Shared Genetic Architecture Between Schizophrenia and Anorexia Nervosa: A Cross-trait Genome-Wide Analysis.

BACKGROUND AND HYPOTHESIS: Schizophrenia (SCZ) and anorexia nervosa (AN) are 2 severe and highly heterogeneous disorders showing substantial familial co-aggregation. Genetic factors play a significant role in both disorders, but the shared genetic etiology between them is yet to be investigated. STUDY DESIGN: Using summary statistics from recent large genome-wide association studies on SCZ (Ncases = 53 386) and AN (Ncases = 16 992), a 2-sample Mendelian randomization analysis was conducted to explore the causal relationship between SCZ and AN. MiXeR was employed to quantify their polygenic overlap. A conditional/conjunctional false discovery rate (condFDR/conjFDR) framework was adopted to identify loci jointly associated with both disorders. Functional annotation and enrichment analyses were performed on the shared loci. STUDY RESULTS: We observed a cross-trait genetic enrichment, a suggestive bidirectional causal relationship, and a considerable polygenic overlap (Dice coefficient = 62.2%) between SCZ and AN. The proportion of variants with concordant effect directions among all shared variants was 69.9%. Leveraging overlapping genetic associations, we identified 6 novel loci for AN and 33 novel loci for SCZ at condFDR <0.01. At conjFDR <0.05, we identified 10 loci jointly associated with both disorders, implicating multiple genes highly expressed in the cerebellum and pituitary and involved in synapse organization. Particularly, high expression of the shared genes was observed in the hippocampus in adolescence and orbitofrontal cortex during infancy. CONCLUSIONS: This study provides novel insights into the relationship between SCZ and AN by revealing a shared genetic component and offers a window into their complex etiology.

Impact of traumatic brain injury on risk for schizophrenia and bipolar disorder.

The impact of traumatic brain injury (TBI) on subsequent risk of schizophrenia (SCZ) or bipolar disorder (BD) remains contested. Possible genetic and environmental confounding effects have also been understudied. Therefore, we aim to investigate the impact of TBI on the risk of SCZ and BD and whether the effect varies by injury severity, age at injury, and sex. We identified 4,184 SCZ and 18,681 BD cases born between 1973 and 1998 in the Swedish National Registers. Case-control samples matched (1:5) on birth year, sex, and birthplace were created along with a family design study, with cases matched to non-case full siblings. TBI was associated with higher risk of SCZ and BD (IRR=1.33 for SCZ, IRR=1.78 for BD). The association remained significant in the sibling comparison study. Moderate or severe TBI was associated with higher risk for both SCZ and BD compared to mild TBI. Older age at injury was associated with higher risk of SCZ and BD, and the effect of TBI was stronger in women than men. Findings indicate that TBI is a risk factor for both SCZ and BD with differential impact by age, severity and sex and that this association cannot be explained by familial confounding alone.

Environmental risk factors for schizophrenia and bipolar disorder from childhood to diagnosis: a Swedish nested case-control study.

BACKGROUND: Shared genetic risk between schizophrenia (SCZ) and bipolar disorder (BD) is well-established, yet the extent to which they share environmental risk factors remains unclear. We compare the associations between environmental exposures during childhood/prior to disorder onset with the risk of developing SCZ and BD. METHODS: We conducted a Swedish register-based nested case-control study using 4184 SCZ cases and 18 681 BD cases diagnosed 1988-2013. Cases were matched to five controls by birth year, birth region, and sex. Conditional logistic regression was used to estimate incidence rate ratios (IRR) for SCZ and BD for each exposure (severe childhood infections, adverse childhood experiences (ACEs), substance use disorders (SUDs), urban birth/longest residence). RESULTS: All SUD types were associated with very high risk (IRR 4.9-25.5), and all forms of ACEs with higher risk (IRR 1.5-4.3) for both disorders. In the mutually adjusted models, ACEs demonstrated slightly higher risk for BD (SCZ IRR 1.30, 1.19-1.42; BD IRR 1.49, 1.44-1.55), while for SUD, risk was higher for SCZ (SCZ IRR 9.43, 8.15-10.92; BD IRR 5.50, 5.15-5.88). Infections were associated with increased risk of BD (IRR 1.21, 1.17-1.26) but not SCZ. Urban birth and urban longest residence were associated with higher risk of SCZ (IRR 1.19, 1.03-1.37), while only the combination of urban birth and rural longest residence showed higher risk for BD (IRR 1.24, 1.13-1.35). CONCLUSIONS: There were both shared and unique environmental risk factors: SUDs and ACEs were risk factors for both disorders, while infections were more strongly associated with BD and urbanicity with SCZ.

