The added value of daily diary data in 1- and 3-year prediction of psychopathology and psychotic experiences in individuals at risk for psychosis

This study aimed to assess whether adding information on psychological experiences derived from a daily diary to baseline cross-sectional data could improve short- (1-year) and long-term (3-years) prediction of psychopathology and positive psychotic experiences (PEs). We used 90-day daily diary data from 96 individuals in early subclinical risk stages for psychosis. Stepwise linear regression models were built for psychopathology and PEs at 1- and 3-years follow-up, adding: (1) baseline questionnaires, (2) the mean and variance of daily psychological experiences, and (3) individual symptom network density. We assessed whether similar results could be achieved with a subset of the data (7-14- and 30-days). The mean and variance of the diary improved model prediction of short- and long-term psychopathology and PEs, compared to prediction based on baseline questionnaires solely. Similar results were achieved with 7-14- and 30-day subsets. Symptom network density did not improve model prediction except for short-term prediction of PEs. Simple metrics, i.e., the mean and variance from 7 to 14 days of daily psychological experiences assessments, can improve short- and long-term prediction of both psychopathology and PEs in individuals in early subclinical stages for psychosis. Diary data could be a valuable addition to clinical risk prediction models for psychopathology development.

Country-level social mobility and inequalities in adolescent health behaviours in 32 countries

Background

Higher family affluence is associated with healthier behaviours in adolescents, but the strength of this association varies across countries. Differences in social mobility at the country-level, i.e. the extent to which adolescents develop a different socioeconomic status (SES) than their parents, may partially explain why the association between family affluence and adolescent health behaviours is stronger in some countries than in others.

Methods

Using data from adolescents aged 11-15 years from 32 different countries, participating in the 2017/2018 wave of the Health Behaviour in School-aged Children (HBSC) study (N = 185,086), we employed multilevel regression models with cross-level interactions to examine whether country-level social mobility moderates the association between family affluence and adolescent health behaviours (i.e. moderate-to-vigorous physical activity, vigorous physical activity, healthy foods consumed, unhealthy foods consumed, having breakfast regularly, weekly smoking).

Results

Higher family affluence was more strongly associated with higher levels of physical activity in countries characterized by high levels of social mobility (cross-level interaction linear regression coefficient 0.34; 95% CI 0.08 to 0.60; p = 0.009 for moderate-to-vigorous physical activity, and 0.31; 0.11 to 0.50; p = 0.002 for vigorous physical activity). No cross-level interactions were found for any of the other health behaviours.

Conclusions

Our findings suggest that differences in social mobility at the country-level may contribute to cross-national variations in socioeconomic inequalities in adolescent physical activity. Further research can shed light on the mechanisms linking country-level social mobility to inequalities in adolescent physical activity to identify targets for policy and interventions.

Key messages

• This is one of the first studies to investigate country-level social mobility in relation to health equity. Inequalities in adolescent physical activity were steeper in socially mobile countries.

• Stronger efforts to engage adolescents from low-affluent families in physical activity may be necessary in countries characterized by high levels of social mobility.

The STRESS-NL database: A resource for human acute stress studies across the Netherlands

Stress initiates a cascade of (neuro)biological, physiological, and behavioral changes, allowing us to respond to a challenging environment. The human response to acute stress can be studied in detail in controlled settings, usually in a laboratory environment. To this end, many studies employ acute stress paradigms to probe stress-related outcomes in healthy and patient populations. Though valuable, these studies in themselves often have relatively limited sample sizes. We established a data-sharing and collaborative interdisciplinary initiative, the STRESS-NL database, which combines (neuro)biological, physiological, and behavioral data across many acute stress studies in order to accelerate our understanding of the human acute stress response in health and disease (www.stressdatabase.eu). Researchers in the stress field from 12 Dutch research groups of 6 Dutch universities created a database to achieve an accurate inventory of (neuro)biological, physiological, and behavioral data from laboratory-based human studies that used acute stress tests. Currently, the STRESS-NL database consists of information on 5529 individual participants (2281 females and 3348 males, age range 6-99 years, mean age 27.7 ± 16 years) stemming from 57 experiments described in 42 independent studies. Studies often did not use the same stress paradigm; outcomes were different and measured at different time points. All studies currently included in the database assessed cortisol levels before, during and after experimental stress, but cortisol measurement will not be a strict requirement for future study inclusion. Here, we report on the creation of the STRESS-NL database and infrastructure to illustrate the potential of accumulating and combining existing data to allow meta-analytical, proof-of-principle analyses. The STRESS-NL database creates a framework that enables human stress research to take new avenues in explorative and hypothesis-driven data analyses with high statistical power. Future steps could be to incorporate new studies beyond the borders of the Netherlands; or build similar databases for experimental stress studies in rodents. In our view, there are major scientific benefits in initiating and maintaining such international efforts.

Educational level, attention problems, and externalizing behaviour in adolescence and early adulthood

Background

Social causation as well as health-related selection may contribute to educational gradients in adolescents' attention problems (AP) and externalizing behaviour (EB). From past studies it is unclear which of these mechanisms predominates, as AP and EB have the potential to disrupt adolescents' educational careers, but may also be affected by differences in their social environment. Furthermore, gradients in AP and EB may reflect ‘third variables' already present in childhood, such as parental socioeconomic status (SES) and IQ. We investigated social causation and health-related selection in the development of educational differences in EB and AP.

Methods

We used data from a Dutch population-based cohort (TRAILS Study; n = 2,229), including measurements of educational level, EB, and AP at ages around 14, 16, 19, 22, and 26 years. First, we evaluated the directionality in longitudinal associations between education, EB, and AP with cross-lagged panel models, with and without adjusting for pre-existing individual differences using fixed effects. Second, we assessed the role of parental SES and IQ in childhood both as confounders in longitudinal associations, and as predictors of AP, EB, and educational level around age 14.

Results

In fixed effects models, AP, but not EB, consistently predicted decreases in educational level throughout all of adolescence and young adulthood. Regarding social causation, differences in parental SES contributed to increases in EB amongst the lower educational tracks in mid-adolescence. Childhood IQ and parental SES strongly predicted education around age 14. Parental SES, but not IQ, also predicted early adolescent AP and EB.

Conclusions

We found health-related selection attributable to AP throughout all phases of adolescence and young adulthood. Further, our results highlight the role of social causation from parental SES in determining adolescent educational level, AP, and EB.

Key messages

AP have the potential to negatively impact adolescents’ educational careers and may trigger downward mobility in the educational system in all phases of adolescence and young adulthood. The results of this study call for actions to reduce the impact of AP on education. Further, it is essential to address the effects of insufficient economic resources on education and mental health.

