Genetics and genomics of depression

Exploring the potential of drug repurposing for treating depression

Researchers are interested in drug repurposing or drug repositioning of existing pharmaceuticals because of rising costs and slower rates of new medication development. Other investigations that authorized these treatments used data from experimental research and off-label drug use. More research into the causes of depression could lead to more effective pharmaceutical repurposing efforts. In addition to the loss of neurotransmitters like serotonin and adrenaline, inflammation, inadequate blood flow, and neurotoxins are now thought to be plausible mechanisms. Because of these other mechanisms, repurposing drugs has resulted for treatment-resistant depression. This chapter focuses on therapeutic alternatives and their effectiveness in drug repositioning. Atypical antipsychotics, central nervous system stimulants, and neurotransmitter antagonists have investigated for possible repurposing. Nonetheless, extensive research is required to ensure their formulation, effectiveness, and regulatory compliance.

Identification of a strong genetic risk factor for major depressive disorder in the human virome

The heritability of major depressive disorder (MDD) is reportedly 30-50%. However, the genetic basis of its heritability remains unknown. Within SITH-1, a risk factor for MDD in human herpesvirus 6B (HHV-6B), we discovered a gene polymorphism with a large odds ratio for an association with MDD. It was a sequence whose number of repeats was inversely correlated with SITH-1 expression. This number was significantly lower in MDD patients. Rates for 17 or fewer repeats of the sequence were 67.9% for MDD and 28.6% for normal controls, with an odds ratio of 5.28. For patients with 17 or less repeats, the rate for presence of another MDD patient in their families was 47.4%, whereas there were no MDD patients in the families of patients with more than 17 repeats. Since HHV-6B is transmitted primarily mother to child and within families and persists for life, this gene polymorphism could potentially influence heritability of MDD.

Visual impairment and depression in China: a 7-year follow-up study from national longitudinal surveys

OBJECTIVES

To explore the longitudinal association between visual impairment (VI) and depression among adults 45 years and older in China based on a nationally representative follow-up dataset.

SETTING

Participants in China from the China Health and Retirement Longitudinal Study were included.

PARTICIPANTS

A total of 6748 participants from two waves of the China Health and Retirement Longitudinal Study 2011-2018 were included for analysis by age group.

PRIMARY AND SECONDARY OUTCOME MEASURES

VI and depression were defined by self-diagnosis and the Center for Epidemiological Studies Depression Scale-10, respectively. Lagged dependent variable regression models with ordinary least squares estimation were used to evaluate the association between VI and depression. Age was divided into three groups, that is, 45-54, 55-64, and 65 years and older, to explore the relationship between VI and depression in different age groups.

RESULTS

In our study sample, VI remarkably predicted an increase in depressive scores. The magnitude of depressive scores increased among those with VI points greater than 3.517 (β=3.517; 95% CI=2.697 to 4.331) points than those without VI in the 7-year follow-up. Significant relationships were also found between VI and depression in the three age groups in the sensitivity analysis.

CONCLUSION

VI was associated with an increase in depression scores over a 7-year period. Female respondents, low educational attainment and high alcohol intake significantly predicted an increase in depressive status.

Acute tryptophan depletion alters affective touch perception

RATIONALE

Affiliative tactile interactions help regulate physiological arousal and confer resilience to acute and chronic stress. C-tactile afferents (CTs) are a population of unmyelinated, low threshold mechanosensitive cutaneous nerve fibres which respond optimally to a low force stimulus, moving at between 1 and 10 cm/s. As CT firing frequencies correlate positively with subjective ratings of touch pleasantness, they are hypothesised to form the first stage of encoding affiliative tactile interactions. Serotonin is a key modulator of social responses with known effects on bonding.

OBJECTIVES

The aim of the present study was to determine the effect of acutely lowering central serotonin levels on perceptions of CT-targeted affective touch.

METHODS

In a double blind, placebo-controlled design, the effect of acute tryptophan depletion (ATD) on 25 female participants' ratings of directly and vicariously experienced touch was investigated. Psychophysical techniques were used to deliver dynamic tactile stimuli; some velocities were targeted to optimally activate CTs (1-10 cm/s), whereas other, faster and slower strokes fell outside the CT optimal range. Discriminative tactile function, cold pain threshold and tolerance were also measured.

RESULTS

ATD significantly increased pleasantness ratings of both directly and vicariously experienced affective touch, increasing discrimination of the specific hedonic value of CT targeted velocities. While ATD had no effect on either tactile or cold pain thresholds, there was a trend for reduced tolerance to cold pain.

CONCLUSIONS

These findings are consistent with previous reports that depletion of central serotonin levels modulates neural and behavioural responsiveness to appetitive sensory signals.

Effects of Acute Tryptophan Depletion on Human Taste Perception

Taste perception has been reported to vary with changes in affective state. Distortions of taste perception, including blunted recognition thresholds, intensity, and hedonic ratings have been identified in those suffering from depressive disorders. Serotonin is a key neurotransmitter implicated in the etiology of anxiety and depression; systemic and peripheral manipulations of serotonin signaling have previously been shown to modulate taste detection. However, the specific effects of central serotonin function on taste processing have not been widely investigated. Here, in a double-blind placebo-controlled study, acute tryptophan depletion was used to investigate the effect of reduced central serotonin function on taste perception. Twenty-five female participants aged 18-28 attended the laboratory on two occasions at least 1 week apart. On one visit, they received a tryptophan depleting drink and on the other, a control drink was administered. Approximately, 6 h after drink consumption, they completed a taste perception task which measured detection thresholds and supra-threshold perceptions of the intensity and pleasantness of four basic tastes (sweet, sour, bitter, and salt). While acutely reducing central levels of serotonin had no effect on the detection thresholds of sweet, bitter, or sour tastes, it significantly enhanced detection of salt. For supra-threshold stimuli, acutely reduced serotonin levels significantly enhanced the perceived intensity of both bitter and sour tastes and blunted pleasantness ratings of bitter quinine. These findings show manipulation of central serotonin levels can modulate taste perception and are consistent with previous reports that depletion of central serotonin levels enhances neural and behavioral responsiveness to aversive signals.

Predicting differential diagnosis between bipolar and unipolar depression with multiple kernel learning on multimodal structural neuroimaging

One of the greatest challenges in providing early effective treatment in mood disorders is the early differential diagnosis between major depression (MDD) and bipolar disorder (BD). A remarkable need exists to identify reliable biomarkers for these disorders. We integrate structural neuroimaging techniques (i.e. Tract-based Spatial Statistics, TBSS, and Voxel-based morphometry) in a multiple kernel learning procedure in order to define a predictive function of BD against MDD diagnosis in a sample of 148 patients. We achieved a balanced accuracy of 73.65% with a sensitivity for BD of 74.32% and specificity for MDD of 72.97%. Mass-univariates analyses showed reduced grey matter volume in right hippocampus, amygdala, parahippocampal, fusiform gyrus, insula, rolandic and frontal operculum and cerebellum, in BD compared to MDD. Volumes in these regions and in anterior cingulate cortex were also reduced in BD compared to healthy controls (n = 74). TBSS analyses revealed widespread significant effects of diagnosis on fractional anisotropy, axial, radial, and mean diffusivity in several white matter tracts, suggesting disruption of white matter microstructure in depressed patients compared to healthy controls, with worse pattern for MDD. To best of our knowledge, this is the first study combining grey matter and diffusion tensor imaging in predicting BD and MDD diagnosis. Our results prompt brain quantitative biomarkers and multiple kernel learning as promising tool for personalized treatment in mood disorders.

