Identification of expression quantitative trait loci associated with schizophrenia and affective disorders in normal brain tissue

Schizophrenia and the affective disorders, here comprising bipolar disorder and major depressive disorder, are psychiatric illnesses that lead to significant morbidity and mortality worldwide. Whilst understanding of their pathobiology remains limited, large case-control studies have recently identified single nucleotide polymorphisms (SNPs) associated with these disorders. However, discerning the functional effects of these SNPs has been difficult as the associated causal genes are unknown. Here we evaluated whether schizophrenia and affective disorder associated-SNPs are correlated with gene expression within human brain tissue. Specifically, to identify expression quantitative trait loci (eQTLs), we leveraged disorder-associated SNPs identified from 11 genome-wide association studies with gene expression levels in post-mortem, neurologically-normal tissue from two independent human brain tissue expression datasets (UK Brain Expression Consortium (UKBEC) and Genotype-Tissue Expression (GTEx)). Utilizing stringent multi-region meta-analyses, we identified 2,224 cis-eQTLs associated with expression of 40 genes, including 11 non-coding RNAs. One cis-eQTL, rs16969968, results in a functionally disruptive missense mutation in CHRNA5, a schizophrenia-implicated gene. Importantly, comparing across tissues, we find that blood eQTLs capture < 10% of brain cis-eQTLs. Contrastingly, > 30% of brain-associated eQTLs are significant in tibial nerve. This study identifies putatively causal genes whose expression in region-specific tissue may contribute to the risk of schizophrenia and affective disorders.

Vulnerabilities in sequencing and task switching in healthy youth offspring of parents with mood disorders

INTRODUCTION

Visuospatial processing and task switching are impaired in individuals with mood disorders. It is unknown whether early deficits are present before mood symptom on set or are related to risk for a specific type of mood disorder. To investigate, we compared visual attention and task switching during sequencing among never-disordered youth with parental family histories of bipolar (BD) and major depressive disorders (MDD) and healthy controls (HC) with no personal or family history of psychopathology.

METHOD

8-17-year-old youth of parents with BD (n = 31, "BD-risk"), youth of parents with MDD (n = 49, "MDD-risk"), and demographically similar HC (n = 31, "HC") were examined using the Delis-Kaplan Executive Functioning System Trail Making Test. Seed-based resting-state functional connectivity (RSFC) was collected from a subset of 88 participants (25 BD-risk, 37 MDD-risk, 26 HC) to investigate group differences in RSFC related to visuospatial processing.

RESULTS

BD-risk and MDD-risk offspring had impaired sequencing and task switching, demonstrated by reduced scores on visual scanning, F(2, 108) = 4.12, p = .02, number sequencing, F(2, 88) = 4.75, p = .01, letter sequencing, F(2, 108) = 4.24, p = .02, and number-letter sequencing, F(2, 108) = 4.66, p = .01, compared to scores in HC. RSFC between the posterior cingulate (PCC) and clusters in the subcallosal cortex, amygdala, and hippocampus significantly differed among HC, BD-risk, and MDD-risk groups. PCC-subcallosal/limbic RSFC was positively coupled in the MDD-risk and BD-risk groups and negatively coupled in HCs.

CONCLUSIONS

Youth at familial risk for mood disorders demonstrate visuospatial deficits early in the processing stream. Improved methods for identifying at-risk children with the earliest possible neurocognitive impairments may inform remediation strategies that could prevent mood disorders.

Factorial structure and familial aggregation of the Hypomania Checklist-32 (HCL-32): Results of the NIMH Family Study of Affective Spectrum Disorders

BACKGROUND

There is substantial evidence that bipolar disorder (BD) manifests on a spectrum rather than as a categorical condition. Detection of people with subthreshold manifestations of BD is therefore important. The Hypomania Checklist-32 (HCL-32) was developed as a tool to identify such people.

PURPOSE

The aims of this paper were to: (1) investigate the factor structure of HCL-32; (2) determine whether the HCL-32 can discriminate between mood disorder subtypes; and (3) assess the familial aggregation and cross-aggregation of hypomanic symptoms assessed on the HCL with BD.

PROCEDURES

Ninety-six probands recruited from the community and 154 of their adult first-degree relatives completed the HCL-32. Diagnosis was based on semi-structured interviews and family history reports. Explanatory factor analysis and mixed effects linear regression models were used.

FINDINGS

A four-factor ("Activity/Increased energy," "Distractibility/Irritability", "Novelty seeking/Disinhibition, "Substance use") solution fit the HCL-32, explaining 11.1% of the total variance. The Distractibility/Irritability score was elevated among those with BP-I and BP-II, compared to those with depression and no mood disorders. Higher HCL-32 scores were associated with increased risk of BD-I (OR = 1.22, 95%CI 1.14-1.30). The "Distractibility/Irritability" score was transmitted within families (β = 0.15, p = 0.040). However, there was no familial cross-aggregation between mood disorders and the 4 HCL factors.