[Psychopathology, risk factors and possible interventions in the early years: Dutch cohort research]

Background Multiple factors contribute to the development of psychiatric disorders. Aim To discuss factors in pregnancy and early childhood that contribute to the development of psychiatric problems. Method Overview of the findings of four major Dutch child cohorts. Results Based on findings of four major Dutch child cohorts, we describe risk factors during pregnancy and early childhood that contribute to the development of psychopathology. Conclusion The identified risk factors and mechanisms can serve as targets for follow-up research, prevention, and intervention. Tijdschrift voor psychiatrie 63(2021)2, 107-110.

Education and alcohol use in adolescence – The role of social causation and health-related selection

Background

Both social causation and health-related selection may influence educational gradients in alcohol use in adolescence. From past studies it is unclear which of these mechanisms predominates, as drinking may be both a cause and consequence of low educational attainment. Furthermore, gradients in alcohol use may reflect 'third variables' already present in childhood, such as parental socioeconomic status (SES), effortful control, and IQ. We investigated social causation and health-related selection in the development of educational gradients in alcohol use.

Methods

We used data from a Dutch population-based cohort (TRAILS Study; n = 2,229), including measurements of educational level and drinking at ages around 14, 16, 19, 22, and 26 years. First, we evaluated the directionality in longitudinal associations between education and alcohol use with cross-lagged panel models, with and without adjusting for pre-existing individual differences using fixed effects. Second, we assessed the role of childhood characteristics around age 11, i.e. IQ, effortful control, and parental SES, both as confounders in these longitudinal associations, and as predictors of educational level and drinking around age 14.

Results

In fixed effects models, lower education at age 14 strongly predicted increases in drinking at 16. From age 19 onward, we found a non-significant tendency towards opposite associations, with higher education predicting increases in alcohol use. Alcohol use was not associated with subsequent changes in education. All childhood characteristics strongly predicted education around age 14 and, to a lesser extent, early drinking.

Conclusions

We found conclusive evidence for social causation from education to alcohol use in early adolescence only, and no evidence for selection attributable to alcohol use. By determining initial educational level, childhood characteristics also predict subsequent trajectories in alcohol use.

Key messages

Our findings illustrate the importance of social causation in relation to alcohol use in early adolescence, while no support was found for health-related selection from alcohol use to education. Parental SES, effortful control, and IQ in childhood strongly predicted educational level in early adolescence, which subsequently predicted trajectories in alcohol use during adolescence.

Robust longitudinal multi-cohort results: The development of self-control during adolescence

Longitudinal data from multiple cohorts may be analyzed by Bayesian research synthesis. Here, we illustrate this approach by investigating the development of self-control between age 13 and 19 and the role of sex therein in a multi-cohort, longitudinal design. Three Dutch cohorts supplied data: the Netherlands Twin Register (NTR; N = 21,079), Research on Adolescent Development and Relationships-Young (RADAR-Y; N = 497), and Tracking Adolescents' Individual Lives Survey (TRAILS; N = 2229). Self-control was assessed by one measure in NTR and RADAR-Y, and three measures in TRAILS. In each cohort, we evaluated evidence for competing informative hypotheses regarding the development of self-control. Subsequently, we aggregated this evidence over cohorts and measures to arrive at a robust conclusion that was supported by all cohorts and measures. We found robust evidence for the hypothesis that on average self-control increases during adolescence (i.e., maturation) and that individuals with lower initial self-control often experience a steeper increase in self-control (i.e., a pattern of recovery). From self-report, boys have higher initial self-control levels at age 13 than girls, whereas parents report higher self-control for girls.

Parental Age in Relation to Offspring's Neurodevelopment

Objective: Advanced parenthood increases the risk of severe neurodevelopmental disorders like autism, Down syndrome and schizophrenia. Does advanced parenthood also negatively impact offspring's general neurodevelopment?Method: We analyzed child-, father-, mother- and teacher-rated attention-problems (N = 38,024), and standardized measures of intelligence (N = 10,273) and educational achievement (N = 17,522) of children from four Dutch population-based cohorts. The mean age over cohorts varied from 9.73-13.03. Most participants were of Dutch origin, ranging from 58.7%-96.7% over cohorts. We analyzed 50% of the data to generate hypotheses and the other 50% to evaluate support for these hypotheses. We aggregated the results over cohorts with Bayesian research synthesis.Results: We mostly found negative linear relations between parental age and attention-problems, meaning that offspring of younger parents tended to have more attention problems. Maternal age was positively and linearly related to offspring's IQ and educational achievement. Paternal age showed an attenuating positive relation with educational achievement and an inverted U-shape relation with IQ, with offspring of younger and older fathers at a disadvantage. Only the associations with maternal age remained after including SES. The inclusion of child gender in the model did not affect the relation between parental age and the study outcomes.Conclusions: Effects were small but significant, with better outcomes for children born to older parents. Older parents tended to be of higher SES. Indeed, the positive relation between parental age and offspring neurodevelopmental outcomes was partly confounded by SES.

Author Correction: GWAS of lifetime cannabis use reveals new risk loci, genetic overlap with psychiatric traits, and a causal effect of schizophrenia liability

Several occurrences of the word 'schizophrenia' have been re-worded as 'liability to schizophrenia' or 'schizophrenia risk', including in the title, which should have been "GWAS of lifetime cannabis use reveals new risk loci, genetic overlap with psychiatric traits, and a causal effect of schizophrenia liability," as well as in Supplementary Figures 1-10 and Supplementary Tables 7-10, to more accurately reflect the findings of the work.

GWAS of lifetime cannabis use reveals new risk loci, genetic overlap with psychiatric traits, and a causal influence of schizophrenia

Cannabis use is a heritable trait that has been associated with adverse mental health outcomes. In the largest genome-wide association study (GWAS) for lifetime cannabis use to date (N = 184,765), we identified eight genome-wide significant independent single nucleotide polymorphisms in six regions. All measured genetic variants combined explained 11% of the variance. Gene-based tests revealed 35 significant genes in 16 regions, and S-PrediXcan analyses showed that 21 genes had different expression levels for cannabis users versus nonusers. The strongest finding across the different analyses was CADM2, which has been associated with substance use and risk-taking. Significant genetic correlations were found with 14 of 25 tested substance use and mental health-related traits, including smoking, alcohol use, schizophrenia and risk-taking. Mendelian randomization analysis showed evidence for a causal positive influence of schizophrenia risk on cannabis use. Overall, our study provides new insights into the etiology of cannabis use and its relation with mental health.

The association between executive functioning and psychopathology: general or specific?

BACKGROUND

We modeled both psychopathology and executive function (EF) as bi-factor models to study if EF impairments are transdiagnostic or relate to individual syndromes, and concurrently, if such associations are with general EF or specific EF impairments.

METHODS

Data were obtained from the Tracking Adolescents' Individual Lives Survey (TRAILS; N = 2230). Psychopathology was assessed with parent-report questionnaires at ages 11, 14, 16, and 19, and EF with tasks from the Amsterdam Neuropsychological Tasks program at ages 11 and 19. Bi-factor models were fitted to the data using confirmatory factor analysis. Correlations were estimated to study the associations between general or specific components of both psychopathology and EF.