Defining Major Depressive Disorder Cohorts Using the EHR: Multiple Phenotypes Based on ICD-9 Codes and Medication Orders

Background

Major Depressive Disorder (MDD) is one of the most common mental illnesses and a leading cause of disability worldwide. Electronic Health Records (EHR) allow researchers to conduct unprecedented large-scale observational studies investigating MDD, its disease development and its interaction with other health outcomes. While there exist methods to classify patients as clear cases or controls, given specific data requirements, there are presently no simple, generalizable, and validated methods to classify an entire patient population into varying groups of depression likelihood and severity.

Methods

We have tested a simple, pragmatic electronic phenotype algorithm that classifies patients into one of five mutually exclusive, ordinal groups, varying in depression phenotype. Using data from an integrated health system on 278,026 patients from a 10-year study period we have tested the convergent validity of these constructs using measures of external validation, including patterns of psychiatric prescriptions, symptom severity, indicators of suicidality, comorbidity, mortality, health care utilization, and polygenic risk scores for MDD.

Results

We found consistent patterns of increasing morbidity and/or adverse outcomes across the five groups, providing evidence for convergent validity.

Limitations

The study population is from a single rural integrated health system which is predominantly white, possibly limiting its generalizability.

Conclusion

Our study provides initial evidence that a simple algorithm, generalizable to most EHR data sets, provides categories with meaningful face and convergent validity that can be used for stratification of an entire patient population.

Higher plasma leptin and lower C-peptide levels are associated with depression: A cross-sectional study

BACKGROUND

Depression is a seriously disabling public health problem with very high world-wide prevalence. This study examined cross-sectional association between depression and both inflammatory markers and laboratory data involved in metabolic disturbance among Japanese subjects.

METHODS

This cross-sectional study is a secondly analysis for the data of the Iwaki Health Promotion Project 2014 (1167 subjects). Plasma inflammatory markers and laboratory metabolic data involved were used. Center for Epidemiologic Studies Depression Scale (CES-D) was used to assess the prevalence and severity of depressive symptoms. Participants with CES-D scores ≥ 16 were assigned to the 'Depression' group (Group D). Differences between group Non-depression (ND) and D were estimated using χ² test or Fisher's exact test for categorical variables and Student's t-test or Mann-Whitney test for continuous variables. Multivariate logistic regression analysis was also used to identify characteristics, co-morbidities, conditions and laboratory data associated with depression after adjusting for possible confounding factors.

RESULTS

There were significant differences in sex, age, blood pressure, interleukin (IL)-6, fasting blood sugar (FBS), hemoglobin A1c (HbA1c), and cortisol level using univariate analysis between the two groups. However, multivariate logistic regression analysis indicated that lower age, lower C-peptide, and higher leptin were associated with the depression.

CONCLUSION

This study showed that higher plasma leptin and lower C-peptide levels were significantly associated with depressive symptoms. No significant association was found between plasma inflammatory markers and depressive symptoms after adjusting for possible confounding factors.

Evaluation of Serum Interleukin-6 and C-reactive Protein Levels in Drug-naïve Major Depressive Disorder Patients

Background Major depressive disorder (MDD) is a disabling health problem with a very high global prevalence and burden. Alteration of inflammatory markers in depression is of growing interest to many psychiatry researchers. This study aimed to examine the serum levels of interleukin-6 (IL-6) and C-reactive protein (CRP) in MDD patients to find out their association with depression. Materials and methods The present study recruited 88 MDD patients and 86 control subjects matched by age, gender, and body mass index (BMI). The Hamilton depression rating scale (Ham-D) was used on all patients to measure their severity of depression. Serum levels of IL-6 and CRP were analyzed by commercially available enzyme-linked immunosorbent assay (ELISA) kits (Abcam, Cambridge, MA, USA). Results The mean values of serum levels of IL-6 and CRP were 2.94 ± 0.12 pg/mL and 0.99 ± 0.02 mg/L for the patient group and 2.42 ± 0.21 pg/mL and 1.09 ± 0.06 mg/L for the control group, respectively. We found significantly elevated concentrations of serum IL-6 in MDD patients compared with control subjects (p < 0.001). However, the alteration of serum CRP levels was not significant between the groups (p = 0.126). Ham-D scores of patients were positively correlated with serum IL-6 (r = 0.552; p = 0.004) and CRP (r = 0.621; p < 0.001) levels. Moreover, serum IL-6 and CRP levels were observed to be positively correlated (r = 0.452; p = 0.043) with each other in depression. Conclusions The present study suggests that increased serum IL-6 level might be a contributing factor to the pathogenesis of depression.

Treatment of depression with Chai Hu Shu Gan San: a systematic review and meta-analysis of 42 randomized controlled trials

Background

Depression is a common mental disorder. Chai Hu Shu Gan San, a traditional Chinese medicine, is used to treat depression empirically. We present a systematic review and meta-analysis of the therapeutic efficacy and safety of Chai Hu Shu Gan San in treating depression.

Methods

Several databases, including PubMed, China National Knowledge Internet, Wanfang, Chongqing VIP, and the Cochrane library, were systematically searched from their date of foundation to January 1, 2017. In this review, wehave included randomized control trials that compared Chai Hu Shu Gan San (or its combination with a regular Western medicine) with a regular Western medicine alone for the treatment of depression. Two investigators independently extracted and analyzed the data using RevMan 5.2.0 software. Mean difference (with a 95% confidence interval) was used as efficacy indices for outcomes.

Results

We included 42 studies involving 3234 patients with depression in 15 different types of diseases. Meta analyses showed better effect of Chai Hu Shu Gan San than fluoxetine for pure depression (MD = − 1.59, from − 2.82 to − 0.37, 4 trials, I² = 26%), for post-stroke depression (MD = − 4.20, from − 6.20 to − 2.19, 7 trials, I² = 96%), and for postpartum depression (MD = − 4.10, from − 7.48 to − 0.72 7 trials, I² = 86%). None of the articles reported severe adverse events of oral administration of Chai Hu Shu Gan San. Furthermore, any adverse effects of using Chai Hu Shu Gan San alone were fewer than those of regular Western medicines.

Conclusions

This review found that Chai Hu Shu Gan San has some advantages in treating depression, especially post-stroke depression and post-partum depression. A meticulously designed and conducted randomized control trial is needed for further evaluation.

Neuropharmacological and neurochemical evaluation of N-n-propyl-3-ethoxyquinoxaline-2-carboxamide (6n): a novel serotonergic 5-HT3 receptor antagonist for co-morbid antidepressant- and anxiolytic-like potential using traumatic brain injury model in rats

BACKGROUND

Several preclinical studies have shown that serotonergic 5-HT3 receptor antagonists play an important role in the management of neuropsychiatric disorders, such as depression and anxiety. In the present study the compound "6n" (N-n-propyl-3-ethoxyquinoxaline-2-carboxamide), a novel 5-HT3 receptor antagonist with an optimal log P (2.52) and pA2 (7.6) value was screened for its neuro-pharmacological potential in chronic rodent models of depression and anxiety named traumatic brain injury (TBI).

METHODS

In this model, a 1 cm midline scalp incision was made, and the muscles were retracted to expose the skull. A stainless steel disc (10 mm in diameter and 3 mm in depth) was placed centrally between the lambda and bregma regions. The injury was induced using the impact acceleration model of TBI. Specifically, a 400 g metal weight was dropped from a height of 1 m guided by a straight pipe, onto the metal disc placed over the rat's skull.

RESULTS

The behavioral anomalies of the TBI rats were attenuated by the chronic treatment of compound 6n (1 and 2 mg/kg, p.o.; 14 days) as observed by the modified open field test (ambulation, rearing, and fecal pellet), sucrose consumption test (% sucrose consumption), elevated plus maze [% open arm entries [OAE] and % time spent in open arm (TSOA)], and marble burying test (numbers). In addition, 6n also increased the levels of neurotransmitters (norepinephrine and serotonin) and brain derived neurotrophic factor (BDNF) in TBI rats.

