Etiologies of rapidly progressive dementias: A systematic review and meta-analysis of causes in worldwide and Latin America

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Background Rapidly progressive dementia (RPD) is a group of neurological diseases, where three etiologies are particularly relevant: neurodegenerative, prion and autoimmune encephalitis (AIE) diseases. Objective The aim of this study is to conduct a systematic review and meta-analysis of the frequency of these etiologies causing RPD in worldwide and Latin America (LatAm). Methods A systematic review and meta-analysis were conducted. A bibliographic search of publications related to the etiologies of RPD was done. The etiologies, the timeframe definition (<1 year versus <2 years) and the study's place of origin were analyzed. Results A total of 10 articles were selected for the analysis in this study (n = 1006 patients). Three studies were originated in LatAm cohorts (two from Argentina and one from Brazil). The global prevalence of RPD due to neurodegenerative disease was 23% CI95% [11%; 42%]; prion diseases, 16% CI95% [9%; 28%]; and AIE, 12% CI95% [6%; 22%]. Comparing each overall proportion of etiologies of LatAm versus non-LatAm there were statistically significant differences for AIE (25% versus 8%, respectively, p < 0.01). In the case of timeframe definitions, the comparison of the etiological percentage did not show statistically significant differences. Conclusions From our results, approximately a half of the causes of RPD were due to neurodegenerative, prion, and AIE diseases. Future studies will be needed to analyze this issue both globally and regionally.