SnapShot: GI tract development.

The endoderm germ layer contributes to the respiratory and gastrointestinal (GI) lineages during development, giving rise to an array of specialized epithelial cell types lining organs, including the thyroid, thymus, lungs, liver, biliary system, pancreas, and intestines. This SnapShot timelines and summarizes key stages following gastrulation, including endoderm patterning, organ specification, and organogenesis. A lineage tree of the developing endocrine pancreas is outlined to further illustrate this process.

From QTL to gene: C. elegans facilitates discoveries of the genetic mechanisms underlying natural variation.

Although many studies have examined quantitative trait variation across many species, only a small number of genes and thereby molecular mechanisms have been discovered. Without these data, we can only speculate about evolutionary processes that underlie trait variation. Here, we review how quantitative and molecular genetics in the nematode Caenorhabditis elegans led to the discovery and validation of 37 quantitative trait genes over the past 15 years. Using these data, we can start to make inferences about evolution from these quantitative trait genes, including the roles that coding versus noncoding variation, gene family expansion, common versus rare variants, pleiotropy, and epistasis play in trait variation across this species.

The genetic architecture of youth anxiety: a study protocol.

BACKGROUND: Anxiety disorders are the most common psychiatric problems among Canadian youth and typically have an onset in childhood or adolescence. They are characterized by high rates of relapse and chronicity, often resulting in substantial impairment across the lifespan. Genetic factors play an important role in the vulnerability toward anxiety disorders. However, genetic contribution to anxiety in youth is not well understood and can change across developmental stages. Large-scale genetic studies of youth are needed with detailed assessments of symptoms of anxiety disorders and their major comorbidities to inform early intervention or preventative strategies and suggest novel targets for therapeutics and personalization of care. METHODS: The Genetic Architecture of Youth Anxiety (GAYA) study is a Pan-Canadian effort of clinical and genetic experts with specific recruitment sites in Calgary, Halifax, Hamilton, Toronto, and Vancouver. Youth aged 10-19 (n = 13,000) will be recruited from both clinical and community settings and will provide saliva samples, complete online questionnaires on demographics, symptoms of mental health concerns, and behavioural inhibition, and complete neurocognitive tasks. A subset of youth will be offered access to a self-managed Internet-based cognitive behavioral therapy resource. Analyses will focus on the identification of novel genetic risk loci for anxiety disorders in youth and assess how much of the genetic risk for anxiety disorders is unique or shared across the life span. DISCUSSION: Results will substantially inform early intervention or preventative strategies and suggest novel targets for therapeutics and personalization of care. Given that the GAYA study will be the biggest genomic study of anxiety disorders in youth in Canada, this project will further foster collaborations nationally and across the world.

Alterations in resting-state functional activity and connectivity for major depressive disorder appetite and weight disturbance phenotypes.

BACKGROUND: Major depressive disorder (MDD) is often accompanied by changes in appetite and weight. Prior task-based functional magnetic resonance imaging (fMRI) findings suggest these MDD phenotypes are associated with altered reward and interoceptive processing. METHODS: Using resting-state fMRI data, we compared the fractional amplitude of low-frequency fluctuations (fALFF) and seed-based connectivity (SBC) among hyperphagic (n = 77), hypophagic (n = 66), and euphagic (n = 42) MDD groups and a healthy comparison group (n = 38). We examined fALFF and SBC in a mask restricted to reward [nucleus accumbens (NAcc), putamen, caudate, ventral pallidum, and orbitofrontal cortex (OFC)] and interoceptive (anterior insula and hypothalamus) regions and also performed exploratory whole-brain analyses. SBC analyses included as seeds the NAcc and also regions demonstrating group differences in fALFF (i.e. right lateral OFC and right anterior insula). All analyses used threshold-free cluster enhancement. RESULTS: Mask-restricted analyses revealed stronger fALFF in the right lateral OFC, and weaker fALFF in the right anterior insula, for hyperphagic MDD v. healthy comparison. We also found weaker SBC between the right lateral OFC and left anterior insula for hyperphagic MDD v. healthy comparison. Whole-brain analyses revealed weaker fALFF in the right anterior insula, and stronger SBC between the right lateral OFC and left precentral gyrus, for hyperphagic MDD v. healthy comparison. Findings were no longer significant after controlling for body mass index, which was higher for hyperphagic MDD. CONCLUSIONS: Our results suggest hyperphagic MDD may be associated with altered activity in and connectivity between interoceptive and reward regions.

