Preventing dementia in Italy: Estimations of modifiable risk factors and public health implications.

Background: Dementia is a major global public health challenge, with over 50 million cases in 2020, projected to reach 152 million by 2050. Effective prevention strategies are needed to reduce the impact of modifiable risk factors associated with dementia, particularly in countries with ageing populations like Italy. The Population Attributable Fraction (PAF) and Potential Impact Fraction (PIF) are key metrics for understanding and reducing dementia cases through targeted interventions.

Objectives: This study aimed to revise and expand PAF estimates for dementia in Italy, integrate them with PIF calculations, and assess the alignment of regional health policies with these risk factors. Additionally, the study explored regional variations in PAFs and evaluated the potential for reducing dementia incidence through feasible public health interventions.

Design: A cross-sectional analysis was conducted using data from two national public health surveillance systems, PASSI and PASSI d'Argento (PdA), to estimate PAFs and PIFs for dementia at both national and regional levels. The study used data collected between 2017 and 2019.

Setting: Data were drawn from 19 Italian regions and two autonomous provinces, providing national and subnational estimates of modifiable risk factors for dementia.

Participants: The study population included a nationally representative sample of 86,494 individuals aged 18-64 (PASSI) and 48,516 individuals aged 65 and older (PdA).

Measurements: PAFs were calculated for 11 of the 12 modifiable risk factors identified by the Lancet Commission in 2021, with data from the PASSI and PdA systems. PIFs were calculated to estimate the potential reduction in dementia cases under different intervention scenarios. Regional variations in PAFs were assessed and aligned with health policies outlined in the Regional Prevention Plans.

Results: The national combined PAF for 11 modifiable risk factors was 39.6 % (95 % CI: 20.8-55.9). Midlife hypertension and physical inactivity were the most significant contributors, accounting for 12.3 % of the total PAF. Cardiovascular risk factors collectively explained over 50 % of preventable dementia cases. Regional PAFs ranged from 31.7 % to 47.5 %, with a clear north-south gradient; southern regions exhibited higher PAFs due to cardiovascular factors. Despite broad consistency between national and regional PAFs, significant variability was found in how regions addressed risk factors, particularly air pollution. At the national level, a 10 % reduction in risk factors would prevent 54,495 dementia cases, with subnational PIFs ranging from 3.7 % to 6.0 %.

Conclusions: This study highlights the substantial potential for dementia prevention in Italy through targeted public health interventions. However, significant regional disparities in PAFs and the alignment of health policies underscore the need for a more nuanced, regionally tailored approach. Future strategies should integrate both PAF and PIF to maximize the impact of interventions, particularly in addressing cardiovascular risk factors. These findings can guide the development of evidence-based policies to reduce dementia incidence across Italy.