A study of mortality from Alzheimer’s disease & other dementias

Ananya Ghosal, MAKAUT(WB)

40-50 million people are suffering from Alzheimer’s and other dementias worldwide. Due to the tendency of population aging and population growth, the number may rise to 100 million people suffering from the disease by 2050. From the population-based epidemiological study, dementia has been underreported on death certificates, even after including all contributing conditions and other significant conditions. The reporting on dementia on death is related to the location of the death as the deaths mostly occur in long-term care centers like psychiatric hospitals rather than home or general hospitals.

The previous repetition of the Global Burden of Diseases (GBD) is the only available worldwide estimate of dementia mortality. GBD 2015 introduced a new methodology for the estimation of dementia mortality. From GBD 2015, 2016, 2017 estimation of excess mortality which was derived from countries as a cause of death per general dementia cases. The method presumes that excess mortality is dependent on heterogeneous general data and sparse and is constant over time and location.

Methods

• Systematic review- In PubMed, there were 34 studies which were extracted. The data was heterogeneous and consist of (dementia, Alzheimer’s disease, and cognitive impairment).

• Analysis- The excess risk of dementia death was analyzed using the Bayesian bias-reduction meta-regression model. The model is consisting of the study of heterogeneity and adds uncertainty from heterogeneity to the coefficient estimate. The control categories included smoking and alcohol consumption, more extensive cardiovascular disease factors such as cholesterol and blood pressure, educational attainment, and basic cardiovascular disease comorbidities.

• Prevalence estimation- The Bayesian meta-regression tool i.e., DisMod MR-2.1 is used in non-fatal modeling for GBD. When the mortality is combined with the incidence data higher prevalence was reported.

• Calculation of excess dementia death-The multiplication of attributed risk and prevalence is the calculation of excess death which shows the total number of excess dementia death. The individual who died due to dementia had clinical markers end-stage disease one year before death. The subtraction with end-stage disease markers in those without dementia from those with dementias shows the individuals who have died with end-stage, severe dementia.

• Final calculation results-The proportions of those individuals who die with severe disease due to excess dementia and total excess dementia deaths give rise to the number of deaths due to dementia. The age-standardized rate was calculated by following World Population Standard for GBD. Aggregating the estimate from the detailed location was calculated to get a regional and global estimate.

Conclusion

In the year 2019, 1.55 million deaths were reported of end-stage dementia where the majority were women. Common comorbid conditions resulted in estimating excess mortality in those with dementia. Population aging is the main factor for increasing the number of dementia deaths which gives rise to the volume of dementia mortality. The current estimation method deleted all dependencies from the vital registration system. Meta-analytic methods were utilized to estimate global mortality due to dementia. To give more precise information on dementia mortality, the analysis should be strengthened.  

Also read: Human genome from the sediments of Georgia Cave

Reference: Nichols, E., & Vos, T. (2020). Estimating the global mortality from Alzheimer’s disease and other dementias: A new method and results from the Global Burden of Disease study 2019: Epidemiology / Prevalence, incidence, and outcomes of MCI and dementia. Alzheimer’s & Dementia, 16(S10). https://doi.org/10.1002/alz.042236

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