Este trabalho teve como objetivo principal investigar o desempenho das funções executivas (FEs), a relação com a velocidade de processamento da informação e com medidas subjetivas e fisiológica do estresse em indivíduos diagnosticados com Esclerose Múltipla (EM) com incapacidade leve e moderada, avaliada pela Expanded Disability Status Scale (EDSS). O primeiro estudo corresponde a uma revisão sistemática da literatura sobre o estresse e as FEs na EM. No segundo estudo, foram apresentados os dados da comparação entre grupos no desempenho FEs e as correlações entre a cognição e a velocidade de processamento da informação. Os grupos estudados foram: controles saudáveis (n = 35); EM com EDDS 3 (n = 37); EM com EDSS entre 4-6 (n = 32). O grupo de EM com EDSS entre 4-6 apresentou pior desempenho em controle inibitório e planejamento em comparação aos demais grupos, sendo que as correlações significativas entre a velocidade de processamento da informação e o desempenho das FEs estiveram mais presentes no grupo controle e de EM com EDDS 3. No terceiro estudo, foram apresentados dados das correlações entre as FEs e medidas de estresse através da percepção e do cortisol no grupo de controles saudáveis (n = 35) e de EM (n = 69). Os dados mostraram mínimas associações entre o cortisol, especialmente, no controle inibitório e a influência de baixos níveis de cortisol na resolução de problemas⁄flexibilidade cognitiva no grupo de EM em comparação ao grupo de controles saudáveis. Concluiu-se que o desempenho das FEs pode estar associado ao nível de incapacidade medido pela EDSS de indivíduos diagnosticados com EM, sendo que a velocidade de processamento da informação parece não estar associada, de forma significativa, às FEs de indivíduos com maior incapacidade. Na presente amostra, o estresse percebido não esteve associado às FEs, porém, níveis baixos de cortisol parecem prejudicar determinados subcomponentes executivos no grupo de EM. Dados da revisão sistemática mostraram uma associação indireta entre a percepção do estresse a o desempenho das FEs após diferentes intervenções. / The main objective of this study was to investigate the performance of executive functions (EF), the relationship with information processing speed and subjective and physiological measures of stress in individuals diagnosed with Multiple Sclerosis (MS); mild and moderate disability, evaluated by Expanded Disability Status Scale (EDSS). Initially, the literature on stress and EF in MS is systematically reviewed. In the second study, we present the data of the comparison between groups in the EF performance and the correlations between the cognition and the speed of information processing. The groups studied were: healthy controls (n = 35); MS with EDDS 3 (n = 37); MS with EDSS between 4-6 (n = 32). The MS group with EDSS between 4-6 had worse performance in inhibitory control and planning in comparison to the other groups, and the significant correlations between the information processing speed and the performance of the EF were more evident in the control and MS groups with EDDS 3. In the third study, data are presented on correlations between EF and stress measures through perception and cortisol in healthy controls (n = 35) and MS (n = 69). The data showed minimal associations between cortisol, especially the influence of low cortisol levels on inhibitory control and problem-solving-cognitive flexibility in the MS group compared to the healthy controls group. We concluded that the performance of EF may be associated with the level of disability measured by the EDSS of individuals diagnosed with MS, and the speed of information processing seems not to be significantly associated to the EF of individuals with greater disability. In the present sample, perceived stress was not associated with EF, but low levels of cortisol appear to impair certain executive subcomponents in the MS group. However, data from the systematic review showed an indirect association between the perception of stress and the performance of EF after different interventions.