RESULTS

A bi-factor model with a general psychopathology factor, alongside internalizing (INT), externalizing, attention deficit/hyperactivity (ADHD), and autism spectrum (ASD) problem domains, and a bi-factor model with a general EF factor, alongside specific EFs were adequately fitting measurement models. The best-fitting model between EF and psychopathology showed substantial associations of specific EFs with the general psychopathology factor, in addition to distinct patterns of association with ASD, ADHD, and INT problems.

CONCLUSIONS

By studying very diverse psychopathology domains simultaneously, we show how EF impairments cross diagnostic boundaries. In addition to this generic relation, ADHD, ASD, and INT symptomatology show separable profiles of EF impairments. Thus, inconsistent findings in the literature may be explained by substantial transdiagnostic EF impairments. Whether general EF or specific EFs are related to psychopathology needs to be further studied, as differences in fit between these models were small.

Positive affective functioning in anhedonic individuals' daily life: Anything but flat and blunted

BACKGROUND

Anhedonia, the decreased interest and pleasure, is often described as 'flat' or 'blunted' positive affect (PA). Yet, little is known about PA functioning in anhedonic individuals' daily lives. The current study investigates PA reactivity to pleasurable experiences in anhedonia together with its relevant temporal dynamics (i.e., variability, instability, and inertia), and expands current knowledge by exploring the role of arousal therein.

METHODS

Using the Experience Sampling Method (ESM), we collected 90 assessments of real-life PA experiences across 30 days in 18-24 year old individuals with anhedonia (N=69) and without anhedonia (N=69).

RESULTS

Multilevel analyses showed that anhedonia was associated with less intense pleasure experience, and lower levels of PA. Contrary to predictions from laboratory research and depression theory, individuals with anhedonia showed more variability and less stability in PA, and no signs of blunted PA reactivity. In fact, when exploring high and low arousal PA, individuals with anhedonia showed a slightly stronger reactivity to pleasurable experiences in high-arousal PA but not low-arousal PA.

LIMITATIONS

We did not control for previous pleasure experiences and, instead of the last positive event, accumulation of positive events may have determined the change in high-arousal PA.

CONCLUSIONS

Individuals with anhedonia are likely less 'flat' or 'blunted' than generally thought. Although replication is warranted, impairments in high-arousal positive emotions may be of particular interest in the clinical treatment of anhedonia.

Self-esteem in Early Adolescence as Predictor of Depressive Symptoms in Late Adolescence and Early Adulthood: The Mediating Role of Motivational and Social Factors

Ample research has shown that low self-esteem increases the risk to develop depressive symptoms during adolescence. However, the mechanism underlying this association remains largely unknown, as well as how long adolescents with low self-esteem remain vulnerable to developing depressive symptoms. Insight into this mechanism may not only result in a better theoretical understanding but also provide directions for possible interventions. To address these gaps in knowledge, we investigated whether self-esteem in early adolescence predicted depressive symptoms in late adolescence and early adulthood. Moreover, we investigated a cascading mediational model, in which we focused on factors that are inherently related to self-esteem and the adolescent developmental period: approach and avoidance motivation and the social factors social contact, social problems, and social support. We used data from four waves of the TRAILS study (N = 2228, 51% girls): early adolescence (mean age 11 years), middle adolescence (mean age 14 years), late adolescence (mean age 16 years), and early adulthood (mean age 22 years). Path-analyses showed that low self-esteem is an enduring vulnerability for developing depressive symptoms. Self-esteem in early adolescence predicted depressive symptoms in late adolescence as well as early adulthood. This association was independently mediated by avoidance motivation and social problems, but not by approach motivation. The effect sizes were relatively small, indicating that having low self-esteem is a vulnerability factor, but does not necessarily predispose adolescents to developing depressive symptoms on their way to adulthood. Our study contributes to the understanding of the mechanisms underlying the association between self-esteem and depressive symptoms, and has identified avoidance motivation and social problems as possible targets for intervention.

Functional outcomes of child and adolescent mental disorders. Current disorder most important but psychiatric history matters as well

BACKGROUND

Various sources indicate that mental disorders are the leading contributor to the burden of disease among youth. An important determinant of functioning is current mental health status. This study investigated whether psychiatric history has additional predictive power when predicting individual differences in functional outcomes.

METHOD

We used data from the Dutch TRAILS study in which 1778 youths were followed from pre-adolescence into young adulthood (retention 80%). Of those, 1584 youths were successfully interviewed, at age 19, using the World Health Organization Composite International Diagnostic Interview (CIDI 3.0) to assess current and past CIDI-DSM-IV mental disorders. Four outcome domains were assessed at the same time: economic (e.g. academic achievement, social benefits, financial difficulties), social (early motherhood, interpersonal conflicts, antisocial behavior), psychological (e.g. suicidality, subjective well-being, loneliness), and health behavior (e.g. smoking, problematic alcohol, cannabis use).

RESULTS

Out of the 19 outcomes, 14 were predicted by both current and past disorders, three only by past disorders (receiving social benefits, psychiatric hospitalization, adolescent motherhood), and two only by current disorder (absenteeism, obesity). Which type of disorders was most important depended on the outcome. Adjusted for current disorder, past internalizing disorders predicted in particular psychological outcomes while externalizing disorders predicted in particular health behavior outcomes. Economic and social outcomes were predicted by a history of co-morbidity of internalizing and externalizing disorder. The risk of problematic cannabis use and alcohol consumption dropped with a history of internalizing disorder.

CONCLUSION

To understand current functioning, it is necessary to examine both current and past psychiatric status.

Discrepancies Between Perceptions of the Parent-Adolescent Relationship and Early Adolescent Depressive Symptoms: An Illustration of Polynomial Regression Analysis

Adolescence is a critical period for the development of depressive symptoms. Lower quality of the parent-adolescent relationship has been consistently associated with higher adolescent depressive symptoms, but discrepancies in perceptions of parents and adolescents regarding the quality of their relationship may be particularly important to consider. In the present study, we therefore examined how discrepancies in parents' and adolescents' perceptions of the parent-adolescent relationship were associated with early adolescent depressive symptoms, both concurrently and longitudinally over a 1-year period. Our sample consisted of 497 Dutch adolescents (57 % boys, M age = 13.03 years), residing in the western and central regions of the Netherlands, and their mothers and fathers, who all completed several questionnaires on two occasions with a 1-year interval. Adolescents reported on depressive symptoms and all informants reported on levels of negative interaction in the parent-adolescent relationship. Results from polynomial regression analyses including interaction terms between informants' perceptions, which have recently been proposed as more valid tests of hypotheses involving informant discrepancies than difference scores, suggested the highest adolescent depressive symptoms when both the mother and the adolescent reported high negative interaction, and when the adolescent reported high but the father reported low negative interaction. This pattern of findings underscores the need for a more sophisticated methodology such as polynomial regression analysis including tests of moderation, rather than the use of difference scores, which can adequately address both congruence and discrepancies in perceptions of adolescents and mothers/fathers of the parent-adolescent relationship in detail. Such an analysis can contribute to a more comprehensive understanding of risk factors for early adolescent depressive symptoms.

