Skip to main content

Currently Skimming:

9 Cognitive Aging, Dementia, and the Future of an Aging Population - Kenneth M. Langa
Pages 249-268

The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.


From page 249...
... have been the focus of increasing attention from researchers, clinicians, and policy makers due to the projected significant increase in the number of dementia cases -- and the associated burdens to patients, families, and government support programs -- that is expected to result from the worldwide growth in the elderly population. However, a growing number of population-based studies have reported that the age-specific incidence and prevalence of dementia in a number of high-income countries may have declined over the past 25 years, suggesting that trends in some combination of demographic, behavioral, medical, and environmental factors have led to a decrease in dementia risk among older adults in these countries.
From page 250...
... and race/ethnicity in dementia risk, general health status, and life expectancy. The nature and causes of these disparities, how they have grown in past decades, and how they might be mitigated in the future are also extremely important issues for demographers, policy makers, and other researchers to address in the coming decades.
From page 251...
... ­ Education-related increases in "cognitive reserve" is a widely cited theory ­ for how education may decrease dementia risk. The cognitive reserve hypothesis posits that the cognitive challenges and stimulation associated with education lead to changes in brain structure (e.g., more neurons and more connections among the neurons)
From page 252...
... . Tracking dementia trends across countries with differing time trends in educational attainment may provide opportunities for a better understanding of the causal pathways leading from early-life education to late-life dementia risk (Langa et al., 2018)
From page 253...
... showed that a life course perspective regarding the impact of CRFs on cognitive decline is important, as the cumulative exposure to elevated levels of CRFs over 25 years of follow-up in individuals who were 18 to 30 years old at baseline was associated with significantly worse cognitive function in middle age. As discussed in more detail below, the importance of CRFs, especially in early and midlife, as
From page 254...
... potential causes for late-life dementia may be one reason for the clear SES disparities in brain health and dementia risk, since CRFs are more prevalent in individuals from low-SES groups and the SES disparities in the prevalence of those risk factors has been increasing in recent decades. An important issue regarding the relationship of CRFs to late-life dementia risk is whether better prevention or treatment of CRFs will not only reduce age-specific dementia risk later in life but will also lead to an extension of life expectancy that will, in turn, lead to a greater number of dementia cases due to people living to much older ages, when dementia risk increases sharply.
From page 255...
... The different conclusions from these two analyses hinge on the relative magnitude of the decrease in dementia incidence associated with a decline in CRFs compared to the decrease in future mortality risk; this relative magnitude is currently uncertain. Future research to more clearly define how prevention and treatment of CRFs throughout the life course are related to both future dementia risk and mortality at older ages will be especially important to determine the public health implications of population-level trends in CRFs and their treatment and to determine whether additional years of life are more likely to be spent with good or poor cognitive function (Schoeni et al., 2018)
From page 256...
... used tax records to examine income and life expectancy across time and region in the United States between 2001 and 2014. Similar to the National Academies analysis, those with high income had significantly longer life expectancies, and the income gap in life expectancy increased significantly during the 13-year period.
From page 257...
... , leading the authors to conclude that education's impact on the building of cognitive reserve throughout the life course, and chronic stress that may result from low SES, are likely important pathways leading to SES and racial/ethnic disparities in late-life dementia risk. Many other studies support the value of using a life course perspective to better understand and identify the complex and overlapping factors that have led to the large and growing SES and racial/ethnic disparities in dementia risk in the United States (for a review, see Glymour and Manly, 2008)
From page 258...
... . Other characteristics of one's neighborhood, separate from potential toxins in the physical environment, have also been shown to be related to cognitive function and dementia risk.
From page 259...
... 379) called this the "Next Frontier" in understanding and management of AD and proposed that in the future, AD may no longer be "a disease leading to irrevocable cognitive and functional decline and death, but rather a chronic condition like cardiovascular disease, AIDS, or some cancers that can often be managed with early intervention." One especially important new insight is that the brain pathologies and changes leading to AD and dementia are often present for decades prior to the onset of any cognitive decline.
From page 260...
... 260 PART V: DISABILITY AND COGNITIVE HEALTH OF THE OLDER POPULATION FIGURE 9-2  Dynamic biomarkers of the Alzheimer's disease pathological cascade. SOURCE: Reprinted with permission from Elsevier.
From page 261...
... Finally, given the significant SES and racial/ethnic disparities in dementia risk noted above, one other key issue regarding the generalizability of current data is important to consider regarding potential treatments for preclinical AD. Since nearly all of the data on biomarker and neuroimaging testing to identify preclinical AD have thus far come from volunteer samples, with very limited representation of less-educated and minority individuals, there is still significant uncertainty regarding the generalizability of those studies to low-SES and minority populations.
From page 262...
... Is online education a lower-cost option that will provide similar benefits for building cognitive reserve? The growing evidence that Alzheimer's disease and vascular disease are closely linked and may even be "two hits" of the same pathological process provides an important potential target for decreasing dementia risk, given the very high prevalence of CRFs among middle-aged and older adults and the known behavioral and pharmacologic interventions to prevent or treat them.
From page 263...
... Addressing these growing disparities in both dementia risk and life expectancy should be the main focus of public health and public policy in the decades ahead. REFERENCES Ailshire, J., Karraker, A., and Clarke, P
From page 264...
... . Cognitive function in the community setting: The neighbourhood as a source of "cognitive reserve"?
From page 265...
... . Examining trends in dementia incidence and prevalence using an Age-Period-Cohort framework.
From page 266...
... Collaboration. A two-decade dementia incidence comparison from the Cognitive Function and Ageing Studies I and II.
From page 267...
... . GWAS of 126,559 individuals identifies genetic variants associated with educational attainment.
From page 268...
... . Early adult to midlife cardiovascular risk factors and cognitive function.


This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More information on Chapter Skim is available.