Stress and Cognitive Reserve as independent factors of neuropsychological performance in healthy elderly.

João Carlos Centurion Cabral,Martina Mazzoleni,Gessyka Wanglon Veleda,Elton Pinto Colares,Vera Torres Das Neves,Lucas Neiva-Silva

doi:10.1590/1413-812320152111.17452015

Abstract

Exposure to high levels of cortisol and self-reported stress, as well as cognitive reserve, have been linked to Alzheimer's disease pathology. However, there are no studies on the interaction of these variables. The present study aims to assess the associations of measures of cortisol, self-reported stress, and cognitive reserve with neuropsychological performance in healthy elderly people; besides, to test the interactions between these variables. Cross-sectional analyzes were conducted using data on stress, cognitive reserve and clinical conditions in 145 healthy elderly adults. A neuropsychological battery was used to assess executive functions, verbal memory and processing speed. Measurement of salivary cortisol at the circadian nadir was taken. A negative association between different stress measures and performance on tasks of memory, executive functions and processing speed was observed. Elderly people with higher cognitive reserve showed superior performance on all neuropsychological measures. No significant interaction between stress and cognitive reserve to neuropsychological performance was observed. These results indicate that older adults with high levels of stress and reduced cognitive reserve may be more susceptible to cognitive impairment.

Highlights

Social and environmental variables can have a significant effect on neuropsychological functioning, increasing vulnerability to cognitive impairment and dementia in the elderly
The salivary cortisol levels at nadir had a mean of 6.95 ng/mL (standard error (SE) = 0, 37), and showed no significant associations with age, gender, education and socioeconomic status of the participants, nor were there significant differences between the groups classified as high or low perceived stress and those classified as high or low cognitive reserve
This effect size was small, the relationship is consistent for all three measured variables

Summary

Introduction

Social and environmental variables can have a significant effect on neuropsychological functioning, increasing vulnerability to cognitive impairment and dementia in the elderly. Alzheimer’s disease (AD), the most common type of dementia, is characterized: (a) clinically, by cognitive decline, especially of episodic memory; (b) morphologically, by brain atrophy, being initially affected the hippocampal formation and entorhinal cortex; and (c) histologically, by reduction of synaptic density, presence of neurofibrillary tangles of Tau protein and aggregates of amyloid-β peptide (Aß)[1,2]. Even in healthy people, when these interactions disrupt the functioning of nervous system, there may be a reduction of brain reserves, leading to a higher susceptibility to cognitive impairment[7]. Due to the wide variability in cognitive abilities of older people, the factors associated with these differences remain to be elucidated

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Conclusion