Alzheimer’s disease is the most common form of dementia in older adults. Globally, over 55 million people live with dementia, and there are nearly 10 million new cases every year. As population aging accelerates, the need for a better understanding of the disease and for better treatments presents an urgent and major health challenge.
Dementia is particularly prevalent in Asia, where the population is aging faster than on any other continent. Almost a third of Japan’s population is over 65 compared to the U.S., where the figure is closer to 17%. More than 6 million people in the U.S. currently live with Alzheimer’s though that figure is expected to jump to nearly 13 million by 2050. In 2022, the estimated national cost of Alzheimer’s and other dementias was $321 billion. One in three U.S. seniors dies with Alzheimer’s or other dementia, more than breast cancer and prostate cancer combined.
As the world ages and people live longer, other countries are watching Asia for guidance and insight on how best to respond to this public health challenge. Yale School of Public Health Associate Professor Xi Chen, an affiliate of Yale’s Alzheimer’s Disease Research Center and a faculty member in the Department of Health Policy and Management recently served as guest editor of a special issue of the China CDC Weekly focused on Alzheimer’s disease and related dementias (ADRD) worldwide.
What was the purpose of the Alzheimer’s disease issue of the China CDC Weekly?
Xi Chen: The special issue attempts to improve the awareness of ADRD, a disease that is increasingly imposing major threats globally. We analyzed ADRD in 28 countries including China, the United Kingdom, the United States, Israel, and 24 countries in the European Union. The studies featured in the publication document global patterns and trends for ADRD, promote more equitable and efficient resource allocations for people living with dementia, and suggest ways to enhance care quality and the well-being of caregivers. The issue also explores ways to optimize health policy and practices for this fast-growing patient population. Specific topics involved inpatient care, hospitalization outcomes, and costs for dementia patients as well as COVID-19 stay-at-home orders and cognitive health; polypharmacy among dementia patients; and early-life disadvantages and disparities in cognitive aging. Caregiving and long-term care needs for people with dementia is also discussed.
What were some of the key findings in the publication?
XC: Through this special issue, our interdisciplinary team of experts aimed to present novel evidence on ADRD prevention, interventions, and care that may be applied at the global scale.
There are three key messages: First, it is never too early in the life course for dementia prevention. In addition to the modifiable risk factors for dementia in midlife or later life identified in previous work, this special issue further demonstrates that better early life circumstances, especially family socioeconomic status, could substantially narrow cross-country gaps in cognition in older ages.
Second, disparities in ADRD disease burden, underdiagnosis, and inadequate and inequitable allocation of resources for dementia care remain common in both developed and developing countries. This often leads disadvantaged dementia patients to preventable hospital admissions with poor outcomes and high costs.
Third, home-based, community-based, and institutional care account for the largest share of overall social costs dementia patients incur and will continue to increase rapidly. Care use rises significantly with the severity of functional limitations and cognitive impairment. Long-term care financing has been a global challenge. A heightened need for state-funded support for people with dementia and their caregivers is often unmet with the current decentralized and fragmented long-term care financing system.
What global patterns and trends in ADRD did the issue identify?
XC: Worldwide, the number of people living with dementia is rapidly increasing and is projected to triple by 2050, rising particularly in low-income and middle-income countries where around two-thirds of people with dementia currently live. In the meantime, the age-specific incidence of dementia has fallen in some developed countries. More advantageous early life environments and effective interventions in midlife or later life may play an important positive role. Cross-country comparisons in this special issue may offer insights into opportunities for countries to learn from each other as they strive to support people living with dementia.
Moreover, with a growing number of people living with dementia, the practice of taking multiple medications to manage symptoms or comorbidities, i.e., polypharmacy, has become a global health challenge due to the adverse effects of concurrent medications. This special issue identifies a higher prevalence of polypharmacy.
Lastly, lack of social support negatively impacts cognitive functioning and increases the risk of cognitive impairment. During the pandemic, social isolation and loneliness was like a tsunami for dementia patients, especially for those in formal care facilities. However, for community-dwelling older adults, COVID restriction policies, such as stay-at-home orders, may impose more muted impacts.
How can we promote health equity for people with or at risk of ADRD?
XC: There are two key aspects through which we may substantially promote health equity for people at risk of ADRD. First, disadvantaged individuals need prevention strategies and early interventions. Prevention and interventions at both individual and aggregate policy levels, from early stages of life throughout the life course, will help mitigate disparities. For example, educational segregation has been widely linked to racial and ethnic disparities in brain development and risk of dementia. Marked racial and ethnic gaps in prevalence and incidence of dementia persist in the U.S. Policies that promote better quality and experiences of education may help reduce these gaps for younger generations.
Second, countries have been striving to offer more equitable care financing, organization, and delivery of services for people living with dementia, which requires building a sustainable health care and long-term care workforce, improving insurance policies, and integrating current fragmented care systems. In this issue, we document large geographic variations in health care use, outcomes, and costs for patients hospitalized for dementia in developing countries like China, where the largest global population of adults living with dementia resides. Despite improved access to health services, gaps in equity and efficiency of dementia care and management remain.
What policy and practice changes are necessary to improve ADRD care?
XC: Health policy and practices on ADRD studied in this special issue and in general call for acting now on dementia prevention, intervention, and care to improve well-being for individuals with dementia and their families, and thus society.
Prevention and interventions are about policy and individuals. Contributions to the risk of dementia and its mitigation begin early and continue throughout life, so it is never too early or too late. These actions require both public health and social programs and individually tailored interventions. For instance, leveraging the identified modifiable risk factors, policies on ADRD should prioritize more equitable education and public health initiatives minimizing the risks of exposure to air pollution, head injury, smoking, excessive alcohol use, hypertension, hearing loss, obesity, depression, physical inactivity, diabetes, and social isolation to reduce young-onset and later-life dementia.
In addition to population strategies, individualized interventions should target high-risk groups with these identified risk characteristics. Care provision should consider the person, as well as their family caregivers. For example, evidence is accumulating for the effectiveness of psychosocial interventions tailored to the patient’s needs to manage neuropsychiatric symptoms. Evidence-based interventions for caregivers can reduce depressive and anxiety symptoms and be cost-effective in the long term.
What are the greatest challenges facing ADRD research, treatment. and quality of care?
XC: As one of the most expensive and rapidly rising diseases, we are faced with several major challenges related to ADRD. First, there is no cure, and we even have no consensus about its causes. All existing treatments are symptomatic drugs, meaning that there are no disease-modifying drugs targeting the underlying causes of disease. In the last 20 years, 400+ ADRD drugs have been brought to clinical trials but failed. The extremely high risk of drug R&D will undermine the affordability of new treatments. Second, while dementia tends to be underdiagnosed in most countries, the disappointing results of clinical trials of new treatments shifts attention from treating symptomatic individuals to identifying and treating at-risk individuals without symptoms, which carries the risk of overdiagnosis. It is therefore difficult to minimize both the risks of underdiagnosis and overdiagnosis. Third, many risk factors are structural and cluster around minority groups. Tackling these factors will involve not only health promotion but also systematic societal actions to improve the circumstances in which people live their lives, such as eliminating discrimination and improving nutrition, education, and environmental quality. Lastly, while modifiable risk factors have been identified, behavior change is difficult, and some associations may not be causal.