Key subphenotypes of bipolar disorder are differentially associated with polygenic liabilities for bipolar disorder, schizophrenia, and major depressive disorder.

Bipolar disorder (BD) features heterogenous clinical presentation and course of illness. It remains unclear how subphenotypes associate with genetic loadings of BD and related psychiatric disorders. We investigated associations between the subphenotypes and polygenic risk scores (PRS) for BD, schizophrenia, and major depressive disorder (MDD) in two BD cohorts from Sweden (N = 5180) and the UK (N = 2577). Participants were assessed through interviews and medical records for inter-episode remission, psychotic features during mood episodes, global assessment of functioning (GAF, function and symptom burden dimensions), and comorbid anxiety disorders. Meta-analyses based on both cohorts showed that inter-episode remission and GAF-function were positively correlated with BD-PRS but negatively correlated with schizophrenia-PRS (SCZ-PRS) and MDD-PRS. Moreover, BD-PRS was negatively, and MDD-PRS positively, associated with the risk of comorbid anxiety disorders. Finally, SCZ-PRS was positively associated with psychotic symptoms during mood episodes. Assuming a higher PRS of certain psychiatric disorders in cases with a positive family history, we further tested the associations between subphenotypes in index BD people and occurrence of BD, schizophrenia, or MDD in their relatives using Swedish national registries. BD patients with a relative diagnosed with BD had: (1) higher GAF and lower risk of comorbid anxiety than those with a relative diagnosed with schizophrenia or MDD, (2) lower risk of psychotic symptoms than those with a relative diagnosed with schizophrenia. Our findings shed light on the genetic underpinnings of the heterogeneity in clinical manifestations and course of illness in BD, which ultimately provide insights for developing personalized approaches to the diagnosis and treatment.

The impact of genetic risk for schizophrenia on eating disorder clinical presentations.

A growing body of literature recognizes associations between eating disorders (EDs) and schizophrenia and suggests that familial liability to schizophrenia in individuals with anorexia nervosa (AN) reveals distinct patterns of clinical outcomes. To further investigate the influence of schizophrenia genetic liability among individuals with EDs, we evaluated the associations between schizophrenia polygenic risk scores (PRS) and clinical presentations of individuals with EDs including their overall health condition and ED-related symptoms. Using data from two previous studies of the genetics of EDs comprising 3,573 Anorexia Nervosa Genetics Initiative (ANGI) cases and 696 Binge Eating Genetics Initiative (BEGIN) cases born after 1973 and linked to the Swedish National Patient Register, we examined the association of schizophrenia PRS on ED clinical features, psychiatric comorbidities, and somatic and mental health burden. Among ANGI cases, higher schizophrenia PRS was statistically significantly associated with higher risk of major depressive disorder (MDD) measured by hazard ratio (HR) with 95% confidence interval (CI) (HR [95% CI]: 1.07 [1.02, 1.13]) and substance abuse disorder (SUD) (HR [95% CI]: 1.14 [1.03, 1.25]) after applying multiple testing correction. Additionally, higher schizophrenia PRS was associated with decreased clinical impairment assessment scores (-0.56, 95% CI: [-1.04, -0.08]) at the conventional significance level (p < 0.05). Further, in BEGIN cases, higher schizophrenia PRS was statistically significantly associated with earlier age at first ED symptom (-0.35 year, 95% CI: [-0.64, -0.06]), higher ED symptom scores (0.16, 95% CI: [0.04, 0.29]), higher risk of MDD (HR [95% CI]: 1.18 [1.04, 1.34]) and SUD (HR [95% CI]: 1.36 [1.07, 1.73]). Similar, but attenuated, patterns held in the subgroup of exclusively AN vs other eating disorder (OED) cases. These results suggest a similar pattern of influence of schizophrenia PRS for AN and OED cases in terms of psychiatric comorbidities, but a different pattern in terms of ED-related clinical features. The disparity of the effect of schizophrenia PRS on AN vs OED merits further investigation.

