A qualitative approach to guide choices for designing a diary study.

BACKGROUND: Electronic diaries are increasingly used in diverse disciplines to collect momentary data on experienced feelings, cognitions, behavior and social context in real life situations. Choices to be made for an effective and feasible design are however a challenge. Careful and detailed documentation of argumentation of choosing a particular design, as well as general guidelines on how to design such studies are largely lacking in scientific papers. This qualitative study provides a systematic overview of arguments for choosing a specific diary study design (e.g. time frame) in order to optimize future design decisions. METHODS: During the first data assessment round, 47 researchers experienced in diary research from twelve different countries participated. They gave a description of and arguments for choosing their diary design (i.e., study duration, measurement frequency, random or fixed assessment, momentary or retrospective assessment, allowed delay to respond to the beep). During the second round, 38 participants (81%) rated the importance of the different themes identified during the first assessment round for the different diary design topics. RESULTS: The rationales for diary design choices reported during the first round were mostly strongly related to the research question. The rationales were categorized into four overarching themes: nature of the variables, reliability, feasibility, and statistics. During the second round, all overarching themes were considered important for all diary design topics. CONCLUSIONS: We conclude that no golden standard for the optimal design of a diary study exists since the design depends heavily upon the research question of the study. The findings of the current study are helpful to explicate and guide the specific choices that have to be made when designing a diary study.

Psychological Interventions for Children with Functional Somatic Symptoms: A Systematic Review and Meta-Analysis.

OBJECTIVE: To analyze the effectiveness of psychological treatments on symptom load and associated disability in children with functional somatic symptoms, and to explore potential moderators of effects. STUDY DESIGN: Cochrane, PubMed, PsycINFO, EMBASE, and CINAHL were searched for randomized controlled trials published in peer-reviewed journals. Randomized controlled trials studying the effect of a psychological treatment on symptom load and disability in children with functional somatic symptoms were selected. Data on symptom load, disability, and school absence directly post-treatment and at follow-up were extracted by 2 assessors. Studies were appraised with the Cochrane risk of bias tool. Standardized mean differences were pooled in a random-effects model. Heterogeneity in effect-sizes was explored by use of meta-regressions. PROSPERO Registration ID: CRD42015029667. RESULTS: Out of 4098 identified records, 27 studies were included in this review of which 21 were included in meta-analyses. Psychological treatments reduced symptom load (Hedges g = -0.61), disability (Hedges g = -0.42), and school absence (Hedges g = -0.51) post-treatment in children suffering from various functional somatic symptoms. Effects were maintained at follow-up. Type and duration of symptoms, age, and treatment dose did not explain heterogeneity in effect-sizes between studies. Effect-sizes should be interpreted with caution because of the variety in outcome measures, unexplained heterogeneity in found effects and potential publication bias. CONCLUSIONS: Psychological interventions reduce symptom load, disability, and school absence in children with functional somatic symptoms. Future research should clarify which patient and treatment characteristics modify outcomes.

Mood and Anxiety Disorders in Chronic Fatigue Syndrome, Fibromyalgia, and Irritable Bowel Syndrome: Results From the LifeLines Cohort Study.

OBJECTIVE: Functional somatic syndromes (FSSs) have often been linked to psychopathology. The aim of the current study was to compare prevalence rates of psychiatric disorders among individuals with chronic fatigue syndrome (CFS), fibromyalgia (FM), and irritable bowel syndrome (IBS). METHODS: This study was conducted in 94,516 participants (mean [standard deviation] age = 44.6 [12.5] years, 58.7% women) of the general-population cohort LifeLines. FSSs were assessed by self-reports. Mood disorders (i.e., major depressive disorder and dysthymia) and anxiety disorders (i.e., generalized anxiety disorder, social phobia, panic disorder with/without agoraphobia, and agoraphobia) were assessed by means of the Mini International Neuropsychiatric Interview. Risks on psychiatric disorders were compared for individuals with CFS, FM, and IBS by using logistic regression analyses adjusted for age and sex. RESULTS: Prevalence rates of CFS, FM, and IBS were 1.3%, 3.0%, and 9.7%, respectively. Individuals with CFS, FM, and IBS had significantly more mood (odds ratios [ORs] = 1.72-5.42) and anxiety disorders (ORs = 1.52-3.96) than did individuals without FSSs, but prevalence rates were low (1.6%-28.6%). Individuals with CFS more often had mood (ORs = 2.00-4.08) and anxiety disorders (ORs = 1.63-2.32) than did individuals with FM and IBS. Major depressive disorder was more common in FM than in IBS (OR = 1.58, 95% confidence interval = 1.24-2.01), whereas these groups did not differ on dysthymia or anxiety disorders. CONCLUSIONS: Mood and anxiety disorders are more prevalent in individuals with FSSs, and particularly CFS, than in individuals without FSSs. However, most individuals with FSSs do not have mood or anxiety disorders.