In light of collated research linking temperament traits and executive performance, the aim of this study is to explore, in a large non-clinical sample, the differences in executive performance profiles among participants with different intensities of the trait Novelty Seeking (NS). A further aim is to establish which facets of NS contribute to these differences. The NS temperament dimension and its subscales were operationalised as scores on the Temperament and Character Inventory (TCI), which is based on the psychobiological theory of personality. The University of Pennsylvania Computerised Neuropsychological Test Battery (PennCNP) of executive functioning (EF) and abstract reasoning was used to measure participants’ neuropsychological EF. The total sample of participants (n= 461) was divided into high NS (n= 216) and low NS (n= 245) groups to investigate any significant differences between them. Further analysis was then conducted in order to analyse the relationship between the NS scale, the four subscales (Exploratory Excitability, Impulsiveness, Extravagance, and Disorderliness), and performance in executive tasks. The findings of this study indicated significant differences between groups with different intensities of NS, with the high NS group functioning notably better in performance and reaction time. Furthermore, this study showed that facets of NS, such as impulsiveness was a significant contributor to EF performance outcomes. / Dissertation (MA)--University of Pretoria, 2013. / Psychology / unrestricted

The study investigated an organized semantic fluency task, (the Controlled Animal Fluency Task - CAFT) as a measure of executive functioning (EF) in adults, and the relationship with instrumental activities of daily living (IADL). Participants (N = 266) consisted of a clinical sample (n = 142) utilizing neuropsychological assessment data collected at an outpatient psychological center, and a community sample (n = 124). The clinical sample was a heterogeneous mixed neurological group including a variety of health conditions and comorbid anxiety and depression. The CAFT Animals by Size demonstrated a significant positive correlation with Category Fluency (r = .71, n = 142, p < .001) , Animal Fluency (r = .70, n = 142, p < .001), and with other, established neuropsychological measures. The CAFT Animals by Size condition demonstrated a significant moderate negative correlation with IADL for the sample as a whole (r = -.46, n = 248, p < .001), and for the clinical sample (r = -.38, n = 129, p < .001), but not for the community sample. In a hierarchical regression analysis, CAFT Animal by Size explained additional variance in IADL (&#916;R2 = .15). In a hierarchical regression analysis predicting IADL with the control variables entered first, followed by Category Fluency, with CAFT Animal by Size entered last, CAFT Animals by Size did not make a significant additional contribution. A stepwise forward regression indicated Category Fluency, education, and Category Switching are better predictors of IADL than CAFT Animals by Size. Normative data for the CAFT were calculated separately for age groups and education levels. Simple logistic regression indicated CAFT Animal by Size was a significant predictor of clinical or community group membership. A second logistic regression analysis indicated the CAFT Animal by Size condition improved the prediction of membership in the clinical versus the community group, compared to the MMSE alone. Applications of the CAFT are discussed.

Este trabalho teve como objetivo principal investigar o desempenho das funções executivas (FEs), a relação com a velocidade de processamento da informação e com medidas subjetivas e fisiológica do estresse em indivíduos diagnosticados com Esclerose Múltipla (EM) com incapacidade leve e moderada, avaliada pela Expanded Disability Status Scale (EDSS). O primeiro estudo corresponde a uma revisão sistemática da literatura sobre o estresse e as FEs na EM. No segundo estudo, foram apresentados os dados da comparação entre grupos no desempenho FEs e as correlações entre a cognição e a velocidade de processamento da informação. Os grupos estudados foram: controles saudáveis (n = 35); EM com EDDS 3 (n = 37); EM com EDSS entre 4-6 (n = 32). O grupo de EM com EDSS entre 4-6 apresentou pior desempenho em controle inibitório e planejamento em comparação aos demais grupos, sendo que as correlações significativas entre a velocidade de processamento da informação e o desempenho das FEs estiveram mais presentes no grupo controle e de EM com EDDS 3. No terceiro estudo, foram apresentados dados das correlações entre as FEs e medidas de estresse através da percepção e do cortisol no grupo de controles saudáveis (n = 35) e de EM (n = 69). Os dados mostraram mínimas associações entre o cortisol, especialmente, no controle inibitório e a influência de baixos níveis de cortisol na resolução de problemas⁄flexibilidade cognitiva no grupo de