# An analysis of the global, regional, and national epidemiology and trends of Alzheimer's disease and other dementias linked to smoking from 1990 to 2021 and projections to 2050

## TL;DR

This study examines how smoking contributes to Alzheimer's and other dementias worldwide from 1990 to 2021 and predicts future trends up to 2050.

## Contribution

The study provides global projections of smoking-related dementia burden and identifies key demographic and regional disparities.

## Key findings

- Smoking-related dementia deaths and disability increased from 1990 to 2021, with males and older adults most affected.
- High-middle SDI regions had the highest age-standardized rates of smoking-related dementia burden in 2021.
- Population growth was the main driver of increased dementia burden, despite declines in age-standardized rates.

## Abstract

This research assesses the smoking-related impact on Alzheimer's disease and other dementias (ADOD), analyzing variables such as sex, age, sociodemographic index (SDI), region, and country from 1990 to 2021, with forecasts to 2050.

Using data from the Global Burden of Disease Study 2021, we examined smoking-related ADOD trends from 1990 to 2021, focusing on deaths, disability-adjusted life years (DALYs), years of life lost (YLLs), and years lived with disability (YLDs) by age, sex, SDI, location, and country. We quantified trends with estimated annual percentage changes and used decomposition analysis to evaluate the effects of population growth, aging, and epidemiological shifts. A frontier analysis identified improvement areas and disparities among countries by development status. Time series prediction models were used to predict smoking-attributable ADOD trends from 2022 to 2050, considering population profiles.

Between 1990 and 2021, there was an observable upward trend in deaths, DALYs, YLLs, and YLDs. In 2021, the burden of smoking-attributable age-related diseases predominantly impacted males across all age groups. Females, however, experienced a more pronounced reduction in age-standardized rates (ASR) of deaths, DALYs, YLLs, and YLDs compared to their male counterparts. The data from 2021 reveal that ASR of deaths, DALYs, and YLLs increased with age, reaching a peak among individuals aged ≥95 years. These ASR trends were consistent across genders, although higher rates were observed in males than in females. In 2021, the high-middle SDI region recorded the highest ASR of deaths, DALYs, YLLs, and YLDs. All five SDI regions experienced declines in ASR of deaths, DALYs, YLLs, and YLDs, with the high-SDI region demonstrating the most significant reductions in the estimated annual percentage change (EAPC). Decomposition analyses suggested that population growth was the primary factor contributing to the increase in overall deaths.

From 1990 to 2021, there was an increase in deaths, DALYs, YLLs, and YLDs attributable to smoking-related ADOD, with projections indicating a continued rise globally until 2050. The burden of disease is mainly caused by males and middle-aged and elderly people, which should be given sufficient attention. Understanding epidemiological factors is crucial for designing effective, tailored interventions to mitigate the global burden.