CONCLUSIONS

Our findings suggest that the HCL-32 discriminates the mood disorder subtypes, is familial and may provide a dimensional index of propensity to BD. Future studies should explore the heritability of symptoms, rather than focusing on diagnoses.

Affective Disturbances During Withdrawal from Chronic Intermittent Ethanol Inhalation in C57BL/6J and DBA/2J Male Mice

BACKGROUND

Alcohol use disorders are characterized by a complex behavioral symptomatology, which includes the loss of control over alcohol consumption and the emergence of a negative affective state when alcohol is not consumed. Some of these symptoms can be recapitulated in rodent models, for instance following chronic intermittent ethanol (EtOH; CIE) vapor inhalation. However, the detection of negative affect in mice withdrawn from CIE has proven challenging and variable between strains. This study aimed to detect reliable indices of negative emotionality in CIE-exposed C57BL/6J (C57) and DBA/2J (DBA) mice. Males were used because they are known to escalate their voluntary EtOH consumption upon CIE exposure, which is hypothesized to be driven by negative reinforcement (relief from negative affect).

METHODS

Adult male mice were exposed to 4 to 6 weeks of CIE and were evaluated 3 to 10 days into withdrawal in the social approach, novelty-suppressed feeding, digging, marble burying, and bottle brush tests.

RESULTS

Withdrawal from CIE decreased sociability in DBA mice but not in C57 mice. Conversely, hyponeophagia was exacerbated by CIE in C57 mice but not in DBA mice. Withdrawal from CIE robustly increased digging activity in both strains, even in the absence of marbles. Aggressive responses to bottle brush attacks were elevated in both C57 and DBA mice following CIE exposure, but CIE had an opposite effect on defensive responses in the 2 strains (increase in C57 vs. decrease in DBA).

CONCLUSIONS

Our results indicate that withdrawal from CIE elicits negative emotionality in both C57 and DBA mice, but different tests need to be used to measure the anxiogenic-like effects of withdrawal in each strain. Increased digging activity and irritability-like behavior represent novel indices of affective dysfunction associated with withdrawal from CIE in both mouse strains. Our findings enrich the characterization of the affective symptomatology of protracted withdrawal from CIE in mice.

Risk for affective disorders is associated with greater prefrontal gray matter volumes: A prospective longitudinal study

Background

Major depression and bipolar disorders aggregates in families and are linked with a wide range of neurobiological abnormalities including cortical gray matter (GM) alterations. Prospective studies of individuals at familial risk may expose the neural mechanisms underlying risk transmission.

Methods

We used voxel based morphometry to investigate changes in regional GM brain volume, over a seven-year period, in 37 initially healthy individuals having a mono- or di-zygotic twin diagnosed with major depression or bipolar disorder (high-risk group; mean age 41.6 yrs.) as compared to 36 individuals with no history of affective disorders in the index twin and first-degree relatives (low-risk group; mean age 38.5 yrs.).

Results

Groups did not differ in regional GM volume changes over time. However, independent of time, high-risk twins had significantly greater GM volumes in bilateral dorsal anterior cingulate, inferior frontal gyrus and temporoparietal regions as compared to low-risk twins. Further, individuals who developed an affective disorder at follow-up (n = 12), had relatively the largest GM volumes, both at baseline and follow-up, in the right dorsal anterior cingulate cortex and right inferior frontal cortex compared to high- and low-risk twins who remained well at follow-up.

Conclusion

This pattern of apparently stable grater regional GM volume may constitute a neural marker of an increased risk for developing an affective disorder in individuals at familial risk.

Environmental perturbation of the circadian clock during pregnancy leads to transgenerational mood disorder-like behaviors in mice

It remains unknown whether chronic circadian disturbance (CCD) during pregnancy can lead to mood disorders in the offspring. Here we show that pregnant mice in the F0 generation that were exposed to CCD stress displayed depression-like behaviors, and produced offspring in the F1 and F2 generations that also exhibited mood-associated behavioral phenotypes despite the lack of direct stressful experiences during their postnatal or adult period. Prenatal CCD stress was correlated with the elevation of plasma corticosterone levels in F1 mice. Furthermore, the diurnal expression profiles of core circadian clock genes were disrupted in the suprachiasmatic nucleus of F1 mice. Proteomics analysis revealed that prenatal CCD stress resulted in distinct changes in protein expression in the hypothalamus of female F1 mice, in particular proteins that were associated with cellular activities, metabolism, development and diseases. Sex-specific differences in melanocortin 4 receptor expression were apparent in the CCD F1 generation. We conclude that maternal exposure to chronic circadian disturbance during pregnancy can lead to sex-specific mood disorders that persist for at least two filial generations. The underlying mechanisms may depend on transgenerational changes in plasma corticosterone levels, circadian pacemaking, and hypothalamic protein expression.

