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Minerva Medica 2021 Apr 21

DOI: 10.23736/S0026-4806.21.07454-1


language: English

A systematic review of studies reporting a decreasing trend in the incidence and prevalence of dementia

Flavia MAYER 1, Giulia REMOLI 1, Ilaria BACIGALUPO 1, Ilaria PALAZZESI 1, Paola PISCOPO 2, Guido BELLOMO 1, Marco CANEVELLI 1, 3, Massimo CORBO 4, Nicola VANACORE 1, Eleonora LACORTE 1

1 National Centre for Disease Prevention and Health Promotion, Italian National Institute of Health, Rome, Italy; 2 Department of Neurosciences, Italian National Institute of Health, Rome, Italy; 3 Sapienza University of Rome, Rome, Italy; 4 Department of Neurorehabilitation Sciences, Casa di Cura privata del Policlinico, Milan, Italy


INTRODUCTION: The progressive ageing of the population is one of the main socio-demographic phenomena, taking place at a global level. Several recent population-based studies conducted worldwide suggest that the age-specific risk of dementia may be changing in some countries and areas.
EVIDENCE ACQUISITION: This systematic review was performed using the methodology proposed by the Cochrane handbook for systematic reviews and reported following the PRISMA statement. A structured bibliographic search was performed on the databases PubMed, ISI Web of Science and the Cochrane Database of Systematic Reviews. All included studies were qualitatively assessed using the Methodological Evaluation of Observational REsearch (MORE).
EVIDENCE SYNTHESIS: The bibliographic search yielded 2394 records. Three more articles were retrieved from other sources. A total of 10 studies were included, 5 reported data on a possible reduction in the prevalence of dementia, and 5 reported data on a possible reduction in its incidence.
DISCUSSION AND CONCLUSIONS: The present systematic review focused on the recent observations of a possible decrease in the frequency of dementia and cognitive impairment in some Western countries (US, UK, Sweden, the Netherlands, France, Iceland) between 1977 and 2014. The included studies have a high heterogeneity in terms of the clinical criteria used to diagnose dementia, and of the criteria used to define the clinical condition preceding dementia, such as isolated cognitive impairment. Moreover, the methodological quality with which they were conducted was also heterogeneous, with scores ranging from 1 to 7 using the MORE tool.

KEY WORDS: Epidemiology; Prevalence studies; Incidence studies; Systematic review; Dementia; Alzheimer’s disease

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