EM em comparação ao grupo de controles saudáveis. Concluiu-se que o desempenho das FEs pode estar associado ao nível de incapacidade medido pela EDSS de indivíduos diagnosticados com EM, sendo que a velocidade de processamento da informação parece não estar associada, de forma significativa, às FEs de indivíduos com maior incapacidade. Na presente amostra, o estresse percebido não esteve associado às FEs, porém, níveis baixos de cortisol parecem prejudicar determinados subcomponentes executivos no grupo de EM. Dados da revisão sistemática mostraram uma associação indireta entre a percepção do estresse a o desempenho das FEs após diferentes intervenções. / The main objective of this study was to investigate the performance of executive functions (EF), the relationship with information processing speed and subjective and physiological measures of stress in individuals diagnosed with Multiple Sclerosis (MS); mild and moderate disability, evaluated by Expanded Disability Status Scale (EDSS). Initially, the literature on stress and EF in MS is systematically reviewed. In the second study, we present the data of the comparison between groups in the EF performance and the correlations between the cognition and the speed of information processing. The groups studied were: healthy controls (n = 35); MS with EDDS 3 (n = 37); MS with EDSS between 4-6 (n = 32). The MS group with EDSS between 4-6 had worse performance in inhibitory control and planning in comparison to the other groups, and the significant correlations between the information processing speed and the performance of the EF were more evident in the control and MS groups with EDDS 3. In the third study, data are presented on correlations between EF and stress measures through perception and cortisol in healthy controls (n = 35) and MS (n = 69). The data showed minimal associations between cortisol, especially the influence of low cortisol levels on inhibitory control and problem-solving-cognitive flexibility in the MS group compared to the healthy controls group. We concluded that the performance of EF may be associated with the level of disability measured by the EDSS of individuals diagnosed with MS, and the speed of information processing seems not to be significantly associated to the EF of individuals with greater disability. In the present sample, perceived stress was not associated with EF, but low levels of cortisol appear to impair certain executive subcomponents in the MS group. However, data from the systematic review showed an indirect association between the perception of stress and the performance of EF after different interventions.

No description available.

Purpose: Moderate-intensity aerobic exercise (MAE) has been shown to elicit improvements in cognition and subsequent academic performance among preadolescents. Aerobic exercise has also shown to increase cortisol release in response to increasing exercise intensity. However, it is unknown if increased cortisol levels following exercise are related to acute improvements in executive function following a bout of MAE in preadolescents. The purpose of this study was to examine the potential effects of increased cortisol release after acute MAE on attention and working memory among preadolescents. Methods: Eleven preadolescents [6 males, 5 females] volunteered to participate in this study (age=9.45±1.03). Participants were randomized in a counterbalanced fashion to 30 minutes of rest or 30 minutes of treadmill MAE (60-70% HR max). Immediately pre-post each condition, participants completed a cognitive battery consisting of tests of attention (Flanker Test) and working memory (List Sorting Working Memory Test), as well as salivary samples for the analysis of cortisol. Linear Regression models were used to assess significance of covariates. Generalized linear models were used to assess significance of changes in each dependent variable against time, condition, time*condition and change in cortisol. Tukey’s HSD post-hoc tests for multiple comparisons were used to assess the effect of condition on working memory, attention, and salivary cortisol. Results: There was a significant effect of condition on working memory (F=3.16, p =0.04), with no change from pre-post rest (p=0.93) and improving from pre-post exercise (p=0.04). There was no effect of condition on attention or salivary cortisol, most likely due to a small sample size. Multiple linear regression models showed a significant effect of age (p=0.03) and change in cortisol (p=0.007) on working memory. Conclusion: Exercise had a positive effect on working memory, however, we were unable to relate this improvement to changes in salivary cortisol due to a lack of statistical power. This study could provide insight into the physiological effects of increased cortisol release on cognition, specifically in regard to working memory. However, more data are needed to achieve sufficient statistical power to detect these relationships.