Migration and risk of schizophrenia and bipolar disorder: A Swedish national study.

OBJECTIVE: Prior studies report increased risk of schizophrenia (SCZ) in migrants relative to the native-born population; however, few have investigated bipolar disorder (BD) and migrant characteristics which may influence risk. We aimed to examine the risk of SCZ and BD in migrants and their children relative to those of Swedish ancestry, and whether risk varied by age at migration, region of origin, sex, and parental migrant status. METHODS: We conducted a nested case-control study using 5539 SCZ cases and 20,577 BD cases diagnosed 1988-2013, individually matched to five population-based controls by birth year and sex. Conditional logistic regression was used to evaluate the risk of SCZ and BD by migrant status, region of origin and age at migration, with models stratified by sex. RESULTS: First-generation migrants had increased risk of SCZ and decreased risk of BD. There was a distinct pattern of risk for SCZ by age at migration. Childhood migrants from all regions had increased risk of SCZ, particularly those from Africa. In contrast, risk for BD declined with age at migration, with increased risk only in Nordic child migrants. SCZ and BD diagnoses were decreased in adult migrants, elevated in second-generation migrants (with risk differing by number of migrant parents and greater for those with migrant fathers) and higher in male migrants (vs. female). CONCLUSIONS: Age at migration, sex, and region of origin affect risk of SCZ and BD. Further research is required to determine how migration-related factors influence disease etiology and the receipt of these diagnoses.

Genetics of circulating inflammatory proteins identifies drivers of immune-mediated disease risk and therapeutic targets.

Circulating proteins have important functions in inflammation and a broad range of diseases. To identify genetic influences on inflammation-related proteins, we conducted a genome-wide protein quantitative trait locus (pQTL) study of 91 plasma proteins measured using the Olink Target platform in 14,824 participants. We identified 180 pQTLs (59 cis, 121 trans). Integration of pQTL data with eQTL and disease genome-wide association studies provided insight into pathogenesis, implicating lymphotoxin-α in multiple sclerosis. Using Mendelian randomization (MR) to assess causality in disease etiology, we identified both shared and distinct effects of specific proteins across immune-mediated diseases, including directionally discordant effects of CD40 on risk of rheumatoid arthritis versus multiple sclerosis and inflammatory bowel disease. MR implicated CXCL5 in the etiology of ulcerative colitis (UC) and we show elevated gut CXCL5 transcript expression in patients with UC. These results identify targets of existing drugs and provide a powerful resource to facilitate future drug target prioritization.

Lack of guidelines and translational knowledge is hindering the implementation of psychiatric genetic counseling and testing within Europe - A multi-professional survey study.