Three decades of eating disorders in Dutch primary care: decreasing incidence of bulimia nervosa but not of anorexia nervosa

BACKGROUND

Whether the incidence of eating disorders in Western, industrialized countries has changed over time has been the subject of much debate. The purpose of this primary-care study was to examine changes in the incidence of eating disorders in The Netherlands during the 1980s, 1990s and 2000s.

METHOD

A nationwide network of general practitioners (GPs), serving a representative sample (~1%) of the total Dutch population, recorded newly diagnosed patients with anorexia nervosa (AN) and bulimia nervosa (BN) in their practice during 1985-1989, 1995-1999, and 2005-2009. GPs are key players in the Dutch healthcare system, as their written referral is mandatory in order to get access to specialized (mental) healthcare, covered by health insurance. Health insurance is virtually universal in The Netherlands (99% of the population). A substantial number of GPs participated in all three study periods, during which the same case identification criteria were used and the same psychiatrist was responsible for making the final diagnoses. Incidence rates were calculated and for comparison between periods, incidence rate ratios.

RESULTS

The overall incidence rate of BN decreased significantly in the past three decades (from 8.6 per 100,000 person-years in 1985-1989 to 6.1 in 1995-1999, and 3.2 in 2005-2009). The overall incidence of AN remained fairly stable during three decades, i.e. 7.4 per 100,000 person-years in 1985-1989, 7.8 in 1995-1999, and 6.0 in 2005-2009.

CONCLUSIONS

The incidence rate of BN decreased significantly over the past three decades, while the overall incidence rate of AN remained stable.

Genome-wide association study of lifetime cannabis use based on a large meta-analytic sample of 32 330 subjects from the International Cannabis Consortium

Cannabis is the most widely produced and consumed illicit psychoactive substance worldwide. Occasional cannabis use can progress to frequent use, abuse and dependence with all known adverse physical, psychological and social consequences. Individual differences in cannabis initiation are heritable (40-48%). The International Cannabis Consortium was established with the aim to identify genetic risk variants of cannabis use. We conducted a meta-analysis of genome-wide association data of 13 cohorts (N=32 330) and four replication samples (N=5627). In addition, we performed a gene-based test of association, estimated single-nucleotide polymorphism (SNP)-based heritability and explored the genetic correlation between lifetime cannabis use and cigarette use using LD score regression. No individual SNPs reached genome-wide significance. Nonetheless, gene-based tests identified four genes significantly associated with lifetime cannabis use: NCAM1, CADM2, SCOC and KCNT2. Previous studies reported associations of NCAM1 with cigarette smoking and other substance use, and those of CADM2 with body mass index, processing speed and autism disorders, which are phenotypes previously reported to be associated with cannabis use. Furthermore, we showed that, combined across the genome, all common SNPs explained 13-20% (P<0.001) of the liability of lifetime cannabis use. Finally, there was a strong genetic correlation (rg=0.83; P=1.85 × 10(-8)) between lifetime cannabis use and lifetime cigarette smoking implying that the SNP effect sizes of the two traits are highly correlated. This is the largest meta-analysis of cannabis GWA studies to date, revealing important new insights into the genetic pathways of lifetime cannabis use. Future functional studies should explore the impact of the identified genes on the biological mechanisms of cannabis use.

Predicting mental disorders from hypothalamic-pituitary-adrenal axis functioning: a 3-year follow-up in the TRAILS study

BACKGROUND

Hypothalamic-pituitary-adrenal axis functioning, with cortisol as its major output hormone, has been presumed to play a key role in the development of psychopathology. Predicting affective disorders from diurnal cortisol levels has been inconclusive, whereas the predictive value of stress-induced cortisol concentrations has not been studied before. The aim of this study was to predict mental disorders over a 3-year follow-up from awakening and stress-induced cortisol concentrations.

METHOD

Data were used from 561 TRAILS (TRacking Adolescents' Individual Lives Survey) participants, a prospective cohort study of Dutch adolescents. Saliva samples were collected at awakening and half an hour later and during a social stress test at age 16. Mental disorders were assessed 3 years later with the Composite International Diagnostic Interview (CIDI).

RESULTS

A lower cortisol awakening response (CAR) marginally significantly predicted new disorders [odds ratio (OR) 0.77, p = 0.06]. A flat recovery slope predicted disorders with a first onset after the experimental session (OR 1.27, p = 0.04). Recovery revealed smaller, non-significant ORs when predicting new onset affective or anxiety disorders, major depressive disorder, or dependence disorders in three separate models, corrected for all other new onsets.

CONCLUSIONS

Our results suggest that delayed recovery and possibly reduced CAR are indicators of a more general risk status and may be part of a common pathway to psychopathology. Delayed recovery suggests that individuals at risk for mental disorders perceived the social stress test as less controllable and less predictable.

Mental health in Dutch adolescents: a TRAILS report on prevalence, severity, age of onset, continuity and co-morbidity of DSM disorders

BACKGROUND

With psychopathology rising during adolescence and evidence suggesting that adult mental health burden is often due to disorders beginning in youth, it is important to investigate the epidemiology of adolescent mental disorders.

METHOD

We analysed data gathered at ages 11 (baseline) and 19 years from the population-based Dutch TRacking Adolescents' Individual Lives Survey (TRAILS) study. At baseline we administered the Achenbach measures (Child Behavior Checklist, Youth Self-Report) and at age 19 years the World Health Organization's Composite International Diagnostic Interview version 3.0 (CIDI 3.0) to 1584 youths.

RESULTS

Lifetime, 12-month and 30-day prevalences of any CIDI-DSM-IV disorder were 45, 31 and 15%, respectively. Half were severe. Anxiety disorders were the most common but the least severe whereas mood and behaviour disorders were less prevalent but more severe. Disorders persisted, mostly by recurrence in mood disorders and chronicity in anxiety disorders. Median onset age varied substantially across disorders. Having one disorder increased subjects' risk of developing another disorder. We found substantial homotypic and heterotypic continuity. Baseline problems predicted the development of diagnosable disorders in adolescence. Non-intact families and low maternal education predicted externalizing disorders. Most morbidity concentrated in 5-10% of the sample, experiencing 34-55% of all severe lifetime disorders.