BACKGROUND: With the proportion of the world’s elderly population continuing to increase dramatically, tremendous amounts of research have focused on detecting the earliest signs of cognitive impairment before the onset of dementia. The pathophysiology of dementia is complex and recent genetic and biomarker studies have identified new biological pathways that might modify the risk of dementia. One potential risk factor, altered serum phosphorus levels, has been studied with respect to its potential impact on human cognition. The association between serum phosphorus and cognition needs further investigation using a population that is free of CKD. OBJECTIVE: I used data from the Framingham Offspring Study (FOS) cohort to investigate the cross-sectional association between measured serum phosphorus within the normal range and cognitive performance in women and men. METHODS: Participants from the FOS who attended the ninth examination cycle were included in this analysis (N=1253). The Wechsler Memory Scale: Logical Memory – Immediate and Delayed recall (LM-IR and LM-DR) and Visual reproduction – Immediate and Delayed recall (VR-IR and VR-DR) tests were used to assess verbal and visual memory, respectively. Times for the Trailmaking Test – Parts A and B along with the difference between the two tests (B-A) were used to assess attention, psychomotor speed, and executive functioning. Participants were categorized according to levels of fasting serum phosphorus as follows: Low Phosphorus - 2.0-<3.1 mg/dL for men and 2.6-<3.6 mg/dL for women, Moderate Phosphorus - 3.1-<3.6 mg/dL for men and 3.6-<3.9 mg/dL for women, High Phosphorus - 3.6-<5.2 mg/dL for men and 3.9-<5.3 mg/dL for women. Mean cognitive scores were compared across categories using a least squares general fit linear model. Multivariable logistic regression models were used to investigate the association between higher serum phosphorus levels and odds of cognitive impairment within each cognitive test. RESULTS: We did not find any statistically significant differences in mean scores on the Logical Memory, Visual Reproduction, and Trailmaking – Part A tests among the categories of fasting serum phosphorus. There was no association between higher serum phosphorus levels and odds of cognitive impairment on any of the verbal and visual memory tests. In men, higher serum phosphorus levels were associated with poorer performance on the Trailmaking Test – Part B (High phosphorus: -0.50 ± 0.04, Moderate phosphorus: -0.40 ± 0.03, Low phosphorus : -0.33 ± 0.04; P-trend: <0.002) and the difference in log-transformed times between the Trailmaking Test – Part B and A tests (High phosphorus: -1.16 ± 0.02, Moderate phosphorus: -1.10 ± 0.02, Low phosphorus: -1.07 ± 0.02; P-trend: <0.004). Higher serum phosphorus levels were associated with an 80% greater odds of having a cognitively impaired score on Trailmaking Test – Part B-A in men (OR: 1.81, 1.11-2.94), and this association was strengthened when adjusting for additional confounding variables (OR: 2.02, 1.15-3.54). There was no such association in women. Using a cubic spline regression analysis, we treated serum phosphorus as a continuous variable and observed a positive linear association between phosphorus and total time or Trailmaking – Part B-A in men. In particular, the odds of cognitive impairment increased at levels of phosphorus above 3.5 mg/dL. CONCLUSIONS: This study demonstrated that higher serum phosphorus levels were associated with poorer performance on the Trailmaking Test – Part B, and in times represented by the Trailmaking Test – Part B-A time in men. We also observed that higher fasting serum phosphorus levels as a continuous variable were associated with increased odds of cognitive impairment on Trailmaking Test – Part B-A in men. We found no association between higher serum phosphorus levels and lower verbal and visual memory scores or increased odds of cognitive impairment on those scores. Since fewer women had cognitive impairment on these test, statistical power was limited for some of these analyses. Future studies are necessary to examine the mechanistic pathways by which serum phosphorus could impact cognition and whether these effects are independent of cardiovascular disease.

The 21st century world is characterized by globalization, optimization, high performance demands, and continuous acceleration of processes. Not surprisingly, stress has steadily become more prevalent over the past years and has become a permanent challenge for many of us. Still we are always expected to perform at our best, and an impairment of cognitive performance can be devastating, particularly in the professional world. This ubiquity in daily life of chronic stress, cognitive demands, and their potential interactions was the motivation for this dissertation. Among cognitive processes executive functioning (EF) are of particular interest, as they represent set of fundamental cognitive abilities for mastering daily life. More precisely, EF is described as higher-order cognitive processes that control and coordinate complex cognitive tasks (Diamond, 2013; Miyake et al., 2000). The primary aim of this dissertation was to investigate the interplay between chronic stress and EF in detail. A three-year longitudinal cohort, the StressCog cohort, was established for this purpose. In order to understand the longitudinal interplay between chronic stress and EF, methodological foundations and cross-sectional matters had to be investigated first. As a result, this dissertation encompasses the following three studies: With classical laboratory designs, the estimation of generalizable and robust effects on the relationship between chronic stress and EF is impaired. Therefore, the StressCog study was