Predictors for persistence of functional somatic symptoms in adolescents.

OBJECTIVE: To identify risk factors for persistence of functional somatic symptoms (FSS; ie, somatic symptoms that cannot be sufficiently explained by underlying organic pathology). STUDY DESIGN: The first (N = 2230, mean age = 11.1 years [SD 0.6], 50.8% girls), second (N = 2149, mean age = 13.7 years [SD 0.5], 51.0% girls), and third (N = 1816, mean age = 16.3 years [SD 0.7], 52.3% girls) assessment waves of the general population study TRacking Adolescents' Individual Lives Survey were used. FSS were assessed with the Youth Self-Report and the Child Behavior Checklist. Growth mixture models were used to identify different subgroups of adolescents on the basis of the developmental trajectory of their symptoms. Adolescents with persistent symptoms were compared with adolescents with decreasing symptoms with a multivariable logistic regression analysis. RESULTS: In our general population cohort, 4.1% of adolescents suffered from persistent FSS. Risk factors for persistent FSS were being a girl (OR 4.69, 95% CI 2.17-10.12), suffering from depressive symptoms (OR 5.35, 95% CI 1.46-16.62), poor self-rated health (OR 1.56, 95% CI 1.02-2.39), and high parent-reported FSS (OR 4.03, 95% CI 1.20-13.54). Anxiety, parental overprotection, school absenteeism, and diversity of symptoms did not predict persistence of FSS. CONCLUSIONS: This study identified risk factors for persistence of FSS in adolescents. Future studies might study effects of coping strategies and iatrogenic factors on symptom persistence.

School absenteeism as a perpetuating factor of functional somatic symptoms in adolescents: the TRAILS study.

OBJECTIVE: To examine whether school absenteeism is a perpetuating factor of functional somatic symptoms and whether this holds true for bullied adolescents. STUDY DESIGN: This study is part of the longitudinal population-based study Tracking Adolescents' Individual Lives Survey. Data from assessment wave 2 (n = 2149; 51.0% girls; mean age = 13.65, SD = 0.53) and assessment wave 3 (n = 1816; 53.3% girls; mean age = 16.25, SD = 0.72) were used. Peer victimization was assessed by peer nominations, school absenteeism by both parent and teacher reports, and functional somatic symptoms with the Youth Self-Report. RESULTS: With structural equation modeling, school absenteeism at the second wave, adjusted for functional somatic symptoms at the second wave, was revealed to predict functional somatic symptoms at the third wave in the entire cohort (ß = 0.12; 95% CI, 0.02-0.22), but not in the subgroup of bullied adolescents (ß = -0.13; 95% CI, -0.62--0.26). However, the difference between bullied and unbullied adolescents did not reach significance. CONCLUSION: This study provides evidence that school absenteeism is a perpetuating factor of functional somatic symptoms in adolescents. A clinical intervention study is necessary to examine whether preventing school absenteeism truly helps to reduce functional somatic symptoms in adolescents.

Anxiety and depression are risk factors rather than consequences of functional somatic symptoms in a general population of adolescents: the TRAILS study.

