The Study
Global Burden of Alzheimer's disease and other dementias in adults aged 65 years and older, 1991–2021: population-based study
This study looked at lots of health data from around the world to see how many older people have dementia and how it’s changed over 30 years. It found that more people have dementia now, and it’s linked to things like being overweight or having high blood sugar—but it doesn’t prove those things cause dementia, just that they often happen together.
Analysis score
Maximum 85 for a systematic review with meta-analysis.
Where the score came from
More older people are getting dementia because people are living longer and more of them are reaching old age.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 539 / 100
Quality score
Systematic reviews and meta-analyses of cohort studies. They sit above a single cohort study but below a single randomized trial, because the underlying evidence is still observational.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Yes — this means dementia is becoming a bigger global health problem, especially in countries with aging populations and rising obesity and diabetes.
- 2In 2021, 49 million older adults had dementia, up from 18.7 million in 1991.
- 3It caused 8 million deaths and 25 million years of lost healthy life.
- 4Women had more cases than men.
- 5High blood sugar and obesity were linked to more cases, while smoking's link got weaker.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Frontiers in Public Health
Year
2025
Authors
Xiaopeng Zhu, Y. Jing, Lai Xia, Xingsheng Wang, Deng Juan, Long Yan, Baoshan Li
Related Content
Claims (6)
Between 1991 and 2021, the percentage of adults aged 65 and older with dementia worldwide rose by 160%, and this rise was linked to higher levels of obesity and elevated fasting blood glucose.
Alzheimer's disease and other dementias are growing most quickly in wealthier countries, especially in East Asia, where the number of cases and deaths per person is rising faster than anywhere else.
From 1991 to 2021, the number of adults aged 65 and older with Alzheimer's disease and other dementias worldwide rose from 18.7 million to 49 million, a 160% increase, primarily because people are living longer and the population is aging.
Between 1991 and 2021, the number of deaths from Alzheimer's disease and other dementias per 100,000 people aged 65 and older rose from 6.5 to 14, reflecting a 115% increase over that period.
In 2021, Alzheimer's disease and other dementias resulted in 8.02 million deaths and 25.38 million disability-adjusted life years worldwide among people aged 65 and older, and nearly two-thirds of this burden occurred in women.
Among adults aged 65 and older, high fasting glucose and high body mass index are linked to a large number of dementia-related disabilities and deaths worldwide, with these conditions contributing 1,638 and 833 disability-adjusted life years per 100,000 people in 2021, and both contributions have risen over time.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.