Methylation of lysine 36 on histone H3 is required to control transposon activities in somatic cells.

Transposable elements constitute a substantial portion of most eukaryotic genomes and their activity can lead to developmental and neuronal defects. In the germline, transposon activity is antagonized by the PIWI-interacting RNA pathway tasked with repression of transposon transcription and degrading transcripts that have already been produced. However, most of the genes required for transposon control are not expressed outside the germline, prompting the question: what causes deleterious transposons activity in the soma and how is it managed? Here, we show that disruptions of the Histone 3 lysine 36 methylation machinery led to increased transposon transcription in Drosophila melanogaster brains and that there is division of labour for the repression of transposable elements between the different methyltransferases Set2, NSD, and Ash1. Furthermore, we show that disruption of methylation leads to somatic activation of key genes in the PIWI-interacting RNA pathway and the preferential production of RNA from dual-strand piRNA clusters.

Efficient Contextual Ontological Model of n-Qubit Stabilizer Quantum Mechanics.

The most well-known tool for studying contextuality in quantum computation is the n-qubit Stabilizer state tableau representation. We provide an extension that not only describes the quantum state but is also outcome deterministic. The extension enables a value assignment to exponentially many Pauli observables, yet it remains quadratic in both memory and computational complexity. Furthermore, we show that the mechanisms employed for contextuality and measurement disturbance are wholly separate. The model will be useful for investigating the role of contextuality in n-qubit quantum computation.

Transposon activity, local duplications and propagation of structural variants across haplotypes drive the evolution of the Drosophila S2 cell line.

BACKGROUND: Immortalized cell lines are widely used model systems whose genomes are often highly rearranged and polyploid. However, their genome structure is seldom deciphered and is thus not accounted for during analyses. We therefore used linked short- and long-read sequencing to perform haplotype-level reconstruction of the genome of a Drosophila melanogaster cell line (S2-DRSC) with a complex genome structure. RESULTS: Using a custom implementation (that is designed to use ultra-long reads in complex genomes with nested rearrangements) to call structural variants (SVs), we found that the most common SV was repetitive sequence insertion or deletion (> 80% of SVs), with Gypsy retrotransposon insertions dominating. The second most common SV was local sequence duplication. SNPs and other SVs were rarer, but several large chromosomal translocations and mitochondrial genome insertions were observed. Haplotypes were highly similar at the nucleotide level but structurally very different. Insertion SVs existed at various haplotype frequencies and were unlinked on chromosomes, demonstrating that haplotypes have different structures and suggesting the existence of a mechanism that allows SVs to propagate across haplotypes. Finally, using public short-read data, we found that transposable element insertions and local duplications are common in other D. melanogaster cell lines. CONCLUSIONS: The S2-DRSC cell line evolved through retrotransposon activity and vast local sequence duplications, that we hypothesize were the products of DNA re-replication events. Additionally, mutations can propagate across haplotypes (possibly explained by mitotic recombination), which enables fine-tuning of mutational impact and prevents accumulation of deleterious events, an inherent problem of clonal reproduction. We conclude that traditional linear homozygous genome representation conceals the complexity when dealing with rearranged and heterozygous clonal cells.

Modulation of RNA stability regulates gene expression in two opposite ways: through buffering of RNA levels upon global perturbations and by supporting adapted differential expression.

The steady state levels of RNAs, often referred to as expression levels, result from a well-balanced combination of RNA transcription and decay. Alterations in RNA levels will therefore result from tight regulation of transcription rates, decay rates or both. Here, we explore the role of RNA stability in achieving balanced gene expression and present genome-wide RNA stabilities in Drosophila melanogaster male and female cells as well as male cells depleted of proteins essential for dosage compensation. We identify two distinct RNA-stability mediated responses involved in regulation of gene expression. The first of these responds to acute and global changes in transcription and thus counteracts potentially harmful gene mis-expression by shifting the RNA stability in the direction opposite to the transcriptional change. The second response enhances inter-individual differential gene expression by adjusting the RNA stability in the same direction as a transcriptional change. Both mechanisms are global, act on housekeeping as well as non-housekeeping genes and were observed in both flies and mammals. Additionally, we show that, in contrast to mammals, modulation of RNA stability does not detectably contribute to dosage compensation of the sex-chromosomes in D. melanogaster.

DamID transcriptional profiling identifies the Snail/Scratch transcription factor Kahuli as an Alk target in the Drosophila visceral mesoderm.