Piloting a multidisciplinary approach to improve outcomes of fetal whole exome sequencing: An overview of workflow and case example.

INTRODUCTION: Whole exome sequencing (WES) has increasingly become integrated into prenatal care and genetic testing pathways. Current studies of prenatal WES have focused on diagnostic yield. The possibility of obtaining a variant of uncertain significance and lack of provider expertise are frequently described as common barriers to clinical integration of prenatal WES. We describe the implementation and workflow for a multidisciplinary approach to effectively integrate prenatal WES into maternal-fetal care to overcome these barriers. METHODS: A multidisciplinary team reviews and approves potential cases for WES. This team reviews WES results, reclassifying variants as appropriate and provides recommendations for postnatal care. A detailed description of this workflow is provided, and a case example is included to demonstrate effectiveness of this approach. Our team has approved 62 cases for WES with 45 patients ultimately pursuing WES. We have achieved a diagnostic yield of 40% and the multidisciplinary team has played a role in variant interpretation in 50% of the reported variants of uncertain significance. CONCLUSIONS: This approach facilitates communication between prenatal and postnatal care teams and provides accurate interpretation and recommendations for identified fetal variants. This model can be replicated to ensure appropriate patient care and effective integration of novel genomic technologies into prenatal settings.

Paraprofessional delivery of online narrative exposure therapy for firefighters.

Firefighters are at increased risk for developing posttraumatic stress disorder (PTSD) and face numerous barriers to accessing mental health care. Innovative ways to increase access to evidence-based interventions are needed. This study was a case series testing the acceptability, feasibility, and preliminary effectiveness of a paraprofessional-delivered, virtual narrative exposure therapy (eNET) intervention for PTSD. Participants were 21 firefighters who met the criteria for clinical or subclinical probable PTSD and completed 10-12 sessions of eNET via videoconference. Participants completed self-report measures pre- and postintervention and at 2- and 6-month follow-ups as well as a postintervention qualitative interview. Paired samples t tests evidenced statistically significant decreases in PTSD, anxiety, and depressive symptom severity and functional impairment from pre- to postintervention, ds = 1.08-1.33, and in PTSD and anxiety symptom severity and functional impairment from preintervention to 6-month follow-up, ds = 0.69-1.10. The average PTSD symptom severity score fell from above to below the clinical cutoff for probable PTSD at postintervention and follow-ups. Qualitative interviews indicated that paraprofessionals were considered central to participants' success and experience with the intervention. No adverse events or safety concerns were raised. This study is an important step in demonstrating that appropriately trained and supervised paraprofessionals can effectively deliver eNET to firefighters with PTSD.

A spontaneous complex structural variant in rcan-1 increases exploratory behavior and laboratory fitness of Caenorhabditis elegans.

