Gabriela Tomé Oliveira Engelmann, Joice Coutinho de Alvarenga, Giovanna Correia Pereira Moro, Ivonne Carolina Bolaños Burgos, Mariana Figueiredo Miranda, Millena Figueiredo Miranda, Aline Siqueira de Souza, Marcelle Ferreira Saldanha, Erika Oliveira Hansen, Natalia Silva Dias, Fabiana Carla Matos da Cunha Cintra, Bruna Fulgêncio Dias, Anna Luiza da Silva Souza, Andréa Teixeira Carvalho, Pamela V Martino-Adami, Marco Túlio Gualberto Cintra, Ludimila Labanca, Igor Nunes Lanna, Rafaela Teixeira de Ávila, Jonas Jardim de Paula, Luciana Costa-Silva, Daniela Valadão Freitas Rosa, Débora Marques de Miranda, Marco Aurélio Romano-Silva, Luiz Armando Cunha de Marco, Alfredo Ramírez, Bernardo de Mattos Viana, Maria Aparecida Camargos Bicalho
Overall, annualized dementia conversion rate in the MCI group was 10.72 per 100 person-years (95% confidence interval [CI]: 8.54% to 13.29%). In addition, 40.39% of participants progressed to dementia during a mean follow-up time of 3.75 years (standard deviation: 3.28), with an estimated cumulative incidence of 29.85% at 3 years (95% CI: 22.74% to 36.96%), accounting for death as a competing event.
BACKGROUND: Prevalence of dementia is higher in low- and middle-income countries (LMICs). However, longitudinal studies characterizing cognitive decline and its clinical and epidemiological predictors remain scarce in Brazil.
METHODS: Participants were enrolled from 2011 to 2025 and followed through May 2026. A total of 887 participants were classified as cognitively unimpaired (CU) (n = 274), mild cognitive impairment (MCI) (n = 378), or dementia of the Alzheimer's type (DAT) (n = 235). CU and MCI participants were followed until dementia conversion, which was analyzed under competing risks using cumulative incidence functions and Fine-Gray models.
RESULTS: Overall, annualized dementia conversion rate in the MCI group was 10.72 per 100 person-years (95% confidence interval [CI]: 8.54% to 13.29%). In addition, 40.39% of participants progressed to dementia during a mean follow-up time of 3.75 years (standard deviation: 3.28), with an estimated cumulative incidence of 29.85% at 3 years (95% CI: 22.74% to 36.96%), accounting for death as a competing event.
DISCUSSION: This study adds valuable information for LMICs. However, estimates should be interpreted considering attrition and competing mortality.