Ketvel, Laila
(Helsingin yliopisto, 2021)
Objective: Both stress-related exhaustion and depression have previously been associated with a decline in cognitive performance, but there is a lack of evidence on whether these conditions have different associations with different cognitive domains and whether they have additive effects on cognitive performance. Furthermore, very little is known about the cognitive effects of chronic stress-related exhaustion. Consequently, the aims of this study were to 1) examine the associations between current stress-related exhaustion and cognitive performance, 2) investigate whether different developmental trajectories of stress-related exhaustion are differently associated with cognitive performance, 3) compare the association between stress-related exhaustion and cognitive performance to the relationship between depressive symptoms and cognitive performance, 4) examine if individuals with comorbid stress-related exhaustion and depression have lower cognitive performance than individuals with at most one of these conditions (i.e., whether clinical stress-related exhaustion and clinical depression might have additive effects on cognitive performance).
Methods: The data used in the study was a Finnish population-based sample of six cohorts born between 1962 and 1977 from the Cardiovascular Risk in Young Finns Study. Stress-related exhaustion was assessed using the Maastricht Questionnaire, depressive symptoms with the Beck Depression Inventory, and cognitive performance with four subtests of the Cambridge Neuropsychological Test Automated Battery, measuring visuospatial associative learning, reaction time, sustained attention, and executive functions. Cognitive performance and depressive symptoms were assessed in 2012, and stress-related exhaustion in 2001, 2007, and 2012. Participants were 35 to 50 years old in 2012. Linear associations between stress-related exhaustion and cognitive performance (N = 905) and depressive symptoms and cognitive performance (N = 904) were examined by conducting multivariate regression analyses. Age, sex, socioeconomic status, and parents’ socioeconomic status were controlled in the regression models. Additionally, multivariate analyses of variance were performed to investigate the different developmental trajectories of stress-related exhaustion and their relation to cognitive performance (N = 541) and the associations of comorbid stress-related exhaustion and depression with cognitive performance (N = 1273).
Results and conclusion: The main finding was that high stress-related exhaustion is associated with slower reaction times, but not with performance in spatial working memory, visuospatial associative learning, or executive functions. Ongoing, chronic stress-related exhaustion was more strongly associated with slower reaction times than short-term exhaustion experienced years ago. Compared to depressive symptoms, high stress-related exhaustion was associated with slower reaction times also when subclinical cases were included, whereas only clinical levels of depressive symptoms had an association with slower reaction times. There were no differences in cognitive performance between individuals with only stress-related exhaustion or depression and those with comorbid stress-related exhaustion and depression, which supports the notion that these conditions do not have additive effects on cognitive performance. These findings add to the existing evidence of the cognitive effects of stress-related exhaustion in the general population and have several practical implications. Further research is needed on the topic, preferably with longitudinal designs, more comprehensive cognitive measures, and clinical assessment of the psychiatric symptoms.