Over long evolutionary timescales, major changes to the copy number, function, and genomic organization of genes occur, however, our understanding of the individual mutational events responsible for these changes is lacking. In this report, we study the genetic basis of adaptation of two strains of C. elegans to laboratory food sources using competition experiments on a panel of 89 recombinant inbred lines (RIL). Unexpectedly, we identified a single RIL with higher relative fitness than either of the parental strains. This strain also displayed a novel behavioral phenotype, resulting in higher propensity to explore bacterial lawns. Using bulk-segregant analysis and short-read resequencing of this RIL, we mapped the change in exploration behavior to a spontaneous, complex rearrangement of the rcan-1 gene that occurred during construction of the RIL panel. We resolved this rearrangement into five unique tandem inversion/duplications using Oxford Nanopore long-read sequencing. rcan-1 encodes an ortholog to human RCAN1/DSCR1 calcipressin gene, which has been implicated as a causal gene for Down syndrome. The genomic rearrangement in rcan-1 creates two complete and two truncated versions of the rcan-1 coding region, with a variety of modified 5' and 3' non-coding regions. While most copy-number variations (CNVs) are thought to act by increasing expression of duplicated genes, these changes to rcan-1 ultimately result in the reduction of its whole-body expression due to changes in the upstream regions. By backcrossing this rearrangement into a common genetic background to create a near isogenic line (NIL), we demonstrate that both the competitive advantage and exploration behavioral changes are linked to this complex genetic variant. This NIL strain does not phenocopy a strain containing an rcan-1 loss-of-function allele, which suggests that the residual expression of rcan-1 is necessary for its fitness effects. Our results demonstrate how colonization of new environments, such as those encountered in the laboratory, can create evolutionary pressure to modify gene function. This evolutionary mismatch can be resolved by an unexpectedly complex genetic change that simultaneously duplicates and diversifies a gene into two uniquely regulated genes. Our work shows how complex rearrangements can act to modify gene expression in ways besides increased gene dosage.

Exploration of baseline and early changes in neurocognitive characteristics as predictors of treatment response to bupropion, sertraline, and placebo in the EMBARC clinical trial.

BACKGROUND: Treatment for major depressive disorder (MDD) is imprecise and often involves trial-and-error to determine the most effective approach. To facilitate optimal treatment selection and inform timely adjustment, the current study investigated whether neurocognitive variables could predict an antidepressant response in a treatment-specific manner. METHODS: In the two-stage Establishing Moderators and Biosignatures of Antidepressant Response for Clinical Care (EMBARC) trial, outpatients with non-psychotic recurrent MDD were first randomized to an 8-week course of sertraline selective serotonin reuptake inhibitor or placebo. Behavioral measures of reward responsiveness, cognitive control, verbal fluency, psychomotor, and cognitive processing speeds were collected at baseline and week 1. Treatment responders then continued on another 8-week course of the same medication, whereas non-responders to sertraline or placebo were crossed-over under double-blinded conditions to bupropion noradrenaline/dopamine reuptake inhibitor or sertraline, respectively. Hamilton Rating for Depression scores were also assessed at baseline, weeks 8, and 16. RESULTS: Greater improvements in psychomotor and cognitive processing speeds within the first week, as well as better pretreatment performance in these domains, were specifically associated with higher likelihood of response to placebo. Moreover, better reward responsiveness, poorer cognitive control and greater verbal fluency were associated with greater likelihood of response to bupropion in patients who previously failed to respond to sertraline. CONCLUSION: These exploratory results warrant further scrutiny, but demonstrate that quick and non-invasive behavioral tests may have substantial clinical value in predicting antidepressant treatment response.

Common molecular mechanisms of SLC6A1 variant-mediated neurodevelopmental disorders in astrocytes and neurons.