set up to make use of internet-based data assessment within domestic environments. Study 1 addressed the feasibility of internet-based response time data, including the common concern that internet-based response time data collected in domestic environments is subject to increased data variability (Chetverikov & Upravitelev, 2016; Reips, 2002). To this end, performance measures collected in the laboratory were compared with measures collected in domestic environments. We found that a setting-related difference in the variability of conventional performance measures (i.e., response times and error rates), as well as diffusion model-based measures is only of small size. An overall increase of variance of approximately 5% was visible in domestic environments. However, as internet-based assessments allow for the recruitment of larger sample sizes (Reips, 2002) the loss of static power can be easily compensated. Therefore, the findings of Study 1 support the use of internet-based cognitive data collection in domestic environments. This formed a valuable basis regarding the collection and interpretation of the StressCog data used in Study 2 and Study 3. In order to get a broad picture of chronic stress the StressCog study aimed for multimethod assessment. The subjective (i.e., perceived) extent of chronic stress and conceptually related constructs were assessed by multiple self-reported measures. The objective (i.e., physiological) extent of chronic stress was assessed via hair cortisol concentration, which has been established as a widely accepted biological marker of chronic stress (E. Russell et al., 2012; Stalder & Kirschbaum, 2012). Surprisingly, however, multiple studies have shown that hair cortisol concentration is, at best, only weakly correlated with subjective chronic stress (Stalder et al., 2017; Staufenbiel et al., 2013; Weckesser et al., 2019). This lack of psychoendocrine covariance was addressed in Study 2 by investigating the construct validity of commonly used chronic stress instruments. A multidimensional item response theory approach was applied in order to display the overlap between items of commonly used measures of chronic stress, depressiveness, and neuroticism. A common latent scale covered the major amount of variance (40% to 48%). It appeared that the overlap of content is mainly based on fatigue, which is a core symptom of depressiveness. Similar to previously reported findings, the common latent scale displayed only a weak association with hair cortisol concentration. It can therefore be argued that items of self-reported chronic stress do not reflect the physiological (i.e., endocrine) aspect of chronic stress to a satisfactory extent. Thus, the results of Study 2 were a valuable basis for the interpretation of chronic stress data in Study 3. In Study 3, we investigated the cross-sectional association between chronic stress and EF. The study made use of data from the baseline assessment of the StressCog cohort (N = 514). Using structural equation modelling, we found no evidence for a meaningful association between chronic stress (i.e., self-reported measures and hair cortisol concentration) and a common latent EF factor. The results found in Study 3 were further supported by unpublished longitudinal StressCog data and analyses making use of diffusion model performance measures. Considering the mainstream of existing findings, which suggests chronic stress to be negatively associated with EF (e.g., Deligkaris et al., 2014; Sandi, 2013), an absence of an association between chronic stress and EF seems surprising. However, other existing findings support this perspective (Castaneda et al., 2011a; McLennan et al., 2016). Beyond this, the results of Study 1 and 2 help to explain why a lack of an association between chronic stress and EF is quite plausible. As within traditional, laboratory-based settings a recruitment of larger samples sizes is difficult and costly, most existing studies lack large, representative samples. In consequence, many findings are based on narrow sample characteristics. Supported by the findings of Study 1, the StressCog study made use of internet-based data collection, which led to the establishment of one the largest, population-based cohorts in the field. Thus, the results presented in this dissertation can be seen as much more robust and representative than many other studies that suggest opposing results. The findings of Study 2 allow for the assumption that many studies in the field make use of questionable self-report instruments and that subjective (i.e., self-reported) measures of chronic stress are only weakly related to objective (i.e., HCC) measures. In consequence, results always depend on the operationalization of the chronic stress measures being used. Caution is advised when comparing opposing results of different measures. With regard to our daily life demands, it may appear quite promising that no association between chronic stress and EF was found in this dissertation. However, these results should not be misunderstood. It has been demonstrated countless times that chronic stress can severely affect the human organism, causing various negative effects that go far beyond a possible impairment of cognitive abilities. Knowing that chronic stress can impair EF under certain circumstances leads to the central question of what conditions make stress toxic. In order to answer this question further systematic research is needed, in which representative samples and experimental study designs will be of crucial help. As long as these questions are not satisfactorily clarified, it seems best to deal with the challenges of chronic stress in a conscious and responsible manner.

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