CONCLUSIONS

The result suggests that compound 6n exhibited antidepressant- and anxiolytic-like effects in rodent models of depression and anxiety.

The Association of Cigarette Smoking With Depression and Anxiety: A Systematic Review

BACKGROUND

Many studies report a positive association between smoking and mental illness. However, the literature remains mixed regarding the direction of this association. We therefore conducted a systematic review evaluating the association of smoking and depression and/or anxiety in longitudinal studies.

METHODS

Studies were identified by searching PubMed, Scopus, and Web of Science and were included if they: (1) used human participants, (2) were longitudinal, (3) reported primary data, (4) had smoking as an exposure and depression and/or anxiety as an outcome, or (5) had depression and/or anxiety as the exposure and smoking as an outcome.

RESULTS

Outcomes from 148 studies were categorized into: smoking onset, smoking status, smoking heaviness, tobacco dependence, and smoking trajectory. The results for each category varied substantially, with evidence for positive associations in both directions (smoking to later mental health and mental health to later smoking) as well as null findings. Overall, nearly half the studies reported that baseline depression/anxiety was associated with some type of later smoking behavior, while over a third found evidence that a smoking exposure was associated with later depression/anxiety. However, there were few studies directly supporting a bidirectional model of smoking and anxiety, and very few studies reporting null results.

CONCLUSIONS

The literature on the prospective association between smoking and depression and anxiety is inconsistent in terms of the direction of association most strongly supported. This suggests the need for future studies that employ different methodologies, such as Mendelian randomization (MR), which will allow us to draw stronger causal inferences.

IMPLICATIONS

We systematically reviewed longitudinal studies on the association of different aspects of smoking behavior with depression and anxiety. The results varied considerably, with evidence for smoking both associated with subsequent depression and anxiety, and vice versa. Few studies supported a bidirectional relationship, or reported null results, and no clear patterns by gender, ethnicity, clinical status, length to follow-up, or diagnostic test. Suggesting that despite advantages of longitudinal studies, they cannot alone provide strong evidence of causality. Therefore, future studies investigating this association should employ different methods allowing for stronger causal inferences to be made, such as MR.

Cognitive Deficits as a Mediator of Poor Occupational Function in Remitted Major Depressive Disorder Patients

Cognitive deficits in major depressive disorder (MDD) patients have been described in numerous studies. However, few reports have aimed to describe cognitive deficits in the remitted state of MDD and the mediational effect of cognitive deficits on occupational outcome. The aim of the current review is to synthesize the literature on the mediating and moderating effects of specific domains of cognition on occupational impairment among people with remitted MDD. In addition, predictors of cognitive deficits found to be vocationally important will be examined. Upon examination of the extant literature, attention, executive function and verbal memory are areas of consistent impairment in remitted MDD patients. Cognitive domains shown to have considerable impact on vocational functioning include deficits in memory, attention, learning and executive function. Factors that adversely affect cognitive function related to occupational accommodation include higher age, late age at onset, residual depressive symptoms, history of melancholic/psychotic depression, and physical/psychiatric comorbidity, whereas higher levels of education showed a protective effect against cognitive deficit. Cognitive deficits are a principal mediator of occupational impairment in remitted MDD patients. Therapeutic interventions specifically targeting cognitive deficits in MDD are needed, even in the remitted state, to improve functional recovery, especially in patients who have a higher risk of cognitive deficit.

Melanin-Concentrating Hormone (MCH): Role in REM Sleep and Depression

The melanin-concentrating hormone (MCH) is a peptidergic neuromodulator synthesized by neurons of the lateral sector of the posterior hypothalamus and zona incerta. MCHergic neurons project throughout the central nervous system, including areas such as the dorsal (DR) and median (MR) raphe nuclei, which are involved in the control of sleep and mood. Major Depression (MD) is a prevalent psychiatric disease diagnosed on the basis of symptomatic criteria such as sadness or melancholia, guilt, irritability, and anhedonia. A short REM sleep latency (i.e., the interval between sleep onset and the first REM sleep period), as well as an increase in the duration of REM sleep and the density of rapid-eye movements during this state, are considered important biological markers of depression. The fact that the greatest firing rate of MCHergic neurons occurs during REM sleep and that optogenetic stimulation of these neurons induces sleep, tends to indicate that MCH plays a critical role in the generation and maintenance of sleep, especially REM sleep. In addition, the acute microinjection of MCH into the DR promotes REM sleep, while immunoneutralization of this peptide within the DR decreases the time spent in this state. Moreover, microinjections of MCH into either the DR or MR promote a depressive-like behavior. In the DR, this effect is prevented by the systemic administration of antidepressant drugs (either fluoxetine or nortriptyline) and blocked by the intra-DR microinjection of a specific MCH receptor antagonist. Using electrophysiological and microdialysis techniques we demonstrated also that MCH decreases the activity of serotonergic DR neurons. Therefore, there are substantive experimental data suggesting that the MCHergic system plays a role in the control of REM sleep and, in addition, in the pathophysiology of depression. Consequently, in the present report, we summarize and evaluate the current data and hypotheses related to the role of MCH in REM sleep and MD.

Down-regulation of PRKCB1 expression in Han Chinese patients with subsyndromal symptomatic depression

BACKGROUND

Subsyndromal symptomatic depression (SSD) is a common disease with significant social dysfunction. However, SSD is still not well understood and the pathophysiology of it remains unclear.

METHODS

We classified 48 candidate genes for SSD according to our previous study into clusters and pathways using DAVID Bioinformatics Functional Annotation Tool. We further replicated the result by using real-time Quantitative PCR (qPCR) studies to examine the expression of identified genes (i.e., STAT5b, PKCB1, ABL1 and NRAS) in another group of Han Chinese patients with SSD (n = 50). We further validated the result by examining PRKCB1 expression collected from MDD patients (n = 20). To test whether a deficit in PRKCB1 expression leads to dysregulation in PRKCB1 dependent transcript networks, we tested mRNA expression levels for the remaining 44 genes out of 48 genes in SSD patients. Finally, the power of discovery was improved by incorporating information from Quantitative Trait (eQTL) analysis.

RESULTS

The results showed that the PRCKB1 gene expression in peripheral blood mononuclear cells (PBMC) was 33.3% down-regulated in SSD patients (n = 48, t = 3.202, p = 0.002), and a more dramatic (n = 17, 49%) down-regulation in MDD patients than control (n = 49, t = 2.114, p = 0.001). We also identified 37 genes that displayed a strong correlation with PRKCB1 mRNA expression levels in SSD patients. The expression of PRKCB1 was regulated by multiple single nucleotide polymorphisms (SNPs) both at the transcript level and exon level.

CONCLUSIONS

In conclusion, we first found a significant decrease of PRCKB1 mRNA expression in SSD, suggesting PRKCB1 might be the candidate gene and biomarker for SSD.

Associations of cannabis and cigarette use with depression and anxiety at age 18: findings from the Avon Longitudinal Study of Parents and Children

Introduction

Substance use is associated with common mental health disorders, but the causal effect of specific substances is uncertain. We investigate whether adolescent cannabis and cigarette use is associated with incident depression and anxiety, while attempting to account for confounding and reverse causation.

Methods

We used data from ALSPAC, a UK birth cohort study, to investigate associations between cannabis or cigarettes (measured at age 16) and depression or anxiety (measured at age 18), before and after adjustment for pre-birth, childhood and adolescent confounders. Our imputed sample size was 4561 participants.

