Forecasting the Prevalence of Alzheimer's Disease at Mild Cognitive Impairment and Mild Dementia Stages in France in 2022

BackgroundGiven the evolution of early diagnosis guidelines and future disease-modifying therapies, estimating the prevalence of Alzheimer's disease (AD) at early stages is key.ObjectiveTo estimate the number of people living with mild cognitive impairment (MCI) due to AD and mild AD dementia in France in 2022 that could be eligible to future AD therapies.MethodsA step-by-step approach was defined based on disease stages definition and clinical practice. In line with AD guidelines, amyloid-positive profile is considered in our estimates to enhance the diagnosis accuracy of early stages of AD. Age-stratified prevalence from French cohort and international pooled analyses were identified to feed the different steps. To consider uncertainty around mean prevalence values, low and high scenarii based on the lower and upper bounds of the 95% confidence interval were conducted.ResultsWe estimated that 2.5 (low scenario: 1.7-high scenario: 3.6) million people suffer from mild cognitive impairment in France in 2022 among whom 1.65 (low: 1.5-high: 1.8) million people meet the criteria for mild cognitive impairment due to AD i.e., with amyloid positive profile. The expected number of clinical AD dementia is estimated at 925,886 people. Among those, 379,278 people suffer from mild AD dementia based on clinical diagnosis, including 311,043 (low: 289,174-high: 328,332) cases with amyloid positive profile.ConclusionMCI due to AD, and mild dementia stages are potentially of high prevalence. Population-based studies are needed to confirm those estimates.