The effects of optimism, religion, and hope on mood and anxiety disorders in women with the FMR1 premutation

BACKGROUND

The FMR1 premutation, caused by a CGG trinucleotide repeat expansion on the FMR1 gene, has been identified as a genetic risk factor for mood and anxiety disorders. Building on recent studies identifying increased risk for mood and affective disorders in this population, we examined effects of potential protective factors (optimism, religion, hope) on depression and anxiety diagnoses in a prospective, longitudinal cohort.

METHODS

Eighty-three women with the FMR1 premutation participated in the Structured Clinical Interview for DSM-IV-TR Disorders at two-time points, 3 years apart. Participants also completed measures of optimism, religion, personal faith, hope, and child and family characteristics. We used logistic regression to examine correlates of major depressive disorder (MDD) and anxiety disorders at the initial assessment, as well as predictors of the diagnostic course over time.

RESULTS

Lower optimism and higher religious participation relevant to fragile X syndrome at the initial assessment were associated with a lifetime history of MDD. Lower optimism also predicted the occurrence and reoccurrence of an anxiety disorder 3 years later.

CONCLUSIONS

In women with the FMR1 premutation, elevated optimism may reduce the occurrence or severity of MDD and anxiety disorders. These findings underscore the importance of supporting mental health across the FMR1 spectrum of involvement.

Neurocognitive performance as an endophenotype for mood disorder subgroups

BACKGROUND

There is growing evidence that neurocognitive function may be an endophenotype for mood disorders. The goal of this study is to examine the specificity and familiality of neurocognitive functioning across the full range of mood disorder subgroups, including Bipolar I (BP-I), Bipolar II (BP-II), Major Depressive Disorders (MDD), and controls in a community-based family study.

METHODS

A total of 310 participants from 137 families with mood spectrum disorders (n=151) and controls (n=159) completed the University of Pennsylvania's Computerized Neurocognitive Battery (CNB) that assessed the accuracy and speed of task performance across five domains. Mixed effects regression models tested association and familiality.

RESULTS

Compared to those without mood disorders, participants with BP-I had increased accuracy in complex cognition, while participants with MDD were more accurate in emotion recognition. There was also a significant familial association for accuracy of complex cognition. Mood disorder subgroups did not differ in performance speed in any of the domains.

LIMITATIONS

The small number of BP-I cases, and family size limited the statistical power of these analyses, and the cross-sectional assessment of neurocognitive function precluded our ability to determine whether performance precedes or post dates onset of disorder.

CONCLUSIONS

This is one of the few community-based family studies of potential neurocognitive endophenotypes that includes the full range of mood disorder subgroups. There were few differences in neurocognitive function except enhanced accuracy in specific domains among those with BP-I and MDD. The differential findings across specific mood disorder subgroups substantiate their heterogeneity in other biologic and endophenotypic domains.

Social defeat disrupts reward learning and potentiates striatal nociceptin/orphanin FQ mRNA in rats

RATIONALE

Mood disorders can be triggered by stress and are characterized by deficits in reward processing, including disrupted reward learning (the ability to modulate behavior according to past rewards). Reward learning is regulated by the anterior cingulate cortex (ACC) and striatal circuits, both of which are implicated in the pathophysiology of mood disorders.

OBJECTIVES

Here, we assessed in rats the effects of a potent stressor (social defeat) on reward learning and gene expression in the ACC, ventral tegmental area (VTA), and striatum.

METHODS

Adult male Wistar rats were trained on an operant probabilistic reward task (PRT) and then exposed to 3 days of social defeat before assessment of reward learning. After testing, the ACC, VTA, and striatum were dissected, and expression of genes previously implicated in stress was assessed.

RESULT

Social defeat blunted reward learning (manifested as reduced response bias toward a more frequently rewarded stimulus) and was associated with increased nociceptin/orphanin FQ (N/OFQ) peptide mRNA levels in the striatum and decreased Fos mRNA levels in the VTA. Moreover, N/OFQ peptide and nociceptin receptor mRNA levels in the ACC, VTA and striatum were inversely related to reward learning.

CONCLUSIONS

The behavioral findings parallel previous data in humans, suggesting that stress similarly disrupts reward learning in both species. Increased striatal N/OFQ mRNA in stressed rats characterized by impaired reward learning is consistent with accumulating evidence that antagonism of nociceptin receptors, which bind N/OFQ, has antidepressant-like effects. These results raise the possibility that nociceptin systems represent a molecular substrate through which stress produces reward learning deficits in mood disorders.