Results

Both cannabis (unadjusted OR 1.50, 95% CI 1.26, 1.80) and cigarette use (OR 1.37, 95% CI 1.16, 1.61) increased the odds of developing depression. Adjustment for pre-birth and childhood confounders partly attenuated these relationships though strong evidence of association persisted for cannabis use. There was weak evidence of association for cannabis (fully adjusted OR 1.30, 95% CI 0.98, 1.72) and insufficient evidence for association for cigarette use (fully adjusted OR = 0.97, 95% CI 0.75, 1.24) after mutually adjusting for each other, or for alcohol or other substance use. Neither cannabis nor cigarette use were associated with anxiety after adjustment for pre-birth and childhood confounders.

Conclusions

Whilst evidence of association between cannabis use and depression persisted after adjusting for pre-term and childhood confounders, our results highlight the difficulties in trying to estimate and interpret independent effects of cannabis and tobacco on psychopathology. Complementary methods are required to robustly examine effects of cannabis and tobacco on psychopathology.

Shuganjieyu capsule increases neurotrophic factor expression in a rat model of depression

Shuganjieyu capsule has been approved for clinical treatment by the State Food and Drug Ad-ministration of China since 2008. In the clinic, Shuganjieyu capsule is often used to treat mild to moderate depression. In the rat model of depression established in this study, Shuganjieyu capsule was administered intragastrically daily before stress. Behavioral results confirmed that depressive symptoms lessened after treatment with high-dose (150 mg/kg) Shuganjieyu capsule. Immunohistochemistry results showed that high-dose Shuganjieyu capsule significantly increased phosphorylation levels of phosphorylation cyclic adenosine monophosphate response element binding protein and brain-derived neurotrophic factor expression in the medial prefrontal cortex and hippocampal CA3 area. Overall, our results suggest that in rats, Shuganjieyu capsule effec-tively reverses depressive-like behaviors by increasing expression levels of neurotrophic factors in the brain.

Amygdala-function perturbations in healthy mid-adolescents with familial liability for depression

OBJECTIVE

Functional magnetic resonance imaging (fMRI) studies have identified increased amygdala responses to negative stimuli as a risk marker of depression in adults, and as a state marker of depression in adults and adolescents. Hyperreactivity of the amygdala has been linked to negatively biased emotional processing in depression. However, no study has elucidated whether similar amygdala perturbations can be found in healthy mid-adolescents with familial liability for depression. We hypothesized that healthy 14-year-olds with relatives with depression would demonstrate increased amygdala responses to negative stimuli, as compared with their peers with no family history of mental disorders.

METHOD

We investigated a community-based sample of 164 typically developing 14-year-olds without record of past or current mental disorders. Of these individuals, 28 fulfilled criteria for family history of depression, and 136 served as controls. Groups did not differ with regard to cognitive ability, depressive symptomatology, and anxiety. During fMRI they performed a perceptual discrimination task in which visual target and distractor stimuli varied systematically with regard to emotional valence.

RESULTS

Both a hypothesis-driven region-of-interest analysis and a whole-brain analysis of variance revealed that negative distractors elicited greater amygdala activation in adolescents with a family history of depression compared to controls. Amygdala responses also differed during the processing of negative target stimuli, but effects were reversed.

CONCLUSION

Our study demonstrates that familial liability for depression is associated with correlates of negatively biased emotional processing in healthy adolescents. Amygdala perturbations during the processing of negative stimuli might reflect an early and subtle risk marker for depression.

Addiction science: Uncovering neurobiological complexity

Until very recently addiction-research was limited by existing tools and strategies that were inadequate for studying the inherent complexity at each of the different phenomenological levels. However, powerful new tools (e.g., optogenetics and designer drug receptors) and high throughput protocols are starting to give researchers the potential to systematically interrogate "all" genes, epigenetic marks, and neuronal circuits. These advances, combined with imaging technologies (both for preclinical and clinical studies) and a paradigm shift toward open access have spurred an unlimited growth of datasets transforming the way we investigate the neurobiology of substance use disorders (SUD) and the factors that modulate risk and resilience. This article is part of a Special Issue entitled 'NIDA 40th Anniversary Issue'.

Do we need pharmacogenetics to personalize antidepressant therapy?

This review examines the role of drug metabolism and drug target polymorphism in determining the clinical response to antidepressants. Even though antidepressants are the most effective available treatment for depressive disorders, there is still substantial need for improvement due to the slow onset of appreciable clinical improvement and the association with side effects. Moreover, a substantial group of patients receiving antidepressant therapy does not achieve remission or fails to respond entirely. Even if the large variation in antidepressant treatment outcome across individuals remains poorly understood, one possible source of this variation in treatment outcome are genetic differences. The review focuses on a few polymorphisms which have been extensively studied, while reporting a more comprehensive reference to the existing literature in table format. It is relatively easy to predict the effect of polymorphisms in drug metabolizing enzymes, such as cytochromes P450 2D6 (CYP2D6) and cytochrome P450 2C19 (CYP2C19), which may be determined in the clinical context in order to explain or prevent serious adverse effects. The role of target polymorphism, however, is much more difficult to establish and may be more relevant for disease susceptibility and presentation rather than for response to therapy.

Strain vulnerability and resiliency in the chick anxiety-depression model

Increasing research is focused on genetic contributions to variability in stress-related endophenotypes in humans and animal model simulations. The current study sought to identify strain vulnerabilities and resiliencies to an isolation-stressor in the chick anxiety-depression model. Nine different strains of socially raised chicks were tested in isolated or non-isolated conditions for 90 min in which distress vocalization (DVoc) rates were collected and then transformed to depression-like phase threshold (@ 25, 50, 75 and 95%) latencies. In general, chicks in the non-isolated condition displayed relatively low DVoc rates throughout the test session, despite some variability in initial rates. Chicks in the isolated condition displayed relatively high DVoc rates in the first 3 min, indicative of an anxiety-like state, which declined by approximately 50% within 10-25 min in all strains and remained stable thereafter, indicative of a depression-like state. Contrast effects revealed that, relative to all other strains, the Black Australorp strain displayed shorter and the Producrain displayed longer depression threshold latencies, respectively. Of the remaining strains, the Silver Laced Wyandotte displayed depression thresholds that best represent an intermediate stress response. These findings identify vulnerable and resilient strains for examining depression-related endophenotypes in the chick anxiety-depression model.

No interaction between serotonin transporter gene (5-HTTLPR) polymorphism and adversity on depression among Japanese children and adolescents

BACKGROUND

Identification of gene × environment interactions (G × E) for depression is a crucial step in ascertaining the mechanisms underpinning the disorder. Earlier studies have indicated strong genetic influences and numerous environmental risk factors. In relation to childhood and adolescent depression, evidence is accumulating that the quality of the parental environment is associated with serotonin biology in children. We hypothesized that maternal depression is a crucial environmental risk factor associated with serotonin-regulating genes.

METHODS

This study was designed to ascertain the G × E interaction for diagnosis of depression in a Japanese pediatric sample. DNA samples from 55 pediatric patients with depression and 58 healthy schoolchildren were genotyped for the 5-HTT (2 short (S) alleles at the 5-HTT locus) promoter serotonin-transporter-linked polymorphic region (5-HTTLPR) polymorphism. We examined whether an adverse parental environment, operationalized as the mother's history of recurrent major depressive disorder, interacts with 5-HTTLPR polymorphism to predict patients' depression symptoms.

RESULTS

Binary logistic regression analyses revealed that maternal depression (adversity), gender, and FSIQ significantly affect the diagnosis of depression among children and adolescents. However, no main effect was found for adversity or genotype. Results of multivariable logistic regression analyses using stepwise procedure have elicited some models with a good fit index, which also suggests no interaction between 5-HTTLPR and adversity on depression.