Development of the Drosophila visceral muscle depends on Anaplastic Lymphoma Kinase (Alk) receptor tyrosine kinase (RTK) signaling, which specifies founder cells (FCs) in the circular visceral mesoderm (VM). Although Alk activation by its ligand Jelly Belly (Jeb) is well characterized, few target molecules have been identified. Here, we used targeted DamID (TaDa) to identify Alk targets in embryos overexpressing Jeb versus embryos with abrogated Alk activity, revealing differentially expressed genes, including the Snail/Scratch family transcription factor Kahuli (Kah). We confirmed Kah mRNA and protein expression in the VM, and identified midgut constriction defects in Kah mutants similar to those of pointed (pnt). ChIP and RNA-Seq data analysis defined a Kah target-binding site similar to that of Snail, and identified a set of common target genes putatively regulated by Kah and Pnt during midgut constriction. Taken together, we report a rich dataset of Alk-responsive loci in the embryonic VM and functionally characterize the role of Kah in the regulation of embryonic midgut morphogenesis.

The role of H3K36 methylation and associated methyltransferases in chromosome-specific gene regulation.

In Drosophila, two chromosomes require special mechanisms to balance their transcriptional output to the rest of the genome. These are the male-specific lethal complex targeting the male X chromosome and Painting of fourth targeting chromosome 4. Here, we explore the role of histone H3 methylated at lysine-36 (H3K36) and the associated methyltransferases­Set2, NSD, and Ash1­in these two chromosome-specific systems. We show that the loss of Set2 impairs the MSL complex­mediated dosage compensation; however, the effect is not recapitulated by H3K36 replacement and indicates an alternative target of Set2. Unexpectedly, balanced transcriptional output from the fourth chromosome requires intact H3K36 and depends on the additive functions of NSD and Ash1. We conclude that H3K36 methylation and the associated methyltransferases are important factors to balance transcriptional output of the male X chromosome and the fourth chromosome. Furthermore, our study highlights the pleiotropic effects of these enzymes.

Global surgery for medical students - is it meaningful? A mixed-method study.

INTRODUCTION: There has been an increase in global health courses at medical universities in high-income countries. Their effect on students, however, is poorly understood. In 2016 an elective global surgery course was introduced for medical students at Karolinska Institutet in Sweden. The course includes a theoretical module in Sweden and a two-week clinical rotation in Uganda. The present study aimed to assess the format and determine its effect on students' knowledge of global surgery and approach towards patients of non-Swedish origin. METHOD: A mixed-methods design was used. Semi-structured case-based interviews were conducted individually with 18 students and analysed using qualitative content analysis. Examination scores and the course evaluation were analysed with Kruskal Wallis one-way analysis of variance, Pearson's Chi-square and a Wilcoxon signed-rank test as appropriate. RESULTS: The course was appreciated and students reported gained insights and interest in global surgery. Students' ability to reason about global surgery issues was improved after the course. Students considered complicating aspects in the meeting with patients of non-Swedish origin. Students with abroad clinical experience felt less compelled to act on preconceptions. DISCUSSION: The global surgery course at Karolinska Institutet is appreciated and students gained valuable knowledge. The case-based interviews acted as a catalyst for reflection and showed that students felt insecure as they lacked knowledge about globally common surgical conditions and struggled with generalized preconceptions of patients of non-Swedish origin. To further support students to integrate theoretical knowledge and professional development, we suggest the introduction of problem-based learning. CONCLUSION: The ability of the course to inspire students' commitment to global surgery is promising as this engagement is the key to reaching the goal of equitable health globally. Offering such courses is a step towards inspiring and recruiting the future clinicians and researchers needed for expanding the field of global surgery.

Social and sex differences in psychiatric comorbidity and psychosocial functioning among adolescents with depression.