Genetic research has identified a large number of genetic variants, both rare and common, underlying neurodevelopmental disorders (NDD) and major psychiatric disorders. Currently, these findings are being translated into clinical practice. However, there is a lack of knowledge and guidelines for psychiatric genetic testing (PsychGT) and genetic counseling (PsychGC). The European Union-funded COST action EnGagE (CA17130) network was started to investigate the current implementation status of PsychGT and PsychGC across 35 participating European countries. Here, we present the results of a pan-European online survey in which we gathered the opinions, knowledge, and practices of a self-selected sample of professionals involved/interested in the field. We received answers from 181 respondents. The three main occupational categories were genetic counselor (21.0%), clinical geneticist (24.9%), and researcher (25.4%). Of all 181 respondents, 106 provide GC for any psychiatric disorder or NDD, corresponding to 58.6% of the whole group ranging from 43.2% in Central Eastern Europe to 66.1% in Western Europe. Overall, 65.2% of the respondents reported that genetic testing is offered to individuals with NDD, and 26.5% indicated the same for individuals with major psychiatric disorders. Only 22.1% of the respondents indicated that they have guidelines for PsychGT. Pharmacogenetic testing actionable for psychiatric disorders was offered by 15%. Interestingly, when genetic tests are fully covered by national health insurance, more genetic testing is provided for individuals with NDD but not those with major psychiatric disorders. Our qualitative analyses of responses highlight the lack of guidelines and knowledge on utilizing and using genetic tests and education and training as the major obstacles to implementation. Indeed, the existence of psychiatric genetic training courses was confirmed by only 11.6% of respondents. The question on the relevance of up-to-date education and training in psychiatric genetics on everyday related practice was highly relevant. We provide evidence that PsychGC and PsychGT are already in use across European countries, but there is a lack of guidelines and education. Harmonization of practice and development of guidelines for genetic counseling, testing, and training professionals would improve equality and access to quality care for individuals with psychiatric disorders within Europe.

Impact of Early-Life Factors on Risk for Schizophrenia and Bipolar Disorder.

BACKGROUND AND HYPOTHESIS: Schizophrenia (SCZ) and bipolar disorder (BD) have shared genetic risk and clinical symptoms, yet the extent to which environmental risk factors are shared is not well known. We aimed to examine the associations of early-life environmental exposures with the risk of SCZ and BD. STUDY DESIGN: We conducted a Swedish register-based nested case-control study using 4184 SCZ and 18 681 BD cases diagnosed 1988-2013, individually matched to 5 population-based controls by birth year, sex and birthplace. Conditional logistic regression was used to evaluate the risk of SCZ and BD by seasonality, severe prenatal infections, and perinatal factors. STUDY RESULTS: Seasonality had similar patterns of risk for both disorders: Higher risk for births November-December; lower risk April-June. Experiencing any perinatal factor was associated with a significantly higher risk of SCZ (incidence rate ratio [IRR] 1.19, 95%CI 1.11-1.63) and to a lesser extent BD (IRR 1.08, 95%CI 1.05-1.12). Prenatal infections were only associated with a greater risk of SCZ (IRR 1.30, 95%CI 1.04-1.63). In the mutually adjusted model, only perinatal factors were associated with outcomes. Several perinatal factors were associated with both disorders, but estimates were significantly higher for SCZ for low birth weight, low APGAR, and high parity. Congenital malformations were only associated with risk of SCZ, and jaundice with BD. CONCLUSIONS: Adverse perinatal factors and winter birth were the risk factors for both disorders, while severe prenatal infections were only risk a factor for SCZ. Early-life exposures were associated with a higher risk of both disorders, but may play a larger role in the development of SCZ than BD.

Melatonin use and the risk of self-harm and unintentional injuries in youths with and without psychiatric disorders.