CONCLUSIONS

At late adolescence, 22% of youths have experienced a severe episode and 23% only mild episodes. This psychopathology is rather persistent, mostly due to recurrence, showing both monotypic and heterotypic continuity, with family context affecting particularly externalizing disorders. High problem levels at age 11 years are modest precursors of incident adolescent disorders. The burden of mental illness concentrates in 5-10% of the adolescent population.

Mental health problems are associated with low-frequency fluctuations in reaction time in a large general population sample. The TRAILS study

BACKGROUND

Increased intra-subject reaction time variability (RT-ISV) as coarsely measured by the standard deviation (RT-SD) has been associated with many forms of psychopathology. Low-frequency RT fluctuations, which have been associated with intrinsic brain rhythms occurring approximately every 15-40s, have been shown to add unique information for ADHD. In this study, we investigated whether these fluctuations also relate to attentional problems in the general population, and contribute to the two major domains of psychopathology: externalizing and internalizing problems.

METHODS

RT was monitored throughout a self-paced sustained attention task (duration: 9.1 ± 1.2 min) in a Dutch population cohort of young adults (n=1455, mean age: 19.0 ± 0.6 years, 55.1% girls). To characterize temporal fluctuations in RT, we performed direct Fourier Transform on externally validated frequency bands based on frequency ranges of neuronal oscillations: Slow-5 (0.010-0.027 Hz), Slow-4 (0.027-0.073 Hz), and three additional higher frequency bands. Relative magnitude of Slow-4 fluctuations was the primary predictor in regression models for attentional, internalizing and externalizing problems (measured by the Adult Self-Report questionnaire). Additionally, stepwise regression models were created to investigate (a) whether Slow-4 significantly improved the prediction of problem behaviors beyond the RT-SD and (b) whether the other frequency bands provided important additional information.

RESULTS

The magnitude of Slow-4 fluctuations significantly predicted attentional and externalizing problems and even improved model fit after modeling RT-SD first (R(2) change=0.6%, P<.01). Subsequently, adding Slow-5 explained additional variance for externalizing problems (R(2) change=0.4%, P<.05). For internalizing problems, only RT-SD made a significant contribution to the regression model (R(2)=0.5%, P<.01), that is, none of the frequency bands provided additional information.

CONCLUSIONS

Low-frequency RT fluctuations have added predictive value for attentional and externalizing, but not internalizing problems beyond global differences in variability. This study extends previous findings in clinical samples of children with ADHD to adolescents from the general population and demonstrates that deconstructing RT-ISV into temporal components can provide more distinctive information for different domains of psychopathology.

Glucocorticoid receptor gene (NR3C1) methylation following stressful events between birth and adolescence. The TRAILS study

Stress early in life is a known risk factor for the development of affective disorders later in life. Epigenetic mechanisms, such as DNA methylation, may have an important role in mediating that risk. Recent epigenetic research reported on the long-term relationship between traumatic stress in childhood and DNA methylation in adulthood. In this study, we examined the impact of various types of stress (perinatal stress, stressful life events (SLEs) and traumatic youth experiences) on methylation of the glucocorticoid receptor gene (NR3C1) in the blood of a population sample of 468 adolescents (50.4% female, mean age 16.1 years). Second, we determined whether stress at different ages was associated with higher NR3C1 methylation. NR3C1 methylation rates were higher after exposure to SLEs and after exposure to traumatic youth experiences. NR3C1 methylation in adolescence was not higher after exposure to perinatal stress. Experience of SLEs in adolescence was associated with a higher NR3C1 methylation, independently of childhood SLEs. We demonstrate that not only traumatic youth experiences but also (more common) SLEs are associated with higher NR3C1 methylation. In addition, our findings underline the relevance of adolescent stress for epigenetic changes in the NR3C1 gene.

Physical activity and onset of depression in adolescents: a prospective study in the general population cohort TRAILS

Although it has often been suggested that physical activity and depression are intertwined, only few studies have investigated whether specific aspects of physical activity predict the incidence of major depression in adolescents from the general population. Therefore the aim of this study was to investigate the effects of nature, frequency, duration and intensity of physical activity during early adolescence on the onset of a major depressive episode in early adulthood. In a population sample of adolescents (N = 1396), various aspects of physical activity were assessed at early adolescence (mean age 13.02, SD = 0.61). Major depressive episode onset was assessed using the Composite International Diagnostic Interview. A Cox regression model was performed to investigate whether physical activity characteristics and their interactions with gender predicted a major depressive episode onset up until mean age 18.5 (SD = 0.61). The individual characteristics of physical activity (nature, frequency, duration and intensity) or their interactions with gender did not predict a major depressive episode onset (p values >0.05). So far, there is no prospective evidence that physical activity protects against the development of adolescent depressive episodes in either boys or girls.

Baseline cortisol measures and developmental pathways of anxiety in early adolescence

OBJECTIVE

This study investigated whether baseline cortisol measures predicted future anxiety, and compared cortisol values of groups with different developmental pathways of anxiety.

METHOD

Cortisol levels were assessed in 1768 individuals (10-12 years). Anxiety levels were assessed at the same age and 2 years later.

RESULTS

Cortisol measures did not predict future anxiety levels. Individuals with persistent anxiety problems did not show higher morning cortisol levels than those with persistently low, decreasing, or increasing anxiety levels. Instead, individuals with persistently high anxiety levels showed significantly lower evening cortisol levels than all other individuals. Further, participants with increasing anxiety levels showed higher morning cortisol levels (area under the curve; AUC) than individuals with persistently low anxiety levels.

CONCLUSION

The extent to which the HPA-axis - by itself - plays a role in the aetiology of anxiety is questionable. Interactions of the HPA-axis with other biological or environmental factors may be more important.

[Stress reactivity as an underlying mechanism of anxiety? Findings from the TRAILS study]

This short report provides an overview of the results of a recent Dutch study on the relation between anxiety and the reactivity of two important stress response systems: the autonomic nervous system and the hypothalamic-pituitary-adrenal axis. Future research will have to investigate the reactivity of both stress response systems in combination with several other important biological, psychological and social factors. In this way it should be possible to obtain more insight into the complex and interacting systems that underlie anxiety.

Higher cortisol awakening response in young adolescents with persistent anxiety problems

OBJECTIVE

The aims of the present study were to test the association between current anxiety problems and basal cortisol levels in a large population sample of young preadolescents, and to test if HPA-axis activity differs between individuals with no, only current, or persistent anxiety problems.

METHOD

Cortisol levels of 10- to 12-year olds (n = 1,768) from the general population were measured on three time points during the day. A self-report questionnaire (RCADS) was used to assess current anxiety, a parent-report questionnaire (TPBQ) to assess anxiety problems at age 4.

RESULTS

Associations between cortisol levels and current anxiety problems were not found. However, individuals with persistent anxiety problems had higher morning cortisol levels and a higher cortisol awakening response.

CONCLUSION

Apparently, only persistent, and not current, anxiety problems are associated with higher HPA-axis activity. Alterations in HPA-axis activity might underlie persistent anxiety problems, or result from the stress accompanied by persistent anxiety problems.

