The report by Stallard et al. is provocative for two reasons. First, in their attempts to correct national projections of dementia prevalence for the modest downturns in prevalence reported by several studies, the authors convey a message of hope. That is to say, the future certainly holds a large percentage of older adults in the U.S. living with dementia, but that percentage and the corresponding number of their families and affected communities may be smaller than previously forecast. Prior projections typically assumed that dementia incidence and survival would remain unchanged over time.…More
The second reason this paper is provocative—and here I could be mistaken, but I am concerned—is that it mainly reflects the experience of white older adults. If that is the case, the hope offered—to families and to individuals—may be less. Why does this matter? The racial and ethnic composition of the U.S. older adult population is poised to change over coming decades. Among adults age 65 and older, the percentage who are black is projected to increase from 11 to 14, and the percentage who are Hispanic is slated to nearly double from 11 to 20. During this same period, the percentage who are white is projected to drop from 75 to 65. These patterns are exaggerated among those 85 and older (Census.gov). It is individuals from this group who make up most of the participants in studies of secular trends in dementia incidence and prevalence. This limitation of the evidence base was also described by the authors of the systematic review cited by the authors (Mukadam et al., 2024).
The underrepresentation of black, Hispanic/Latino older adults in research on secular trends in dementia, as in research on dementia in general, is critical because, in the U.S., black older adults have about twice the risk of dementia as do whites (Muir et al., 2024). Estimates of dementia risk in Hispanic older adults are sparser and often based on smaller sizes. Most of the few studies in this population suggest that they face dementia risks similar to that of, or exceed, the dementia risk among non-Hispanic whites (Alzheimer’s Association 2024). The few studies to evaluate how dementia prevalence and/or incidence has been changing over time among black or Hispanic older adults are equivocal. Some have found little change over time, whereas others have observed a decline in dementia prevalence among black adults, but with little change in the dementia prevalence disparity between black and white adults (Rajan et al., 2019; Chen and Zissimopoulo, 2018; Power et al., 2021).
It may be that dementia prevalence has been falling among these underrepresented populations. The evidence isn’t as robust as it is in the larger evidence among white individuals, and the evidence that does exist is based on sample sizes of black and/or Hispanic older adults that are sometimes an order of magnitude smaller than the samples of white participants. Frustrating matters further, as Livingston et al. state in their Lancet Commission report on dementia risk factors, most of what we know about how to prevent and treat dementia comes from studies of older white adults (Livingston et al., 2024). The populations of black and Hispanic older adults are growing, but we have painfully few indications about what their future dementia experience will be.
References:
Mukadam N, Wolters FJ, Walsh S, Wallace L, Brayne C, Matthews FE, Sacuiu S, Skoog I, Seshadri S, Beiser A, Ghosh S, Livingston G.
Changes in prevalence and incidence of dementia and risk factors for dementia: an analysis from cohort studies.
Lancet Public Health. 2024 Jul;9(7):e443-e460.
PubMed.
Muir RT, Hill MD, Black SE, Smith EE.
Minimal clinically important difference in Alzheimer's disease: Rapid review.
Alzheimers Dement. 2024 May;20(5):3352-3363. Epub 2024 Apr 1
PubMed.
Rajan KB, Weuve J, Barnes LL, Wilson RS, Evans DA.
Prevalence and incidence of clinically diagnosed Alzheimer's disease dementia from 1994 to 2012 in a population study.
Alzheimers Dement. 2019 Jan;15(1):1-7. Epub 2018 Sep 7
PubMed.
Chen C, Zissimopoulos JM.
Racial and ethnic differences in trends in dementia prevalence and risk factors in the United States.
Alzheimers Dement (N Y). 2018;4:510-520. Epub 2018 Oct 5
PubMed.
Livingston G, Huntley J, Liu KY, Costafreda SG, Selbæk G, Alladi S, Ames D, Banerjee S, Burns A, Brayne C, Fox NC, Ferri CP, Gitlin LN, Howard R, Kales HC, Kivimäki M, Larson EB, Nakasujja N, Rockwood K, Samus Q, Shirai K, Singh-Manoux A, Schneider LS, Walsh S, Yao Y, Sommerlad A, Mukadam N.
Dementia prevention, intervention, and care: 2024 report of the Lancet standing Commission.
Lancet. 2024 Aug 10;404(10452):572-628. Epub 2024 Jul 31
PubMed.