BACKGROUND: Sleep disorders in youth have been associated with increased risks of injury, including suicidal behavior. This study investigated whether melatonin, which is the most common medication for sleep disturbances in youth in Sweden, is associated with a decreased risk of injury. METHODS: This population-based cohort study included 25,575 youths who initiated melatonin treatment between ages 6 and 18. Poisson regression was used to estimate rate of injuries in the year prior to and following melatonin treatment initiation. A within-individual design was used to estimate relative risks by comparing injury risk in the last unmedicated month with injury risks in the 12 months after medication initiation. Analyses were stratified by sex, injury type, psychiatric comorbidities and age at melatonin-treatment initiation. RESULTS: While body injuries, falls and transport accident rates were comparable in the year before and after melatonin-treatment initiation, the risk of self-harm was highest in the months immediately prior to medication, and decreased thereafter. This was particularly prominent among adolescents with depression and/or anxiety, with females displaying greater absolute risks than males. Compared to the last unmedicated month, the 12 months post medication initiation had decreased relative risks for self-harm, with an IRR [95% CI] in the month following melatonin-treatment initiation of 0.46 [0.27-0.76] among adolescent females with psychiatric disorders, after excluding antidepressant users. CONCLUSIONS: Decreased risk of intentional self-harm was observed following melatonin-treatment initiation among females with depression and anxiety, suggesting that sleep interventions could be considered in an effort to reduce risk of self-harm in this population.

Association of family history of schizophrenia and clinical outcomes in individuals with eating disorders.

BACKGROUND: Familial co-aggregation studies of eating disorders (EDs) and schizophrenia reveal shared genetic and environment factors, yet their etiological and clinical relationship remains unclear. We evaluate the influence of schizophrenia family history on clinical outcomes of EDs. METHODS: We conducted a cohort evaluation of the association between family history of schizophrenia and ED clinical features, psychiatric comorbidities, and somatic and mental health burden in individuals born in Sweden 1977-2003 with anorexia nervosa (AN) or other EDs (OED: bulimia nervosa, binge-eating disorder, and ED not otherwise specified). RESULTS: Of 12 424 individuals with AN and 20 716 individuals with OED, 599 (4.8%) and 1118 (5.4%), respectively, had a family history of schizophrenia (in up to third-degree relatives). Among individuals with AN, schizophrenia in first-degree relatives was significantly associated with increased comorbid attention-deficit/hyperactivity disorder (ADHD) [HR(95% CI) 2.26 (1.27-3.99)], substance abuse disorder (SUD) [HR (95% CI) 1.93 (1.25-2.98)], and anxiety disorders [HR (95% CI) 1.47 (1.08-2.01)], but higher lowest illness-associated body mass index (BMI) [1.14 kg/m2, 95% CI (0.19-2.10)]. Schizophrenia in any relative (up to third-degree) in AN was significantly associated with higher somatic and mental health burden, but lower ED psychopathology scores [-0.29, 95% CI (-0.54 to -0.04)]. Schizophrenia in first-degree relatives in individuals with OED was significantly associated with increased comorbid ADHD, obsessive-compulsive disorder, SUD, anxiety disorders, somatic and mental health burden, and suicide attempts. CONCLUSIONS: We observed different patterns of ED-related outcomes, psychiatric comorbidity, and illness burden in individuals with EDs with and without family histories of schizophrenia and provide new insights into the diverse manifestations of EDs.

Early-Onset Type 2 Diabetes and Mood, Anxiety, and Stress-Related Disorders: A Genetically Informative Register-Based Cohort Study.

OBJECTIVE: To assess the association and familial coaggregation between early-onset type 2 diabetes (diagnosed before age 45 years) and mood, anxiety, and stress-related disorders and estimate the contribution of genetic and environmental factors to their co-occurrence. RESEARCH DESIGN AND METHODS: This population-based cohort study included individuals born in Sweden during 1968-1998, from whom pairs of full siblings, half-siblings, and cousins were identified. Information on diagnoses of early-onset type 2 diabetes and mood (including unipolar depression and bipolar disorder), anxiety, and stress-related disorders was obtained from the National Patient Register. Logistic and Cox regression models were used to assess the phenotypic association and familial coaggregation between type 2 diabetes and psychiatric disorders. Quantitative genetic modeling was conducted in full and maternal half-sibling pairs to estimate the relative contributions of genetic and environmental factors to the association. RESULTS: Among a total of 3,061,192 individuals, 7,896 (0.3%) were diagnosed with early-onset type 2 diabetes. These individuals had higher risks of any diagnosis (odds ratio [OR] 3.62 [95% CI 3.44, 3.80]) and specific diagnosis of unipolar depression (3.97 [3.75, 4.22]), bipolar disorder (4.17 [3.68, 4.73]), anxiety (3.76 [3.54, 3.99]), and stress-related disorders (3.35 [3.11, 3.61]). Relatives of individuals with early-onset type 2 diabetes also had higher overall risks of the examined psychiatric disorders (ORs 1.03-1.57). These associations are largely explained by genetic factors (51-78%), with the rest explained by nonshared environmental factors. CONCLUSIONS: Our findings highlight the burden of mood, anxiety, and stress-related disorders in early-onset type 2 diabetes and demonstrate that shared familial liability may contribute to their co-occurrence, suggesting that in the future research investigators should aim to identify shared risk factors and ultimately refine preventive and intervention strategies.