Chronotype and sleep quality as a subphenotype in association studies of clock genes in mood disorders

Genetic background and clinical picture of mood disorders (MD) are complex and may depend on many genes and their potential interactions as well as environmental factors. Therefore, clinical variations, or endophenotypes, were suggested for association studies. The aim of the study was to investigate association between the chronotype (CH) and quality of sleep characteristics with polymorphisms CLOCK, ARNTL, TIMELESS and PER3 genes in MD. We included a total sample of 111 inpatients and 126 healthy controls. To assess CH we applied Morningness-Eveningness Questionnaire (MEQ). Additionally, we defined the quality and patterns of sleep using The Pittsburgh Sleep Quality Index (PSQI) and Epworth Sleepiness Scale (ESS). We applied Kruskal-Wallis test to determine associations. The main positive findings refer to associations between selected polymorphisms and: 1) chronotype with the ARNTL gene (rs11824092 and rs1481892) and the CLOCK (rs1268271) 2) sleep duration with the CLOCK gene (rs3805148) and the TIM gene (rs2291739) 3) daytime dysfunction with the PER3 gene (rs228727, rs228642, rs10864315) 4) subjective sleep quality with the ARNTL gene (rs11824092, rs1982350) 5) sleep disturbances with the ARNTL gene (rs11600996) We also found the significant epistatic interactions between polymorphism of the PER3 gene (rs2640909) & the CLOCK gene (rs11932595) and following sleep quality variables: sleep duration, habitual sleep efficiency and subjective sleep quality. The present study suggests a putative role of the analyzed clock genes polymorphisms in chronotype in the control group and in sleep quality disturbances in the course of MD. The results indicate that PSQI variables can be used to refine phenotype in association studies of clock genes in MD.

Risk. Impact of having a first-degree relative with affective disorder: a 7-year follow-up study

This study investigated a high-risk sample in order to elucidate risk factors for affective disorder. Healthy monozygotic (MZ) and dizygotic (DZ) twins with and without a co-twin with a history of affective disorder were identified through nationwide registers. Two risk groups were identified: the high-risk group comprised twins at risk of developing affective disorder (DZ or MZ twin; index co-twin affected); the low risk group (control group) comprised twins at low risk of developing affective disorder (DZ or MZ twin; index co-twin not affected). At baseline 234 participants were divided into groups according to their risk for affective disorder; they were followed up at 6-month intervals with posted questionnaires assessing depression. After a mean follow-up period of 7 years, the participants were invited to participate in an individual interview. A total of 36 participants (31 high-risk twins and 5 low-risk twins) developed a psychiatric disorder during the 7-year follow-up period: 24 developed mood disorder (67%), 7 anxiety disorder (19%) and 5 (14%) substance abuse, schizophrenia or personality disorder.   The results showed that familial risk, impaired stress tolerance and discrete cognitive dysfunction seem to be core predictors of affective illness. It is possible to identify a cluster of prodromal symptoms encompassing subclinical anxiety and depressive symptoms, higher neuroticism and cognitive problems. The cognitive problems may further be related to the cross-sectional finding that high-risk twins had lower hippocampal volumes. Further, 2 genetic polymorphisms: the 5-HTTLPR and the brain-derived neurotrophic factor (BDNF) Val66Met polymorphisms were not directly associated with familial risk for affective disorder and did not predict illness onset. Similarly, salivary cortisol levels and whole-blood BDNF levels did not predict subsequent illness. The more complex 2-way interactions between 5-HTTLPR and life events suggested that high-risk individuals and individuals carrying the short s allele are exposed to more stressors and that this seems to contribute to an overall enhanced risk and thus accelerate the onset of illness. Low-risk individuals seem to experience fewer life events and may exhibit resilience to their adverse psychological effects. Overall, having a 1st-degree relative with affective disorder matters. This thesis demonstrates that high-risk studies are informative, allowing observation and investigation of the pathological processes that occur prior to the onset of illness. There is a lack of prospective intervention studies assessing psychopathology in well-defined, high-risk samples and it is obvious that future research must transcend diagnostic boundaries in order to have an impact on prevention. Furthermore, there is a need to move beyond the notion of ''magic bullets'', instead developing an integrated paradigm encompassing clusters of biomarkers related to behavioural measures of developmental psychopathology. Finally, as most psychiatric treatment developed to date target end-state disorders, the identification of high-risk individuals and mapping of individual risk profiles should be a priority in order to facilitate early treatment and prevention.

