Population attributable fraction of potentially modifiable risk factors for dementia among United States Veterans: A retrospective cohort study 2000‐2020.

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AbstractBackgroundPrior international research has indicated that up to 40% of dementia risk may be amenable to prevention, before symptoms occur, by intervening on various factors. Whether modifiable factors vary between countries or within countries among different populations is beginning to be explored. Veterans are increasingly at elevated risk for dementia and cognitive decline due to health, lifestyle, and military‐related risk factors.MethodsData were collected from male and female United States (US) Veterans (≥45 years with no prevalent dementia by January 1, 2000) who had at least one inpatient or outpatient visit within Veterans Health Administration. 8,317,615 individuals were followed to January 1, 2020 to identify potential modifiable risk factors and subsequent dementia diagnoses. We calculated adjusted hazard ratios (aHR) and weighted population‐attributable fractions (PAF) for Alzheimer’s disease (AD) and Alzheimer’s disease related dementia (ADRD) for the following factors: hearing loss, smoking, obesity, depression, post‐traumatic stress disorder (PTSD), hypertension, diabetes, traumatic brain injury (TBI), and heavy alcohol use. Our models were adjusted for age at baseline, sex, race/ethnicity, and marital status and the PAFs accounted for communality among risk factors.ResultsOver the 20 year follow‐up period, 995,821 (12%) US Veterans developed AD/ADRD. The three highest risks for AD/ADRD were TBI (aHR: 3.11 [95% CI:3.08, 3.13]), depression (aHR: 3.06 [95% CI: 3.05, 3.07), and PTSD (aHR: 1.91 [95% CI: 1.90, 1.92]) (Table 1). A weighted estimate of 53.7% (95% CI, 53.2%, 54.1%) of Veteran dementia cases were attributable to the evaluated risk factors. The greatest attributable fraction of AD/ADRD cases was observed for depression (PAF, 19.3%; 95% CI 19.3%, 19.4%), hypertension (PAF, 14.4%; 95% CI: 14.3%, 14.5%), and diabetes (PAF, 6.4%; 95% CI: 6.3%, 6.4%).ConclusionThe PAF for modifiable risk factors for AD/ADRD is higher than in previous world reports, due to not only greater prevalence of cardiovascular risk factors among Veterans, but also due to higher prevalence of military‐related risk factors including PTSD and TBI. Targeted interventions to reduce key risk factors may decrease the projected rise in dementia cases among Veterans over the next several decades.