Global burden of subarachnoid hemorrhage in young adults, 1990-2021: disparities, risk factors, and projections to 2050.
Wu D, Dong S, et al. • Neurological sciences : official journal of the Italian Neurological Society and of the Italian Society of Clinical Neurophysiology • 2026
SAH in young adults represents a non-uniform burden-transition pattern, with declining age-standardized rates but persistent premature mortality and DALYs, higher incidence in high-SDI settings, and greater fatal and disabling burden in lower-resource settings.
Key Findings
Results
In 2021, subarachnoid hemorrhage caused 55,012 deaths and 3.19 million DALYs among young adults aged 15-49 years globally.
Data were drawn from the Global Burden of Disease 2021 dataset covering 204 countries from 1990 to 2021.
The study population was restricted to young adults aged 15-49 years, a group rarely isolated in prior global SAH analyses.
Despite declining age-standardized rates over time, the absolute burden remained substantial through 2021.
Metrics included age-standardized incidence rates (ASIR), age-standardized prevalence rates, age-standardized death rates, and age-standardized DALY rates.
Results
Age-standardized incidence rates of SAH in young adults declined over the 1990-2021 period, but the absolute burden remained substantial.
Temporal trends were assessed using estimated annual percentage changes (EAPCs) and age-period-cohort models.
The decline in ASIR did not translate into elimination of premature mortality or disability-adjusted life years.
The study characterized this as a 'non-uniform burden-transition pattern.'
Projections using Bayesian age-period-cohort models suggested continued decline through 2050, though uncertainty widened after 2040.
Results
High-SDI regions showed higher SAH incidence in young adults, whereas lower-SDI regions bore a greater mortality and DALY burden.
Socio-demographic index (SDI) level was used to stratify cross-country disparities across 204 countries.
Higher incidence in high-SDI settings contrasted with higher fatality and disability rates in lower-resource settings.
Environmental and occupational risks remained more prominent contributors to SAH burden in low-SDI settings.
Metabolic risks were identified as the leading contributors globally using population attributable fractions.
Results
Males had a higher DALY burden from SAH, whereas females had higher prevalence among young adults.
Sex-specific disparities were quantified using age-standardized DALY rates and age-standardized prevalence rates.
The divergence between higher male DALYs and higher female prevalence suggests sex differences in both disease course and survival.
This sex-based disparity pattern was observed at the global level across the 1990-2021 study period.
Results
Metabolic risks were the leading globally attributable risk factors for SAH in young adults, while environmental and occupational risks were more prominent in low-SDI settings.
Risk attribution was assessed using population attributable fractions (PAFs).
An exploratory machine learning analysis with SHapley Additive exPlanations (SHAP) was conducted to further evaluate risk factor contributions.
The prominence of environmental and occupational risks in low-SDI settings suggests region-specific risk profiles that differ from high-income countries.
These findings support stronger metabolic-risk reduction strategies in high-SDI settings.
Results
Bayesian age-period-cohort model projections suggest a continued decline in SAH burden among young adults through 2050, with increasing uncertainty after 2040.
Projections extended from 2021 to 2050 using Bayesian age-period-cohort (BAPC) models.
Uncertainty in the projections widened notably after 2040, limiting confidence in longer-term estimates.
The projected decline was observed across age-standardized metrics including incidence, mortality, and DALY rates.
Age-period-cohort models were also used to assess historical temporal trends from 1990 to 2021.
Results
The age-period-cohort analysis identified distinct period and cohort effects contributing to temporal trends in SAH burden among young adults.
Age-period-cohort models were applied to decompose temporal trends into age, period, and cohort components.
This approach allowed the study to go beyond simple trend analysis to identify generational and era-specific patterns.
The analysis covered 1990-2021 data from 204 countries.
What This Means
This research suggests that subarachnoid hemorrhage (SAH) — a type of bleeding around the brain often caused by a ruptured aneurysm — continues to impose a major health burden on young adults (ages 15-49) worldwide, causing over 55,000 deaths and 3.19 million years of healthy life lost in 2021 alone. While the rate of new cases has been gradually declining since 1990, the total number of people affected remains large. Importantly, the study found that wealthier countries tend to have higher rates of diagnosis, while lower-income countries suffer more deaths and disability from the condition — likely because they have less access to timely medical care and screening.
The study also found meaningful differences by sex and geography in terms of which risk factors matter most. Men were more likely to experience severe disability or death, while women had higher rates of living with the condition. Globally, metabolic risk factors — such as high blood pressure and obesity-related conditions — were the biggest contributors to SAH burden, while in lower-income regions, environmental and occupational hazards played a larger role. Looking ahead, projections suggest the burden will continue to decrease through 2050, though these forecasts become less certain beyond 2040.
This research suggests that different strategies are needed in different parts of the world: high-income countries may benefit most from better management of metabolic risk factors like blood pressure and cholesterol, while lower-income regions urgently need improved blood pressure screening, access to specialist care, and better acute treatment facilities. The findings highlight that while global progress is being made, young people in lower-resource settings remain disproportionately vulnerable to dying or being permanently disabled by this condition.
Wu D, Dong S, Gong J, Li F, Wang C, Wang S, et al.. (2026). Global burden of subarachnoid hemorrhage in young adults, 1990-2021: disparities, risk factors, and projections to 2050.. Neurological sciences : official journal of the Italian Neurological Society and of the Italian Society of Clinical Neurophysiology. https://doi.org/10.1007/s10072-026-09344-2