BACKGROUND: It is well known that functional somatic symptoms (FSS) are associated with anxiety and depression. However, evidence is lacking about how they are related to FSS. The aim of this study was to clarify these relationships and examine whether anxiety and depression are distinctly related to FSS. We hypothesized that anxiety contributes to the development of FSS and that depression is a consequence of FSS. METHODS: FSS, anxiety, and depression were measured in adolescents (N = 2230, 51% women) by subscales of the Youth Self-Report during three assessment waves (adolescents successively aged: 10-12, 12-14, and 14-17) and by corresponding subscales of the Child Behavior Checklist. Using structural equation models, we combined trait and state models of FSS with those of anxiety and depression, respectively. We identified which relationships (contemporaneous and two-year lagged) significantly connected the states of FSS with the states of anxiety and depression. RESULTS: Trait variables were all highly interrelated (r = .54-.63). Contrary to our hypothesis, both state anxiety (beta = .35) and state depression (beta = .45) had a strong contemporaneous effect on state FSS. In turn, state FSS had a weak two-year lagged effect on state anxiety (beta = .11) and an even weaker effect on state depression (beta = .06). CONCLUSIONS: While the effect of anxiety and depression on FSS is strong and immediate, FSS exert a weaker and delayed influence on anxiety and depression. Further research should be done to detect the exact ways in which anxiety and depression lead to FSS, and FSS lead to anxiety and depression.

Age-specific associations between cardiac vagal activity and functional somatic symptoms: a population-based study.

BACKGROUND: Functional somatic symptoms (FSS) are symptoms not explained by underlying organic pathology. It has frequently been suggested that dysfunction of the autonomic nervous system (ANS) contributes to the development of FSS. We hypothesized that decreased cardiac vagal activity is cross-sectionally and prospectively associated with the number of FSS in the general population. METHODS: This study was performed in a population-based cohort of 774 adults (45.1% male, mean age +/- SD 53.5 +/- 10.7 years). Participants completed the somatization section of the Composite International Diagnostic Interview surveying the presence of 43 FSS. ANS function was assessed by spectral analysis of heart rate variability in the high-frequency band (HRV-HF), reflecting cardiac vagal activity. Follow-up measurements of HRV-HF and FSS were performed approximately 2 years later. RESULTS: Linear regression analyses, with adjustments for gender, age, body mass index, anxiety, depression, smoking, alcohol use, and frequency of exercise, revealed an interaction of cardiac vagal activity with age: HRV-HF was negatively associated with FSS in adults 52 years (beta = 0.13, t = 2.51, p = 0.012). Longitudinal analysis demonstrated a similar pattern. CONCLUSIONS: Decreased cardiac vagal activity is associated with a higher number of FSS in adults aged 52 years needs further exploration. The role of age should be acknowledged in future studies on ANS function in the etiology of FSS.

Effect of treatment on cognitive and attention problems in children with narcolepsy type 1.

STUDY OBJECTIVES: To ascertain the presence of cognitive and attention problems in treatment naïve children with narcolepsy type 1 (NT1) and to explore whether children recently diagnosed with NT1 improve with respect to cognition and attention problems 1 year after regular treatment for NT1. METHODS: A total of 15 treatment naïve children (7-15 years) with recently diagnosed NT1 were recruited from three sleep medicine centers in the Netherlands. The control group consisted of 15 healthy children, being frequency matched on age and gender. Both groups were investigated at baseline to examine intelligence profile (Wechsler Intelligence Scale for Children [WISC] III), attention problems, and processing speed (Bourdon Vos and sustained attention to respond task [SART]). These tests were repeated in children with NT1 1 year after regular (behavioral and medication) treatment for NT1. RESULTS: Children with NT1 scored significantly lower on the verbal scale and processing speed subscale of the WISC III, showed more fluctuations in reaction time of the Bourdon Vos and made more mistakes during the SART than the healthy control group at baseline. Children with NT1 significantly improved on total IQ score, and on the WISC indices processing speed, and perceptual organization 1 year after treatment. At follow-up, test scores of treated children were largely comparable to those of the control group at baseline. CONCLUSIONS: Children with NT1 show improvement in several cognitive domains 1 year after start of treatment. Our findings stress the need for early detection and treatment of narcolepsy in childhood.

Parental overprotection predicts the development of functional somatic symptoms in young adolescents.

OBJECTIVE: To examine whether parental overprotection contributes to the development of functional somatic symptoms (FSS) in young adolescents. In addition, we aimed to study whether this potential effect of parental overprotection is mediated by parenting distress and/or moderated by the adolescent's sex. STUDY DESIGN: FSS were measured in 2230 adolescents (ages 10 to 12 years from the Tracking Adolescents' Individual Lives Survey) by the Somatic Complaints subscale of the Youth Self Report at baseline and at follow-up 2 1/2 years later. Parental overprotection as perceived by the child was assessed by means of the EMBU-C (Swedish acronym for my memories of upbringing-child version). Parents completed the Parenting Stress Index. Linear regression analyses were performed adjusted for FSS at baseline and sex. RESULTS: Parental overprotection was a predictor of the development of FSS in young adolescents (beta = 0.055, P < .01). Stratified analyses revealed that maternal overprotection was a predictor of the development of FSS in girls (beta = 0.085, P < .02), whereas paternal overprotection was a predictor of the development of FSS in boys (beta = 0.072, P < .01). A small (5.7%) but significant mediating effect of maternal parenting stress in the relationship between parental overprotection and FSS was found. CONCLUSIONS: Parental overprotection may play a role in the development of FSS in young adolescents.