CONCLUSIONS

To assess G × E interaction, data obtained from children and adolescents who had been carefully diagnosed categorically and data from age-matched controls were analyzed using logistic regression. Despite an equivocal interaction effect, adversity and gender showed significant main effects.

Mainstreaming sex and gender analysis in public health genomics

BACKGROUND

The integration of genome-based knowledge into public health or public health genomics (PHG) aims to contribute to disease prevention, health promotion, and risk reduction associated with genetic disease susceptibility. Men and women differ, for instance, in susceptibilities for heart disease, obesity, or depression due to biologic (sex) and sociocultural (gender) factors and their interaction. Genome-based knowledge is rapidly increasing, but sex and gender issues are often not explored.

OBJECTIVE

To explore the implications of a sex and gender analysis for PHG.

METHODS

We explore genome-based knowledge in relation to sex and gender aspects using depression as an example, gender equality, and the intersection of sex and gender with other social stratifiers such as ethnic background or socioeconomic status.

RESULTS

We advocate a sex- and gender-sensitive genomics research agenda alongside studies that provide sex-disaggregated data rather than controls based on sex. Such a research agenda is needed to guide research on how genomics is understood and perceived by men and women across groups, and for the equitable and responsible translation of such knowledge into the public health domain.

CONCLUSIONS

Including sex and gender analysis in PHG research will not only shed more light on phenomena such as diseases with a higher prevalence in either men or women, but will ultimately lead to gendered innovations by way of exploring how gendered and cultural environments increase or safeguard genetic predispositions.

The serotonin transporter gene linked polymorphic region is associated with the behavioral response to repeated stress exposure in infant rhesus macaques

The short allele of the serotonin transporter linked polymorphic region (5-HTTLPR) moderates the effects of stress on vulnerability to mood and anxiety disorders. The mechanism by which this occurs may relate to differential sensitivity to stressful life events. Here we explored whether 5-HTTLPR and sex affected behavioral responses to repeated maternal separation in infant rhesus macaques. Behaviors were collected during the acute (Day 1) and the chronic (Days 2-4) phases of the separation, and the effects of duration of separation (acute vs. chronic), genotype (long/long vs. short allele), and sex (male vs. female) on behavioral responses were analyzed across four successive separations. Males increased their levels of locomotion with repeated maternal separation, whereas females exhibited an increase in frequency of self-directed behavior, a measure of "depression-like" behavior. The short-allele predicted increased environmental exploration, particularly during the chronic phase of social separation, indicative of higher arousal. In addition, the short-allele carriers were more likely to increase their levels of self-directed behavior during the chronic phase of separation, as a function of repeated exposures. These findings suggest that the short allele may increase reactivity to repeated, chronic stressors, leaving them more vulnerable to affective psychopathology, with females particularly vulnerable.

The WAG/Rij strain: a genetic animal model of absence epilepsy with comorbidity of depression [corrected]

A great number of clinical observations show a relationship between epilepsy and depression. Idiopathic generalized epilepsy, including absence epilepsy, has a genetic basis. The review provides evidence that WAG/Rij rats can be regarded as a valid genetic animal model of absence epilepsy with comorbidity of depression. WAG/Rij rats, originally developed as an animal model of human absence epilepsy, share many EEG and behavioral characteristics resembling absence epilepsy in humans, including the similarity of action of various antiepileptic drugs. Behavioral studies indicate that WAG/Rij rats exhibit depression-like symptoms: decreased investigative activity in the open field test, increased immobility in the forced swimming test, and decreased sucrose consumption and preference (anhedonia). In addition, WAG/Rij rats adopt passive strategies in stressful situations, express some cognitive disturbances (reduced long-term memory), helplessness, and submissiveness, inability to make choice and overcome obstacles, which are typical for depressed patients. Elevated anxiety is not a characteristic (specific) feature of WAG/Rij rats; it is a characteristic for only a sub-strain of WAG/Rij rats susceptible to audiogenic seizures. Interestingly, WAG/Rij rats display a hyper-response to amphetamine similar to anhedonic depressed patients. WAG/Rij rats are sensitive only to chronic, but not acute, antidepressant treatments, suggesting that WAG/Rij rats fulfill a criterion of predictive validity for a putative animal model of depression. However, more and different antidepressant drugs still await evaluation. Depression-like behavioral symptoms in WAG/Rij rats are evident at baseline conditions, not exclusively after stress. Experiments with foot-shock stress do not point towards higher stress sensitivity at both behavioral and hormonal levels. However, freezing behavior (coping deficits) and blunted response of 5HT in the frontal cortex to uncontrollable sound stress, increased c-fos expression in the terminal regions of the meso-cortico-limbic brain systems and greater DA response of the mesolimbic system to forced swim stress suggest that WAG/Rij rats are vulnerable to some, but not to all types of stressors. We propose that genetic absence epileptic WAG/Rij rats have behavioral depression-like symptoms, are vulnerable to stress and might represent a model of chronic low-grade depression (dysthymia). Both 5HT and DAergic abnormalities detected in the brain of WAG/Rij rats are involved in modulation of vulnerability to stress and provocation of behavioral depression-like symptoms. The same neurotransmitter systems modulate SWDs as well. Recent studies suggest that the occurrence and repetition of absence seizures are a precipitant of depression-like behavior. Whether the neurochemical changes are primary to depression-like behavioral alterations remains to be determined. In conclusion, the WAG/Rij rats can be considered as a genetic animal model for absence epilepsy with comorbidity of dysthymia. This model can be used to investigate etiology, pathogenic mechanisms and treatment of a psychiatric comorbidity, such as depression in absence epilepsy, to reveal putative genes contributing to comorbid depressive disorder, and to screen novel psychotropic drugs with a selective and/or complex (dual) action on both pathologies.

Addiction as a systems failure: focus on adolescence and smoking

OBJECTIVE

Scientific advances in the field of addiction have forever debunked the notion that addiction reflects a character flaw under voluntary control, demonstrating instead that it is a bona fide disease of the brain. The aim of this review is to go beyond this consensus understanding and explore the most current evidence regarding the vast number of genetic, developmental, and environmental factors whose complex interactions modulate addiction risk and trajectory.

METHOD

Focusing on childhood and adolescent smoking as a paradigm, we review the important risk factors for the development of addictions, starting at the level of genetics and closing with a focus on sociocultural and policy factors.

RESULTS

A critical review of the pertinent literature provides a detailed view of the cumulative power of risk and protection factors across different phenomenological levels to modulate the risk of undesirable outcomes, particularly for young people. The result represents a compelling argument for the need to engage in comprehensive, multilevel approaches to promoting health.

CONCLUSIONS

Today, the field of medicine understands more about disease than about health; however it need not be that way. The view of drug addiction as a systems failure should help refocus our general approach to developing dynamic models and early comprehensive interventions that optimize the ways in which we prevent and treat a complex, developmental disorder such as drug addiction.

Gene × environment vulnerability factors for PTSD: the HPA-axis

Post-traumatic stress disorder (PTSD) is a severely debilitating psychiatric condition. Although a lifetime trauma incidence of 40-90% has been reported in the general population, the overall lifetime prevalence for PTSD ranges between 7-12%, suggesting individual-specific differences towards the susceptibility to PTSD. While studies investigating main genetic effects associated with PTSD have yielded inconsistent findings, there is growing evidence supporting the role of gene-environment (G × E) interactions in PTSD. The hypothalamus pituitary adrenal (HPA) axis is one of the main systems activated after exposure to a trauma and perturbations in this system are one of the more consistent neurobiological abnormalities observed in PTSD. Genes regulating the HPA-axis are therefore interesting candidates for G × E studies in PTSD. This article will review the concept and initial results of G × E interactions with polymorphisms in these genes for PTSD. In addition, the use of alternate phenotypes and more complex interaction models such as G × G × E or G × E × E will be explored. Finally, putative molecular mechanisms for these interactions will be presented. The research presented in this article indicates that a combined analysis of environmental, genetic, endophenotype and epigenetic data will be necessary to better understand pathomechanisms in PTSD. This article is part of a Special Issue entitled 'Post-Traumatic Stress Disorder'.