Solute carrier family 6 member 1 (SLC6A1) is abundantly expressed in the developing brain even before the CNS is formed. Its encoded GABA transporter 1 (GAT-1) is responsible for the reuptake of GABA into presynaptic neurons and glia, thereby modulating neurotransmission. GAT-1 is expressed globally in the brain, in both astrocytes and neurons. The GABA uptake function of GAT-1 in neurons cannot be compensated for by other GABA transporters, while the function in glia can be partially replaced by GABA transporter 3. Recently, many variants in SLC6A1 have been associated with a spectrum of epilepsy syndromes and neurodevelopmental disorders, including myoclonic atonic epilepsy, childhood absence epilepsy, autism, and intellectual disability, but the pathomechanisms associated with these phenotypes remain unclear. The presence of GAT-1 in both neurons and astrocytes further obscures the role of abnormal GAT-1 in the heterogeneous disease phenotype manifestations. Here we examine the impact on transporter trafficking and function of 22 SLC6A1 variants identified in patients with a broad spectrum of phenotypes. We also evaluate changes in protein expression and subcellular localization of the variant GAT-1 in various cell types, including neurons and astrocytes derived from human patient induced pluripotent stem cells. We found that a partial or complete loss-of-function represents a common disease mechanism, although the extent of GABA uptake reduction is variable. The reduced GABA uptake appears to be due to reduced cell surface expression of the variant transporter caused by variant protein misfolding, endoplasmic reticulum retention, and subsequent degradation. Although the extent of reduction of the total protein, surface protein, and the GABA uptake level of the variant transporters is variable, the loss of GABA uptake function and endoplasmic reticulum retention is consistent across induced pluripotent stem cell-derived cell types, including astrocytes and neurons, for the surveyed variants. Interestingly, we did not find a clear correlation of GABA uptake function and the disease phenotypes, such as myoclonic atonic epilepsy versus developmental delay, in this study. Together, our study suggests that impaired transporter protein trafficking and surface expression are the major disease-associated mechanisms associated with pathogenic SLC6A1 variants. Our results resemble findings from pathogenic variants in other genes affecting the GABA pathway, such as GABAA receptors. This study provides critical insight into therapeutic developments for SLC6A1 variant-mediated disorders and implicates that boosting transporter function by either genetic or pharmacological approaches would be beneficial.

Balancing selection shapes density-dependent foraging behaviour.

The optimal foraging strategy in a given environment depends on the number of competing individuals and their behavioural strategies. Little is known about the genes and neural circuits that integrate social information into foraging decisions. Here we show that ascaroside pheromones, small glycolipids that signal population density, suppress exploratory foraging in Caenorhabditis elegans, and that heritable variation in this behaviour generates alternative foraging strategies. We find that natural C. elegans isolates differ in their sensitivity to the potent ascaroside icas#9 (IC-asc-C5). A quantitative trait locus (QTL) regulating icas#9 sensitivity includes srx-43, a G-protein-coupled icas#9 receptor that acts in the ASI class of sensory neurons to suppress exploration. Two ancient haplotypes associated with this QTL confer competitive growth advantages that depend on ascaroside secretion, its detection by srx-43 and the distribution of food. These results suggest that balancing selection at the srx-43 locus generates alternative density-dependent behaviours, fulfilling a prediction of foraging game theory.

Parenting-related trauma exposure among parents of children with intellectual and developmental disorders: Development and validation of the Parenting Trauma Checklist.

Parents of children with intellectual and developmental disorders (IDDs) often encounter parenting-related traumatic events. Trauma exposure is a risk factor for mental health problems, including posttraumatic stress disorder (PTSD). Little is known regarding the types of traumatic events that parents commonly experience and how to best assess parenting-related trauma exposure. To address this gap, we developed the Parenting Trauma Checklist (PTC) and tested its psychometric properties. The PTC was created based on an extensive literature review and consultation with stakeholders, which led to the creation of a 17-item instrument. Participants (N = 424) were Canadian parents of children with IDDs who completed an online test battery that included the PTC and several questionnaires to assess PTSD symptoms, global mental and physical health, lifetime trauma exposure, and functional impairment, which were included to test the validity of the new instrument. The PTC demonstrated good construct validity. Ninety four percent of the sample reported parenting-related trauma exposure. Parents reported having experienced an average of 5.79 parenting-related traumatic events, with seeing their child undergo a medical procedure the most frequently endorsed event (68.6%). Experiencing more parenting-related traumatic events was positively associated with higher PTSD symptom levels, r = .35, p < .001. The PTC is a promising instrument that can be used to examine parenting-related trauma exposure. The measure can be used as a screening tool to detect parents' risk of traumatic stress disorders, evaluate traumatic experiences, and assess whether trauma-focused treatment is warranted.

How to measure barriers in accessing mental healthcare? Psychometric evaluation of a screening tool in parents of children with intellectual and developmental disabilities.