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 24h, 1week, 2weeks, 4weeks, and 3months. RESULTS: Symptom burden significantly increased with each step increase in time frame until 4weeks, with no further increase when comparing 4weeks and 3months. The time frame of 4weeks provided the strongest associations between somatic symptom burden and health anxiety (B=1.635; 95%CI: 1.368 to 1.938; p≤0.001). This was also true when analysing the association between QoL and the symptom groups of musculoskeletal (B=-1.54; 95%CI: -1.93 to -1.16;p≤0.001) and gastrointestinal symptoms (B=-0.71; 95%CI: -0.96 to -0.47;p≤0.001). CONCLUSION: An assessment time frame of 4weeks for somatic symptom questionnaires reflects clinically relevant somatic symptom burden in terms of QoL and health anxiety best, followed by the 3months' time frame.

Physical Activity and Sleep in Chronic Fatigue Syndrome and Fibromyalgia Syndrome: Associations with Symptom Severity in the General Population Cohort LifeLines.

Objective: The aim of the current study was to compare physical activity and sleep duration between patients with chronic fatigue syndrome (CFS), patients with fibromyalgia syndrome (FMS), and controls and to examine the association between physical activity level and sleep duration with symptom severity within these patient groups. Methods: This study used data of LifeLines, a general population cohort in which 1.0% (n=943, 63.7% female, age 44.9 (SD 11.6) years) reported CFS, 3.0% (n=2,714; 91.6% female; age 48.4 (SD 10.7) years) reported FMS, and 95.7% (n=87,532; 57.9% female; age 44.3 (SD 12.4) years) reported neither CFS nor FMS. Physical activity, sleep duration, and symptom severity were assessed by questionnaires and analysed using ANCOVA and regression analyses, adjusted for age, sex, body mass index, smoking, and educational level. Results: Patients with CFS and FMS had significantly lower physical activity scores (8834 ± 5967 and 8813 ± 5549 MET ∗ minutes) than controls (9541 ± 5533; p < 0.001). Patients with CFS had the longest sleep duration (466 ± 86 minutes) compared to patients with FMS and controls (450 ± 67 and 446 ± 56; p < 0.001). A linear association between physical activity, sleep duration, and symptom severity was only found in controls, in whom higher physical total activity scores and longer sleep duration were associated with a lower symptom severity. In contrast, quadratic associations were found in all groups: both relatively low and high physical activity scores and relatively short and long sleep duration were associated with higher symptom severity in CFS, FMS, and controls. Conclusion: This study indicates that patients with CFS or FMS sleep longer and are less physically active than controls on average. Both low and high levels of physical activity and short and long sleep duration are associated with higher symptom severity, suggesting the importance of patient-tailored treatment.

Life events and functional somatic symptoms: A population study in older adolescents.

The purpose of this study was to investigate the effect of negative life events on functional somatic symptoms (FSSs) in adolescents, based on data from 957 participants of the population cohort TRacking Adolescents' Individual Lives Survey. Life events experienced between age 16 and age 19 were assessed with the Kendler's Life Stress interview. FSSs at age 19 and age 16 were measured with the Youth and Adult Self-Report. The hypotheses were tested by the use of a latent change model. Life events predicted FSSs, even when adjusted for pre-event levels of FSSs, symptoms of anxiety and depression, and socio-economic status (B = 0.006, 95% CI [0.003, 0.008], ß = .32). Whereas illness-related life events did not predict FSSs independently (B = -0.003, 95% CI [-0.005, 0.09], ß = .05), non-illness-related life events did (B = 0.007, 95% CI [0.004, 0.010], ß = .31). A past-year diagnosis of anxiety and/or depression had a significant influence on the association between life events and FSSs (B = 0.37, 95% CI [0.30, 0.46], ß = .71), while female sex, exposure to childhood adversities, and family malfunctioning had not. In conclusion, our findings show that FSSs are associated with negative life events in older adolescents. We did not find evidence for stronger effects of illness-related events.