The association between oxytocin receptor gene (OXTR) polymorphisms and affective temperaments, as measured by TEMPS-A

BACKGROUND

Oxytocin is associated with social interaction, trust, and affectivity. Affective temperaments are traits based on Kraepelin's typological definition of the "fundamental states" of manic-depressive illness. These states can be measured by the Temperament Evaluation of Memphis, Pisa, Paris and San Diego-Autoquestionnaire version (TEMPS-A). The objective of this study is to assess the association between oxytocin receptor gene (OXTR) polymorphisms and affective temperaments.

METHODS

Participants consisted of 493 genetically unrelated, non-clinical Japanese subjects (307 males and 186 females). The Mini-International Neuropsychiatric Interview (MINI) was used to screen and exclude those who had a lifetime diagnosis of schizophrenia or other psychotic disorders. Fifteen OXTR tag single nucleotide polymorphisms (SNPs) were genotyped using TaqMan® or direct sequencing. The Haploview 4.1. software determined the haplotype block structure. Haplotype-based quantitative trait association analysis with Bonferroni correction using PLINK 1.06 software was used to assess the association between haplotypes and the following affective temperaments: depressive, cyclothymic, hyperthymic, irritable, and anxious.

RESULTS

Two haplotype blocks were identified on the OXTR. The depressive temperament was significantly associated with the most frequent haplotype GGGTGTC (rs11131149/rs2243370/rs2243369/rs13316193/rs2254298/rs2268493/rs2268491) (corrected P<0.05).

LIMITATIONS

This study consisted of participants from a corporation and the effect sizes were small.

CONCLUSIONS

The findings suggest that an OXTR haplotype is associated with a discrete depressive temperament. Clarification of the biological basis of this temperamental trait may help to elucidate the pathophysiology of depressive disorder.

Life course perspectives on the epidemiology of depression

Life course epidemiology seeks to understand how determinants of health and disease interact across the span of a human life, and has made significant contributions to understanding etiological mechanisms in many chronic diseases, including schizophrenia. The life course approach is ideal for understanding depression: causation in depression appears to be multifactorial, including interactions between genes and stressful events, or between early life trauma and later stress in life; timing of onset and remission of depression varies widely, indicating differing trajectories of symptoms over long periods of time, with possible differing causes and differing outcomes; and early life events and development appear to be important risk factors for depression, including exposure to acute and chronic stress in the first years of life. To better understand etiology and outcome of depression, future research must move beyond basic epidemiologic techniques that link specific exposures to specific outcomes and embrace life course principles and methods. Time-sensitive modelling techniques that are able to incorporate multiple interacting factors across long periods of time, such as structural equation models, will be critical in understanding the complexity of causal and influencing factors from early development to the end stages of life. Using these models to identify key pathways that influence trajectories of depression across the life course will help guide prevention and intervention.

Use of genomic assessments and interventions in psychiatric nursing practice

The purpose of this study was to determine the impact of a genomic educational session by measuring participants' application of the class content to their nursing care. A sample of 65 psychiatric nurses participated in a staff development activity and completed a survey. Every respondent reported use of a genomic assessment or intervention with a patient from their clinical practice. The mean use of genomic assessment and intervention items was 5.5 out of the possible 10 which were identified and described in the educational session, providing evidence that nurses are able to include genomic assessments and interventions when caring for a patient with a psychiatric disorder.

Cognitive functioning in patients with affective disorders and schizophrenia: a meta-analysis

There is considerable evidence for cognitive dysfunction in schizophrenia and affective disorders, but the pattern of potential similarities or differences between diagnostic groups remains uncertain. The objective of this study was to conduct a quantitative review of studies on cognitive performance in schizophrenia and affective disorders. Relevant articles were identified through literature search in major databases for the period between January 1980 and December 2005. Meta-analytic treatment of the original studies revealed widespread cognitive deficits in patients with schizophrenia and affective disorders in intellectual ability and speed of information processing, in encoding and retrieval, rule discovery and in response generation and response inhibition. Differences between diagnostic groups were quantitative rather than qualitative.

Variations in tryptophan hydroxylase 2 linked to decreased serotonergic activity are associated with elevated risk for metabolic syndrome in depression

Major depression and the metabolic syndrome (MetS) are interacting clinical conditions influenced by genetic susceptibility. For both disorders, impaired serotonergic neurotransmission in specific brain areas has been suggested. This led us to investigate whether variants in the gene coding for tryptophan hydroxylase 2 (TPH2), the brain-specific and rate-limiting enzyme for serotonin biosynthesis, might be predictive for an increased liability for the development of MetS in depressed patients. In a case-control study consisting of 988 patients with recurrent unipolar depression (RUD) and 1023 psychiatric healthy controls, MetS components were ascertained according to the International Diabetes Foundation criteria. A total of 41 single nucleotide polymorphisms fully covering the TPH2 gene region were genotyped in stage 1 (300 patients/300 controls), resulting in significant genetic associations of polymorphisms located in exon 7 and intron 8 of TPH2 and the occurrence of MetS in depressed patients after correction for age, gender and multiple testing (51 RUD-MetS/179 RUD-non-MetS). We were able to confirm the significant association of rs17110690 in stage 2 (688 patients/723 controls; 110 RUD-MetS/549 RUD-non-MetS) and to link risk-genotypes and risk-haplotypes for MetS to lower TPH2 mRNA expression and to lower 5-hydroxyindoleacetic acid levels in cerebrospinal fluid previously reported in functional studies. Our findings suggest that TPH2 polymorphisms characterize a subgroup of depressed patients who are especially prone to develop metabolic disorders induced by a genotype-dependent impairment of serotonergic neurotransmission. Identifying depressed patients at high risk for MetS using genetic variants could have direct clinical impact on individualized disease management and prevention strategies.

Assessing the neuronal serotonergic target-based antidepressant stratagem: impact of in vivo interaction studies and knockout models

Depression remains a challenge in the field of affective neuroscience, despite a steady research progress. Six out of nine basic antidepressant mechanisms rely on serotonin neurotransmitter system. Preclinical studies have demonstrated the significance of serotonin receptors (5-HT_1-3,6,7), its signal transduction pathways and classical down stream targets (including neurotrophins, neurokinins, other peptides and their receptors) in antidepressant drug action. Serotonergic control of depression embraces the recent molecular requirements such as influence on proliferation, neurogenesis, plasticity, synaptic (re)modeling and transmission in the central nervous system. The present progress report analyses the credibility of each protein as therapeutically relevant target of depression. In vivo interaction studies and knockout models which identified these targets are foreseen to unearth new ligands and help them transform to drug candidates. The importance of the antidepressant assay selection at the preclinical level using salient animal models/assay systems is discussed. Such test batteries would definitely provide antidepressants with faster onset, efficacy in resistant (and co-morbid) types and with least adverse effects. Apart from the selective ligands, only those molecules which bring an overall harmony, by virtue of their affinities to various receptor subtypes, could qualify as effective antidepressants. Synchronised modulation of various serotonergic sub-pathways is the basis for a unique and balanced antidepressant profile, as that of fluoxetine (most exploited antidepressant) and such a profile may be considered as a template for the upcoming antidepressants. In conclusion, 5-HT based multi-targeted antidepressant drug discovery supported by in vivo interaction studies and knockout models is advocated as a strategy to provide classic molecules for clinical trials.