Internalizing and externalizing problems in adolescence: general and dimension-specific effects of familial loadings and preadolescent temperament traits

BACKGROUND

We investigated the links between familial loading, preadolescent temperament, and internalizing and externalizing problems in adolescence, hereby distinguishing effects on maladjustment in general versus dimension-specific effects on either internalizing or externalizing problems.

METHOD

In a population-based sample of 2230 preadolescents (10-11 years) familial loading (parental lifetime psychopathology) and offspring temperament were assessed at baseline by parent report, and offspring psychopathology at 2.5-years follow-up by self-report, teacher report and parent report. We used purified measures of temperament and psychopathology and partialled out shared variance between internalizing and externalizing problems.

RESULTS

Familial loading of internalizing psychopathology predicted offspring internalizing but not externalizing problems, whereas familial loading of externalizing psychopathology predicted offspring externalizing but not internalizing problems. Both familial loadings were associated with Frustration, low Effortful Control, and Fear. Frustration acted as a general risk factor predicting severity of maladjustment; low Effortful Control and Fear acted as dimension-specific risk factors that predicted a particular type of psychopathology; whereas Shyness, High-Intensity Pleasure, and Affiliation acted as direction markers that steered the conditional probability of internalizing versus externalizing problems, in the event of maladjustment. Temperament traits mediated one-third of the association between familial loading and psychopathology. Findings were robust across different composite measures of psychopathology, and applied to girls as well as boys.

CONCLUSIONS

With regard to familial loading and temperament, it is important to distinguish general risk factors (Frustration) from dimension-specific risk factors (familial loadings, Effortful Control, Fear), and direction markers that act as pathoplastic factors (Shyness, High-Intensity Pleasure, Affiliation) from both types of risk factors. About one-third of familial loading effects on psychopathology in early adolescence are mediated by temperament.

Determinants of salivary cortisol levels in 10-12 year old children; a population-based study of individual differences

The hypothalamic-pituitary-adrenal (HPA)-axis is a central component of the body's neuroendocrine response to stress. Its major end-product cortisol has profound effects on mood and behavior. Although it has often been suggested, it remains unknown whether differences in HPA-axis physiology are part of an individual's vulnerability to psychopathology, and constitute a causal factor in its development. In order to study the contribution of HPA-axis physiology to the development of psychopathology, we measured HPA-axis physiology in a community-cohort of 1768 10-12 year-old children. The aims of the here presented study were twofold: (1) to obtain data on HPA-axis function in a large cohort of pre- and early-adolescent children, both in terms of total hormonal output and in terms of the dynamics of cortisol secretion (by means of the cortisol awakening response); and (2) to study potential confounders of the cortisol-psychopathology relationship in this age group, such as season of sampling, age, gender, pubertal development, perinatal variables and BMI. We found a wide interindividual variability in HPA-axis function. An increase in cortisol in the first 30 min after awakening was present in 70.7% of children, but the increase appears lower in children than in adults. In addition, this study suggests that season of sampling and gender may act as potential confounders in the cortisol-psychopathology relationship. We will follow these children longitudinally for the development of psychopathology in the period from childhood into adulthood. This period covers adolescence, which is a critical time for the appearance and development of psychiatric disorders.

Positive life change and remission of non-psychotic mental illness. A competing outcomes approach

BACKGROUND

Episode duration in non-psychotic mental illness is associated with personal characteristics of patients, like age or personality. Part of these links may be mediated by life change, a predictor of episode duration in its own right.

METHODS

In 170 primary care patients who suffered 4171 person-months of non-psychotic mental illness diagnosed according to Bedford College Criteria, we examined to what extent associations with episode duration of nine person-linked variables including personal vulnerability, coping styles and social support, are mediated by their effects on the occurrence, during episodes, of positive life changes (PLC) assessed using the Life Events and Difficulties Schedule. Cox regression for competing endpoints was used to analyse the simultaneous effects of baseline variables on PLC and on remission, whether spontaneous or not.

RESULTS

Irrespective of diagnosis and symptom intensity, PLC during episodes increases remission rates 2.9-fold (P<0.001). Remission rates are higher in patients with larger social networks and who seek more help but this is partly because such persons experience more PLC earlier during episodes. Lower neuroticism is also linked with shorter episode duration but this effect is unmediated by PLC.

LIMITATIONS

Mental state may bias dating and reporting of life change. Treatment aspects were not recorded. Elderly subjects were not included.

CONCLUSION

PLC occurrence during common mental illness is associated with psychosocial variables which are also overall predictors of episode remission. Thus, PLC mediates between patients' psychosocial make-up and their chances of speedy recovery. This has implications for the management of non-psychotic mental illness.

Does educational background explain inequalities in care service use for mental health problems in the Dutch general population?

OBJECTIVE

To investigate whether (1) education predicts the use of care services for mental health problems, independently of mental disorder and functional impairment and (2) education modifies the association between mental disorder and service use.

METHOD

Predictors of service use were recorded at baseline, and service use itself at 12-month follow-up, in a representative sample (N=7076) of the Dutch population, using the Composite International Diagnostic Interview.

RESULTS

People with more education were less likely to use primary care but more likely to use mental health care. The effects on both types of care remained significant after adjustment for mental disorder and functional impairment. Lower education tended to strengthen the association between mood or anxiety disorder and primary care use.

CONCLUSION

Further research on inequalities in service use will benefit from additional explanatory analyses and from the inclusion of sociopsychological variables, like cost-benefit considerations in decisions to use services.

Functional disability and neuroticism as predictors of late-life depression

The authors investigated the association of premorbidly-assessed disability and neuroticism with the onset of late-life depression in 86 depressed and 72 randomly selected control persons, originating from a 1993 Dutch community study of elderly people. Compared with elderly people with average levels of disability and neuroticism, people with low levels were significantly less likely to develop a depressive disorder. High scorers, on the other hand, did not differ significantly from the average group. Furthermore, the data tend to suggest that the increased risk for depression associated with disability was larger for patients with higher levels of neuroticism.

Urinary free cortisol excretion in elderly persons with minor and major depression

Several studies have found that cortisol hypersecretion may occur in severely depressed patients, characterized by melancholic features. On the other hand, illness chronicity seems to be related to low, rather than high, cortisol levels. This study aims to trace factors associated with 24-h urinary free cortisol levels in a sample of 23 elderly persons with major or minor depression and 21 non-depressed control subjects. Depressive episodes were subdivided according to severity and chronicity (i.e. length and recurrence). None of the depressed persons showed unusually high 24-h cortisol levels, and cortisol excretion was not elevated as compared with that in the control group, regardless of subtype of depression. The results suggest, however, that hyposecretion of cortisol may be a feature of chronic depressive episodes, especially in males.

