Data files

Vrijen, C., Schenk, H. M., Hartman, C. A., Oldehinkel, A. J. (2016). Measuring BDNF in saliva using commercial ELISA: Results from a small pilot study. Psychiatry Research 254. https://doi.org/10.1016/j.psychres.2017.04.034 Datafiles and syntaxes belonging to this article can be downloaded. Please note that the data files are only to be used for the purpose of checking the analyses. If you would like to use the data for other purposes, please send a specified request to [email protected]

Measuring BDNF in saliva using commercial ELISA: Results from a small pilot study

Vrijen, C., Schenk, H. M., Hartman, C. A., Oldehinkel, A. J. (2016). Measuring BDNF in saliva using commercial ELISA: Results from a small pilot study. Psychiatry Research, 254. https://doi.org/10.1016/j.psychres.2017.04.034 Datafiles and syntaxes belonging to this article can be downloaded. Please note that the data files are only to be used for the purpose of checking the analyses. If you would like to use the data for other purposes, please send a specified request to [email protected]

Syntax

Vrijen, C., Schenk, H. M., Hartman, C. A., Oldehinkel, A. J. (2016). Measuring BDNF in saliva using commercial ELISA: Results from a small pilot study. Psychiatry Research 254. https://doi.org/10.1016/j.psychres.2017.04.034 Datafiles and syntaxes belonging to this article can be downloaded. Please note that the data files are only to be used for the purpose of checking the analyses. If you would like to use the data for other purposes, please send a specified request to [email protected]

Measuring BDNF in saliva using commercial ELISA: Results from a small pilot study

Brain-derived neurotrophic factor (BDNF) is a protein often studied in psychiatric populations. Commercial ELISA kits have been validated for measuring BDNF in blood plasma and serum, but blood collection is an invasive method which cannot always be used. The aim of this pilot study was to explore the noninvasive alternative of measuring BDNF in saliva. Three different commercial ELISA kits were used to analyze parallel plasma and saliva samples from six healthy adults. In total 33 plasma and 33 saliva samples were analyzed according to manufacturers' standard protocols. BDNF was successfully measured in plasma in two of the three kits, of which the results correlated highly (r(s) =.88). BDNF could not be measured reliably in saliva. The results of this pilot study suggest that techniques of commercial BDNF kits may not be ready for noninvasive saliva measurements, which limits the sampling frequency and settings

The four week time frame for somatic symptom questionnaires reflects subjective symptom burden best

Objective: Various questionnaires are available to assess somatic symptom burden, however their assessment time frames vary largely. The aim of this study was to investigate the most relevant assessment time frame for somatic symptoms by relating somatic symptom burden, with varying time frames, to quality of life (QoL) and health anxiety as indicators for clinical relevance of symptoms. Methods: This study was performed in data derived from a convenience sample of 3477 participants (age: 48.0 (SD 14.1), 66.4% female) of the Dutch research platform HowNutsAreTheDutch. Symptom burden was assessed using all items from the Patient Health Questionnaire-15 (PHQ-15) and 6 items of the Symptom Checklist-90 SOM (SCL-90 SOM). Five versions of the questionnaire were constructed, which evaluated symptom burden during the past 24 h, 1 week, 2 weeks, 4 weeks, and 3 months. Results: Symptom burden significantly increased with each step increase in time frame until 4 weeks, with no further increase when comparing 4 weeks and 3 months. The time frame of 4 weeks provided the strongest associations between somatic symptom burden and health anxiety (B = 1.635; 95%CI: 1.368 to 1.938; p Conclusion: An assessment time frame of 4 weeks for somatic symptom questionnaires reflects clinically relevant somatic symptom burden in terms of QoL and health anxiety best, followed by the 3 months' time frame

Individual Heterogeneity in the Relations Between Sleep, Inflammation, and Somatic Symptoms

