New AGHLS research published; Number and appraisal of daily hassles and life events in young adulthood: the association with physical activity and screen time: a longitudinal cohort study

Young adults face radical life changes regarding residence, marriage, family and work that may negatively impact their health behaviours. Therefore, we investigated the associations of the number of daily hassles and life events and their subjective appraisal with physical activity and screen time in young adulthood.

Data came from participants of the Amsterdam Growth and Health Longitudinal Study (AGAHLS). Self-reported physical activity (min/wk) was used from wave 6 (1991; mean age 27), wave 7 (1993; mean age 29), wave 8 (1996/1997; mean age 32) and 9 (2000; mean age 36). Self-reported screen time (h/wk) was assessed in waves 8 and 9. The number and the appraisal of daily hassles and major life events were assessed with the Everyday Problem Checklist and Life Events List, respectively (including five life event domains, i.e.: health, work, home/family, personal/social relations, and finances). The final sample included 474 participants for the physical activity analyses and 475 participants for the screen time analyses. To test the longitudinal associations of daily hassles and life events with physical activity and screen time, univariable and multivariable Generalised Estimating Equations were performed. Effect modification by gender was tested.

Physical activity levels were higher in those who had experienced more daily hassles. People who reported higher subjective appraisal in the work and finances life event domains also had higher levels of physical activity, although only the subjective appraisal in the finances domain remained significant in the multivariable model. No significant associations between number and subjective appraisal of daily hassles and life events and screen time were observed.

The occurrence of specific life events may be more influential for people’s physical activity behaviour than their respective sum or emotional tone. Still, the assessment of daily hassles may be a relevant addition in this research field. Finally, we suggest that daily hassles and life events are less important for explaining screen time behaviour than for physical activity.

Read the full article here.


The Association between IGF-1 Polymorphisms, IGF-1 Serum Levels, and Cognitive Functions in Healthy Adults

Several studies have demonstrated an association between polymorphisms in the insulin-like growth factor-1 (IGF-1) gene and IGF-1 serum levels. IGF-1 levels have been associated with cognitive functioning in older persons and growth hormone deficient patients. The present study investigates whether IGF-1 polymorphisms, IGF-1 levels, and cognition are interconnected in healthy adults. Data of 277 participants (mean age: 42.4 years) of the Amsterdam Growth and Health Longitudinal Study on IGF-1 promoter polymorphisms, IGF-1 serum level, spatial working memory (SWM), paired associate learning (PAL), and IQ tests were analyzed. (M)ANOVAs were applied to confirm the associations between IGF-1 polymorphisms and IGF-1 levels and between IGF-1 levels and cognition. Three groups were distinguished based on specific IGF-1 polymorphism alleles: a homozygote 192 bp/192 bp genotype, a heterozygote 192 bp/x genotype, and a noncarrier x/x genotype. Although different IGF-1 levels were found for the three genotypes, performance on all cognitive tasks and IQ measures was similar. Despite the associations between IGF-1 polymorphisms and IGF-1 levels, no association was found between cognition and IGF-1 levels. It seems that IGF-1 does not play a role in the cognitive performance of healthy middle-aged adults. Possible, IGF-1 fulfills a more developmental and protective role in cognition which becomes apparent during childhood, old-age, or disease.

Read the full article here.

Bas van Bussel defends his PhD thesis

Bas van Bussel defended his thesis “Endothelial dysfunction and low‐grade inflammation: determined by diet and cause of arterial stiffness” at Maastricht University on May 28, 2014. His thesis contains several chapters describing AGHLS data. Congratulations!

Changes in aerobic fitness in boys and girls over a period of 25 years: data from the Amsterdam Growth And Health Longitudinal Study revisited and extended

Han Kemper, the founder of the AGHLS recently published an article about the AGHLS in Pediatric Exercise Science:

