Cognitive function of Brazilian elderly persons: longitudinal study with non-clinical community sample.

Several biopsychosocial changes in individuals' life might happen, resulting in a decline of long-term cognitive abilities. In this way, the aim of this study was to compare cognition in non-clinical older adults in Brazil during a four-year period, as well as to examine which variables may explain cognitive function variations identified during this time. For this purpose, a longitudinal study was developed including 108 older Brazilians in phase I and 64 in phase II, from 2013 to 2017. Socio-demographic variables were assessed and the following instruments were administered: the Mini-Mental State Examination (MMSE), the Wechsler Adult Intelligence Scale (WAIS) - 3rd Edition - Digital Symbol-Coding subtests, the Verbal Fluency Test (animal category), the Rey Auditory-Verbal Learning Test, the Beck Anxiety Inventory (BAI), and the Geriatric Depression Scale 15-item version (GDS-15). In order to compare cognitive variables, the Wilcoxon signed-rank test for repeated measures was used. Temporal comparisons of nominal variables were carried out using McNemar's chi-square tests for matched pairs. Finally, multiple linear regression and correlation analyses were applied, using the participants' cognitive performance variation scores (Δ) as dependent variables. Global cognitive function delayed verbal episodic memory, and processing speed experienced a significant decline in four years. Symptoms of anxiety were the main predictor of cognitive performance variations in this sample.