Renate H. M. de Groot

The association between objectively measured physical activity and academic achievement in Dutch adolescents: findings from the GOALS study.

The main goal of this study was to investigate the association between objectively measured physical activity and academic achievement in adolescents. Students in Grades 7 and 9 (N = 255) were included. Overall, we found no significant dose-response association between physical activity and academic achievement. However, in Grade 7 total physical activity volume (Total PA) was negatively associated with academic achievement, while moderate-to-vigorous intensity physical activity (MVPA) was negatively associated with both academic achievement and mathematics performance. In contrast, in Grade 9 both Total PA and MVPA were positively associated with mathematics performance. In addition, the overall association between MVPA and academic achievement followed an inverted U-shaped curve. Finally, Total PA was positively associated with executive functioning, while executive functioning in turn mediated the associations between Total PA and both academic achievement and mathematics performance. These results indicate that the association between physical activity and academic achievement in adolescents is complex and might be affected by academic year, physical activity volume and intensity, and school grade.

Academic motivation mediates the influence of temporal discounting on academic achievement during adolescence

Lee, N. C., Krabbendam, L., Dekker, S. J., Boschloo, A. M., De Groot, R. H. M., & Jolles, J. (2012). Academic motivation mediates the influence of temporal discounting on academic achievement during adolescence. Trends in Neuroscience and Education, 1(1), 43-48.

Serum Iron Parameters, HFE C282Y Genotype, and Cognitive Performance in Older Adults: Results From the FACIT Study

Although iron homeostasis is essential for brain functioning, the effects of iron levels on cognitive performance in older individuals have scarcely been investigated. In the present study, serum iron parameters and hemochromatosis (HFE) C282Y genotype were determined in 818 older individuals who participated in a 3-year randomized, placebo-controlled double-blind trial examining the effects of folic acid on carotid intima-media thickness. All participants had slightly elevated homocysteine levels and were vitamin B12 replete. Cognitive functioning was assessed at baseline and after 3 years by means of a neuropsychological test battery. At baseline, increased serum ferritin was associated with decreased sensorimotor speed, complex speed, and information-processing speed and increased serum iron was associated with decreased sensorimotor speed. Cognitive performance over 3 years was not associated with HFE C282Y genotype or iron parameters. In conclusion, serum iron parameters do not show a straightforward relationship with cognitive functioning, although elevated iron levels may decrease cognitive speed in older individuals susceptible to cognitive impairment.

Learning and navigating in hypertext

Hierarchical menus and tag clouds were compared when learning from hypertext.We captured logging, eye movements and task performance.Tag clouds lead to more focused search without impairing task performance.Focused search showed in less page revisits and longer consulting of tag clouds.Tag clouds support navigation and can facilitate learning from hypertext. As hypertext learning environments (HLE) are widely used in education, it is important to study and know the effects and consequences of its use. HLEs are non-linear which means that students have to develop ways of navigating through them. Thus, developing interfaces that facilitate and even guide navigation is important for learning. Research showed that successful learning in HLEs depends on both learner characteristics and HLE features. This study investigated an HLE navigation feature (navigational support with either a tag-cloud or conventional hierarchical menu), task complexity (fact-finding vs. information-gathering task) and a user characteristic (gender). Results show that neither navigational support nor gender is associated with differences in task performance. However, there are differences in information processing. Participants using a tag clouds looked longer at the navigational support and shorter at the overview pages. Combined with fewer revisits of webpages in the tag cloud condition, this indicates a more focused selection of pages. The deeper processing of information needed for the information-gathering task was reflected in fewer visits to, but longer viewing times of pages. As no differences in task performance were found, tag clouds seem to be as effective for performance as more traditional navigation structures for navigational support.

Physical activity in the school setting: cognitive performance is not affected by three different types of acute exercise

Recent studies indicate that a single bout of physical exercise can have immediate positive effects on cognitive performance of children and adolescents. However, the type of exercise that affects cognitive performance the most in young adolescents is not fully understood. Therefore, this controlled study examined the acute effects of three types of 12-min classroom-based exercise sessions on information processing speed and selective attention. The three conditions consisted of aerobic, coordination, and strength exercises, respectively. In particular, this study focused on the feasibility and efficiency of introducing short bouts of exercise in the classroom. One hundred and ninety five students (5th and 6th grade; 10–13 years old) participated in a double baseline within-subjects design, with students acting as their own control. Exercise type was randomly assigned to each class and acted as between-subject factor. Before and immediately after both the control and the exercise session, students performed two cognitive tests that measured information processing speed (Letter Digit Substitution Test) and selective attention (d2 Test of Attention). The results revealed that exercising at low to moderate intensity does not have an effect on the cognitive parameters tested in young adolescents. Furthermore, there were no differential effects of exercise type. The results of this study are discussed in terms of the caution which should be taken when conducting exercise sessions in a classroom setting aimed at improving cognitive performance.

Working memory in middle-aged males: age-related brain activation changes and cognitive fatigue effects

We examined the effects of aging and cognitive fatigue on working memory (WM) related brain activation using functional magnetic resonance imaging. Age-related differences were investigated in 13 young and 16 middle-aged male school teachers. Cognitive fatigue was induced by sustained performance on cognitively demanding tasks (compared to a control condition). Results showed a main effect of age on left dorsolateral prefrontal and superior parietal cortex activation during WM encoding; greater activation was evident in middle-aged than young adults regardless of WM load or fatigue condition. An interaction effect was found in the dorsomedial prefrontal cortex (DMPFC); WM load-dependent activation was elevated in middle-aged compared to young in the control condition, but did not differ in the fatigue condition due to a reduction in activation in middle-aged in contrast to an increase in activation in the young group. These findings demonstrate age-related activation differences and differential effects of fatigue on activation in young and middle-aged adults.

