Dementia affects over 57 million people worldwide, and this number is expected to climb significantly. By 2030, it is estimated that 78 million people will have dementia, and by 2050, this figure could reach 139 million. Despite these alarming projections, a surprising new study suggests that the risk of developing dementia may have declined with each successive generation. However, experts urge caution in interpreting these findings.
The study analyzed data from 62,437 individuals aged 70 and over, drawn from three longitudinal cohort studies on aging conducted in the United States, Europe, and England. Researchers compared probable dementia diagnoses across eight generational cohorts, ranging from those born between 1890-1913 to those born between 1944-48.
Assessing Dementia Risk Across Generations
To evaluate dementia risk, researchers employed an algorithm that considered participants’ demographic characteristics, cognitive performance, and daily functioning abilities. These are standard tools used in clinical practice for diagnosing dementia. The algorithm’s projections were validated against a sub-sample from the US Aging, Demographics and Memory study, which included participants with clinical dementia diagnoses. The algorithm showed an over 85% agreement with clinical diagnosis data.
Once dementia status was established, the researchers developed two models to explore the relationship between age, cohort, and dementia onset. They also considered gross domestic product (GDP) in their analyses, given the established correlation between GDP and health outcomes. The findings revealed a decrease in dementia cases with each subsequent generation. In the US, for example, 25% of those born between 1890-1912 developed dementia, compared to only 15% of those born between 1939-1943.
Geographical Variations and Gender Differences
In England, the study indicated that nearly 16% of individuals born between 1924-28 developed dementia, compared with around 15% of those born between 1934-38. Interestingly, the decline in dementia cases appeared more pronounced among women than men. However, the reasons behind this generational decline remain unclear, particularly as recent cohorts show reduced dementia cases.
Limitations and Considerations
While the study utilized a large sample from well-established aging research cohorts, its findings are based solely on data from high-income countries. Dementia is often better diagnosed and managed in these regions due to superior healthcare services. In contrast, dementia remains highly stigmatized in low- and middle-income countries, where awareness and diagnosis are less prevalent.
This disparity highlights a significant limitation of the study: the lack of representative data from lower-income countries, where most dementia cases are expected to occur. Additionally, the study’s prediction model, despite its high agreement with clinical diagnoses, may have missed certain dementia cases. The model also did not differentiate between dementia subtypes, such as Alzheimer’s disease, Lewy Body dementia, or semantic dementia, each with distinct symptoms.
Future Implications and Projections
Despite the study’s findings, global dementia cases are projected to increase due to longer life expectancies and an aging population. Dementia primarily affects individuals over 65, so as more people reach this age, the risk of developing dementia grows. The world population is also expanding, particularly in low- and middle-income countries, where healthcare infrastructure is often inadequate to address modifiable dementia risk factors.
Socioeconomic disparities further complicate the picture, as individuals from disadvantaged backgrounds face greater health inequalities, potentially increasing their dementia risk. However, the study did not account for these socioeconomic factors, making it challenging to predict differences in dementia prevalence among younger generations.
As Clarissa Giebel, Senior Research Fellow at the Institute of Population Health, University of Liverpool, notes, the study’s findings should be interpreted with caution. While they offer hope, they do not necessarily indicate a continuing decline in dementia prevalence for future generations.
This article is republished from The Conversation under a Creative Commons license. Read the original article.
