these fluid biomarkers are not ready for prime time, and they must be used in conjunction with other AD diagnostic measures, such as neuroimaging or cognitive/clinical assessments, Zetterberg noted during the symposium.
For another, many of these countries’ health care systems are not designed to care for people with chronic illnesses, especially for the comorbidities that tend to afflict the elderly. Until recently, developing nations, owing to poverty and high child-mortality rates, have had younger populations, hence their health care systems are structured around treating single, acute diseases such as infections.
Moreover, dementia is poorly understood in many of these nations, and the result can be stigmatization and minimal care. In Nigeria, for example, some people still ascribe dementia to possession by evil spirits or to witchcraft, causing families to conceal their medical problems, according to Ogunniyi. Superstition in Colombia has long called Alzheimer's "La Bobera," or "the foolishness."
Many medical professionals are not trained in dementia. In China, lack of education on dementia is a significant problem, Shi said. As a result, dementia diagnoses are made differently in academic hospitals than they are in non-academic and county hospitals, resulting in wrong and missed diagnoses. To properly use fluid biomarkers, education is key, Zetterberg told his colleagues. “There is a need to be able to understand when to test and what the results mean with respect to Alzheimer’s disease pathogenesis,” he said. Practitioners also need training on how to communicate biomarker results to their patients.
This doesn’t mean fluid biomarkers aren’t a viable option in low- and middle-income nations. “Nigeria can afford to do biomarker assays both as a research tool and as part of routing assessment of cases,” Ogunniyi wrote to Alzforum. “Patients who receive care at tertiary care centers, and in big cities like Lagos and Abuja, can afford such tests when adequately educated on the benefits and clinical utilization.”
For anyone in these nations—as indeed in developed countries—the speakers recommended lifestyle choices, such as a healthy diet, physical activity, limiting alcohol consumption, practicing social engagement, and avoiding air pollution, as much as possible. “Those are the goals of our care at the moment, as that would help prevent dementias according to the Lancet Commission on dementia,” wrote Ogunniyi.
Beyond lifestyle recommendations, Zetterberg hopes that research-grade assays for phosphorylated tau and other biomarkers in plasma can be standardized and certified, and then adopted into clinical practice in the near future. Blood tests are less costly than PET scans and less invasive than CSF tests.
Zetterberg envisions these biomarkers being distributed to, and used by, general practitioners and other doctors who aren’t dementia experts. Hopefully, this means the tests will reach larger populations and rural areas in developing nations, thus helping millions of people with dementia who currently lack care. In addition, biomarkers will make it easier for scientists to stratify people with dementia into subgroups for clinical trials, thus increasing the trial's ability to predict how fast people will progress, according to Carla Abdelnour from Fundació ACE in Barcelona, Spain.—Helen Santoro
- Living on the Edge: Moderately Low Aβ42 in CSF Predicts Decline
- NfL: Useful in Differential Diagnosis?
- Where to Now, Phospho-Tau?
- Shetty P. Grey matter: ageing in developing countries. Lancet. 2012 Apr 7;379(9823):1285-7. PubMed.
- Adeloye D, Auta A, Ezejimofor M, Oyedokun A, Harhay MO, Rudan I, Chan KY. Prevalence of dementia in Nigeria: a systematic review of the evidence. J Glob Health Rep. 2019;3 Epub 2019 Mar 27 PubMed.
- Burlá C, Camarano AA, Kanso S, Fernandes D, Nunes R. [A perspective overview of dementia in Brazil: a demographic approach]. Cien Saude Colet. 2013 Oct;18(10):2949-56. PubMed.
- Feter N, Leite JS, Rombaldi A. Who are the patients diagnosed with dementia in Brazil? A nation‐wide descriptive study. Alzheimer's & Dementia, 07 December 2020
- Jia L, Quan M, Fu Y, Zhao T, Li Y, Wei C, Tang Y, Qin Q, Wang F, Qiao Y, Shi S, Wang YJ, Du Y, Zhang J, Zhang J, Luo B, Qu Q, Zhou C, Gauthier S, Jia J, Group for the Project of Dementia Situation in China. Dementia in China: epidemiology, clinical management, and research advances. Lancet Neurol. 2020 Jan;19(1):81-92. Epub 2019 Sep 4 PubMed.
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