Preventing dementia is possible. The fraction of cases attributable to modifiable factors in Italy

Abstract Background Worldwide, approximately 50 million people live with dementia. The Lancet Commission, in its latest report in 2020, identifies 12 ‘modifiable’ risk factors associated with dementia, estimating that they account for about 40% of overall dementia cases. The study aimed to estimate the population attributable fraction (PAF) of dementia cases in Italy due to these factors. Methods Relative risks (RR) of each factor and formulas for estimating PAF are derived from the Lancet Commission’s report. Prevalence data were obtained from the Italian surveillance systems PASSI and PASSI d’Argento (PdA), which provide information on 11 of the 12 identified risk factors. The total sample 2017-19 included 86,494 individuals aged 18-64 and 48,516 individuals aged over 65. The Communality, used for ‘weighted’ estimates of PAFs, was calculated via principal components analysis of the inter-risk-factor tetrachoric correlation matrix, using data derived from the overall PASSI and PdA sample. Results In Italy, it is estimated that 39.5% of dementia cases are attributable to 11 of the 12 modifiable risk factors, equivalent to 445,150 out of 1,126,961 estimated cases as of January 1, 2023. Among the risk factors with the greatest impact are hypertension before the age of 65 (weighted PAF=6.3%); sedentariness after the age of 65 (weighted PAF=5.9%); low education in youth (weighted PAF = 5%); depression and social isolation after the age of 65 (weighted PAF=4.5% and 4.4%), as well as diabetes (weighted PAF=3.9%) and smoking (weighted PAF=2.4%). Conclusions Although it is necessary to to gather further evidence on the role and mechanisms of action of each factor, the importance of prevention and promotion of health and social well-being in the field of dementia is now evident. Key messages • Having an overall national sample of adults and elderly people is a unique tool that allows an estimation of dementia cases attributable to modifiable risk factors. • Dementia prevention may also be possible by acting on modifiable risk factors.