The projections presented by Stallard et al. are based on existing data for the United States over the past 40 years and on some important assumptions. The projections are reasonable if we accept those assumptions. On the optimistic side, we can argue that history offers reasons for hope. The burden of disease is malleable and may change with time. Humans can modify the burden of disease with political, social, and medical interventions. On the less optimistic side, we must remember that the changes in risk over time may vary by sex and gender, across ethnic and cultural groups, and across U.S. states or countries worldwide. Trends in chronic diseases, such as dementia, reflect complex interactions of multiple risk and protective factors or events. The changes are very delicate, unstable, and contingent. The incidence of dementia has declined over the past 30 or 40 years in some countries but the future remains uncertain.…More
We need to continue to study the trends in risk of dementia in the coming years, and we need to continue to implement interventions targeting the known modifiable risk factors. Even though a dementia decline has begun, it might not last in the coming decades. The future depends on the balance of diverging trends. The increasing education levels, the reduction in smoking and the introduction of medications to better control hypertension, hyperlipidemia, diabetes, or depression may support the prediction of a continuing reduction in risk. However, obesity, diabetes, hypertension, depression, multi-morbidity, and polypharmacy are increasing over time. These trends may dampen the decline and may even contribute to an increasing risk of dementia in the future. For example, increasing rates of dementia over time have been reported for Japan and Italy, and stable rates were reported for Nigeria.
Stallard et al. have summarized existing evidence from population representative studies in the U.S. and beyond to propose that future dementia numbers may not rise as much as has been suggested by others (Stallard et al., 2025). They rightly highlight consistent findings that age-specific prevalence and incidence has been shown to be lower in more recent birth cohorts than earlier ones. They extrapolate these reductions across time to provide future scenarios that still include substantial increases in numbers due to population aging, but are less alarming.…More
The exercise is appropriately cautious, pointing out that there are major uncertainties. Risk and protective factors, such as obesity, diabetes, heart disease, etc., are changing substantially across time, and affect individuals at different life stages. We do not know what the causal windows might be in terms of these risk factors, and the reasons for the age-specific declines remain largely unknown. All the risk factors that we understand, including those within and outside the Lancet Commission’s most recent list (Livingston et al., 2024), cluster with disadvantage.
There is little active fieldwork that is truly representative of the many communities within the U.S., drilling down deeply to understand variation in prevalence and incidence. The large national studies are important, but they need to be supplemented by estimates from robust descriptive epidemiological work in contemporary older populations who were not included. The danger of using national studies without such additional work is that they can, despite huge efforts, still miss substantial populations at varying risk because their sampling approaches simply cannot reach those people.
Ideally, national studies would also be validated at regular intervals along the lines of the Aging Demographics and Memory Study, using both past diagnostic study criteria and those in use today (Langa et al., 2005). As with hypertension and diabetes, changing the criteria across time creates an instability in understanding what the true changes in populations are, as noted by the authors. Moving toward preclinical states automatically increases the proportion of the population included in that diagnostic criterion.
Such biases need to be understood—as they can push estimates both up and down.
The authors rightly note that these quite critical international findings have largely been underplayed in our media and have not really reached our politicians. Who, if they understood the implications, would perhaps support more efforts for primary prevention at scale, including the research efforts in this area (Walsh et al., 2022). On a positive note, investment into initiatives such as the Gateway Exposome Coordinating Centre by the NIA should yield very valuable information for the increasing number of researchers interested in this area. Some risk and protective factors are “no-brainers” and there is already evidence supporting more work on intervention in this regard, aligned to healthy ageing itself (Walsh et al., 2023; Mukadam et al., 2024). The WHO Ageing focus and the Population Level Approaches to Dementia Risk Reduction are both working with life-course policy analysis to encourage such action (World Health Organization, 2022; Walsh et al., 2023).
References:
Stallard PJ, Ukraintseva SV, Doraiswamy PM.
Changing Story of the Dementia Epidemic.
JAMA. 2025 Mar 12; Epub 2025 Mar 12
PubMed.
Livingston G, Huntley J, Liu KY, Costafreda SG, Selbæk G, Alladi S, Ames D, Banerjee S, Burns A, Brayne C, Fox NC, Ferri CP, Gitlin LN, Howard R, Kales HC, Kivimäki M, Larson EB, Nakasujja N, Rockwood K, Samus Q, Shirai K, Singh-Manoux A, Schneider LS, Walsh S, Yao Y, Sommerlad A, Mukadam N.
Dementia prevention, intervention, and care: 2024 report of the Lancet standing Commission.
Lancet. 2024 Aug 10;404(10452):572-628. Epub 2024 Jul 31
PubMed.
Langa KM, Plassman BL, Wallace RB, Herzog AR, Heeringa SG, Ofstedal MB, Burke JR, Fisher GG, Fultz NH, Hurd MD, Potter GG, Rodgers WL, Steffens DC, Weir DR, Willis RJ.
