Table 1.
Global, sex, and SDI trends in the incidence of Alzheimer’s disease and other dementias among adults aged 55 years and older, from 1992 to 2021.
Fig 1.
Incidence of Alzheimer’s disease and other dementias among adults aged 55 years and older across 204 countries and territories from 1992 to 2021.
A: World map of ASIR for Alzheimer’s disease and other dementias in 2021; B: World map of net drifts for Alzheimer’s disease and other dementias incidence (i.e., estimated annual percentage change in incidence from the APC model). Net drift captures components of the trends attributable to calendar time and successive birth cohorts. ASIR, age-standardized incidence rate; APC, age-period-cohort.
At the country level, Nigeria and Sao Tome and Principe recorded the lowest ASIR of Alzheimer’s disease and other dementias among adults aged 55 years and older in 2021, whereas China and Germany reported the highest ASIR. Between 1992 and 2021, geographic heterogeneity characterized global Alzheimer’s disease and other dementias ASIR patterns, manifested as rising trends in select countries and territories while a majority demonstrated declining trajectories. (Interpretation of Fig 1).
Table 2.
Global, sex, and SDI trends in the prevalence of Alzheimer’s disease and other dementias among adults aged 55 years and older, from 1992 to 2021.
Fig 2.
Prevalence of Alzheimer’s disease and other dementias among adults aged 55 years and older across 204 countries and territories from 1992 to 2021.
A: World map of ASPR for Alzheimer’s disease and other dementias in 2021; B: World map of net drifts for the prevalence of Alzheimer’s disease and other dementias (i.e., estimated annual percentage change in prevalence from the APC model).Net drift captures components of the trends attributable to calendar time and successive birth cohorts. ASPR, age-standardized prevalence rate; APC, age-period-cohort.
In 2021, China exhibited the highest ASPR globally. While most countries exhibited a declining trend in ASPR from 1992 to 2021, China exhibited a distinct pattern, with the most marked increase in prevalence. (Interpretation of Fig 2).
Table 3.
Global, sex, and SDI trends in the mortality of Alzheimer’s disease and other dementias among adults aged 55 years and older, from 1992 to 2021.
Fig 3.
Mortality from Alzheimer’s disease and other dementias among adults aged 55 years and older across 204 countries and territories, 1992 to 2021.
A: World map of ASMR for Alzheimer’s disease and other dementias in 2021; B: World map of net drifts for Alzheimer’s disease and other dementias mortality (i.e., estimated annual percentage change in mortality from the APC model). Net drift captures components of the trends attributable to calendar time and successive birth cohorts. ASMR, age-standardized mortality rate; APC, age-period-cohort.
In 2021, China, the United States, and Japan had the greatest number of deaths from Alzheimer’s disease and other dementias, while Tokelau and Niue reported the fewest cases. The most significant growth in ASMR was documented in Saint Kitts and Nevis, followed by Kiribati, whereas Palau, the Marshall Islands, and Bahrain saw the largest declines in ASMR. (Interpretation of Fig 3).
Table 4.
Global, sex, and SDI trends in DALYs due to Alzheimer’s disease and other dementias among adults aged 55 years and older, from 1992 to 2021.
Fig 4.
DALYs due to Alzheimer’s disease and other dementias among adults aged 55 years and older across 204 countries and territories from 1992 to 2021.
A: World map of ASR of DALYs for Alzheimer’s disease and other dementias in 2021; B: World map of net drifts for Alzheimer’s disease and other dementias DALYs (i.e., estimated annual percentage change in DALYs from the APC model). Net drift captures components of the trends attributable to calendar time and successive birth cohorts. DALYs, disability-adjusted life-years; ASR, age-standardized rate; APC, age-period-cohort.
In 2021, the ASR of DALYs showed marked geographic disparities, with the highest burdens observed in the Democratic Republic of the Congo, Gabon, and Afghanistan, while Peru had the lowest rate. During the 1992–2021 period, India showed the steepest rise in ASR of DALYs (net drift, 0.5, 95% CI, 0.46 to 0.54). (Interpretation of Fig 4).
Fig 5.
Local drift of ADOD incidence (1992–2021) across SDI quintiles, along with age, period, and birth cohort effects, was analyzed using APC models.
A: Local drift of ADOD incidence across nine age groups (1992–2021). The local drift (i.e., annual percentage change of age-specific incidence, % per year) and its associated 95% CIs are indicated by the dots and shaded areas; B: The age effect is illustrated by longitudinal age-specific rates, adjusted for variations across birth cohorts while accounting for period-specific deviations; C: Period effects are quantified as the relative risk of ADOD incidence across time periods, calculated by comparing age-specific rates in each observation period (e.g., 2017–2021) to those in the baseline period (1992–1996); D: Cohort effects are shown as the cohort relative risk of incidence, calculated as the ratio of age-specific rates from the 1892–1901 cohort to the 1957–1966 cohort, with the reference cohort set at 1932–1941. The dots and shaded areas represent the incidence rates or rate ratios and their corresponding 95% CIs. ADOD, Alzheimer’s disease and other dementias; SDI, socio-demographic index.
Fig 6.
Local drift of ADOD mortality (1992–2021) across SDI quintiles, along with age, period, and birth cohort effects, was analyzed using APC models.
A: Local drift of ADOD mortality across nine age groups (1992–2021). The local drift (i.e., annual percentage change of age-specific mortality, % per year) and its associated 95% CIs are indicated by the dots and shaded areas; B: The age effect is illustrated by longitudinal age-specific rates, adjusted for variations across birth cohorts while accounting for period-specific deviations; C: Period effects are quantified as the relative risk of ADOD mortality across different time periods, calculated by comparing age-specific rates in each observation period (e.g., 2017–2021) to those in the baseline period (1992–1996); D: Cohort effects are shown as the cohort relative risk of mortality, calculated as the ratio of age-specific rates from the 1892–1901 cohort to the 1957–1966 cohort, with the reference cohort set at 1932–1941. The dots and shaded areas represent the incidence rates or rate ratios and their corresponding 95% CIs. ADOD, Alzheimer’s disease and other dementias; SDI, socio-demographic index.
Fig 7.
Future projections of ASIR, ASMR, and the number of ADOD cases (1992–2046).
A: Projected ADOD incidence rates (1992–2046) for both sexes combined, males, and females in the population aged 55 years and older; B: Projected incident cases (1992–2046) for both sexes combined, as well as separately for males and females, in the population aged 55 years and older; C: Projected ADOD mortality rates (1992–2046) for both sexes combined, males, and females in the population aged 55 years and older; D: Projected number of deaths (1992–2046) for both sexes combined, as well as separately for males and females, in the population aged 55 years and older. Solid lines represent observed ASIR and ASMR, while dashed lines indicate ASIR and ASMR projections based on the Nordpred model. ASIR, age-standardized incidence rate; ASMR, age-standardized mortality rate; ADOD, Alzheimer’s disease and other dementias.