By: Meti Abdella
Former Clinical Trial Intake Navigator
By: Timag Sherif
Former Clinical Trial Intake Navigator
Alzheimer’s disease (AD) is the most common form of dementia, a neurodegenerative disease that is characterized by two biological features, β-amyloid plaque and tau tangles 1. The disease makes up 80% of Dementia diagnoses, and between the years 2000 and 2014, the proportion of AD-related deaths has increased by 89% partly due to the aging of the population 2. Around 55 million adults are estimated to have Alzheimer’s and related dementia diseases (ADRD) worldwide, but around 75% remain undiagnosed, reaching up to 90% in lower and middle income Countries3.
Regional variance in prevalence rates suggest that, beyond biological and genetic risk factors, external influences such as where an individual lives may shape their vulnerability to AD. Socio-demographics and economic development influence how countries and governments across the world determine resource allocation and policies4. This article aims to explore how geographic location can influence an individual’s risk of developing Alzheimer’s disease (AD), and the roles that access to healthcare and social support systems play in explaining regional disparities in AD prevalence.
Global Patterns and Prevalence
Studies have found a notable rise in the burden of both Alzheimer’s disease and related dementias (ADRD) globally over the past three decades, including rises in incidence, death, and disability-adjusted life years (DALYs), a measure of years lost due to premature death and years lived with disability 4. It is projected that, by 2050, 68% of the projected increase in the global prevalence and burden of Alzheimer’s. However, the burden and disparities vary across populations, driven by differences in demographic, social, and economic factors. Higher incidence and prevalence rates are observed in developed nations, while lower rates are found in less developed nations. For example, trends over time or between specific regions (e.g., Sub-Saharan Africa vs. Europe) could be explicitly highlighted to better connect the visual data with the narrative. As life expectancy rises in less developed areas, these regions are seeing the fastest increases in deaths and DALYs 4.
Determinants of Geographic Disparities
Regional disparities in global Alzheimer’s disease (AD) rates can be attributed to a range of interconnected factors, including unequal access to and quality of healthcare, differences in social support systems and caregiving structures, as well as in socioeconomic status and educational attainment 6. These disparities are further shaped by gaps in health infrastructure, workforce training, public health funding, cultural attitudes toward aging and dementia, and the pace of population aging across regions.
A. Accessibility and quality of healthcare services
Access to skilled health professionals and diagnostic services allows for earlier detection and more accurate diagnosis of Alzheimer’s disease. Communities that live in isolation, such as rural or low-resource populations, often face challenges including shortages of specialized healthcare providers and facilities as well as difficulty accessing transportation, which can result in untimely or missed diagnosis7,8.
Thus, individuals with Alzheimer’s may not receive regular follow up, management of behavioral and psychiatric symptoms, or monitoring for medication side effects, leading to worse outcomes. Additionally, in some populations, structural barriers, bias and discrimination often limit healthcare access for marginalized minorities9.
B. Socio Economic Development
The Social Developmental Index (SDI), which incorporates education, income, and fertility rates, plays an important role in shaping the global distribution of Alzheimer’s disease. The disease burden is unevenly distributed among countries and populations with different levels of socio-demographic development. Findings reveal that both absolute and relative health inequalities in ADRD have widened and that regions with higher levels of education, economic development, and lower fertility rates (Higher SDI) are associated with higher incidence of ADRD4. Moreover, they are also more susceptible to risk factors related to lifestyle, such as obesity and physical inactivity. Thus, not only is the burden rising globally, but so is the gap between low and high SDI countries, further increasing the disparity between rich and poor nations 4. However, this could also be because of better reporting and a higher proportion of elderly individuals in those regions.
In addition, it was found that low and low-middle SDI regions faced the greatest increases in mortality and DALY rates, driven by weaker health systems, less availability of trained health professionals, lack of policy and prevention efforts, and poor resources for diagnosis, and treatment 10,11. Poverty, lack of access to quality healthcare, and housing insecurity may also amplify the risk of AD over the life course 4,9,10.
C. Lifestyle Factors
Countries where diets are rich in fruits, vegetables, legumes, whole grains, poultry, and fish and where physical activity is a routine part of daily life have shown better cognitive outcomes and lower rates of AD. For instance, a study showed that Nigerians have a lower prevalence of AD compared to populations in the United States, despite a higher genetic risk (APOE ε4 prevalence), partly due to their healthier diets lower in saturated fats and red meat as well as their more active lifestyles 12. In contrast, countries with diets high in saturated fats, simple sugars, and processed foods are linked to higher AD risk and poorer cognitive health outcomes 13.
D. Social networks
In the context of Alzheimer’s disease, social support plays a crucial role in managing cognitive decline and disease progression. The cognitive reserve hypothesis suggests that differences in cognitively stimulating environments can lead to differences in the level of cognitive reserve (CR)14. Individuals with higher levels of CR tend to cope better as the disease progresses and display delayed onset of symptoms15. The study conducted by Peng et al. aimed to evaluate social networks as a cognitively stimulating environment, and the findings suggested that individuals with above average CR had larger and more varied social networks. Moreover, their connections were less tightly clustered than those of people with lower CR14.
Social networks are heavily shaped by cultural values and norms. Culture is a complex construct that influences behavioral, cognitive, and emotional processes, which in turn shapes how social support is structured and experienced. This includes factors such as health behaviors, perceptions of illness, stigma, and even dementia risk. Many East Asian, Latino, and African cultures are considered collectivist, placing a strong emphasis on familial obligations and interdependence, which can enhance social connectedness and support 16. These cultural values may foster the development of larger, more diverse, and interconnected social networks, potentially contributing to higher levels of cognitive reserve.
Some may argue that while collectivist values may enhance social connectedness, they do not fully offset other significant risk factors for dementia. For instance, illiteracy, which was highlighted in a study conducted by Suh et al, was found to play a substantial role in increasing dementia risk17. The study, which evaluated dementia cases attributed to illiteracy across South Korean, Latin American, South Asian, Middle Eastern, and African populations, identified illiteracy as a contributing factor. However, it is important to note that differences in dementia prevalence and test performance across cultural groups are often misattributed to cultural factors when in many cases it stems primarily from disparities in education and literacy levels18. Addressing dementia risk requires consideration of both cultural influences and literacy, as their intersection plays an important role in shaping cognitive resilience and vulnerability. Recognizing this interplay shows the need for research and interventions that address not only cultural context but also disparities in education and literacy.
The risk, diagnosis, treatment, and care for Alzheimer’s disease are not shaped by a single identity or factor, but rather by the intersection of multiple social, economic, and health characteristics including age demographics, socioeconomic status, healthcare infrastructure, sociocultural practices, and lifestyle behaviors.
Conclusion
While Alzheimer’s disease and other dementias are projected to increase dramatically worldwide, the greatest growth is projected to be in low- and middle-income countries. This is due to faster population aging, larger population size, and delayed public health improvements compared to high-income countries. These regions also have fewer resources for prevention, diagnosis, and ongoing care. Regional disparities in Alzheimer’s disease are driven by differences in health infrastructure, public funding, social determinants of health, cultural attitudes, and population aging 6.
These disparities result in unequal diagnosis, care, and outcomes for people with AD around the world. Addressing these gaps is an important undertaking for global public health and requires coordinated international action focused on culturally sensitive diagnostic tools, greater public education, equitable healthcare access, and systematic efforts to reduce disparities in research, diagnosis, and care. Moreover, research and care must recognize and address these overlapping disadvantages to effectively reduce disparities and improve outcomes for all communities.
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