Mood disorders and consequences of pharmacological treatment

Mental health issues are medical problems getting increased attention throughout the world, and depression, only one among several types of mental illnesses, are currently reported as the second leading cause of disability world wide by the World Health Organization. Along this development, increased number of psychiatric diagnoses and increased utilization of medication can be observed. However, whether this increase is because of an actual increase in number of individuals suffering from these disorders, or due to improvements in diagnostics and understanding, or both, is not fully known. What is known, however, is that mental health related suffering is nothing new and can be traced back several thousands of years in human history. Throughout this history, our understanding and view of these disorders that affect our mood and behavior have changed substantially, from being assumed caused by gods or magic, to our modern view of combined environmental and genetic causes. But psychiatry is still a comparatively recent field of medicine and it was not long ago effective drugs targeting these disorders were first introduced. Our understanding of the underlying mechanisms of this suffering is still limited, but recent developments in psychiatric genetics have provided some of the first stable biological underpinnings to mental disorders. In light of these findings, a complicated picture is beginning to take form, in which the etiology appears caused by thousands of genetic factors, but also that a lot of the underlying genetics is shared among the disorders previously thought of as separate. It is within this setting, where many of the current disorder definitions are starting being questioned and the appreciation of genetics behind these disorder is increasing, the studies within thesis have been conducted. In study I, the potential side effect of manic switching due to antidepressant treatment was investigated in a population sample of 3,240 individuals with bipolar disorder. A within-individual design was used to adjust for otherwise unmeasured genetic confounding, and the results indicated that manic switching was confined to bipolar disorder patients treated with an antidepressant monotherapy, whereas patients treated with an antidepressant in combination with a mood stabilizer rather displayed a reduced risk. Study II instead focused on depression around the time of pregnancy, perinatal depression, and to what extent genetics explain the variance in this disorder, and to what extent perinatal depression genetically overlap with depression at other time of life. This was studied with a twin design in a sample of twin mothers (N=3,427) that had answered the Edinburgh Postnatal Depression Scale, and with a sibling design in a sample of sisters (N=580,006) using register data of healthcare contacts. The genetic contribution to, or heritability of, perinatal depression was estimated at 54 and 44% in the twin and sibling designs respectively. Using a bivariate model, a third of the genetic contribution to perinatal depression was found unique for the disorder and not shared with depression at other times of life. Study III was also related to perinatal depression, but focused on potential side effects of antidepressants. In a sample of 392,029 pregnancies, associations between prenatal SSRI exposure and offspring birth size and gestational age was observed. This was followed by within-family analyses (N=1,007) that adjusted for genetic and familial environmental confounding, where the associations between SSRIs and offspring birth size was attenuated, indicating that these associations were likely due to familial confounding. An association between prenatal SSRI exposure and reduced gestational age was observed in both analyses, and could be either due to a causal effect of the medication, or due to confounding factors that the withinfamily design could not adjust for. Perinatal depression was further explored in study IV, where patterns of healthcare utilization were studied among both mothers and fathers based on register data. This included 3.6 million parents and 3.5 million pregnancies, and the occurrence of diagnoses for depressive illness, anxiety disorders, and mental illness in general around the time of pregnancy was contrasted to the occurrence of these diagnoses at other times of life. Overall, a reduction in healthcare utilization for all studied disorder types were observed around this time of life, which may indicate barriers to getting a diagnosis during this time of life. In conclusion, the studies within this thesis demonstrate that genetically informed designs are very useful in epidemiological research. And through the application of these designs with large-scale register data, the studies of this thesis provide enhanced understanding of mental illness in general, and bipolar disorder and perinatal depression in particular

Selective serotonin re-uptake inhibitor use during pregnancy: association with offspring birth size and gestational age.

BACKGROUND: Depression around the time of pregnancy affects at least 1 in 8 women and treatment with selective serotonin re-uptake inhibitors (SSRIs) in pregnant women has been increasing, but research on adverse effects on the fetus have so far commonly used designs unable to account for confounding. We aimed to examine the effects of prenatal SSRI exposure on offspring size outcomes and gestational age, and disentangle whether associations observed were due to the medication or other factors. METHODS: We used a Swedish population-based cohort of 392,029 children and national registers to estimate the associations between prenatal exposure to SSRIs and depression on the outcomes birthweight, birth length, birth head circumference, gestational age at birth and preterm birth. A sub-sample of 1007 children was analysed in a within-family design that accounts for unmeasured parental genetic and environmental confounders. RESULTS: Crude analyses revealed associations between prenatal SSRI exposure, and offspring birth size and gestational age. However, in the within-family analyses, only the association between SSRI exposure and reduced gestational age (-2.3 days; 95% confidence interval -3.8 to -0.8) was observed. CONCLUSIONS: This study indicates that prenatal SSRI exposure may not be causally related to offspring birth size. Rather, our analyses suggest that the association could be caused by other underlying differences instead of the medication per se. A small reduction of gestational age was associated with SSRI exposure in the within-family analysis and could be due to either the exposure, or other factors changing between pregnancies.The Swedish Research CouncilSwedish Initiative for Research on Microdata in the Social and Medical Sciences (SIMSAM).The Swedish Medical Research CouncilThe Swedish foundation for Strategic ResearchThe Swedish Brain FoundationManuscrip

Meta-analysis of genome-wide association studies for neuroticism, and the polygenic association with major depressive disorder