Genetic predisposition for high stress reactivity amplifies effects of early-life adversity

A dysregulation of the hypothalamus-pituitary-adrenocortical (HPA) axis and the experience of early-life adversity are both well-established risk factors for the development of affective disorders, such as major depression. However, little is known about the interaction of these two factors in shaping endophenotypes of the disease. Here, we studied the gene-environment interaction of a genetic predisposition for HPA axis dysregulation with early-life stress (ELS), assessing the short-, as well as the long-lasting consequences on emotional behavior, neuroendocrine functions and gene expression profiles. Three mouse lines, selectively bred for either high (HR), intermediate (IR), or low (LR) HPA axis reactivity, were exposed to one week of ELS using the limited nesting and bedding material paradigm. Measurements collected during or shortly after the ELS period showed that, regardless of genetic background, ELS exposure led to impaired weight gain and altered the animals' coping behavior under stressful conditions. However, only HR mice additionally showed significant changes in neuroendocrine stress responsiveness at a young age. Accordingly, adult HR mice also showed lasting consequences of ELS, including hyperactive stress-coping, HPA axis hyperreactivity, and gene expression changes in the Crh system, as well as downregulation of Fkbp5 in relevant brain regions. We suggest that the genetic predisposition for high stress reactivity interacts with ELS exposure by disturbing the suppression of corticosterone release during a critical period of brain development, thus exerting lasting programming effects on the HPA axis, presumably via epigenetic mechanisms. In concert, these changes lead to the emergence of important endophenotypes associated with affective disorders.

A Functional Vesicular Monoamine Transporter 1 (VMAT1) Gene Variant Is Associated with Affect and the Prevalence of Anxiety, Affective, and Alcohol Use Disorders in a Longitudinal Population-Representative Birth Cohort Study

BACKGROUND

Inter-individual differences in the monoaminergic systems have been shown to moderate the risk for a lifetime history of anxiety, affective, and alcohol use disorders. A common single nucleotide polymorphism in the vesicular monoamine transporter 1 gene (VMAT1 rs1390938 G/A; Thr136Ile) has been reported as functional in vitro and associated with bipolar disorder and anxiety. We aimed at assessing the association between the VMAT1 genotype, affect, and affect-related psychiatric disorders in a longitudinal population-representative study.

METHODS

We used the database of the Estonian Children Personality Behaviour and Health Study (beginning in 1998). Cohorts of initially 9- (recalled at ages 15 and 18 years, n=579) and 15- (recalled at ages 18 and 25 years; n=654) year-old children provided self-reports on impulsivity, anxiety, depressiveness, neuroticism, and alcohol use. In addition, psychiatric assessment based on DSM-IV was carried out in the older cohort at age 25 years.

RESULTS

Subjects homozygous for the less prevalent A (136Ile) allele reported lower maladaptive impulsivity, state and trait anxiety, depressiveness, and neuroticism and were less likely to have been diagnosed with an affective, anxiety, and/or alcohol use disorder by young adulthood. While in the younger cohort alcohol use started at younger age, this birth cohort effect was dependent on genotype: only G allele carriers and in particular the GG homozygotes started alcohol use earlier.

CONCLUSIONS

VMAT1 rs1390938/Thr136Ile is associated with mood, personality, and alcohol use in the general population. Subjects homozygous for the "hyperfunction" allele (AA; Ile/Ile) appear to be more resilient to these disorders.

Distress During Pregnancy: Epigenetic Regulation of Placenta Glucocorticoid-Related Genes and Fetal Neurobehavior

OBJECTIVE

Increased risk of psychopathology is observed in children exposed to maternal prenatal distress, and elevated maternal cortisol and epigenetic regulation of placental glucocorticoid-pathway genes are potential mechanisms. The authors examined maternal distress and salivary cortisol in relation to fetal movement and heart rate ("coupling") and DNA methylation of three glucocorticoid pathway genes-HSD11B2, NR3C1, and FKBP5-in term placentas.

METHOD

Mood questionnaires and salivary cortisol were collected from 61 women between 24-27 gestational weeks, and fetal assessment was conducted at 34-37 weeks. Placental CpG methylation in the three genes was analyzed using 450K Beadchips and bisulfite sequencing; correlations between maternal and fetal variables and DNA methylation were tested; and maternal distress effects on fetal behavior via DNA methylation were investigated.

RESULTS

Perceived stress (Perceived Stress Scale), but not cortisol, was associated with altered CpG methylation in placentas. In the highest tertile of the Perceived Stress Scale, the Beadchip data revealed modestly elevated methylation of HSD11B2, associated with lower fetal coupling (β=-0.51), and modestly elevated methylation of FKBP5, also with lower fetal coupling (β=-0.47). These increases in methylation were validated by bisulfite sequencing, where they occurred in a minority of clones.

CONCLUSIONS

This is the first study to link the effects of pregnant women's distress on the fetus and epigenetic changes in placental genes. Since increased DNA methylation in HSD11B2 and FKBP5 are seen in a minority of bisulfite sequencing clones, these epigenetic changes, and functional consequences, may affect subpopulations of placental cells.