BACKGROUND: To determine social and sex differences in psychosocial functioning and psychiatric comorbidity among adolescents with depression. METHODS: A cohort-based study in Stockholm, Sweden. Adolescents who turned 13 years during 2001-2007, were followed in registers until they turned 18 in 2005-2011, (n = 169,262). In the current study, those with depression at age 13-17 were included (n = 6,439). RESULTS: Adolescents with parents with low (OR=1.5, CI 1.1-2.2) education were more likely to have low psychosocial functioning. Those with parents with low education and low household income were more likely to have comorbid internalizing (OR=1.3, CI 1.0-1.7/1.3, CI 1.0-1.7) and externalizing disorders (OR=2.5, CI 1.5-4.0/2.4, CI 1.4-4.2). Adolescents with parents born outside the Nordic countries were more likely to have comorbid externalizing disorders (OR=1.6, CI 1.1-2.4). No social differences were evident in relation to family receipt of unemployment benefits. Social differences were found for both girls and boys in relation to psychosocial functioning and comorbidity but the magnitude of social differences in depression with comorbidity was overall larger for boys than girls. LIMITATIONS: The findings of the current study can only be generalized to adolescents that have sought care for and been diagnosed with depression, within a setting similar to this study, e.g. with free access to care. CONCLUSION: Adolescents with depression and with more disadvantaged social circumstances in the childhood run a higher risk of psychiatric comorbidity and low psychosocial functioning, which can indicate a lengthy clinical course and poorer response to treatment. Both boys and girls follow this path but partly in different kinds of psychiatric comorbidity.

Symptoms and level of functioning related to comorbidity in children and adolescents with ADHD: a cross-sectional registry study.

BACKGROUND: It is well known that a wide range of psychiatric disorders co-occur with attention deficit hyperactivity disorder. In this study we aimed to examine the associations of psychiatric comorbidity in ADHD with symptom severity and level of functioning. METHODS: We used data from the Swedish National Quality Registry for ADHD Treatment Follow-up and identified comorbid diagnoses in a sample of 3246 Swedish children and adolescents with ADHD. We investigated the association of comorbidity with symptom severity and level of function by multiple linear regressions. RESULTS: Autism spectrum disorder, anxiety and affective disorders, oppositional defiant disorder or conduct disorder, learning disorders, and multiple comorbid disorders associate to lower levels of functioning compared to ADHD only. Multiple comorbidity, autism spectrum disorder, oppositional defiant or conduct disorders and tic disorders relate to ADHD symptom severity. CONCLUSIONS: Comorbidity subgroups with ADHD differ in functional impairment and ADHD symptoms severity. Information on comorbidity profiles could be used for treatment planning more adapted to the individual. Especially those who have autism spectrum disorders and multiple comorbid disorders are at risk of severe ADHD symptoms and low level of functioning.

Randomised trial showed no difference in behavioural symptoms between surgical methods treating paediatric obstructive sleep apnoea.

AIM: Our previous randomised controlled trial of children with obstructive sleep apnoea (OSA) showed no significant differences between adenotonsillectomy (ATE) and adenotonsillotomy (ATT) in improving nocturnal respiration and quality of life after 1 year. The aim of this report was to evaluate the effects on behavioural symptoms using the Strengths and Difficulties Questionnaire (SDQ). METHODS: Children between 2 and 6 years with OSA were randomised to ATT or ATE. Parents, blinded to method, answered the SDQ while their child underwent polysomnography before and 1 year after surgery. Differences between the total SDQ scores were analysed between the treatment groups. RESULTS: The SDQ was filled out in 87% of the cases preoperatively, and in 86% postoperatively. At follow-up, the mean total SDQ score was 9.6 SD ± 5.1 in the ATE group (n = 31), and 8.2 ± 6.7 in the ATT group (n = 37), P = .09. The mean total SDQ score for all was preoperatively 10.6 ± 5.0, and postoperatively 8.8 ± 6.0, P = .0002. CONCLUSION: There were no significant differences in SDQ scores between the groups at follow-up, indicating that the more conservative ATT is a treatment option in paediatric OSA. The whole group of patients showed a significant improvement after surgery.

Painting of Fourth and the X-Linked 1.688 Satellite in D. melanogaster is Involved in Chromosome-Wide Gene Regulation.

