Global, regional, and national burden of dementia attributable to depression among people living with diabetes: a comparative risk assessment study

This study aimed to assess the burden of dementia attributable to depression among individuals with diabetes, and to examine inequalities across countries and sexes. The population attributable fractions (PAFs) and generalized impact fractions (GIFs) for dementia attributable to depression among individuals with diabetes from 1990 to 2016 were calculated by combining the corresponding prevalence of depression and diabetes comorbidity with the relative risks obtained from a systematic review and meta-analysis of cohort studies. Assuming a 5-year lag between depression and dementia onset, these estimates were applied to dementia disability-adjusted life years (DALYs) from 1995 to 2021. Cross-country inequalities were assessed using the slope index of inequality (SII) and the concentration index, and sex differences were related to the Gender Inequality Index (GII). The global PAFs for dementia attributable to depression among individuals with diabetes increased from 1.58% (95% confidence interval [CI] 1.10%, 2.17%) in 1990 to 2.63% (95%CI 1.81%, 3.61%) in 2016. Correspondingly, age-standardized DALYs rates (ASDRs) rose from 22.88 (95%CI 8.75, 50.05) DALYs per 100,000 population in 1995 to 38.08 (95%CI 14.70, 82.51) DALYs per 100,000 population in 2021. This upward trend was consistent across both sexes, with females higher than males. Regionally, the Eastern Mediterranean region reported the highest attributable burden (54.95 DALYs per 100,000 population, 95%CI 20.87, 120.12) in 2021, while the South-East Asia region had the lowest (26.14 DALYs per 100,000 population, 95%CI 9.57, 58.65). Within the socio-demographic index (SDI) regions, those with higher SDI generally had a higher burden. In 2021, the SII was 8.49 (95%CI 0.96, 16.02) and the concentration index was 0.1000 (95%CI 0.0657, 0.1342) globally. In countries with higher GII, the attributable burden among females was relatively greater compared to males. Our research highlights the need for both physical and mental interventions among individuals affected by depression and diabetes, to reduce dementia risk and its associated burden.