Depression in later life: three etiologically different subgroups

BACKGROUND

Various studies support the notion that early onset depression and late onset depression have different etiological pathways. Late onset depression has been found to be a heterogeneous group. This study attempts to divide the late onset group in two subgroups with different aetiology and find evidence for the vascular depression hypothesis.

METHODS

Subjects were 132 depressed elderly persons from the general population, general practitioners and mental health care outpatient clinics. Sixty-four had early-onset depression (< 60), 69 had late-onset depression (> or = 60). The latter group was divided into subjects with (n = 15) and without (n = 15) severe life stress. The groups were compared with respect to a variety of variables including vascular risk factors

RESULTS

Early-onset depression was associated with neuroticism and parental history. Subjects with late-onset depression and no severe life stress had higher vascular risk factors than whose depression was preceded by a severe stressor did.

CONCLUSIONS

Our findings suggest that late life depression can be divided into subgroups with different etiological pathways: (1) early-onset with longstanding psychobiological vulnerability; (2) late-onset as reaction to severe life stress; and (3) late-onset with vascular risk factors.

The interplay and etiological continuity of neuroticism, difficulties, and life events in the etiology of major and subsyndromal, first and recurrent depressive episodes in later life

OBJECTIVE

Stressful life events, long-term difficulties, and high neuroticism are established risk factors for depression. Less is known about their role in late-life depression, how they modify or mediate one another's effects, and whether this differs between major and subsyndromal, first and recurrent episodes.

METHOD

The authors used a prospective case-control design nested in a community survey of elderly subjects that included a measure of neuroticism. They compared 83 survey participants who subsequently developed a depressive episode with 83 randomly selected comparison participants. The authors determined dates of onset, history, and severity of episodes and dates of occurrence and severity of stressful life events and difficulties.

RESULTS

Stressful life events did not mediate the effects of high neuroticism and difficulties at onset, possibly because of the uncontrollable nature of common stressful life events in later life. Without both high neuroticism and difficulties, stressful life events did not increase risk. High neuroticism and difficulties increased risk, even without a stressful life event. In the presence of high neuroticism and/or difficulties, the depressogenic effect of stressful life events was substantial, suggesting effect modification. The authors found no evidence to suggest etiological discontinuity between major and subsyndromal episodes. First and recurrent episodes showed a discontinuous pattern of associations. Severe stressful life events had weaker associations, but high neuroticism and mild stressful life events had stronger associations with recurrent than with first episodes.

CONCLUSIONS

This study demonstrated the usefulness of a dynamic stress-vulnerability model for understanding late-life depression. Evidence was found suggesting etiological discontinuity between first and recurrent but not between major and subsyndromal episodes.

[Drug utilization by the elderly with depressive symptoms]

OBJECTIVE

Obtain a picture of non-psychiatric medication use and depressogenic medication use by elderly people suffering from depression.

DESIGN

Cross-sectional, self-reported by respondents.

METHOD

Information about medication usage and the presence of chronic diseases was obtained from 183 depressive respondents and 96 control respondents. The respondents were aged 55 years or over. They were recruited between April 1996 and May 1998 in the provinces Groningen, Drenthe and Friesland, the Netherlands. Recruitment was via Regional Institutes for Outpatient Mental Health Care (RIAGGs), a psychiatric outpatient clinic, general practitioners participating in the 'Groningen longitudinal ageing study' (GLAS), a survey under the elderly within the general population, and screening with the 'Geriatric depression scale' (score > or = 6) in the GLAS main file.

RESULTS

Respondents with subsyndromal depression recruited via screening were prescribed more depressogenic medication (mean: 3.26 drugs per patient, of which 45.6% depressogenic) than the control group (respective figures: 1.78; 26.1%) and the depressive groups recruited via general practitioners (2.77; 31.8%) or those recruited via RIAGGs/psychiatric outpatient clinic (2.60; 38.3%).

Correlates of symptomatic, minor and major depression in the elderly

BACKGROUND

Associations between different types of depression with clinical characteristics and putative vulnerability factors from several domains (health, disability, personality, familial psychopathology) were studied in a sample of elderly subjects, in order to find arguments that support or discard the notion of discontinuity in correlates of depression.

METHODS

Subjects were 183 depressed elderly persons from the general population, general practitioners and mental health care outpatient clinics, and a random elderly control group (n=74). Depression was subdivided into symptomatic (n=45), DSM-IV minor (n=73), and DSM-IV major (n=65) depression. The groups were compared with respect to a variety of variables from different domains.

RESULTS

Most variables showed a marked difference between the control group and the depressive groups, and smaller or no differences between depressive subtypes.

LIMITATIONS

The data were collected cross-sectionally.

CONCLUSIONS

With a few notable exceptions, all subtypes of depression were significantly different from the control group, while differences between depressive subtypes were generally smaller. Depressive subtypes showed no discontinuum with respect to the associated variables. Similar associations in different subtypes of depression may indicate common vulnerability factors.

Predictors of time to remission from depression in primary care patients: do some people benefit more from positive life change than others?

The authors examined the role of personality, social support, and coping strategies and their interaction with positive life change (PLC) in influencing time to remission from depression in 86 depressed primary care patients (69% women, mean age = 36.6 years), who were followed for 3.5 years. Diagnostic information was obtained by the Present State Examination (J. K. Wing, J. Cooper, & N. Sartorius, 1974), and life change by the Life Events and Difficulties Schedule (G. W. Brown & T. O. Harris, 1978). The association of PLC and other predictors with the time to remission was studied by means of Cox regression. PLC reduced time to remission in women, but not in men. Other predictors that expedited remission were low severity of premorbid difficulties, high self-esteem, and a tension-reducing coping style. Neuroticism modified the effect of PLC in that the remission forward bringing effect of PLC was stronger for highly neurotic people. The results suggests that women and psychologically vulnerable persons benefit most from PLC.

Onset of disability in depressed and non-depressed primary care patients

BACKGROUND

While cross-sectional and longitudinal studies have consistently found depressive illness and disability to be related, understanding whether depression leads to subsequent onset of disability is limited.

METHODS

In the context of the multi-centre international WHO Collaborative Study on Psychological Problems in General Health Care, we followed prospectively consulting non-elderly primary care patients who were essentially disability free at baseline but who differed in baseline depression status, comprising 1051 patients free of physical disability at baseline including 14% depression; 914 free of social disability including 9% depression. Depression status was assessed with the CIDI; patient-reported physical disability with the MOS physical functioning scale and social disability with the BDQ role functioning and number of disability days measures; investigator-rated social disability with the Occupational section of Groningen Social Disability schedule; and the treating physicians rated the severity of physical illness.

RESULTS

In patients essentially disability free at baseline, depressive illness resulted in a 1.5-fold (at 3 months) and a 1.8-fold (at 12 months) increase in risk of onset of physical disability, after controlling for physical disease severity. Depressive illness also resulted in a 2.2-fold (at 3 months) and a 23-fold (at 12 months) increase in risk of onset of social disability, after controlling for physical disease severity, physical disability and onset of physical disability.

