Prevalence, incidence and recovery from anemia and its causes, and the association with cognitive performance in the ELSA-Brasil cohort

Abstract

Anemia and cognitive disorders are common conditions in clinical practice. The association between anemia and cognitive performance has long been subject of debate, with conflicting results. In addition, few studies have evaluated the association between the main causes of anemia and cognitive function in adults. The Brazilian Longitudinal Study of Adult Health (ELSA-Brasil) is a cohort study of 15,105 participants aged 35 to 74 years in six centers in different cities of the country. The largest ELSA-Brasil investigation center is in São Paulo, with 5061 participants. Baseline evaluation took place between August 2010 and December 2012 and consisted of questionnaires, clinical and laboratory tests, and collecting and cryopreserving biological material. Frequency of anemia (hemoglobin levels below 12 g/dl in women and 13 g/dl in men) in the entire cohort was 3.0% in men (N=205) and 7.4% in women (N=609). Restricting the analysis to participants from ELSA-Brasil investigation center in São Paulo, frequency of anemia was 2.2% in men (N=51) and 5.8% in women (N=158). After four years, participants of the ELSA-Brasil study underwent a new assessment. The objectives of this study are: (1) To study the possible association between anemia and its causes and performance on cognitive tests in the participants of the ELSA-Brasil investigation center in São Paulo; (2) To study the incidence and persistence of anemia after four years in participating in the ELSA-Brasil investigation center in São Paulo and its determinants; and (3) study the impact of anemia and their causes in the evolution of performance on cognitive tests of participants aged 55 or older after four years of follow-up in participants from the ELSA-Brasil investigation center in São Paulo. We will use data from cognitive tests at baseline (delayed word recall test, verbal fluency test and trail making test version B) for all participants, and for participants aged 55 or older in the revaluation after four years of follow-up. The cryopreserved blood samples at baseline and after four years will be used for the determination of serum iron, ferritin, total capacity Iron binding, vitamin B12 and folic acid. We will determine the prevalence of anemia and its causes at baseline and the incidence and persistence of anemia after four years of follow-up. We will build binary logistic regression models to study the association between hemoglobin levels and / or diagnosis of anemia and its causes and the performance on cognitive tests at ELSA-Brasil study baseline. Using data from the subgroup of participants aged 55 or older at baseline of the ELSA-Brasil, we will build linear regression models to study the association between the evolutive performance on cognitive tests and hemoglobin levels, anemia and its causes at baseline and after four years of follow up. (AU)