The Aging, Demographics, and Memory Study: study design and methods.
Neuroepidemiology. 2005;25(4):181-91.
PubMed.
Walsh S, Govia I, Wallace L, Richard E, Peters R, Anstey KJ, Brayne C.
A whole-population approach is required for dementia risk reduction.
Lancet Healthy Longev. 2022 Jan;3(1):e6-e8.
PubMed.
Walsh S, Wallace L, Kuhn I, Mytton O, Lafortune L, Wills W, Mukadam N, Brayne C.
Population-level interventions for the primary prevention of dementia: a complex evidence review.
Lancet. 2023 Nov;402 Suppl 1:S13.
PubMed.
Mukadam N, Anderson R, Walsh S, Wittenberg R, Knapp M, Brayne C, Livingston G.
Benefits of population-level interventions for dementia risk factors: an economic modelling study for England.
Lancet Healthy Longev. 2024 Sep;5(9):100611. Epub 2024 Jul 31
PubMed.
World Health Organization.
A blueprint for dementia research.
World Health Organization, 4 October 2022World Health Organization
Walsh S, Govia I, Peters R, Richard E, Stephan BC, Wilson NA, Wallace L, Anstey KJ, Brayne C.
What would a population-level approach to dementia risk reduction look like, and how would it work?.
Alzheimers Dement. 2023 Jul;19(7):3203-3209. Epub 2023 Feb 15
PubMed.
This is an interesting analysis and perspective. It's true that dementia prevalence and incidence appear to be declining with successive birth cohorts. There are many generational changes in risk factor profiles that may explain this, particularly improvements in education and management of chronic health conditions.
This analysis provides evidence to support our forecast from 2011, and subsequent Lancet Commission reports, which estimated that up to half of the anticipated increase in dementia due to the aging of the population could potentially be prevented through risk reduction interventions. This analysis suggests that we have made changes at a societal level that have fundamentally reduced dementia risk at a given age. They provide hope that ongoing and future efforts to target modifiable risk factors will result in continued reductions in dementia risk for younger generations.…More
Comments
Boston University
The report by Stallard et al. is provocative for two reasons. First, in their attempts to correct national projections of dementia prevalence for the modest downturns in prevalence reported by several studies, the authors convey a message of hope. That is to say, the future certainly holds a large percentage of older adults in the U.S. living with dementia, but that percentage and the corresponding number of their families and affected communities may be smaller than previously forecast. Prior projections typically assumed that dementia incidence and survival would remain unchanged over time.…More
The second reason this paper is provocative—and here I could be mistaken, but I am concerned—is that it mainly reflects the experience of white older adults. If that is the case, the hope offered—to families and to individuals—may be less. Why does this matter? The racial and ethnic composition of the U.S. older adult population is poised to change over coming decades. Among adults age 65 and older, the percentage who are black is projected to increase from 11 to 14, and the percentage who are Hispanic is slated to nearly double from 11 to 20. During this same period, the percentage who are white is projected to drop from 75 to 65. These patterns are exaggerated among those 85 and older (Census.gov). It is individuals from this group who make up most of the participants in studies of secular trends in dementia incidence and prevalence. This limitation of the evidence base was also described by the authors of the systematic review cited by the authors (Mukadam et al., 2024).
The underrepresentation of black, Hispanic/Latino older adults in research on secular trends in dementia, as in research on dementia in general, is critical because, in the U.S., black older adults have about twice the risk of dementia as do whites (Muir et al., 2024). Estimates of dementia risk in Hispanic older adults are sparser and often based on smaller sizes. Most of the few studies in this population suggest that they face dementia risks similar to that of, or exceed, the dementia risk among non-Hispanic whites (Alzheimer’s Association 2024). The few studies to evaluate how dementia prevalence and/or incidence has been changing over time among black or Hispanic older adults are equivocal. Some have found little change over time, whereas others have observed a decline in dementia prevalence among black adults, but with little change in the dementia prevalence disparity between black and white adults (Rajan et al., 2019; Chen and Zissimopoulo, 2018; Power et al., 2021).
It may be that dementia prevalence has been falling among these underrepresented populations. The evidence isn’t as robust as it is in the larger evidence among white individuals, and the evidence that does exist is based on sample sizes of black and/or Hispanic older adults that are sometimes an order of magnitude smaller than the samples of white participants. Frustrating matters further, as Livingston et al. state in their Lancet Commission report on dementia risk factors, most of what we know about how to prevent and treat dementia comes from studies of older white adults (Livingston et al., 2024). The populations of black and Hispanic older adults are growing, but we have painfully few indications about what their future dementia experience will be.