Vitamin and mineral status in chronic fatigue syndrome and fibromyalgia syndrome: A systematic review and meta-analysis.

BACKGROUND: Many chronic fatigue syndrome (CFS) and fibromyalgia syndrome (FMS) patients (35-68%) use nutritional supplements, while it is unclear whether deficiencies in vitamins and minerals contribute to symptoms in these patients. Objectives were (1) to determine vitamin and mineral status in CFS and FMS patients as compared to healthy controls; (2) to investigate the association between vitamin and mineral status and clinical parameters, including symptom severity and quality of life; and (3) to determine the effect of supplementation on clinical parameters. METHODS: The databases PubMed, EMBASE, Web of Knowledge, and PsycINFO were searched for eligible studies. Articles published from January 1st 1994 for CFS patients and 1990 for FMS patients till March 1st 2017 were included. Articles were included if the status of one or more vitamins or minerals were reported, or an intervention concerning vitamins or minerals was performed. Two reviewers independently extracted data and assessed the risk of bias. RESULTS: A total of 5 RCTs and 40 observational studies were included in the qualitative synthesis, of which 27 studies were included in the meta-analyses. Circulating concentrations of vitamin E were lower in patients compared to controls (pooled standardized mean difference (SMD): -1.57, 95%CI: -3.09, -0.05; p = .042). However, this difference was not present when restricting the analyses to the subgroup of studies with high quality scores. Poor study quality and a substantial heterogeneity in most studies was found. No vitamins or minerals have been repeatedly or consistently linked to clinical parameters. In addition, RCTs testing supplements containing these vitamins and/or minerals did not result in clinical improvements. DISCUSSION: Little evidence was found to support the hypothesis that vitamin and mineral deficiencies play a role in the pathophysiology of CFS and FMS, and that the use of supplements is effective in these patients. REGISTRATION: Study methods were documented in an international prospective register of systematic reviews (PROSPERO) protocol, registration number: http://www.crd.york.ac.uk/PROSPERO/display_record.asp?ID=CRD42015032528.

A concept mapping study on perpetuating factors of functional somatic symptoms from clinicians' perspective.

OBJECTIVE: The aim of this concept mapping study was to identify the structure and alleged importance of perpetuating factors of functional somatic symptoms (FSS) from the perspective of professionals. Further, we examined to which extent these factors have been addressed in scientific literature. METHODS: Ninety-nine perpetuating factors were sorted with respect to content using a card-sorting task by 61 experienced clinicians (62.3% psychologists, 75.4% female, mean age: 45.7 [SD: 10.6] years, mean duration of experience in treating FSS patients: 10.5 [SD: 7.6] years). These factors had been derived from in-depth interviews with 12 clinicians, with extensive experience in treating FSS. Thirty-eight clinicians rated the importance of the 99 factors on a scale ranging from 1 ('not important at all') to 10 ('extremely important'). RESULTS: Hierarchical cluster analysis revealed three overarching domains of perpetuating factors: 'Hypochondria', 'Social and relational problems' and 'Symptom-related emotions and habits'. These domains comprised 16 clusters, which were rated on importance between 6.1, 'Adverse physical factors and counterproductive lifestyle', and 7.8, 'Frustration and despair regarding the symptoms'. All clusters have been addressed in scientific literature. CONCLUSIONS: This study revealed an encompassing hierarchical structure of somatic, emotional, cognitive, behavioral, and social factors of importance in the perpetuation of FSS based on expert opinions. This structure will guide the development of personalized treatment of FSS.

Sleep problems and pain: a longitudinal cohort study in emerging adults.