Hostility and depressive mood: results from the Whitehall II prospective cohort study

BACKGROUND

The psychosocial vulnerability model of hostility posits that hostile individuals, given their oppositional attitudes and behaviours, are more likely to have increased interpersonal conflicts, lower social support, more stressful life events (SL-E) and higher likelihood of depression. However, little research has tested this hypothesis using large-scale prospective samples. The present study aims to assess the predictive value of hostility for depressive mood.

METHOD

Data are from 3399 participants in the Whitehall II cohort study, aged 35-55 years at baseline (phase 1 1985-1988). Cynical hostility was measured at phase 1. Depressive mood was assessed at phase 7 (2002-2004). Sociodemographic characteristics, health-related behaviours, common mental disorders and antidepressant medication intake were assessed at phase 1. SL-E and confiding/emotional support were measured at phases 1, 2 (1989-1990) and 5 (1997-1999).

RESULTS

Compared with participants in the lowest quartile of cynical hostility, those in the highest quartiles were more likely to have depressive mood [second quartile: odds ratio (OR) 1.58, 95% confidence interval (CI) 1.14-2.20; third quartile: OR 2.78, 95% CI 2.03-3.77; fourth quartile: OR 4.66, 95% CI 3.41-6.36] in analysis adjusted for sociodemographic characteristics. This graded association was somewhat attenuated (18%) but remained robust to adjustments for the covariates measured at baseline and follow-up. The association was also evident in participants free of mental health difficulties at baseline.

CONCLUSIONS

Cynical hostility is a strong and robust predictor of depressive mood. Consideration of personality characteristics may be crucial to the understanding and management of depression.

Oxytocin receptor polymorphisms and adult attachment style in patients with depression

Much evidence of an association between specific attachment styles and depression prompted us to investigate, in depressive disorders, the potential role of polymorphisms within the gene encoding the receptor of the main neurohormone involved in attachment processes, oxytocin. For this purpose, two single nucleotide polymorphisms (SNPs), 6930G>A (rs53576) and 9073G>A (rs2254298), within the oxytocin receptor gene (OXTR), were studied in a cohort of 185 patients with major depression (50.3%) or bipolar I or II disorders (49.7%) and 192 matched healthy controls. A positive association between the GG genotype of OXTR SNPs (6930G>A or 9073G>A) and unipolar depression was demonstrated. In this group, GG individuals showed high scores on Attachment Style Questionnaire factors that have been previously associated with depression. Moreover, the GG genotype was also associated with high levels of adult separation anxiety. These findings support the involvement of the oxytocinergic system in the mechanisms that underlie depression and specific adult attachment styles.

Depression and antidepressants: molecular and cellular aspects

Clinical depression is viewed as a physical and psychic disease process having a neuropathological basis, although a clear understanding of its ethiopathology is still missing. The observation that depressive symptoms are influenced by pharmacological manipulation of monoamines led to the hypothesis that depression results from reduced availability or functional deficiency of monoaminergic transmitters in some cerebral regions. However, there are limitations to current monoamine theories related to mood disorders. Recently, a growing body of experimental data has showed that other classes of endogenous compounds, such as neuropeptides and amino acids, may play a significant role in the pathophysiology of affective disorders. With the development of neuroscience, neuronal networks and intracellular pathways have been identified and characterized, describing the existence of the interaction between monoamines and receptors in turn able to modulate the expression of intracellular proteins and neurotrophic factors, suggesting that depression/antidepressants may be intermingled with neurogenesis/neurodegenerative processes.

Fetal effects of psychoactive drugs

Psychoactive drug use by pregnant women has the potential to effect fetal development; the effects are often thought to be drug-specific and gestational age dependent. This article describes the effects of three drugs with similar molecular targets that involve monoaminergic transmitter systems: cocaine, methamphetamine, and selective serotonin re-uptake inhibitors (SSRIs) used to treat maternal depression during pregnancy. We propose a possible common epigenetic mechanism for their potential effects on the developing child. We suggest that exposure to these substances acts as a stressor that affects fetal programming, disrupts fetal placental monoamine transporter expression and alters neuroendocrine and neurotransmitter system development. We also discuss neurobehavioral techniques that may be useful in the early detection of the effects of in utero drug exposure.

Spike-wave discharges are necessary for the expression of behavioral depression-like symptoms

PURPOSE

The WAG/Rij strain of rats, a well-established model for absence epilepsy, has comorbidity for depression. These rats exhibit depression-like behavioral symptoms such as increased immobility in the forced swimming test and decreased sucrose intake and preference (anhedonia). These depression-like behavioral symptoms are evident in WAG/Rij rats, both at 3-4 and 5-6 months of age, with a tendency to aggravate in parallel with an increase in seizure duration. Here we investigated whether the behavioral symptoms of depression could be prevented by the suppression of absence seizures.

METHODS

Ethosuximide (ETX; 300 mg/kg/day, in the drinking water) was chronically applied to WAG/Rij rats from postnatal day 21 until 5 months. Behavioral tests were done before the cessation of the treatment. Electroencephalography (EEG) recordings were made before and after cessation of treatment to measure seizure severity at serial time-points.

RESULTS

ETX-treated WAG/Rij rats exhibited no symptoms of depression-like behavior in contrast to untreated WAG/Rij rats of the same age. Moreover, treated WAG/Rij rats did not differ from control age-matched Wistar rats. ETX treatment led to almost complete suppression of spike-wave discharges (SWDs) in 5-6 month old WAG/Rij rats. Discontinuation of chronic treatment was accompanied by a gradual emergence of SWDs; however, a persistent reduction in seizure activity was still present 47 days after discontinuation of the chronic treatment.

DISCUSSION

The results suggest that seizure activity is necessary for the expression of depression-like behavioral symptoms and confirm that epileptogenesis can be prevented by early and chronic treatment.

Association of depressive phenotype with affective family history is mediated by affective temperaments

Increasing data support an association of cyclothymic temperament with bipolarity, but our knowledge about the relationship of affective temperaments (ATs) to depressive symptoms based on inheritance in a non-clinical population is limited. The aim of this article was to demonstrate how ATs and affective family history relate to the depressive symptoms in a general population. Subjects comprised 501 Hungarian adults who completed a background questionnaire, the TEMPS-A, the Zung Self-Rating Depression Scale (ZSDS) and the depression subscale of the Brief Symptom Inventory (BSI-D). Stepwise linear regression was performed to analyse the role of ATs and affective family history (AFH(0) and AFH(1)) in the variance of ZSDS and BSI-D scores. Cyclothymic, depressive and anxious temperaments have a significant role in the explained variance of depression scores, and they are all significantly related to AFH(1). Significant differences were found between AFH(1) and AFH(0) groups in ZSDS and BSI-D scores, and these effects were eliminated if ATs were entered as covariates. The probability of having any dominant temperament was more than two-fold in group AFH(1) compared with AFH(0) (OR=2.33). Our results suggest that a crucial part of inherited factors of depression is mediated by affective temperaments.

Candidate region linkage analysis in twins discordant or concordant for depression symptomatology

Genetic risk factors contribute considerably to both clinical affective disorders and subsyndromal mood level. There is moreover evidence to suggest that the genetic basis of bipolar disorder and unipolar depression overlap to some extent, and several linkage analyses have suggested evidence for a common susceptibility locus in affective disorders on chromosome 12q24. In this study we investigated the chromosome 12 candidate region for linkage to the mean level of depression symptomatology, over a 10-year follow-up, using a highly informative sample of concordant and discordant twin pairs selected from 4,731 participants of the Longitudinal Study of Ageing Danish Twins. Our results showed suggestive evidence of linkage to this region with a peak LOD score of 1.91 for marker D12S1634 located at 148 cM, and thus indicates that the previously identified disease locus at 12q24 is also a general vulnerability locus affecting the normal range of mood.