Genetic and Environmental Contribution to the Co-Occurrence of Endocrine-Metabolic Disorders and Depression: A Nationwide Swedish Study of Siblings.

OBJECTIVE: Depression is common in individuals with endocrine-metabolic disorders and vice versa, and a better understanding of the underlying factors contributing to the comorbidity of these disorders is needed. This study investigated the familial coaggregation of depression and endocrine-metabolic disorders and estimated the contribution of genetic and environmental factors to their co-occurrence. METHODS: This population-based cohort study included 2.2 million individuals born in Sweden between 1973 and 1996, with follow-up through 2013. Participants were linked to their biological parents, allowing identification of full siblings, maternal half siblings, and paternal half siblings. Diagnoses of depression and endocrine-metabolic conditions were investigated, with the latter grouped into autoimmune disorders (autoimmune hypothyroidism, Graves' disease, and type 1 diabetes) and non-autoimmune disorders (type 2 diabetes, obesity, and polycystic ovary syndrome). Logistic regression and Cox regression were used to estimate the associations between endocrine-metabolic disorders and depression within the same individual and across siblings. Quantitative genetic modeling was performed to investigate the relative contribution of genetic and environmental influences. RESULTS: Individuals with endocrine-metabolic disorders had a significantly higher risk of depression, with odds ratios ranging from 1.43 (95% CI=1.30, 1.57) for Graves' disease to 3.48 (95% CI=3.25, 3.72) for type 2 diabetes. Increased risks extended to full and half siblings. These correlations were mainly explained by shared genetic influences for non-autoimmune conditions, and by nonshared environmental factors for autoimmune disorders, especially for type 1 diabetes. CONCLUSIONS: These findings provide phenotypic and etiological insights into the co-occurrence of depression and various endocrine-metabolic conditions, which could guide future research aiming at identifying pathophysiological mechanisms and intervention targets.

Association and Familial Coaggregation of Childhood-Onset Type 1 Diabetes With Depression, Anxiety, and Stress-Related Disorders: A Population-Based Cohort Study.

OBJECTIVE: To estimate the association and familial coaggregation of childhood-onset type 1 diabetes with depression, anxiety, and stress-related disorders. RESEARCH DESIGN AND METHODS: This was a population-based cohort study with use of data from Swedish nationwide registers. A total of ∼3.5 million individuals born in Sweden 1973-2007 were linked to their biological parents, full siblings and half-siblings, and cousins. Cox models were used to estimate the association and familial coaggregation of type 1 diabetes with depression, anxiety, and stress-related disorders. RESULTS: Individuals diagnosed with childhood-onset type 1 diabetes (n = 20,005) were found to be at greater risks of all outcomes: any psychiatric diagnosis (adjusted hazard ratio [aHR] 1.66 [95% CI 1.59-1.72]) or specific diagnoses of depression (1.85 [1.76-1.94]), anxiety (1.41[1.33-1.50]), and stress-related disorders (1.75 [1.62-1.89]), as well as use of antidepressants or anxiolytics (1.30 [1.26-1.34]), compared with individuals without type 1 diabetes. Overall, relatives of individuals with type 1 diabetes were at elevated risks of developing these outcomes, with the highest risks seen in parents (aHRs 1.18-1.25), followed by full siblings (aHRs 1.05-1.20), and the magnitudes of risk estimates appear proportional to familial relatedness. CONCLUSIONS: These results support existing evidence that children and adolescents with type 1 diabetes are at greater risks of developing depression, anxiety, and stress-related disorders and indicate that shared familial factors might contribute to these elevated risks. Our findings highlight the need for psychological consulting for children and their families in diabetes care. Quantitative and molecular genetic studies are warranted to further understand the etiology of these psychiatric disorders in type 1 diabetes.