Chromosome-specific regulatory mechanisms provide a model to understand the coordinated regulation of genes on entire chromosomes or on larger genomic regions. In fruit flies, two chromosome-wide systems have been characterized: The male-specific lethal (MSL) complex, which mediates dosage compensation and primarily acts on the male X-chromosome, and Painting of fourth (POF), which governs chromosome-specific regulation of genes located on the 4th chromosome. How targeting of one specific chromosome evolves is still not understood; but repeated sequences, in forms of satellites and transposable elements, are thought to facilitate the evolution of chromosome-specific targeting. The highly repetitive 1.688 satellite has been functionally connected to both these systems. Considering the rapid evolution and the necessarily constant adaptation of regulatory mechanisms, such as dosage compensation, we hypothesised that POF and/or 1.688 may still show traces of dosage-compensation functions. Here, we test this hypothesis by transcriptome analysis. We show that loss of Pof decreases not only chromosome 4 expression but also reduces the X-chromosome expression in males. The 1.688 repeat deletion, Zhr1(Zygotic hybrid rescue), does not affect male dosage compensation detectably; however, Zhr1 in females causes a stimulatory effect on X-linked genes with a strong binding affinity to the MSL complex (genes close to high-affinity sites). Lack of pericentromeric 1.688 also affected 1.688 expression in trans and was linked to the differential expression of genes involved in eggshell formation. We discuss our results with reference to the connections between POF, the 1.688 satellite and dosage compensation, and the role of the 1.688 satellite in hybrid lethality.

Checking mask ventilation before neuromuscular block: A nation-wide survey of anaesthetists' attitudes and thinking.

BACKGROUND: The value of checking mask ventilation before administering neuromuscular blocking drugs is still debated. METHOD: We conducted a survey of the practice of anaesthetists in Sweden, first asking if they use a mask ventilation trial (MVT) as part of routine induction with intubation (not rapid sequence induction or expected difficult airway). We focused on the reasons for or against the MVT, probing the anaesthetists' attitudes in general but also in specific scenarios. RESULTS: The response rate was 54%. We found that 65.1% routinely use a MVT, 21.4% sometimes do and 13.5% never do so. There was no effect for years of experience on the distribution. The most common reason for checking mask ventilation was "to gather information about the airway," while the reason for not using the MVT was mostly "that muscle relaxation often improves mask ventilation." CONCLUSION: We found several interesting comments about airway management at both practical and theoretical levels. The survey highlights that routinely performing a MVT is a common practice in Sweden in spite of the lack of evidence for increased patient safety. Future airway guidelines may need to address this practice.

The Sävsjö-school-project: a cluster-randomized trial aimed at improving the literacy of beginners-achievements, mental health, school satisfaction and reading capacity at the end of grade three using an alternative school curriculum.

BACKGROUND: A curriculum was planned using modern concepts based on the "old" principles to test if such an educational intervention provided pupils with good mental health and a solid basis for good reading and writing skills, as well as generated a positive attitude to learn. These "old" principles were based on previous knowledge derived from school psychiatry (which in Sweden was a branch of child and adolescent psychiatry 1915-1970), educational psychology and the educational approach from the differentiating Swedish School system of 1946-1970 (itself based on the principles of curative education "Heilpädagogie", which was later renamed mental health care). METHODS: All six available schools in the small Swedish city of Sävsjö participated in the study. In these six schools there were eight preschool classes that included every 6-year old child living in the city. In total there were 184 families with 186 children (including 2 pairs of twins) who belonged to these preschool classes and were invited to take part in the study. One family moved just before school-start and 8 decided not to participate, thus 177 children (84 boys and 93 girls, aged 5.6-6.6 years) entered the study. The preschool classes were randomized into an experimental group with four preschool classes and a comparison group with four preschool classes. The experimental group followed a teaching program from the start of the preschool year until the end of grade 3 that was tailored to each student's individual capacity based on the concepts of school maturation and curative education used in the Swedish schools during the period 1946-1970. The comparison group followed today's average Swedish school curriculum. The project was planned as an intervention study covering the preschool year and the first 3 years of elementary school, which was to form a basis for a follow-up when the pupils had left senior high, the 12th year in Swedish public school. The outcome and the achievements were measured at end of grade 3 using standardized tests on reading, writing and mathematical skills. Behavior was assessed at school start and at end of grade 3 using the Child Behavior Check List (CBCL-scales) in addition to a questionnaire on Attention Deficit Hyperactivity Disorder (AD/HD) with criteria from DSM-IV. The children made a self-evaluation of their attitude towards learning. RESULTS: At the end of school year 3, the children in the experimental group had an improved reading capacity (p = 0.002, effect size(es) = 4.35) and reading comprehension (p = 0.03, es = 0.04). They evaluated their own reading (p = 0.02, es = 0.23), writing (p = 0.007, es = 0.35) and mathematical skills (p = 0.003, es = 0.48) as going "very well" when compared to comparison group. Differences regarding intelligence quotas between the groups at the start of school had disappeared by the end of grade 3. No differences referring to CBCL were found at end of grade 3. One child in the comparison group fulfilled criteria for AD/HD, according to parents and teachers. CONCLUSIONS: The alternative curriculum covering the preschool year through the first 3 years of elementary school based on the old principles from curative education ("Heilpädagogie"), educational psychology and school psychiatry gave the children in the experimental group a better reading capacity and reading comprehension.Trial registration The study started in 1998. The data were collected longitudinally and prospectively but have not been analyzed until now, with the children having left senior high. A retrospective registration in the ISRCTN is pending.