OBJECTIVE: Poor sleep is associated with the experience of more somatic symptoms and a proinflammatory state, whereas a proinflammatory state may also result in the experience of more somatic symptoms. However, existing studies ignore individual differences in these associations. We aimed to study relations between sleep, inflammatory markers, and somatic symptoms at a within-individual level. METHODS: Time series of daily data on sleep, somatic symptoms, and inflammation markers in 10 healthy individuals (age, 19-58 years; three men) for 63 days were analyzed. Bidirectional lagged ( t - 1) and contemporaneous ( t ) relations between sleep duration, inflammatory markers (C-reactive protein, interferon-α, interleukin 1RA), and somatic symptoms were analyzed using 24-hour urine and diary data. Unified structural equation modeling was used to analyze the association between sleep duration, the three inflammatory markers, and the amount of somatic symptoms at the individual level. RESULTS: Associations were found between sleep and at least one of three inflammatory markers in four individuals, both positive (three associations) and negative (five associations) and contemporaneous (four associations) and lagged (four associations). Sleep was related to somatic symptoms in four individuals, both positive ( n = 2) and negative ( n = 2) and contemporaneous ( n = 3) and lagged ( n = 1). Inflammatory markers were associated with somatic symptoms in three individuals, both positive (three associations) and negative (one association) and contemporaneous (three associations) and lagged (one associations). Two individuals showed no associations between sleep, inflammatory markers, and somatic symptoms. CONCLUSIONS: We observed a large variability in presence, strength, and direction of associations between sleep, inflammatory markers, and somatic symptoms

Differential association between affect and somatic symptoms at the between- and within-individual level

OBJECTIVES: The established between-subjects associations between affect and somatic symptoms have often been interpreted as indicating a causal effect of affect on somatic symptoms, but it is doubtful whether this is valid. In this study, we evaluate the association between positive affect (PA), negative affect (NA), and somatic symptoms at both the between- and within-subject level. DESIGN AND METHODS: Diary data were collected in the context of an online study called 'HowNutsAreTheDutch'. Participants filled out an online questionnaire, three times a day for 30 consecutive days. A mixed linear model was used to test the contemporaneous and lagged associations between affect and somatic symptoms. RESULTS: Five hundred and eighty-six participants (481 females, median age 39.6 years [range 18.1-71.4]) were included with a total number of 28,264 completed questionnaires. At the between-subjects level, a positive association between NA and somatic symptoms was found (B = .60, p < .001), whereas the negative association between PA and somatic symptoms was much smaller (B = -.14, p = .062). At the within-subject level, PA (B = -.33, p < .001) was more strongly associated with somatic symptoms than NA (B = .13, p < .001). The lagged analyses showed a negative association between previous-day PA and somatic symptoms (B = -.05, p = .001). CONCLUSIONS: The results suggest that NA is more important for differences in symptom levels between subjects, whereas PA is more important for variations in symptom levels within subjects. Moreover, our results suggest that an increase in PA is followed by a decrease in somatic symptoms after 24 hr, which suggests a causal effect. Statement of contribution What is already known on this subject? Affect and somatic processes are closely linked. Cross-sectional studies show, for example, that people with higher levels of negative affect tend to report more somatic symptoms. Findings between individuals, though, might camouflage processes at within-individual level, and it might not always be possible to translate findings at the population level to the individual. However, diary studies are upcoming and show more about processes on individual level. What does this study add? Highlights the difference between processes at the within-individual and the between-individual level. Shows the importance of positive affect at individual level in relation to somatic symptoms. Shows the benefits of the use of new techniques in diary studies

Associations of positive affect and negative affect with allostatic load:A Lifelines Cohort Study

OBJECTIVE: Allostatic load (AL) reflects the deteriorating influences of stress on the body, and comprises a selection of biological markers. AL is associated with negative life events, stress, and negative affect (NA), as well as poor health outcomes. However, whether AL is also associated with positive affect (PA) is not clear. The present study therefore explores the association between PA and AL, accounting for age, sex, NA, and health behaviors. METHODS: Data of 45,225 individuals from the first wave of the multi-disciplinary prospective population-based cohort study Lifelines were used. AL was operationalized as the sum of twelve inflammatory, cardiovascular, and metabolic markers. The association between PA and AL was tested in a cross-sectional study design using multiple linear regression analysis, adjusting for NA, confounders, and health behaviors. In addition, we explored whether the relation was moderated by age, sex and NA. RESULTS: The AL profile was inversely associated with PA (B = -0.083, p<.001), when adjusted for NA, age, sex. The association between AL and PA remained significant after adjusting for health behaviors (B = -0.076, p<.001). A significant moderating effect was found for sex (PA x sex: B= 0.046, p=.001), indicating that the association between PA and AL was stronger in women than in men. CONCLUSIONS: PA was associated with a more favorable AL profile, especially in women. These results add to the evidence that PA might be of relevance to the etiology of disease