Improving lithium dose prediction using population pharmacokinetics and pharmacogenomics: a cohort genome-wide association study in Sweden.

BACKGROUND: Lithium is the most effective treatment for bipolar disorder, resulting in strong suicide prevention effects. The therapeutic range of lithium, however, is narrow and treatment initiation requires individual titration to address inter-individual variability. We aimed to improve lithium dose prediction using clinical and genomic data. METHODS: We performed a population pharmacokinetic study followed by a genome-wide association study (GWAS), including two clinical Swedish cohorts. Participants in cohort 1 were from specialised outpatient clinics at Huddinge Hospital, in Stockholm, Sweden, and participants in cohort 2 were identified using the Swedish National Quality Registry for Bipolar disorder (BipoläR). Patients who received a lithium dose corresponding to at least one tablet of lithium sulphate (6 mmol) per day and had clinically relevant plasma concentrations of lithium were included in the study. Data on age, sex, bodyweight, height, creatinine concentration, estimated glomerular filtration rate (eGFR), lithium preparation, number of tablets of lithium per day, serum lithium concentration, and medications affecting kidney function (C09 antihypertensives, C03 [except C03D] sodium-retaining diuretics, and non-steroidal anti-inflammatory drugs) were obtained retrospectively for several timepoints when possible from electronic health records, BipoläR, and the Swedish prescription registry. The median time between timepoints was 1·07 years for cohort 1 and 1·09 years for cohort 2. The primary outcome of interest was the natural logarithm of total body clearance for lithium (CLLi) associated with the clinical variables. The residual effects after accounting for age and sex, representing the individual-level effects (CLLi,age/sex), were used as the dependent variable in a GWAS. FINDINGS: 2357 patients who were administered lithium (1423 women [60·4%] and 934 men [39·6%]; mean age 53·6 years [range 17-89], mainly of European descent) were included and 5627 data points were obtained. Age (variance explained [R2]: R2cohort1=0·41 and R2cohort2=0·31; both p<0·0001), sex (R2cohort1=0·0063 [p=0·045] and R2cohort2=0·026 [p<0·0001]), eGFR (R2cohort1=0·38 and R2cohort2=0·20; both p<0·0001), comedication with diuretics (R2cohort1=0·0058 [p=0·014] and R2cohort2=0·0026 [p<0·0001]), and agents acting on the renin-aldosterone-angiotensin system (R2cohort1=0·028 and R2cohort2=0·015; both p<0·0001) were clinical predictors of CLLi. Notably, an association between CLLi and serum lithium was observed, with a lower CLLi being associated with higher serum lithium (R2cohort1=0·13 and R2cohort2=0·15; both p<0·0001). In a GWAS of CLLi,age/sex, one locus was associated with a change in CLLi (rs583503; ß=-0·053 [95% CI -0·071 to -0·034]; p<0·00000005). We also found enrichment of the associations with genes expressed in the medulla (p=0·0014, corrected FDR=0·04) and cortex of the kidney (p=0·0015, corrected FDR=0·04), as well as associations with polygenic risk scores for eGFR (p value threshold: 0·05, p=0·01), body-mass index (p value threshold: 0·05, p=0·00025), and blood urea nitrogen (p value threshold: 0·001, p=0·00043). The model based on six clinical predictors explained 61·4% of the variance in CLLi in cohort 1 and 49·8% in cohort 2. Adding genetic markers did not lead to major improvement of the models: within the subsample of genotyped individuals, the variance explained only increased from 59·32% to 59·36% in cohort 1 and from 49·21% to 50·03% in cohort 2 when including rs583503 and the four first principal components. INTERPRETATION: Our model predictors could be used clinically to better guide lithium dosage, shortening the time to reach therapeutic concentrations, thus improving care. Identification of the first genomic locus and PRS to be associated with CLLi introduces the opportunity of individualised medicine in lithium treatment. FUNDING: Stanley Medical Research Institute, Swedish Research Council, Swedish Foundation for Strategic Research, Swedish Brain Foundation, Swedish Research Council, Söderström-Königska Foundation, Bror Gadelius Minnesfond, Swedish Mental Health Fund, Karolinska Institutet and Hospital.

