Associação entre comportamento sedentário e desempenho cognitivo em adultos e idosos: resultados transversais do ELSA-Brasil.

Abstract

A growing body of epidemiological evidence shows that individuals who engage in a high volume of sedentary behavior are at increased risk of morbidity and mortality, regardless of their level of moderate to vigorous physical activity. Sedentary behavior (SB) is defined as any waking behavior characterized by an energy expenditure ≤1.5 metabolic equivalents while in a sitting, reclining, or lying posture. Among the types of sedentary behavior, those that are usually considered as “screen time” (such as watching television and using the computer) and “sitting time” stand out. Although the evidence for the relationship between SB is more consistent for cardiometabolic diseases, the same is not observed for cognitive function (CF). It is possible that CS can have a negative impact on cognitive functions such as attention, memory and executive functions, the latter being associated with dementias. However, the evidence for this relationship is inconsistent and the results controversial. Objective: verify the association between sedentary behavior and cognitive performance in the ELSA-Brasil’s participants. Results. Paper 1: In the first paper, we seek, through a systematic review, verify the evidence investigating the effects of prolonged sitting time and interruption on cognitive performance in healthy adults and the elderly. Searches were carried out in the MEDLINE / PubMed, Scopus and Cochrane Library databases until March 2021. As inclusion criteria were used: Studies with healthy adults and elderly; with cross-sectional, longitudinal, case control, clinical trials and intervention designers; that assessed prolonged sitting time (> 30 minutes) and cognitive function and compared the outcome over sitting time or according to prolonged sitting time uninterrupted versus non-uninterrupted, with or without intervention. Ten studies met the inclusion criteria. Improvements in cognitive function were observed when the prolonged sitting time was interrupted every 30 minutes for 2 minutes of light intensity walking and for 3 minutes of moderate intensity walking. In the other trials, there was no difference in the cognitive function tests when the uninterrupted sitting time was compared with its interruption or reduction. Paper 2: In the second article we aimed to verify the association between different domains of sedentary behavior and performance in cognitive function tests of middle-aged and elderly adults. Cross-sectional study with 6505 middle-aged and elderly adults participating in Wave 2 of ELSA-Brasil, with a median age of 61 years, of both sexes (55.2% women). The different types of SC considered were “sitting time” (during the week and weekend) and “screen time” (leisure, occupational, during the week and weekend). For the assessment of cognitive function, the final scores obtained in the tests of memory, language and executive function were used. Descriptive and comparative analyzes were carried out according to sex. The association between SB and performance on cognitive tests was assessed according to sex by linear regression and adjusted for confounding factors. We found that, for men, sitting time during the week and weekend was associated with better performance in tests of memory, language, and executive function. Screen time at leisure and occupational, both at the weekend, showed a favorable association with performance in the executive function test. Occupational screen time during the week was positively associated with language test performance. For women, sitting time and occupational screen time, both during the week, were shown to be positively associated with performance on memory tests. In the performance of language tests, all the domains of sedentary behavior analyzed were shown to be favorably associated with this, except for screen time during leisure during the week. There was also a positive association between executive function tests and all domains of sedentary behavior. All of these associations were significant (p<0.05) and adjusted for potential confounding factors. There was no potential effect change due to physical activity in this association. For women, sitting time and occupational screen time, both during the week, were shown to be positively associated with performance on memory tests. In the performance of language tests, all domains of sedentary behavior analyzed were favorably associated with this, except for screen time during leisure during the week. We also observed a positive association between executive function tests and all domains of sedentary behavior. All of these associations were significant (p<0.05) and adjusted for potential confounding factors. Paper 3: The third article aimed to verify the discriminative capacity of sedentary behavior (sitting time and occupational and leisure screen time) in identifying cognitive performance in middle-aged and elderly adults. Cross-sectional study with 6505 middle-aged and elderly adults participating in Wave 2 of the ELSA-Brasil. ROC curves were constructed to compare the amount of sedentary behavior with the performance in the executive function test. SB (sitting time, occupational and leisure time) seems to discriminate between low cognitive performance in middle-aged and elderly adults. Regarding the discriminating capacity of sedentary behavior according to sex and age group, the results suggest, in general, a better ability to identify good cognitive performance for women in both age groups. Conclusions: The results from the cross sectional associations suggest that SB seems to improve the cognitive performance (memory, language and executive function). The type of SB (sitting time and screen time), the characteristics of the activities performed during the CS (cognitively stimulating or not) are relevant to understand its association with cognitive performance. However, the extrapolation of these findings should be taken with caution, since the sample in this study is composed mostly of active workers, relatively young, performing cognitively stimulating activities, with high education and socioeconomic status. Prospective studies assessing objectively SB are recommended to better understand the association of SB with performance and cognitive decline.