References:
Mukadam N, Wolters FJ, Walsh S, Wallace L, Brayne C, Matthews FE, Sacuiu S, Skoog I, Seshadri S, Beiser A, Ghosh S, Livingston G. Changes in prevalence and incidence of dementia and risk factors for dementia: an analysis from cohort studies. Lancet Public Health. 2024 Jul;9(7):e443-e460. PubMed.
Muir RT, Hill MD, Black SE, Smith EE. Minimal clinically important difference in Alzheimer's disease: Rapid review. Alzheimers Dement. 2024 May;20(5):3352-3363. Epub 2024 Apr 1 PubMed.
2024 Alzheimer's disease facts and figures. Alzheimers Dement. 2024 May;20(5):3708-3821. Epub 2024 Apr 30 PubMed.
Rajan KB, Weuve J, Barnes LL, Wilson RS, Evans DA. Prevalence and incidence of clinically diagnosed Alzheimer's disease dementia from 1994 to 2012 in a population study. Alzheimers Dement. 2019 Jan;15(1):1-7. Epub 2018 Sep 7 PubMed.
Chen C, Zissimopoulos JM. Racial and ethnic differences in trends in dementia prevalence and risk factors in the United States. Alzheimers Dement (N Y). 2018;4:510-520. Epub 2018 Oct 5 PubMed.
Livingston G, Huntley J, Liu KY, Costafreda SG, Selbæk G, Alladi S, Ames D, Banerjee S, Burns A, Brayne C, Fox NC, Ferri CP, Gitlin LN, Howard R, Kales HC, Kivimäki M, Larson EB, Nakasujja N, Rockwood K, Samus Q, Shirai K, Singh-Manoux A, Schneider LS, Walsh S, Yao Y, Sommerlad A, Mukadam N. Dementia prevention, intervention, and care: 2024 report of the Lancet standing Commission. Lancet. 2024 Aug 10;404(10452):572-628. Epub 2024 Jul 31 PubMed.
View all comments by Jennifer WeuveMayo Clinic
The projections presented by Stallard et al. are based on existing data for the United States over the past 40 years and on some important assumptions. The projections are reasonable if we accept those assumptions. On the optimistic side, we can argue that history offers reasons for hope. The burden of disease is malleable and may change with time. Humans can modify the burden of disease with political, social, and medical interventions. On the less optimistic side, we must remember that the changes in risk over time may vary by sex and gender, across ethnic and cultural groups, and across U.S. states or countries worldwide. Trends in chronic diseases, such as dementia, reflect complex interactions of multiple risk and protective factors or events. The changes are very delicate, unstable, and contingent. The incidence of dementia has declined over the past 30 or 40 years in some countries but the future remains uncertain.…More
We need to continue to study the trends in risk of dementia in the coming years, and we need to continue to implement interventions targeting the known modifiable risk factors. Even though a dementia decline has begun, it might not last in the coming decades. The future depends on the balance of diverging trends. The increasing education levels, the reduction in smoking and the introduction of medications to better control hypertension, hyperlipidemia, diabetes, or depression may support the prediction of a continuing reduction in risk. However, obesity, diabetes, hypertension, depression, multi-morbidity, and polypharmacy are increasing over time. These trends may dampen the decline and may even contribute to an increasing risk of dementia in the future. For example, increasing rates of dementia over time have been reported for Japan and Italy, and stable rates were reported for Nigeria.
View all comments by Walter A. RoccaCambridge University
University of Cambridge
Stallard et al. have summarized existing evidence from population representative studies in the U.S. and beyond to propose that future dementia numbers may not rise as much as has been suggested by others (Stallard et al., 2025). They rightly highlight consistent findings that age-specific prevalence and incidence has been shown to be lower in more recent birth cohorts than earlier ones. They extrapolate these reductions across time to provide future scenarios that still include substantial increases in numbers due to population aging, but are less alarming.…More
The exercise is appropriately cautious, pointing out that there are major uncertainties. Risk and protective factors, such as obesity, diabetes, heart disease, etc., are changing substantially across time, and affect individuals at different life stages. We do not know what the causal windows might be in terms of these risk factors, and the reasons for the age-specific declines remain largely unknown. All the risk factors that we understand, including those within and outside the Lancet Commission’s most recent list (Livingston et al., 2024), cluster with disadvantage.
There is little active fieldwork that is truly representative of the many communities within the U.S., drilling down deeply to understand variation in prevalence and incidence. The large national studies are important, but they need to be supplemented by estimates from robust descriptive epidemiological work in contemporary older populations who were not included. The danger of using national studies without such additional work is that they can, despite huge efforts, still miss substantial populations at varying risk because their sampling approaches simply cannot reach those people.