Diagnostic validity of the MINI-KID disorder classifications in specialized child and adolescent psychiatric outpatient clinics in Sweden.

BACKGROUND: Missing diagnostic information often results poor accuracy of the clinical diagnostic decision process. The Mini International Neuropsychiatric Interview for Children and Adolescents (MINI-KID) is a short standardized diagnostic interview and covers a rather broad range of diagnoses applicable to children and adolescents. MINI-KID disorder classifications have shown test-retest reliability and validity comparable to other standardized diagnostic interviews and is claimed to be a useful tool for diagnostic screening in Child and Adolescent Psychiatric care. The concordance between the Swedish language version of the MINI-KID Interview and LEAD (Longitudinal, Expert, All Data) research diagnoses was studied in secondary child and adolescent psychiatric outpatient care. METHODS: MINI-KID interviews were performed for 101 patients, boys n = 50, girls n = 51, aged 4 to 18 years. The duration of the interview was on average 46 min, the child/adolescent participating together with the parent(s) in most cases. The seven most prevalent diagnoses were included in the analyses. RESULTS: The average overall percent agreement (OPA) between MINI-KID and LEAD was 79.5%, the average percent positive agreement (PPA) 35.4 and the average percent negative agreement (NPA) 92.7. OPA was highest for Obsessive-Compulsive Disorder (OCD) (0.89), Tic disorders (0.88) and Pervasive developmental disorders (0.81). There were similar results in diagnostic agreement comparing the two versions: the standard MINI-KID and MINI-KID for parents. The specific screening questions in MINI-KID resulted in additional preliminary diagnoses compared with the regular initial clinical assessment. CONCLUSIONS: Overall, there was an acceptable agreement between MINI-KID disorder classifications and research diagnoses according to LEAD. The standardized interview MINI-KID could be considered as a tool with the possibility to give valuable information in the diagnostic process in child and adolescent care which is similar to the setting in the present study.

Molecular and genetic organization of bands and interbands in the dot chromosome of Drosophila melanogaster.

The fourth chromosome smallest in the genome of Drosophila melanogaster differs from other chromosomes in many ways. It has high repeat density in conditions of a large number of active genes. Gray bands represent a significant part of this polytene chromosome. Specific proteins including HP1a, POF, and dSETDB1 establish the epigenetic state of this unique chromatin domain. In order to compare maps of localization of genes, bands, and chromatin types of the fourth chromosome, we performed FISH analysis of 38 probes chosen according to the model of four chromatin types. It allowed clarifying the dot chromosome cytological map consisting of 16 loose gray bands, 11 dense black bands, and 26 interbands. We described the relation between chromatin states and bands. Open aquamarine chromatin mostly corresponds to interbands and it contains 5'UTRs of housekeeping genes. Their coding parts are embedded in gray bands substantially composed of lazurite chromatin of intermediate compaction. Polygenic black bands contain most of dense ruby chromatin, and also some malachite and lazurite. Having an accurate map of the fourth chromosome bands and its correspondence to physical map, we found that DNase I hypersensitivity sites, ORC2 protein, and P-elements are mainly located in open aquamarine chromatin, while element 1360, characteristic of the fourth chromosome, occupies band chromatin types. POF and HP1a proteins providing special organization of this chromosome are mostly located in aquamarine and lazurite chromatin. In general, band organization of the fourth chromosome shares the features of the whole Drosophila genome.

Quantum Simulation Logic, Oracles, and the Quantum Advantage.