GAD2 Alternative Transcripts in the Human Prefrontal Cortex, and in Schizophrenia and Affective Disorders

Genetic variation and early adverse environmental events work together to increase risk for schizophrenia. γ-aminobutyric acid (GABA), the major inhibitory neurotransmitter in adult mammalian brain, plays a major role in normal brain development, and has been strongly implicated in the pathobiology of schizophrenia. GABA synthesis is controlled by two glutamic acid decarboxylase (GAD) genes, GAD1 and GAD2, both of which produce a number of alternative transcripts. Genetic variants in the GAD1 gene are associated with increased risk for schizophrenia, and reduced expression of its major transcript in the human dorsolateral prefrontal cortex (DLPFC). No consistent changes in GAD2 expression have been found in brains from patients with schizophrenia. In this work, with the use of RNA sequencing and PCR technologies, we confirmed and tracked the expression of an alternative truncated transcript of GAD2 (ENST00000428517) in human control DLPFC homogenates across lifespan besides the well-known full length transcript of GAD2. In addition, using quantitative RT-PCR, expression of GAD2 full length and truncated transcripts were measured in the DLPFC of patients with schizophrenia, bipolar disorder and major depression. The expression of GAD2 full length transcript is decreased in the DLPFC of schizophrenia and bipolar disorder patients, while GAD2 truncated transcript is increased in bipolar disorder patients but decreased in schizophrenia patients. Moreover, the patients with schizophrenia with completed suicide or positive nicotine exposure showed significantly higher expression of GAD2 full length transcript. Alternative transcripts of GAD2 may be important in the growth and development of GABA-synthesizing neurons as well as abnormal GABA signaling in the DLPFC of patients with schizophrenia and affective disorders.

Combining Psychodynamic Psychotherapy and Pharmacotherapy

Many patients with depression, anxiety disorders, and other psychiatric disorders are treated with combinations of psychodynamic psychotherapy and medication. Whether this is better than monotherapy is an empirical question that requires much more extensive research than is currently available. When medications were first introduced to treat psychiatric illnesses, some psychopharmacologists insisted that it heralded a new area of "biological psychiatry" that would ultimately render psychotherapy obsolete. Psychodynamic theorists and practitioners, on the other hand, argued that psychopharmacology offered only a superficial approach to treatment. Fortunately, these battles are now largely supplanted by the belief that whatever treatment offers the patient the best outcome should be employed, regardless of the therapist's theoretical outlook. This should motivate more extensive study of the value of combination treatment. So far, the few studies that have been done suggest that the combination of psychodynamic psychotherapy and medication may be superior for the treatment of mood and anxiety disorders, but most of these studies have small sample sizes and involve only short-term psychotherapy. An examination of the neuroscience of mood and anxiety disorders and of the mechanism of action of psychodynamic psychotherapy and of antidepressant medication suggests several routes by which the two treatment modalities could be synergistic: stimulation of hippocampal neurogenesis; epigenetic regulation of gene expression; dendritic remodeling; enhanced prefrontal cortical control of limbic system activity; and action at specific neurohormonal and neurotransmitter targets. The evidence for each of these mechanisms is reviewed with an eye toward potential experiments that might be relevant to them.

SLC6A15, a novel stress vulnerability candidate, modulates anxiety and depressive-like behavior: involvement of the glutamatergic system

Major depression is a multifactorial disease, involving both environmental and genetic risk factors. Recently, SLC6A15 - a neutral amino acid transporter mainly expressed in neurons - was proposed as a new candidate gene for major depression and stress vulnerability. Risk allele carriers for a single nucleotide polymorphism (SNP) in a SLC6A15 regulatory region display altered hippocampal volume, glutamate levels, and hypothalamus-pituitary-adrenal axis activity, all markers associated with major depression. Despite this genetic link between SLC6A15 and depression, its functional role with regard to the development and maintenance of depressive disorder is still unclear. The aim of the current study was therefore to characterize the role of mouse slc6a15 in modulating brain function and behavior, especially in relation to stress as a key risk factor for the development of mood disorders. We investigated the effects of slc6a15 manipulation using two mouse models, a conventional slc6a15 knock-out mouse line (SLC-KO) and a virus-mediated hippocampal slc6a15 overexpression (SLC-OE) model. Mice were tested under basal conditions and following chronic social stress. We found that SLC-KO animals displayed a similar behavioral profile to wild-type littermates (SLC-WT) under basal conditions. Interestingly, following chronic social stress SLC-KO animals showed lower levels of anxiety- and depressive-like behavior compared to stressed WT littermates. In support of these findings, SLC-OE animals displayed increased anxiety-like behavior already under basal condition. We also provide evidence that GluR1 expression in the dentate gyrus, but not GluR2 or NR1, are regulated by slc6a15 expression, and may contribute to the difference in stress responsiveness observed between SLC-KO and SLC-WT animals. Taken together, our data demonstrate that slc6a15 plays a role in modulating emotional behavior, possibly mediated by its impact on glutamatergic neurotransmission.