Sleep and pain are thought to be bidirectional related on a daily basis in adolescents with chronic pain complaints. In addition, sleep problems have been shown to predict the long-term onset of musculoskeletal pain in middle-aged adults. Yet, the long-term effects of sleep problems on pain duration and different types of pain severity in emerging adults (age: 18-25) are unknown. This study investigated the cross-sectional and longitudinal relationship between sleep problems and chronic pain, and musculoskeletal pain, headache, and abdominal pain severity in a general population of emerging adults. We studied whether these relationships were moderated by sex and whether symptoms of anxiety and depression, fatigue, or physical inactivity mediated these effects. Data of participants from the longitudinal Dutch TRacking Adolescents' Individual Lives Survey were used. Follow-up data were collected in 1753 participants who participated in the fourth (N = 1668, mean age: 19.0 years [SD = 0.6]) and/or fifth (N = 1501, mean age: 22.3 years [SD = 0.6]) assessment wave. Autoregressive cross-lagged models were used for analyses. Sleep problems were associated with chronic pain, musculoskeletal pain, headache and abdominal pain severity, and predicted chronic pain and an increase in musculoskeletal pain severity at 3 years of follow-up. This prospective effect was stronger in females than in males and was mediated by fatigue but not by symptoms of anxiety and depression or physical inactivity. Only abdominal pain had a small long-term effect on sleep problems. Our results suggest that sleep problems may be an additional target for treatment in female emerging adults with musculoskeletal pain complaints.

Are Cardiac Autonomic Nervous System Activity and Perceived Stress Related to Functional Somatic Symptoms in Adolescents? The TRAILS Study.

OBJECTIVE: Stressors have been related to medically insufficiently explained or functional somatic symptoms (FSS). However, the underlying mechanism of this association is largely unclear. In the current study, we examined whether FSS are associated with different perceived stress and cardiac autonomic nervous system (ANS) levels during a standardized stressful situation, and whether these associations are symptom-specific. METHODS: We examined 715 adolescents (16.1 years, 51.3% girls) from the Dutch cohort study Tracking Adolescents' Individual Lives Sample during the Groningen Social Stress Test (GSST). FSS were assessed by the Youth Self-Report, and clustered into a cluster of overtiredness, dizziness and musculoskeletal pain and a cluster of headache and gastrointestinal symptoms. Perceived stress levels (i.e. unpleasantness and arousal) were assessed by the Self-Assessment Manikin, and cardiac ANS activity by assessing heart rate variability (HRV-HF) and pre-ejection period (PEP). Perceived stress and cardiac ANS levels before, during, and after the GSST were studied as well as cardiac ANS reactivity. Linear regression analyses were used to examine the associations. RESULTS: Perceived arousal levels during (beta = 0.09, p = 0.04) and after (beta = 0.07, p = 0.047) the GSST, and perceived unpleasantness levels before (beta = 0.07, p = 0.048) and during (beta = 0.12, p = 0.001) the GSST were related to FSS during the past couple of months. The association between perceived stress and FSS was stronger for the FSS cluster of overtiredness, dizziness and musculoskeletal pain than for the cluster of headache and gastrointestinal symptoms. Neither ANS activity levels before, during, and after the GSST, nor maximal HF-HRV and PEP reactivity were related to FSS. CONCLUSIONS: This study suggests that perceived stress levels during social stress are related to FSS, whereas cardiac ANS activity and reactivity are not related to FSS.

Functional limitations in functional somatic syndromes and well-defined medical diseases. Results from the general population cohort LifeLines.

OBJECTIVE: Functional somatic syndromes (FSS), defined as physical syndromes without known underlying organic pathology, are sometimes regarded as less serious conditions than well-defined medical diseases (MD). The aims of this study were to evaluate functional limitations in FSS, and to compare the results to MD patients with the same core symptoms. METHODS: This study was performed in 89,585 participants (age: 44.4±12.4 years, 58.5% female) of the general-population cohort LifeLines. Quality of Life (QoL) and work participation were examined as indicators of functional limitations. QoL was assessed with two summary scales of the RAND-36: the physical component summary (PCS) and the mental component summary (MCS). Work participation was assessed with a self-reported questionnaire. QoL and work participation were compared between FSS and MD patients, using Chi-squared tests and ANCOVA-analyses, adjusted for age, sex, educational level, and mental disorders. RESULTS: Of the participants, 11.0% (n=9861) reported a FSS, and 2.7% (n=2395) reported a MD. Total QoL, PCS and MCS were significantly lower in all separate FSS and MD compared to controls (P≤.001). Clinically relevant differences in QoL were found between chronic fatigue syndrome and multiple sclerosis patients, and between fibromyalgia syndrome and rheumatoid arthritis patients. Compared to controls, FSS and MD patients reported a comparably reduced working percentage, increased sick absence, early retirement due to health-related reasons, and disability percentage (P≤.001). CONCLUSION: Functional limitations in FSS patients are common, and as severe as those in patients with MD when looking at QoL and work participation, emphasizing that FSS are serious health conditions.