IMPORTANCE Neuroticism is a pervasive risk factor for psychiatric conditions. It genetically overlaps with major depressive disorder (MDD) and is therefore an important phenotype for psychiatric genetics. The Genetics of Personality Consortium has created a resource for genome-wide association analyses of personality traits in more than 63 000 participants (including MDD cases)

Clinical phenotypes of perinatal depression and time of symptom onset: analysis of data from an international consortium

Background The perinatal period is a time of high risk for onset of depressive disorders and is associated with substantial morbidity and mortality, including maternal suicide. Perinatal depression comprises a heterogeneous group of clinical subtypes, and further refinement is needed to improve treatment outcomes. We sought to empirically identify and describe clinically relevant phenotypic subtypes of perinatal depression, and further characterise subtypes by time of symptom onset within pregnancy and three post-partum periods. Methods Data were assembled from a subset of seven of 19 international sites in the Postpartum Depression: Action Towards Causes and Treatment (PACT) Consortium. In this analysis, the cohort was restricted to women aged 19–40 years with information about onset of depressive symptoms in the perinatal period and complete prospective data for the ten-item Edinburgh postnatal depression scale (EPDS). Principal components and common factor analysis were used to identify symptom dimensions in the EPDS. The National Institute of Mental Health research domain criteria functional constructs of negative valence and arousal were applied to the EPDS dimensions that reflect states of depressed mood, anhedonia, and anxiety. We used k-means clustering to identify subtypes of women sharing symptom patterns. Univariate and bivariate statistics were used to describe the subtypes. Findings Data for 663 women were included in these analyses. We found evidence for three underlying dimensions measured by the EPDS: depressed mood, anxiety, and anhedonia. On the basis of these dimensions, we identified five distinct subtypes of perinatal depression: severe anxious depression, moderate anxious depression, anxious anhedonia, pure anhedonia, and resolved depression. These subtypes have clear differences in symptom quality and time of onset. Anxiety and anhedonia emerged as prominent symptom dimensions with post-partum onset and were notably severe. Interpretation Our findings show that there might be different types and severity of perinatal depression with varying time of onset throughout pregnancy and post partum. These findings support the need for tailored treatments that improve outcomes for women with perinatal depression

Meta-analysis of Genome-Wide Association Studies for Extraversion : Findings from the Genetics of Personality Consortium

Extraversion is a relatively stable and heritable personality trait associated with numerous psychosocial, lifestyle and health outcomes. Despite its substantial heritability, no genetic variants have been detected in previous genome-wide association (GWA) studies, which may be due to relatively small sample sizes of those studies. Here, we report on a large meta-analysis of GWA studies for extraversion in 63,030 subjects in 29 cohorts. Extraversion item data from multiple personality inventories were harmonized across inventories and cohorts. No genome-wide significant associations were found at the single nucleotide polymorphism (SNP) level but there was one significant hit at the gene level for a long non-coding RNA site (LOC101928162). Genome-wide complex trait analysis in two large cohorts showed that the additive variance explained by common SNPs was not significantly different from zero, but polygenic risk scores, weighted using linkage information, significantly predicted extraversion scores in an independent cohort. These results show that extraversion is a highly polygenic personality trait, with an architecture possibly different from other complex human traits, including other personality traits. Future studies are required to further determine which genetic variants, by what modes of gene action, constitute the heritable nature of extraversion.Peer reviewe

Genome-wide association for major depression through age at onset stratification:Major Depressive Disorder Working Group of the Psychiatric Genomics Consortium

Background Major depressive disorder (MDD) is a disabling mood disorder and, despite a known heritable component, a large meta-analysis of GWAS revealed no replicable genetic risk variants. Given prior evidence of heterogeneity by age-at-onset (AAO) in MDD, we tested whether genome-wide significant risk variants for MDD could be identified in cases subdivided by AAO. Method Discovery case-control GWASs were performed where cases were stratified using increasing/decreasing AAO-cutoffs; significant SNPs were tested in nine independent replication samples, giving a total sample of 22,158 cases and 133,749 controls for sub-setting. Polygenic score analysis was used to examine if differences in shared genetic risk exists between earlier and adult onset MDD with commonly co-morbid disorders of schizophrenia, bipolar disorder, Alzheimer’s disease, and coronary artery disease. Results We identify one replicated genome-wide significant locus associated with adult-onset (>27 years) MDD (rs7647854, OR=1.16, 95%CI=1.11-1.21, p=5.2x10-11). Using polygenic score analyses, we show that earlier-onset MDD is genetically more similar to schizophrenia and bipolar disorder than adult-onset. Conclusions We demonstrate that using additional phenotype data previously collected by genetic studies to tackle phenotypic heterogeneity in MDD can successfully lead to the discovery of genetic risk factor despite reduced sample size. Furthermore, our results suggest that the genetic susceptibility to MDD differs between adult- and earlier-onset MDD, with earlier-onset cases having a greater genetic overlap with schizophrenia and bipolar disorder

Harmonization of Neuroticism and Extraversion phenotypes across inventories and cohorts in the Genetics of Personality Consortium : an application of Item Response Theory

Peer reviewe

Applying polygenic risk scores to postpartum depression

The etiology of major depressive disorder (MDD) is likely to be heterogeneous, but postpartum depression (PPD) is hypothesized to represent a more homogenous subset of MDD. We use genome-wide SNP data to explore this hypothesis