Direct, indirect and pleiotropic effects of candidate genes on internalizing disorder psychopathology

BACKGROUND

Twin studies of internalizing disorders suggest that their high co-morbidity is partially explained by shared genetic risk. Few studies have investigated pleiotropic effects of well-validated candidate genes across phenotypes.

METHOD

Subjects were 928 Caucasian patients who presented to an out-patient clinic specializing in the assessment and treatment of anxiety and mood disorders. We constructed latent dimensional phenotypes across the internalizing spectrum (neuroticism, extraversion, depression, generalized anxiety, panic/agoraphobia, social phobia, post-traumatic stress, and obsessions-compulsions) by combining diagnostic criteria with other clinical indicators. We selected multiple variants in four evidence-based candidate genes (SLC6A4, COMT, GAD1, RGS2) with previously reported effects on several of these phenotypes. We conducted genetic association testing of their direct and indirect effects as well as gene × stress interactions (G × E).

RESULTS

We detected 19 nominally significant main effect associations for the 10 polymorphisms tested among the eight phenotypes (24%). These were generally phenotype non-specific, showing pleiotropic effects across multiple domains. The majority of observed sharing was between depression, panic disorder, and post-traumatic stress disorder. Some of these were best explained by mediational models in which genes increase liability for disorders indirectly via their effects on temperament. Limited G × E effects were detected between variants in SLC6A4 and both panic/agoraphobia and post-traumatic stress.

CONCLUSIONS

Examining just a few candidate genes for their potential roles in internalizing phenotypes, we found moderate support for the shared effects of several polymorphisms. These findings highlight the richness and complexity by which genes potentially contribute to psychopathology via pleiotropy, moderation by stress, and mediation by temperament.

Explore the Features of Brain-Derived Neurotrophic Factor in Mood Disorders

Objectives

Brain-derived neurotrophic factor (BDNF) plays important roles in neuronal survival and differentiation; however, the effects of BDNF on mood disorders remain unclear. We investigated BDNF from the perspective of various aspects of systems biology, including its molecular evolution, genomic studies, protein functions, and pathway analysis.

Methods

We conducted analyses examining sequences, multiple alignments, phylogenetic trees and positive selection across 12 species and several human populations. We summarized the results of previous genomic and functional studies of pro-BDNF and mature-BDNF (m-BDNF) found in a literature review. We identified proteins that interact with BDNF and performed pathway-based analysis using large genome-wide association (GWA) datasets obtained for mood disorders.

Results

BDNF is encoded by a highly conserved gene. The chordate BDNF genes exhibit an average of 75% identity with the human gene, while vertebrate orthologues are 85.9%-100% identical to human BDNF. No signs of recent positive selection were found. Associations between BDNF and mood disorders were not significant in most of the genomic studies (e.g., linkage, association, gene expression, GWA), while relationships between serum/plasma BDNF level and mood disorders were consistently reported. Pro-BDNF is important in the response to stress; the literature review suggests the necessity of studying both pro- and m-BDNF with regard to mood disorders. In addition to conventional pathway analysis, we further considered proteins that interact with BDNF (I-Genes) and identified several biological pathways involved with BDNF or I-Genes to be significantly associated with mood disorders.

Conclusions

Systematically examining the features and biological pathways of BDNF may provide opportunities to deepen our understanding of the mechanisms underlying mood disorders.

Characteristics of Bipolar I patients grouped by externalizing disorders

BACKGROUND

Bipolar disorder co-occurs with a number of disorders with externalizing features. The aim of this study is to determine whether Bipolar I (BPI) subjects with comorbid externalizing disorders and a subgroup with externalizing symptoms prior to age 15 have different clinical features than those without externalizing disorders and whether these could be attributed to specific genetic variations.

METHODS

A large cohort (N=2505) of Bipolar I subjects was analyzed. Course of illness parameters were compared between an Externalizing Group, an Early-Onset Subgroup and a Non-Externalizing Group in the Discovery sample (N=1268). Findings were validated using an independent set of 1237 BPI subjects (Validation sample). Genetic analyses were carried out.

RESULTS

Subjects in the Externalizing Group (and Early-Onset Subgroup) tended to have a more severe clinical course, even in areas specifically related to mood disorder such as cycling frequency and rapid mood switching. Regression analysis showed that the differences are not completely explainable by substance use. Genetic analyses identified nominally associated SNPs; calcium channel genes were not enriched in the gene variants identified.

LIMITATIONS

Validation in independent samples is needed to confirm the genetic findings in the present study.