Decline in physical activity during adolescence is not associated with changes in mental health

BackgroundThe majority of studies investigating associations between physical activity and mental health in adolescents have been cross-sectional in design. Potential associations between physical activity and mental health may be better examined longitudinally as physical activity levels tend to decrease in adolescence. Few studies have investigated these associations longitudinally in adolescents and none by measuring physical activity objectively.MethodsA total of 158 Dutch adolescents (mean age 13.6xa0years, 38.6xa0% boys, grades 7 and 9 at baseline) participated in this longitudinal study. Physical activity, depressive symptoms and self-esteem were measured at baseline and at the 1-year follow-up. Physical activity was objectively measured with an ActivPAL3™ accelerometer during one full week. Depressive symptoms were measured with the Center for Epidemiologic Studies Depression Scale (CES-D) and self-esteem was assessed with the Rosenberg Self-Esteem Scale (RSE). Results were analysed using structural equation modelling.ResultsPhysical activity levels decreased 15.3xa0% over a 1-year period (pu2009<u2009.001), with significantly (pu2009=u2009.001) greater decreases during grade 7 (-20.7xa0%) than during grade 9 (-5.0xa0%). Overall, depressive symptoms decreased (-12.1xa0%, pu2009<u2009.001) over a 1-year period, while self-esteem did not change significantly (+2.9xa0%, pu2009=u2009.066). Higher levels of depressive symptoms at baseline predicted a greater decline in depressive symptoms (βu2009=u2009-.51, pu2009<u2009.001) and higher levels of self-esteem at baseline predicted a smaller increase in self-esteem (βu2009=u2009-.48, pu2009<u2009.001). The decline in physical activity did not appear to predict any change in depressive symptoms and self-esteem.ConclusionThe decline in physical activity over a 1-year period during adolescence is not associated with a change in mental health. Further studies in adolescents aiming to investigate whether a change in physical activity is associated with a change in mental health should control for baseline levels of mental health and academic year differences.

Age and educational track influence adolescent discounting of delayed rewards

This study examined age-related changes in a specific aspect of adolescent decision-making, namely the preference for future versus immediate outcomes. A sample of 622 Dutch adolescents aged 12–17 years completed a temporal discounting task. Participants were asked to choose between a delayed reward of €50 or an immediate reward of lower value. The delay interval was varied in three blocks (1 week, 1 month, 6 months). Results showed that preferences for large delayed rewards over smaller immediate rewards increased with age: late adolescents made more long-term decisions than early adolescents. This change was related to educational track. In the lower educational track, an age-related decrease in discounting was found for all three delay intervals. In the higher educational track this decrease only occurred for the 6 month delay interval. However, across all delay intervals enrolment in a higher level educational track was associated with an increased preference for long-term rewards. These results suggest that late adolescents are less susceptible than early adolescents to the competing presence of an immediate reward when making long-term decisions, a skill which becomes increasingly important as they transition into adulthood.

Cortisol and induced cognitive fatigue: Effects on memory activation in healthy males

We investigated the relationship between individual differences in acute fatigue and endogenous cortisol changes elicited by the sustained performance of cognitively demanding tasks (fatigue condition). Healthy males provided salivary cortisol measurements and subjective fatigue ratings, and were scanned (functional magnetic resonance imaging) during memory encoding and recognition tasks in fatigue and control conditions. A group of 15 responders showed significantly higher cortisol levels in the fatigue condition than 12 non-responders. Responders showed higher subjective fatigue and reduced encoding and recognition activation than non-responders in the fatigue condition. An interaction in activation changes in the right hippocampus during encoding reflected decreased activation in responders, but somewhat increased activation in non-responders in the fatigue compared to control condition. Moreover, decreased hippocampal activation in responders was associated with increased subjective fatigue. Findings are consistent with a central role for the hippocampus in differences between responders and non-responders and also implicate the right hippocampus in individual differences in induced cognitive fatigue effects.

Genetic variation in folate metabolism is not associated with cognitive functioning or mood in healthy adults.

The present study examined the associations between genetic variation in folate metabolism on the one hand and cognitive functioning and mood on the other in healthy individuals. Two independent population-based samples were used, including 777 participants, aged 24-82 years, from the Maastricht Aging Study (MAAS); and 818 participants, aged 50-70 years, from the Folic Acid and Carotid Intima-Media Thickness (FACIT) study. Thymidylate synthase (TS) 2R→3R and serine hydroxymethyltransferase (SHMT1) 1420C→T polymorphisms were determined in both populations. In addition, the 5,10-methylenetetrahydrofolate reductase (MTHFR) 677C→T polymorphism was determined in the MAAS population. Cognitive performance was assessed in both populations using a neuropsychological test battery. In the MAAS population only, cognitive performance was retested after 12years of follow-up (n=612), and mood was measured at baseline (n=772) and 12-year follow-up (n=565) by means of the depression subscale of the Symptom Checklist 90. We found that in both study populations, cognitive performance was not associated with TS 2R→3R or SHMT1 1420C→T polymorphisms at baseline, after correction for age, sex, and level of education. The MTHFR 677C→T polymorphism was not associated with cognitive performance in the MAAS population. None of the polymorphisms in the MAAS population were related to mood at baseline or over 12 years. In conclusion, our findings do not support the involvement of genetic variation in folate metabolism in cognitive performance or mood in healthy individuals.