CONCLUSIONS

Among non-elderly primary care patients, depressive illness is associated with onset of physical disability and shows an even stronger association with onset of social disability.

A transition rate model for first admissions to psychiatric institutions

This paper describes the application of a parametric transition rate model, the generalized log-logistic model, to the duration of first admissions to psychiatric institutions. The final model included diagnosis, gender, age, living conditions and year of admission as covariates. Characteristics of the log-logistic model are described extensively. Parametric transition models offer challenging and promising possibilities to model duration of hospital stay.

Prevalence, 20-month incidence and outcome of unipolar depressive disorders in a community sample of adolescents

BACKGROUND

This article presents prospective longitudinal findings on prevalence, incidence, patterns of change and stability of depressive disorders in a community sample of 1228 adolescents.

METHODS

Data were collected at baseline and follow-up (20 months later) in a representative population sample of 1228 adolescents, aged 14-17 at baseline. Diagnostic assessment was based on the Munich Composite International Diagnostic Interview (M-CIDI).

RESULTS

The overall cumulative lifetime incidence of any depressive condition was 20.0% (major depressive disorder (MDD), 12.2%; dysthymia, 3-5%; subthreshold MDD, 6.3%), of which about one-third were incident depressions in the period between baseline and follow-up. Depressive disorders rarely started before the age of 13. Females were about twice as likely as males to develop a depressive disorder. Overall, the 20-month outcome of baseline depression was unfavourable. Dysthymia had the poorest outcome of all, with a complete remission rate of only 33% versus 43% for MDD and 54% for subthreshold MDD. Dysthymia also had the highest number of depressive episodes, and most psychosocial impairment and suicidal behavioural during follow-up. Treatment rates were low (8-23%). Subthreshold MDD associated with considerable impairment had an almost identical course and outcome as threshold MDD.

CONCLUSIONS

DSM-IV MDD and dysthymia are rare before the age of 13, but frequent during adolescence, with an estimated lifetime cumulative incidence of 14%. Only a minority of these disorders in adolescence is treated, and more than half of them persist or remit only partly.

Time trends in mental health care utilization in a Dutch area, 1976-1990

This paper concerns time trends in mental health care utilization in a Dutch area from 1976 to 1990. In general, there was an increase in the use of psychiatric services during the study period, both in terms of the number of new patients (per 1000 population) and in terms of the amount of care utilized per patient. When only intramural services were taken into account the number of new psychiatric patients remained approximately constant, but the number of patients in care at a certain point in time (point prevalence) showed a rising trend. For most part, the increase in inpatient point prevalence rates could be ascribed to the increase in the elderly population (75 years or more). In addition to the proportional increase of the ageing population, a growing amount of psychosocial problems and broadening of the concept of illness were tentatively assumed to be related to the increase in mental health care utilization. Unlike some other countries, deinstitutionalization hardly occurred in the Netherlands.

Monthly variation in the care-based incidence of psychopathology

Monthly first-contact data from the Groningen Psychiatric Case Register were used to study seasonal variation in the care-based incidence of psychiatric morbidity. Both overall and diagnosis-specific rates for a 15-year period (1976-1990) were examined. Regression analysis of overall rates revealed significant monthly deviations from the linear trend. Inspection of diagnosis-specific rates showed that the monthly number of first contacts varied most in patients with relatively mild psychiatric problems such as neuroses. Seasonal variation is believed to be a consequence of both fluctuations in true psychiatric morbidity and 'holiday effects' on supply of services and/or the inclination to ask for help. The relative influence of holiday effects is assumed to be inversely related to psychiatric severity.

Time trends in the care-based incidence of schizophrenia

BACKGROUND

Several studies have suggested a declining first-admission rate for schizophrenia. This study examines the care-based incidence of schizophrenia in a Dutch register area.

METHOD

Data from Groningen psychiatric case register were used to compare first-admission rates for schizophrenia over 1976-90 with those of other functional psychoses, and to consider various potential biases.

RESULTS

Diagnostic habits probably affected time trends in incidence rates. Using a broader definition of schizophrenia, no evidence was found for a decrease in the incidence of schizophrenia. Although first admissions to intramural services showed a (non-significant) decrease, this effect seemed to be neutralised when all mental health services were taken into account.

CONCLUSIONS

Care-based studies of time trends in psychiatric disorders should embrace all mental health services. Furthermore, unless a diagnostic classification system with univocal criteria is used, bias caused by changing diagnostic habits cannot be ruled out.

The structure of common psychiatric symptoms: how many dimensions of neurosis?

In order to replicate and elaborate the two-dimensional model of depression and anxiety underlying the structure of common psychiatric symptoms proposed by Goldberg et al. (1987), we carried out latent trait analyses on PSE symptom data of the original Manchester study and two recent Dutch studies. We used the same analytical strategy as Goldberg et al. to facilitate comparison with the earlier work. It was found that a more comprehensive set of common psychiatric symptoms caused an extra, third dimension to emerge, so that the earlier anxiety dimension became split between a specific anxiety axis characterized by situational and phobic anxiety and avoidance, and a non-specific anxiety axis characterized by free-floating anxiety, various symptoms relating to tension, irritability and restlessness. It is argued that three dimensions are sufficient to account for the covariance between common psychiatric symptoms. A fairly consistent correlation between the non-specific anxiety and the depression dimension was found across sites, as well as independence of the specific anxiety dimension from the other two dimensions. Furthermore, the depression dimension was robust with similar symptom profiles across samples, but there appeared to be local differences in the structure of anxiety symptoms.

The relationship between social dysfunctioning and psychopathology among primary care attenders

The extent of social dysfunctioning and its relationship to psychological disorders among Dutch primary care patients was examined. Social dysfunctioning in these patients was rather limited, but was more pronounced in patients with a psychological disorder than in those without. Disabilities were largely restricted to the occupational and social roles, with family role functioning and self-care relatively intact. Social dysfunctioning was moderately related to psychopathology, with higher levels of dysfunctioning in more severe and depressed cases. The extent of social dysfunctioning among patients with both anxiety and depression was similar to that of patients with a single diagnosis of depression. Depressed patients had a similar level of dysfunctioning to non-psychotic psychiatric out-patients. Analyses regarding the effects of diagnosis and severity on social dysfunctioning revealed considerable overlap between these two aspects of psychopathology. This study supports the need for a simultaneous but separate assessment of psychopathology and social dysfunctioning. However, future research should incorporate additional predictors of social dysfunctioning (e.g. personality, life events, long-term difficulties, physical disorders), and prospective studies should be conducted to clarify the temporal sequences of symptom severity, diagnosis, and comorbidity on the one hand, and social dysfunctioning on the other.