Temporal trends in the prevalence of Alzheimer's disease, 1980–2024: a systematic review and meta-analysis
Background Alzheimer's disease (AD) is the primary cause of dementia and represents a significant public health concern in aging populations. Existing evidence indicates geographic and sex-related differences in AD prevalence; however, comparability across time periods and diagnostic criteria is limited, and data from lower-resource regions remain scarce. This study synthesized evidence on reported AD prevalence from 1980 to 2024 and examined temporal, geographic, demographic, and methodological variation. Methods PubMed, Web of Science, and Embase were systematically searched from inception to December 31, 2024, for observational studies reporting AD prevalence in general or community-based populations. Eligible studies reported prevalence estimates with 95% confidence intervals or provided sufficient data for calculation. Studies with sample sizes below 100 and non-original reports were excluded. Two reviewers independently screened studies and extracted data; disagreements were resolved by a third reviewer. Pooled reported prevalence was estimated using a random-effects model. The review was prospectively registered in PROSPERO (CRD420251111597). Results Fifty-two studies from 19 countries met the inclusion criteria. The pooled reported prevalence of AD was 4.43 per 100 population (95% CI 3.47–5.50). Prevalence was higher among females (4.65 per 100, 95% CI 3.37–6.13) than males (2.30 per 100, 95% CI 1.71–2.97). By survey period, reported prevalence was 3.52 per 100 for 1980–1989, 4.21 for 1990–1999, 4.12 for 2000–2009, and 6.78 for 2010–2024. Adjusted meta-regression did not identify a significant association between survey year and reported prevalence. Estimates also varied by WHO region, Human Development Index (HDI) level, sample size, and study design. Conclusions Reported AD prevalence was substantial and varied by demographic, geographic, and methodological factors. Although prevalence was highest in the most recent survey period, meta-regression did not indicate a consistent global increase over time. Given the extremely high between-study heterogeneity, these findings should be interpreted with caution. More standardized, age-comparable, and geographically representative studies are needed, particularly in underrepresented and lower-resource settings. Systematic review registration https://www.crd.york.ac.uk/PROSPERO/view/CRD420251111597, identifier CRD420251111597.