Caring for children with intellectual and developmental disabilities (IDD) can cause an enormous physical and emotional burden, and therefore these parents have an elevated risk to experience mental health problems. The characteristics of current healthcare systems and parents' responsibilities to care for their children seem to impede their access to mental healthcare. There is so far a lack of instruments to screen for such obstacles. The aim of this study was to develop and validate a scale for measuring barriers to accessing mental healthcare. The Parental Healthcare Barriers Scale (PHBS) was developed on the basis of an extensive literature research, input and discussion from experts and parents with lived experience. A cross-sectional survey was used to collect data from 456 parents of children with IDD. Physical health, mental health, social support, and parenting were measured for concurrent and discriminant validity of the PHBS. The PHBS scale revealed acceptable to good reliability and validity. It consists of four subscales (i.e., support accessibility, personal belief, emotional readiness, and resource availability). The PHBS found parents prioritized their children's treatments over their own mental health challenges (93.4%), did not have enough time (90.4%), and had financial concerns (85.8%). Parents in rural and remote areas had more limited resources. Findings from our study suggest increasing financial support for the parents seeking mental health services, introducing evidence-based treatments, increasing the availability of healthcare services for parents, and adjusting current services to their needs.

Childhood trauma history is linked to abnormal brain connectivity in major depression.

Patients with major depressive disorder (MDD) present with heterogeneous symptom profiles, while neurobiological mechanisms are still largely unknown. Brain network studies consistently report disruptions of resting-state networks (RSNs) in patients with MDD, including hypoconnectivity in the frontoparietal network (FPN), hyperconnectivity in the default mode network (DMN), and increased connection between the DMN and FPN. Using a large, multisite fMRI dataset (n = 189 patients with MDD, n = 39 controls), we investigated network connectivity differences within and between RSNs in patients with MDD and healthy controls. We found that MDD could be characterized by a network model with the following abnormalities relative to controls: (i) lower within-network connectivity in three task-positive RSNs [FPN, dorsal attention network (DAN), and cingulo-opercular network (CON)], (ii) higher within-network connectivity in two intrinsic networks [DMN and salience network (SAN)], and (iii) higher within-network connectivity in two sensory networks [sensorimotor network (SMN) and visual network (VIS)]. Furthermore, we found significant alterations in connectivity between a number of these networks. Among patients with MDD, a history of childhood trauma and current symptoms quantified by clinical assessments were associated with a multivariate pattern of seven different within- and between-network connectivities involving the DAN, FPN, CON, subcortical regions, ventral attention network (VAN), auditory network (AUD), VIS, and SMN. Overall, our study showed that traumatic childhood experiences and dimensional symptoms are linked to abnormal network architecture in MDD. Our results suggest that RSN connectivity may explain underlying neurobiological mechanisms of MDD symptoms and has the potential to serve as an effective diagnostic biomarker.

Effectiveness of an Internet-Based and Telephone-Assisted Training for Parents of 4-Year-Old Children With Disruptive Behavior: Implementation Research.