The role of ADHD genetic risk in mid-to-late life somatic health conditions.

Growing evidence suggests that ADHD, an early onset neurodevelopmental disorder, is associated with poor somatic health in adulthood. However, the mechanisms underlying these associations are poorly understood. Here, we tested whether ADHD polygenic risk scores (PRS) are associated with mid-to-late life somatic health in a general population sample. Furthermore, we explored whether potential associations were moderated and mediated by life-course risk factors. We derived ADHD-PRS in 10,645 Swedish twins born between 1911 and 1958. Sixteen cardiometabolic, autoimmune/inflammatory, and neurological health conditions were evaluated using self-report (age range at measure 42-88 years) and clinical diagnoses defined by International Classification of Diseases codes in national registers. We estimated associations of ADHD-PRS with somatic outcomes using generalized estimating equations, and tested moderation and mediation of these associations by four life-course risk factors (education level, body mass index [BMI], tobacco use, alcohol misuse). Results showed that higher ADHD-PRS were associated with increased risk of seven somatic outcomes (heart failure, cerebro- and peripheral vascular disease, obesity, type 1 diabetes, rheumatoid arthritis, and migraine) with odds ratios ranging 1.07 to 1.20. We observed significant mediation effects by education, BMI, tobacco use, and alcohol misuse, primarily for associations of ADHD-PRS with cardiometabolic outcomes. No moderation effects survived multiple testing correction. Our findings suggests that higher ADHD genetic liability confers a modest risk increase for several somatic health problems in mid-to-late life, particularly in the cardiometabolic domain. These associations were observable in the general population, even in the absence of medical treatment for ADHD, and appear to be in part mediated by life-course risk factors.

Mapping genomic loci implicates genes and synaptic biology in schizophrenia.

Schizophrenia has a heritability of 60-80%1, much of which is attributable to common risk alleles. Here, in a two-stage genome-wide association study of up to 76,755 individuals with schizophrenia and 243,649 control individuals, we report common variant associations at 287 distinct genomic loci. Associations were concentrated in genes that are expressed in excitatory and inhibitory neurons of the central nervous system, but not in other tissues or cell types. Using fine-mapping and functional genomic data, we identify 120 genes (106 protein-coding) that are likely to underpin associations at some of these loci, including 16 genes with credible causal non-synonymous or untranslated region variation. We also implicate fundamental processes related to neuronal function, including synaptic organization, differentiation and transmission. Fine-mapped candidates were enriched for genes associated with rare disruptive coding variants in people with schizophrenia, including the glutamate receptor subunit GRIN2A and transcription factor SP4, and were also enriched for genes implicated by such variants in neurodevelopmental disorders. We identify biological processes relevant to schizophrenia pathophysiology; show convergence of common and rare variant associations in schizophrenia and neurodevelopmental disorders; and provide a resource of prioritized genes and variants to advance mechanistic studies.