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The iBerry study is a population-based cohort study designed to investigate the transition from subclinical symptoms to a psychiatric disorder. Adolescents were selected based on their self-reported emotional and/or behavioral problems assessed by completing the strengths and difficulties questionnaire-youth (SDQ-Y) in their first year of high school. A total of 16,736 SDQ-Y questionnaires completed in the academic years 2014–2015 and 2015–2016 by students in the greater Rotterdam area in the Netherlands were screened. A high-risk group of adolescents was then selected based on the 15% highest-scoring adolescents, and a low-risk group was randomly selected from the 85% lowest-scoring adolescents, with a 2.5:1 ratio between the number of high-risk and low-risk adolescents. These adolescents were invited to come with one parent for a baseline visit consisting of interviews, questionnaires, neuropsychological tests, and biological measurements to assess determinants of psychopathology. A total of 1022 high-risk and low-risk adolescents (mean age at the first visit: 15.0 years) enrolled in the study. The goal of the iBerry study is to follow these adolescents for a 10-year period in order to monitor any changes in their symptoms. Here, we present the study design, response rate, inclusion criteria, and the characteristics of the cohort; in addition, we discuss possible selection effects. We report that the oversampling procedure was successful at selecting a cohort of adolescents with a high rate of psychiatric problems based on comprehensive multi-informant measurements. The future results obtained from the iBerry Study will provide new insights into the way in which the mental health of high-risk adolescents changes as they transition to adulthood. These findings will therefore facilitate the development of strategies designed to optimize mental healthcare and prevent psychopathology.

Although cross-sectional studies have shown that the COVID-19 pandemic has negatively affected the mental health of adolescents, the effect of the pandemic on adolescents with pre-pandemic symptoms is unclear. We, therefore, tested the hypothesis that adolescents had increased emotional and behavioral problems during the lockdowns imposed during the pandemic.This study included three measurements in a prospective cohort of 1022 adolescents who were oversampled based on their high risk of developing psychopathology. Before the pandemic, we assessed depressive, anxiety, stress, oppositional defiant problems, psychotic experiences and suicidality, using the Youth Self-Report; 445 and 333 of these 1,022 adolescents subsequently completed the online questionnaire in the first lockdown (in April 2020) and in the second lockdown (in January 2021), respectively. Multilevel random intercept regression models were used to determine the change in psychiatric symptoms, including an interaction term to assess whether these changes differed based on the severity of symptoms prior to the pandemic. Throughout the pandemic, the majority of the participating adolescents reported having emotional and behavioral symptoms that were within the normal range. Moreover, the mean symptom scores for all six outcomes decreased significantly among adolescents with high clinical severity prior to the pandemic.In contrast to our original hypothesis, the effects of the COVID-19 pandemic may not necessarily be detrimental, at least among a specific subgroup of adolescents with pre-existing mental health problems. Moreover, our finding that most adolescents in this at-risk sample did not report experiencing clinically relevant symptoms during the pandemic reflects their resilience during the pandemic.

ObjectiveSeason of birth has repeatedly been found to be a risk indicator for adverse neurodevelopmental outcomes. Several explanations for this finding have been put forward but no conclusion has been reached. In the current study, we explored the role of sociodemographic and biological factors in the association between season of birth and child IQ.DesignIn a prenatally recruited birth cohort (born in 2002–2006), we examined the association between season of birth and non-verbal IQ at age 6 years among 6034 children. We explored how adjusting for socioeconomic status and maternal IQ, childbirth outcomes, pregnancy vitamin D status, nutritional intake, exposure to infections, and child age relative to peers in class changed the relation between season of birth and child IQ.ResultsWe found that spring birth was associated with lower non-verbal IQ (estimate: more than 1 point; β−1.24 (95% CI −2.31 to −0.17), p=0.02; seasonal trend β−0.40 (95% CI −0.74 to −0.07), p=0.02) than birth in summer. Adjustment for different covariates led to a substantial reduction (−65.0% change, in a seasonal trend analysis) of this association. In particular, sociodemographic factors and maternal IQ (−10.0% and −22.5% change, respectively) contributed.ConclusionsSeason of birth is an indicator of many underlying factors related to child IQ. The observed effects on IQ were small and therefore not of clinical significance.

Evidence is plentiful that fatty acids (TFAs) induce vascular inflammation with adverse metabolic consequences. However, it is not clear whether TFAs increase the risk of vascular pregnancy complications such as preeclampsia. We investigated associations between midpregnancy maternal plasma 18:1 fatty acid (t18:1) concentrations and pregnancy course and outcomes. Participants were 6695 pregnant women and newborns from the Generation R Study, Rotterdam, Netherlands (enrollment in 2001-2005). Maternal midpregnancy (mean ± SD gestational age: 20.7 ± 1.2 wk) t18:1 plasma concentrations were determined and related to gestational age and sex-adjusted birth weight SD scores, placental weight, and the risk of preeclampsia. In addition, we explored potential time trends by testing the association of maternal plasma t18:1 concentrations with birth weight in birth cohorts given the Dutch industry-initiative to lower food TFA contents during the inclusion period. Multiple logistic and linear regression analyses were performed, taking various socioeconomic and biological covariates into account. A higher midpregnancy maternal plasma t18:1 concentration was associated with lower birth weight (SD score, adjusted β: -0.10; 95% CI: -0.15, -0.04; < 0.001) and placental weight (kilograms, adjusted β: -10,65; 95% CI: -20.23, -1.07; = 0.03) and with a higher risk of preeclampsia (adjusted OR: 1.65; 95% CI: 1.10, 2.49; = 0.02). We observed a 31% decrease in the median plasma t18:1 concentration in our population over time, but the association between the plasma t18:1 concentration standardized per birth year and birth weight was comparable between birth-year cohorts (years 2001-2005). A higher maternal midpregnancy plasma t18:1 concentration was associated with lower birth weight and placental weight and with a higher risk of preeclampsia. Although the intake of TFAs in our population decreased during the inclusion period, the association with adverse pregnancy outcomes was unchanged even at lower maternal plasma t18:1 concentrations.