The burden of dementia and dementia due to Down syndrome, Parkinson’s disease, stroke, TBI, and HIV: An analysis for the Global Burden of Disease study 2019

Abstract

AbstractBackgroundIn light of the increasing trends in the global number of individuals affected by dementia and the lack of any available disease‐modifying therapies, it is necessary to fully understand and quantify the global burden of dementia. Previous efforts to quantify the relationships between dementia and stroke, Parkinson’s disease, Down syndrome, traumatic brain injury and HIV, but these analyses have remained isolated and results have not been summarized across disease topics. We estimated the proportion of dementia due to Down syndrome, Parkinson’s disease, clinical stroke, TBI and HIV using consistent and comparable methods, in order to better understand their contribution to the prevalence of dementia.MethodThrough systematic review, we obtained data on the relative risk of dementia with each condition and found sufficient evidence to estimate relative risks for all clinical conditions except HIV. We then estimated relative risks by age using a Bayesian meta‐regression tool and calculated population attributable fractions (PAFs) using the estimates of relative risk and prevalence estimates for each condition from the Global Burden of Disease Study 2019. Finally, we multiplied these estimates by dementia prevalence to calculate the number of dementia cases attributable to each condition.ResultThe relative risk of dementia for all four conditions decreased with age. Relative risks were highest for Down syndrome, followed by Parkinson’s disease, stroke and TBI. However, due to the high prevalence of stroke, the PAF for dementia due to stroke was highest. Overall, Down syndrome, Parkinson’s disease, stroke and TBI explained 9.9% (5.9 to 16.4) of the global prevalence of dementia.ConclusionLess than 10% of dementia prevalence could be explained by Down syndrome, Parkinson’s disease, stroke and TBI. This result emphasizes the large fraction of dementia prevalence unexplained by the four diseases examined in this analysis, and highlights the need for additional epidemiologic research exploring lifestyle risk factors and further research in the basic sciences focused on elucidating intervention approaches to prevent or delay the neuropathological changes that characterize dementia.