BACKGROUND: There is a lack of effectiveness studies when digital parent training programs are implemented in real-world practice. The efficacy of the internet-based and telephone-assisted Finnish Strongest Families Smart Website (SFSW) parent training intervention on the disruptive behavior of 4-year-old children was studied in a randomized controlled trial setting in Southwest Finland between 2011 and 2013. After that, the intervention was implemented nationwide in child health clinics from 2015 onwards. OBJECTIVE: The main aim of this study was to compare the treatment characteristics and effectiveness of the SFSW parent training intervention between the families who received the intervention when it was implemented as a normal practice in child health clinics and the families who received the same intervention during the randomized controlled trial. METHODS: The implementation group comprised 600 families who were recruited in the SFSW intervention between January 2015 and May 2017 in real-world implementation. The RCT intervention group comprised 232 families who were recruited between October 2011 and November 2013. The same demographic and child and parent measures were collected from both study groups and were compared using linear mixed-effect models for repeated measurements. The child psychopathology and functioning level were measured using the Child Behavior Checklist (CBCL) version 1.5-5 for preschool children, the Inventory of Callous-Unemotional Traits (ICU), and a modified version of the Barkley Home Situations Questionnaire. Parenting skills were measured using the 31-item Parenting Scale and the shorter 21-item Depression, Anxiety and Stress Scale (DASS-21). The estimated child and parent outcomes were adjusted for CBCL externalizing scores at baseline, maternal education, duration of the behavior problems, and paternal age. The baseline measurements of each outcome were used as covariates. RESULTS: The implementation group was more likely to complete the intervention than the RCT intervention group (514/600, 85.7% vs 176/232, 75.9%, respectively; P<.001). There were no significant differences between the implementation and RCT intervention groups with regard to child measures, including CBCL externalizing score (-0.2, 95% CI -1.3 to 1.6; P=.83), total score (-0.7, 95% CI -3.0 to 4.5; P=.70), internalizing score (-0.3, 95% CI -1.0 to 1.6; P=.64), and ICU total score (-0.4, 95% Cl -1.9 to 1.2; P=.64). No significant difference was detected in the Parenting Scale total score (0.0, 95% Cl -0.1 to 0.1; P=.50), while DASS-21 total score differed nearly significantly (2.5, 95% Cl 0.0-5.1; P=.05), indicating better improvement in the implementation group. CONCLUSIONS: The internet-based and telephone-assisted SFSW parent training intervention was effectively implemented in real-world settings. These findings have implications for addressing the unmet needs of children with disruptive behavior problems. Our initiative could also provide a quick socially distanced solution for the considerable mental health impact of the COVID-19 pandemic. TRIAL REGISTRATION: ClinicalTrials.gov NCT01750996; https://clinicaltrials.gov/ct2/show/NCT01750996. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): RR2-10.1186/1471-2458-13-985.

Online Video Teletherapy Treatment of Obsessive-Compulsive Disorder Using Exposure and Response Prevention: Clinical Outcomes From a Retrospective Longitudinal Observational Study.

BACKGROUND: Exposure and response prevention, a type of cognitive-behavioral therapy, is an effective first-line treatment for obsessive-compulsive disorder (OCD). Despite extensive evidence of the efficacy of exposure and response prevention (ERP) from clinical studies and in real-world samples, it is still underused as a treatment. This is likely due to the limits to access to care that include the availability of adequately trained therapists, as well as geographical location, time, and cost barriers. To address these, NOCD created a digital behavioral health treatment for OCD using ERP delivered via video teletherapy and with technology-assisted elements including app-based therapy tools and between-session therapist messaging. OBJECTIVE: We examined treatment outcomes in a large naturalistic sample of 3552 adults with a primary OCD diagnosis who received NOCD treatment. METHODS: The treatment model consisted of twice-weekly, live, face-to-face video teletherapy ERP for 3 weeks, followed by 6 weeks of once-weekly brief video teletherapy check-ins for 30 minutes. Assessments were conducted at baseline, at midpoint after completion of 3 weeks of twice-weekly sessions, and at the end of 6 weeks of brief check-ins (endpoint). Longitudinal assessments were also obtained at 3, 6, 9, and 12 months after endpoint. RESULTS: Treatment resulted in clinically and statistically significant improvements, with a 43.4% mean reduction in obsessive-compulsive symptoms (g=1.0; 95% CI 0.93 to 1.03) and a 62.9% response rate. Treatment also resulted in a 44.2% mean reduction in depression, a 47.8% mean reduction in anxiety, and a 37.3% mean reduction in stress symptoms. Quality of life improved by a mean of 22.7%. Reduction in OCD symptoms and response rates were similar for those with mild, moderate, or severe symptoms. The mean duration of treatment was 11.5 (SD 4.0) weeks, and the mean total therapist time was 10.6 (SD 1.1) hours. Improvements were maintained at 3, 6, 9, and 12 months. CONCLUSIONS: In this sample, representing the largest reported treated cohort of patients with OCD to date, video teletherapy treatment demonstrated effectiveness in reducing obsessive-compulsive and comorbid symptoms and improved quality of life. Further, it achieved meaningful results in less than half the total therapist time compared with standard once-weekly outpatient treatment, an efficiency that represents substantial monetary and time savings. The effect size was large and similar to studies of in-person ERP. This technology-assisted remote treatment is readily accessible for patients, offering an advancement in the field in the dissemination of effective evidence-based care for OCD.