Sexual abuse predicts functional somatic symptoms: an adolescent population study.

The main aim of this study was to investigate the effect of childhood sexual abuse on medically not well explained or functional somatic symptoms (FSSs) in adolescents. We hypothesized that sexual abuse predicts higher levels of FSSs and that anxiety and depression contribute to this relationship. In addition, we hypothesized that more severe abuse is associated with higher levels of FSSs and that sexual abuse is related to gastrointestinal FSSs in particular. This study was part of the Tracking Adolescents' Individual Lives Survey (TRAILS): a general population cohort which started in 2001 (N=2,230; 50.8% girls, mean age 11.1 years). The current study uses data of 1,680 participants over four assessment waves (75% of baseline, mean duration of follow-up: 8 years). FSSs were measured by the Somatic Complaints subscale of the Youth Self-Report at all waves. Sexual abuse before the age of sixteen was assessed retrospectively with a questionnaire at T4. To test the hypotheses linear mixed models were used adjusted for age, sex, socioeconomic status, anxiety and depression. Sexual abuse predicted higher levels of FSSs after adjustment for age sex and socioeconomic status (B=.06) and after additional adjustment for anxiety and depression (B=.03). While sexual abuse involving physical contact significantly predicted the level of FSSs (assault; B=.08, rape; B=.05), non-contact sexual abuse was not significantly associated with FSSs (B=.04). Sexual abuse was not a stronger predictor of gastrointestinal FSSs (B=.06) than of all FSSs. Further research is needed to clarify possible mechanisms underlying relationship between sexual abuse and FSSs.

Short report: Functional somatic symptoms are associated with perfectionism in adolescents.

OBJECTIVE: The aim of this study is to investigate the influence of perfectionism on functional somatic symptoms (FSSs) in adolescents. It was hypothesized that perfectionism predicts higher levels of FSSs cross-sectionally and longitudinally, and that anxiety and depression mediate this relationship. DESIGN: This prospective population-based study was part of the Dutch Tracking Adolescents' Individual Lives Survey (N=2230; 50.8% girls). Data from 1878 participants attending the third (T3) or fourth (T4) assessment wave were used (mean age T3: 16.2 (SD:0.7); mean age T4: 19.0 (SD:0.6)). Multiple regression and mediation analyses were performed in Mplus. MAIN OUTCOME MEASURES: FSSs, perfectionism (i.e. the feeling one has to be perfect), anxiety and depression were assessed with the Youth Self-Report at the third and fourth wave. RESULTS: Perfectionism was associated with a higher level of FSSs in adolescents, both cross-sectionally (B=0.11, 95%-CI: 0.08-0.14) and longitudinally (B=0.05, 95%-CI: 0.02-0.08). There was a small indirect effect of perfectionism on FSSs trough anxiety and depression (B=0.02, 95%-CI: 0.003-0.03, k(2)=0.02). CONCLUSION: The results suggest that perfectionism predicts the course of FSSs with a small indirect effect of perfectionism on FSSs trough anxiety and depression. Further research is needed to clarify which aspects of perfectionism are particularly responsible for this effect.

How to assess stress biomarkers for idiographic research?

Associations between stress-related biomarkers, like cortisol or catecholamines, and somatic or psychological symptoms have often been examined at the group level. Studies using this nomothetic approach reported equivocal findings, which may be due to high levels of intra-individual variance of stress biomarkers. More importantly, analyses at the group level provide information about the average patient, but do not necessarily have meaning for individual patients. An alternative approach is to examine data at the level of individual patients in so-called idiographic research. This method allows identifying individuals in whom symptoms are explained by preceding alterations in specific stress biomarkers, based on time series of symptoms and stress biomarkers. To create time series of sufficient length for statistical analysis, many subsequent stress biomarker measurements are needed for each participant. In the current paper, different matrices (i.e. saliva, urine, nail and hair) are discussed in light of their applicability for idiographic research. This innovative approach might lead to promising new insights in the association between stress biomarkers and psychological or somatic symptoms. New collection tools for stress biomarkers, like the use of sweat pads, automated microdialysis systems, dried blood spots, or smartphone applications, might contribute to the feasibility and implementation of idiographic research in the future.