CONCLUSIONS

Our findings support the presence of an externalizing disorder subphenotype within BPI with greater severity of mood disorder and possible specific genetic features.

The ups and downs of modelling mood disorders in rodents

The wide spectrum of disruptions that characterizes major depressive disorder (MDD) and bipolar disorder (BD) highlights the difficulties researchers are posed with as they try to mimic these disorders in the laboratory. Nonetheless, numerous attempts have been made to create rodent models of mood disorders or at least models of the symptoms of MDD and BD. Present antidepressants are all descendants of the serendipitous findings in the 1950s that the monoamine oxidase inhibitor iproniazid and the tricyclic antidepressant imipramine were effective antidepressants. Thus, the need for improved animal models to provide insights into the neuropathology underlying the disease is critical. Such information is in turn crucial for identifying new antidepressants and mood stabilisers. Currently, there is a shift away from traditional animal models to more focused research dealing with an endophenotype-style approach, genetic models, and incorporation of new findings from human neuroimaging and genetic studies. Such approaches are opening up more tractable avenues for understanding the neurobiological and genetic bases of these disorders. Further, such models promise to yield better translational animal models and hence more fruitful therapeutic targets. This overview focuses on such animal models and tests and how they can be used to assess MDD and BD in rodents.

Psychiatric genetics and the primary prevention of psychiatric disorders

The role of genetic factors in the etiology of psychiatric disorders is one that has been long debated. Three 'families' of psychiatric disorders--which 'run' in families--have been observed: the schizophrenias, the affective disorders, and the St. Louis 'family of disorders' which includes antisocial personality, alcoholism, Briquet's syndrome and the hyperactive child syndrome. Such familial clustering could obviously occur on the basis of genetic transmission or on the basis of social learning within the family. Beginning in the 1960's, a number of adoption studies have been conducted. These studies permit an assessment of the relative contributions of genetic and environmental factors to the disorders mentioned above. This paper briefly reviews the strategy of these studies and the results they have obtained. An awareness of these studies and their results is essential to those concerned with the primary prevention of psychiatric disorders.

STin2 VNTR polymorphism is associated with comorbid tobacco use and mood disorders

BACKGROUND

There is a significant comorbidity between mood disorders and tobacco use disorder (TUD), which may be related to both genetic and environmental factors. Gene variants of the 5-HT transporter, such as STin2 VNTR (a variable number of tandem repeats in the functional serotonin transporter intron 2) may be associated with mood disorders and TUD.

AIMS

This study aimed to delineate the association between the STin2 genetic polymorphism and comorbid TUD and mood disorders, including depression or bipolar disorder.

METHODS

We examined the STin2 VNTR polymorphism in never-smokers (n=113); patients with mood disorders without TUD (n=62); patients with TUD without mood disorders (n=90); and patients with both disorders (n=95).

RESULTS

We found a significant association between the STin2 genetic polymorphism and the above diagnostic groups whereby the STin2.12 allele shows a positive association with comorbid TUD and mood disorders (Odds ratio=3.07, 95% CI=1.41-6.68), while the STin2.10/10 homozygous genotype shows a negative association (Odds ratio=0.34, 95% CI=0.16-0.74). Adjusting for years of education, age, gender, marital status and ethnicity did not change these results, but showed that TUD was associated with lower education levels and less stable relationships, whereas mood disorders were related to female gender. A family history of TUD was significantly associated with TUD in subjects without mood disorders only.

CONCLUSIONS

The STin2.12 allele is positively and the STin2.10/10 genotype is negatively associated with comorbid TUD and mood disorders, depression or bipolar depression, suggesting that biological endophenotypes, e.g. disorders in serotonin metabolism, may in part underpin this comorbidity.

Influencing circadian and sleep-wake regulation for prevention and intervention in mood and anxiety disorders: what makes a good homeostat?

All living organisms depend on homeostasis, the complex set of interacting metabolic chemical reactions for maintaining life and well-being. This is no less true for psychiatric well-being than for physical well-being. Indeed, a focus on homeostasis forces us to see how inextricably linked mental and physical well-being are. This paper focuses on these linkages. In particular, it addresses the ways in which understanding of disturbed homeostasis may aid in creating classes of patients with mood and anxiety disorders based on such phenotypes. At the cellular level, we may be able to compensate for the inability to study living brain tissue through the study of homeostatic mechanisms in fibroblasts, pluripotent human cells, and mitochondria and determine how homeostasis is disturbed at the level of these peripheral tissues through exogenous stress. We also emphasize the remarkable opportunities for enhancing knowledge in this area that are offered by advances in technology. The study of human behavior, especially when combined with our greatly improved capacity to study unique but isolated populations, offers particularly clear windows into the relationships among genetic, environmental, and behavioral contributions to homeostasis.