Ideally, national studies would also be validated at regular intervals along the lines of the Aging Demographics and Memory Study, using both past diagnostic study criteria and those in use today (Langa et al., 2005). As with hypertension and diabetes, changing the criteria across time creates an instability in understanding what the true changes in populations are, as noted by the authors. Moving toward preclinical states automatically increases the proportion of the population included in that diagnostic criterion.
Such biases need to be understood—as they can push estimates both up and down.
The authors rightly note that these quite critical international findings have largely been underplayed in our media and have not really reached our politicians. Who, if they understood the implications, would perhaps support more efforts for primary prevention at scale, including the research efforts in this area (Walsh et al., 2022). On a positive note, investment into initiatives such as the Gateway Exposome Coordinating Centre by the NIA should yield very valuable information for the increasing number of researchers interested in this area. Some risk and protective factors are “no-brainers” and there is already evidence supporting more work on intervention in this regard, aligned to healthy ageing itself (Walsh et al., 2023; Mukadam et al., 2024). The WHO Ageing focus and the Population Level Approaches to Dementia Risk Reduction are both working with life-course policy analysis to encourage such action (World Health Organization, 2022; Walsh et al., 2023).
References:
Stallard PJ, Ukraintseva SV, Doraiswamy PM. Changing Story of the Dementia Epidemic. JAMA. 2025 Mar 12; Epub 2025 Mar 12 PubMed.
Livingston G, Huntley J, Liu KY, Costafreda SG, Selbæk G, Alladi S, Ames D, Banerjee S, Burns A, Brayne C, Fox NC, Ferri CP, Gitlin LN, Howard R, Kales HC, Kivimäki M, Larson EB, Nakasujja N, Rockwood K, Samus Q, Shirai K, Singh-Manoux A, Schneider LS, Walsh S, Yao Y, Sommerlad A, Mukadam N. Dementia prevention, intervention, and care: 2024 report of the Lancet standing Commission. Lancet. 2024 Aug 10;404(10452):572-628. Epub 2024 Jul 31 PubMed.
Langa KM, Plassman BL, Wallace RB, Herzog AR, Heeringa SG, Ofstedal MB, Burke JR, Fisher GG, Fultz NH, Hurd MD, Potter GG, Rodgers WL, Steffens DC, Weir DR, Willis RJ. The Aging, Demographics, and Memory Study: study design and methods. Neuroepidemiology. 2005;25(4):181-91. PubMed.
Walsh S, Govia I, Wallace L, Richard E, Peters R, Anstey KJ, Brayne C. A whole-population approach is required for dementia risk reduction. Lancet Healthy Longev. 2022 Jan;3(1):e6-e8. PubMed.
Walsh S, Wallace L, Kuhn I, Mytton O, Lafortune L, Wills W, Mukadam N, Brayne C. Population-level interventions for the primary prevention of dementia: a complex evidence review. Lancet. 2023 Nov;402 Suppl 1:S13. PubMed.
Mukadam N, Anderson R, Walsh S, Wittenberg R, Knapp M, Brayne C, Livingston G. Benefits of population-level interventions for dementia risk factors: an economic modelling study for England. Lancet Healthy Longev. 2024 Sep;5(9):100611. Epub 2024 Jul 31 PubMed.
World Health Organization. A blueprint for dementia research. World Health Organization, 4 October 2022 World Health Organization
Walsh S, Govia I, Peters R, Richard E, Stephan BC, Wilson NA, Wallace L, Anstey KJ, Brayne C. What would a population-level approach to dementia risk reduction look like, and how would it work?. Alzheimers Dement. 2023 Jul;19(7):3203-3209. Epub 2023 Feb 15 PubMed.
View all comments by Sebastian WalshUniversity of California, San Francisco
This is an interesting analysis and perspective. It's true that dementia prevalence and incidence appear to be declining with successive birth cohorts. There are many generational changes in risk factor profiles that may explain this, particularly improvements in education and management of chronic health conditions.
This analysis provides evidence to support our forecast from 2011, and subsequent Lancet Commission reports, which estimated that up to half of the anticipated increase in dementia due to the aging of the population could potentially be prevented through risk reduction interventions. This analysis suggests that we have made changes at a societal level that have fundamentally reduced dementia risk at a given age. They provide hope that ongoing and future efforts to target modifiable risk factors will result in continued reductions in dementia risk for younger generations.…More
View all comments by Deborah BarnesMake a Comment
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