Query complexity is a common tool for comparing quantum and classical computation, and it has produced many examples of how quantum algorithms differ from classical ones. Here we investigate in detail the role that oracles play for the advantage of quantum algorithms. We do so by using a simulation framework, Quantum Simulation Logic (QSL), to construct oracles and algorithms that solve some problems with the same success probability and number of queries as the quantum algorithms. The framework can be simulated using only classical resources at a constant overhead as compared to the quantum resources used in quantum computation. Our results clarify the assumptions made and the conditions needed when using quantum oracles. Using the same assumptions on oracles within the simulation framework we show that for some specific algorithms, such as the Deutsch-Jozsa and Simon's algorithms, there simply is no advantage in terms of query complexity. This does not detract from the fact that quantum query complexity provides examples of how a quantum computer can be expected to behave, which in turn has proved useful for finding new quantum algorithms outside of the oracle paradigm, where the most prominent example is Shor's algorithm for integer factorization.

RNA-on-X 1 and 2 in Drosophila melanogaster fulfill separate functions in dosage compensation.

In Drosophila melanogaster, the male-specific lethal (MSL) complex plays a key role in dosage compensation by stimulating expression of male X-chromosome genes. It consists of MSL proteins and two long noncoding RNAs, roX1 and roX2, that are required for spreading of the complex on the chromosome and are redundant in the sense that loss of either does not affect male viability. However, despite rapid evolution, both roX species are present in diverse Drosophilidae species, raising doubts about their full functional redundancy. Thus, we have investigated consequences of deleting roX1 and/or roX2 to probe their specific roles and redundancies in D. melanogaster. We have created a new mutant allele of roX2 and show that roX1 and roX2 have partly separable functions in dosage compensation. In larvae, roX1 is the most abundant variant and the only variant present in the MSL complex when the complex is transmitted (physically associated with the X-chromosome) in mitosis. Loss of roX1 results in reduced expression of the genes on the X-chromosome, while loss of roX2 leads to MSL-independent upregulation of genes with male-biased testis-specific transcription. In roX1 roX2 mutant, gene expression is strongly reduced in a manner that is not related to proximity to high-affinity sites. Our results suggest that high tolerance of mis-expression of the X-chromosome has evolved. We propose that this may be a common property of sex-chromosomes, that dosage compensation is a stochastic process and its precision for each individual gene is regulated by the density of high-affinity sites in the locus.

Postselection-Loophole-Free Bell Violation with Genuine Time-Bin Entanglement.

Entanglement is an invaluable resource for fundamental tests of physics and the implementation of quantum information protocols such as device-independent secure communications. In particular, time-bin entanglement is widely exploited to reach these purposes both in free space and optical fiber propagation, due to the robustness and simplicity of its implementation. However, all existing realizations of time-bin entanglement suffer from an intrinsic postselection loophole, which undermines their usefulness. Here, we report the first experimental violation of Bell's inequality with "genuine" time-bin entanglement, free of the postselection loophole. We introduced a novel function of the interferometers at the two measurement stations, that operate as fast synchronized optical switches. This scheme allowed us to obtain a postselection-loophole-free Bell violation of more than 9 standard deviations. Since our scheme is fully implementable using standard fiber-based components and is compatible with modern integrated photonics, our results pave the way for the distribution of genuine time-bin entanglement over long distances.

Social differences in diagnosed depression among adolescents in a Swedish population based cohort.

BACKGROUND: Population based research regarding social differences in diagnosed depression in adolescence is sparse. In this study unique material containing in-and outpatient data was used to determine if low social position in childhood increases the risk of diagnosed depression in adolescence. To further examine this association, gender differences and interactions were explored. METHODS: The study population was extracted from the Stockholm Youth Cohort (SYC), a register based cohort containing psychiatric care for all young people in Stockholm County and information about social position. For the purpose of this study, all in the SYC who turned 13 years old during 2001-2007, in total 169,262 adolescents, were followed up in 2005-2011 for diagnoses of depression until age 18. Associations were estimated with Cox regression models and presented as Hazard Ratios (HR). RESULTS: The risk of diagnosed depression was higher for adolescents with parents with low education (HR = 1.1, CI = 1.0-1.2) and medium education (HR = 1.1, CI = 1.1-1.2) compared to high as well as for those with lower household income (for example, medium low, HR = 1.2, CI = 1.1-1.3) and for those with parents who received an unemployment benefit (HR = 1.3, CI = 1.2-1.4). No differences were found for those with the lowest household income compared to those with the highest level. Adolescents with parents born outside the Nordic countries had a lower risk of diagnosed depression (HR = 0.7, CI = 0.6-0.7). An interaction effect was found between gender and parental education. CONCLUSIONS: Social differences were found but the magnitude was modest and gender differences small.