Comparison of Higher-Than-Standard to D-Dimer Driven Thromboprophylaxis in Hospitalized Patients With COVID-19.

Introduction: Coronavirus disease 2019 is a global health threat often accompanied with coagulopathy. Despite use of thromboprophylaxis in this population, thrombotic event rates are high. Materials and methods: This was a multicenter, retrospective cohort study comparing the safety and effectiveness of thromboprophylaxis strategies at 2 institutions in hospitalized patients with coronavirus disease 2019. Regimen A utilized a higher-than-standard thromboprophylaxis dosage and Regimen B received full-dose anticoagulation for any D-dimer 3 mcg/mL or greater and prophylactic for less than 3 mcg/mL. The primary outcome compared the rate of thrombotic events between treatment groups. Secondary endpoints compared rates of major or clinically relevant non-major bleeding as well as the proportion of patients in each group experiencing thrombotic events within 30 days of discharge. Results: One-hundred fifty-three patients were included in the analysis, 64 receiving Regimen A and 89 receiving Regimen B. Seven (4.6%) thrombotic events occurred, 3 (4.7%) in patients receiving Regimen A, and 4 (4.5%) in Regimen B (P = 1.0). Twelve patients (13.5%) receiving Regimen B had a bleeding event versus 2 (3.1%) in Regimen A (P = .04), half of which were major in each group. All patients who bled in either treatment group were receiving mechanical ventilation, and 12 of 14 were receiving full-dose anticoagulation. One patient receiving Regimen A was readmitted with a pulmonary embolism. Conclusions: In this study, the thromboprophylactic regimen impacted bleeding, but no significant difference was seen with thrombotic outcomes. Almost all patients who experienced a bleed were mechanically ventilated and receiving full-dose anticoagulation. The use of full-dose anticoagulation should be cautioned in this population without an additional indication.

Analysis of Epistasis in Natural Traits Using Model Organisms.

The ability to detect and understand epistasis in natural populations is important for understanding how biological traits are influenced by genetic variation. However, identification and characterization of epistasis in natural populations remains difficult due to statistical issues that arise as a result of multiple comparisons, and the fact that most genetic variants segregate at low allele frequencies. In this review, we discuss how model organisms may be used to manipulate genotypic combinations to power the detection of epistasis as well as test interactions between specific genes. Findings from a number of species indicate that statistical epistasis is pervasive between natural genetic variants. However, the properties of experimental systems that enable analysis of epistasis also constrain extrapolation of these results back into natural populations.

Discovery and replication of cerebral blood flow differences in major depressive disorder.

Major depressive disorder (MDD) is a serious, heterogeneous disorder accompanied by brain-related changes, many of which are still to be discovered or refined. Arterial spin labeling (ASL) is a neuroimaging technique used to measure cerebral blood flow (CBF; perfusion) to understand brain function and detect differences among groups. CBF differences have been detected in MDD, and may reveal biosignatures of disease-state. The current work aimed to discover and replicate differences in CBF between MDD participants and healthy controls (HC) as part of the EMBARC study. Participants underwent neuroimaging at baseline, prior to starting study medication, to investigate biosignatures in MDD. Relative CBF (rCBF) was calculated and compared between 106 MDD and 36 HC EMBARC participants (whole-brain Discovery); and 58 MDD EMBARC participants and 58 HC from the DLBS study (region-of-interest Replication). Both analyses revealed reduced rCBF in the right parahippocampus, thalamus, fusiform and middle temporal gyri, as well as the left and right insula, for those with MDD relative to HC. Both samples also revealed increased rCBF in MDD relative to HC in both the left and right inferior parietal lobule, including the supramarginal and angular gyri. Cingulate and prefrontal regions did not fully replicate. Lastly, significant associations were detected between rCBF in replicated regions and clinical measures of MDD chronicity. These results (1) provide reliable evidence for ASL in detecting differences in perfusion for multiple brain regions thought to be important in MDD, and (2) highlight the potential role of using perfusion as a biosignature of MDD.