In the Amsterdam Growth And Health Longitudinal Study (AGAHLS), a group of approximately 650 12- to 14-year-old boys and girls was followed in their growth, and development of their health their lifestyle including diet, physical activity and smoking. One of the main interests was the change in their aerobic fitness. From 12 to 36 years of age in total, eight repeated measurements were performed to measure peak oxygen uptake (peak VO2). In this study the data of peak VO2 are revisited and extended: We made use of all collected data as a mixed longitudinal design including cross-sectionally measured subjects as well as longitudinally measured subjects. This led to the availability of 1,194 boys and 1356 girls. With Generalized Estimating Equations (GEE) the longitudinal changes with chronological age and differences between boys and girls were analyzed. Teenage boys and girls increased their peak VO2 (ml/min) significantly (p < .001) until age 14 in girls and until age 17 in boys. However peak VO2 relative to bodyweight (peak VO2/BW) had significantly (p < .001) decreased over the whole age range from 12 to 36 in both sexes. Vigorous physical activity (VPA) also showed a decrease and was significantly (p < .001) related with lower peak VO2/BW (Beta = 0.001). This relation was stronger in boys than in girls. Because at the start of AGAHLS no fast responding metabolic instruments were available, future longitudinal studies about aerobic fitness should include also measurement of VO2 kinetics.

We are keeping busy!

Homocysteine levels are inversely associated with capillary density in men, not in premenopausal women

Jacqueline Hornstra has published the results of her study looking into the relationship between homocysteine levels and capillary density. The results are published in the European Journal of Clinical Investigation:

Background: Homocysteine is an independent predictor of cardiovascular risk. The mechanisms underlying this link are not fully elucidated. Whereas the role of vascular dysfunction in conduit arteries is extensively studied, the role of the microcirculation in this relationship is largely unexplored. We assessed the relationship between homocysteine levels and microvascular structure and function in a healthy, population-based cohort.

Materials and methods: We cross-sectionally studied 260 participants (aged 42 years, 47% men) of the Amsterdam Growth and Health Longitudinal Study. Nailfold videocapillaroscopy was used to assess capillary density at baseline, during venous occlusion and during peak reactive hyperaemia. The relationship between tertiles of homocysteine and microvascular outcomes was evaluated using linear regression analyses, with adjustment for BMI and blood pressure. Stratified analyses were performed for men and women.

Results: In men, we observed a negative, nonlinear relationship between homocysteine and baseline capillary density, showing a lower capillary density in the highest tertile of homocysteine [adjusted B -8·65 capillaries/mm(2) (95%-CI: -16·05 to -1·25); P = 0·02]. In women, no significant associations were found between homocysteine and microvascular outcomes.

Conclusions: In men, higher homocysteine levels are associated with a reduction in basal perfusion of skin capillaries. This finding provides a novel potential explanation for how homocysteine influences cardiovascular disease risk.

A healthy brain in a healthy body: brain network correlates of physical and mental fitness

In 2006, the AGHLS-team conducted novel MEG brain scans. The first publication analysing these data is out!

A healthy lifestyle is an important focus in today’s society. The physical benefits of regular exercise are abundantly clear, but physical fitness is also associated with better cognitive performance. How these two factors together relate to characteristics of the brain is still incompletely understood. By applying mathematical concepts from ‘network theory’, insights in the organization and dynamics of brain functioning can be obtained. We test the hypothesis that neural network organization mediates the association between cardio respiratory fitness (i.e. VO2 max) and cognitive functioning. A healthy cohort was studied (n = 219, 113 women, age range 41-44 years). Subjects underwent resting-state eyes-closed magneto-encephalography (MEG). Five artifact-free epochs were analyzed and averaged in six frequency bands (delta-gamma). The phase lag index (PLI) was used as a measure of functional connectivity between all sensors. Modularity analysis was performed, and both within and between-module connectivity of each sensor was calculated. Subjects underwent a maximum oxygen uptake (VO2 max) measurement as an indicator of cardio respiratory fitness. All subjects were tested with a commonly used Dutch intelligence test. Intelligence quotient (IQ) was related to VO2 max. In addition, VO2 max was negatively associated with upper alpha and beta band modularity. Particularly increased intermodular connectivity in the beta band was associated with higher VO2 max and IQ, further indicating a benefit of more global network integration as opposed to local connections. Within-module connectivity showed a spatially varied pattern of correlation, while average connectivity did not show significant results. Mediation analysis was not significant. The occurrence of less modularity in the resting-state is associated with better cardio respiratory fitness, while having increased intermodular connectivity, as opposed to within-module connections, is related to better physical and mental fitness.

See PLoS One for more information.

Dagmar Nieboer joins AGHLS-team!

Dagmar Nieboer is conducting her PhD-project alongside her work as a junior lecturer at the Department of Health Sciences at the VU University. She will work part-time on her research projects and part-time on her teaching responsibilities.