Evolution of dementia diagnosis over time (1988–2013): Evidence from French and English cohorts. Implication for secular trends analyses

• Main Authors: Leslie Grasset, Fiona E. Matthews, Karine Pérès, Alexandra Foubert‐Samier, Catherine Helmer, Jean‐François Dartigues, Carol Brayne
• Format: Article
• Language: English
• Published: Wiley 2018-01-01
• Series: Alzheimer’s & Dementia: Diagnosis, Assessment & Disease Monitoring
• Subjects: Dementia; Secular trends; Diagnosis; Incidence; Prevalence
• Online Access: https://doi.org/10.1016/j.dadm.2018.07.005
• ISSN: 2352-8729

Abstract Introduction The aims of this study are to examine the evolution of clinical dementia diagnosis over 3 decades and to investigate secular trends of dementia. Methods Four cohorts covering a period from 1988 to 2013 were used: the Personnes Agées Quid and Three‐City‐Bordeaux studies, and the Cognitive Function and Aging Study (CFAS) I and II. Mini–Mental State Examination scores at clinical diagnosis were evaluated over a 24‐year follow‐up period in French studies. An algorithmic approach was applied to CFAS I and II to provide dementia prevalence and incidence estimates. Results A significant increase of the Mini–Mental State Examination score at diagnosis was observed until 2000 and a significant decrease after. We reported a prevalence of 8.8% for CFAS I (1990–1993) compared with a prevalence of 6.5% in CFAS II (2008–2011). The 2‐year incidence rate was estimated at 31.2/1000 (95% confidence interval = 28.0–34.8) for CFAS I and 15.0/1000 (95% confidence interval = 13.5–16.7) for CFAS II. Discussion Applying a stable algorithm to different cohorts across time can provide a robust method for time trends estimation.