Reward related ventral striatal activity and differential response to sertraline versus placebo in depressed individuals.

Medications to treat major depressive disorder (MDD) are not equally effective across patients. Given that neural response to rewards is altered in MDD and given that reward-related circuitry is modulated by dopamine and serotonin, we examined, for the first time, whether reward-related neural activity moderated response to sertraline, an antidepressant medication that targets these neurotransmitters. A total of 222 unmedicated adults with MDD randomized to receive sertraline (n = 110) or placebo (n = 112) in the Establishing Moderators and Biosignatures of Antidepressant Response in Clinical Care (EMBARC) study completed demographic and clinical assessments, and pretreatment functional magnetic resonance imaging while performing a reward task. We tested whether an index of reward system function in the ventral striatum (VS), a key reward circuitry region, moderated differential response to sertraline versus placebo, assessed with the Hamilton Rating Scale for Depression (HSRD) over 8 weeks. We observed a significant moderation effect of the reward index, reflecting the temporal dynamics of VS activity, on week-8 depression levels (Fs ≥ 9.67, ps ≤ 0.002). Specifically, VS responses that were abnormal with respect to predictions from reinforcement learning theory were associated with lower week-8 depression symptoms in the sertraline versus placebo arms. Thus, a more abnormal pattern of pretreatment VS dynamic response to reward expectancy (expected outcome value) and prediction error (difference between expected and actual outcome), likely reflecting serotonergic and dopaminergic deficits, was associated with better response to sertraline than placebo. Pretreatment measures of reward-related VS activity may serve as objective neural markers to advance efforts to personalize interventions by guiding individual-level choice of antidepressant treatment.

Baseline reward processing and ventrostriatal dopamine function are associated with pramipexole response in depression.

The efficacy of dopamine agonists in treating major depressive disorder has been hypothesized to stem from effects on ventrostriatal dopamine and reward function. However, an important question is whether dopamine agonists are most beneficial for patients with reward-based deficits. This study evaluated whether measures of reward processing and ventrostriatal dopamine function predicted response to the dopamine agonist, pramipexole (ClinicalTrials.gov Identifier: NCT02033369). Individuals with major depressive disorder (n = 26) and healthy controls (n = 26) (mean ± SD age = 26.5 ± 5.9; 50% female) first underwent assessments of reward learning behaviour and ventrostriatal prediction error signalling (measured using functional MRI). 11C-(+)-PHNO PET before and after oral amphetamine was used to assess ventrostriatal dopamine release. The depressed group then received open-label pramipexole treatment for 6 weeks (0.5 mg/day titrated to a maximum daily dose of 2.5 mg). Symptoms were assessed weekly, and reward learning was reassessed post-treatment. At baseline, relative to controls, the depressed group showed lower reward learning (P = 0.02), a trend towards blunted reward-related prediction error signals (P = 0.07), and a trend towards increased amphetamine-induced dopamine release (P = 0.07). Despite symptom improvements following pramipexole (Cohen's d ranging from 0.51 to 2.16 across symptom subscales), reward learning did not change after treatment. At a group level, baseline reward learning (P = 0.001) and prediction error signalling (P = 0.004) were both associated with symptom improvement, albeit in a direction opposite to initial predictions: patients with stronger pretreatment reward learning and reward-related prediction error signalling improved most. Baseline D2/3 receptor availability (P = 0.02) and dopamine release (P = 0.05) also predicted improvements in clinical functioning, with lower D2/3 receptor availability and lower dopamine release predicting greater improvements. Although these findings await replication, they suggest that measures of reward-related mesolimbic dopamine function may hold promise for identifying depressed individuals likely to respond favourably to dopaminergic pharmacotherapy.