Dysbindin gene (DTNBP1) in major depression: association with clinical response to selective serotonin reuptake inhibitors

BACKGROUND

Dysbindin gene (dystrobrevin-binding-protein 1, DTNBP1) variants have been associated with several psychiatric conditions including mood disorders and antidepressant efficacy. We investigated dysbindin gene (DTNBP1) variants in major depression and clinical response to selective serotonin reuptake inhibitors.

METHODS

In this study we investigated the role of DTNBP1 gene (rs3213207, rs2005976, rs760761 and rs2619522) in 313 major depressive outpatients and 149 healthy individuals. One hundred and forty-seven depressive patients were treated with citalopram and evaluated for response (4th week) and remission (12th week) by the 1-item Hamilton Depression Rating Scale. Single nucleotide polymorphisms (SNPs) were assayed by using Applied Biosystems TaqMan technology.

RESULTS

Genotype and haplotype frequencies for four SNPs within DTNBP1 gene did not significantly differ between patients and controls. Allele distribution of SNP rs760761, however, showed a trend of difference between responders and nonresponders (4th week). Haplotype analyses produced a significant association with response to treatment at week 4. No differences were found in remission (12th week).

DISCUSSION

DTNBP seems to have an effect on short-term clinical response to citalopram. New studies focused on other genes involved in glutamatergic neurotransmission and related proteins could help to elucidate the complex mechanism of clinical response to antidepressants.

Genetic variability at HPA axis in major depression and clinical response to antidepressant treatment

BACKGROUND

Dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis has been observed in major depression. Normalization of HPA axis has been suggested to play a role in the mechanisms of action of antidepressants. Our aim was to investigate the influence of genetic variants in CRHR1, CRHR2, CRH-BP and FKBP5 genes on both the vulnerability for depression and the response to antidepressant treatment.

METHODS

The sample consisted of 159 depressive outpatients and 96 healthy controls of Spanish origin. Patients were assessed for clinical features including, among others, age of onset, seasonality or suicidal behavior. The episode was treated with citalopram and followed along 12 weeks. Severity of symptoms was evaluated at the inclusion and then monthly along the follow-up using a 21-item Hamilton Depression Rating Score (HDRS). SNPs were assayed using Applied Biosystems SNaP-Shot and TaqMan technology.

RESULTS

rs110402, in CRHR1 gene, was associated with an increased risk to present a seasonal pattern and an early age of onset of the first depressive episode. Allele G carriers of rs2270007 of CRHR2 gene, showed a worse overall response to citalopram along time of follow-up (Genotype effect F=7.45, P=0.007). G allele carriers showed 2.93 increased risk (95% CI [1.24-6.90]) for non-responding at 4th week to citalopram treatment (chi(2)=7.59, df=1, P=0.006).

LIMITATIONS

On the light of the moderate sample size, associations based on the mentioned polymorphisms need to be considered with caution and require further replication studies in other samples.

CONCLUSIONS

Variability at genes encoding proteins with a pivotal role in HPA axis regulation seems to influence i) the expression of severity variables of the depressive spectrum including early age of onset or a seasonal pattern and ii) the interindividual variation in clinical response to SSRI antidepressants.

Association between the recombinant human serotonin transporter linked promoter region polymorphism and behavior in rhesus macaques during a separation paradigm

Human studies have suggested an association between a variable length polymorphism in the serotonin transporter gene promoter region and vulnerability to anxiety and depression. Relative to the long (l) allele, the short (s) allele increases the risk of developing depression in individuals exposed to stressful life events. An orthologue of the human variant is present in rhesus macaques and allows for studies in animals exposed to stress. Here, we used an established model of early life stress exposure, in which rhesus macaques are raised without adults in a group of peers (peer-only reared [PR]), or with their mothers. At 6 months of age, animals were subjected to 4-day long social separations for 4 consecutive weeks, with 3 days of reunion in between. Data were collected during both the acute (Day 1) and chronic phases (Days 2–4) of separation. Behavioral factors were separately extracted for each phase of separation. For acute separation, the behavioral factors generated were despair and behavioral pathology and, for the chronic phase despair, agitation, and behavioral pathology. During both phases of social separation, PR l/s animals were more likely to exhibit pathological behaviors, whereas PR l/l monkeys show higher levels of despair compared to the other three groups. These findings indicate that early stress affects the behavioral response to separation differently as a function of recombinant human serotonin transporter linked polymorphic repeat genotype and suggest that carriers of the s allele are not only more anxious but may also be more vulnerable to developing behavioral pathology in the face of chronic adversity.

A biopsychosocial model as a guide for psychoeducation and treatment of depression

Effective treatment of severe or chronic unipolar depression requires the combination of pharmacological and psychotherapeutic interventions, and demands a theoretical paradigm integrating biological and psychosocial aspects of depression. Supported by recent research, we propose in our article a biopsychosocial diathesis-stress model of depression. Its basic aim is psychoeducational: to provide therapists, patients, and their environment a constructive conceptual framework to understand depressive complaints, vulnerability, and stress. The core of the model consists of the concept of psychobiological vulnerability, which is determined by risk factors-of a biogenetic, psychological, somatic, and societal nature-and by protective factors. Life events with an idiosyncratic, stress-inducing value interact with this vulnerability, triggering severe or chronic distress that affects the individual's resilience and leads to symptoms of depression. The pathogenesis of depression is symbolized by a negative downward loop, in which interactions among symptoms, vulnerability, and stressors drive the patient toward a depressive condition. Moreover, experiencing recurrent depression influences psychobiological vulnerability, the occurrence of stressors, and tremendously increases the risk of further relapse. The model stresses the self-evident integration of biological and psychological therapeutic interventions that need to focus on symptom reduction and on relapse prevention. Moreover, it offers the patient and therapist a psychoeducational context in which the individual's vulnerability and depressive symptoms can be treated. Finally, applications of the depression model as a therapeutic approach to severe depression in the phases of remoralization, symptom reduction, and relapse prevention are presented.

The genetic background to PTSD

Although extensive research has already been done on the genetic bases of psychiatric disorders, little is known about polygenetic influences in posttraumatic stress disorder (PTSD). This article reviews molecular genetic studies relating to PTSD that were found in a literature search in Medline, Embase and Web of Science. Association studies have investigated 8 major genotypes in connection with PTSD. They have tested hypotheses involving key candidate genes in the serotonin (5-HTT), dopamine (DRD2, DAT), glucocorticoid (GR), GABA (GABRB), apolipoprotein systems (APOE2), brain-derived neurotrophic factor (BDNF) and neuropeptide Y (NPY). The studies have produced inconsistent results, many of which may be attributable to methodological shortcomings and insufficient statistical power. The complex aetiology of PTSD, for which experiencing a traumatic event forms a necessary condition, makes it difficult to identify specific genes that substantially contribute to the disorder. Gene-finding strategies are difficult to apply. Interactions between different genes and between them and the environment probably make certain people vulnerable to developing PTSD. Gene-environmental studies are needed that focus more narrowly on specific, distinct endophenotypes and on influences from environmental factors.

Genetics of obesity and the prediction of risk for health

Obesity has always existed in human populations, but until very recently was comparatively rare. The availability of abundant, energy-rich processed foods in the last few decades has, however, resulted in a sharp rise in the prevalence of obesity in westernized countries. Although it is the obesogenic environment that has resulted in this major healthcare problem, it is acting by revealing a sub-population with a pre-existing genetic predisposition to excess adiposity. There is substantial evidence for the heritability of obesity, and research in both rare and common forms of obesity has identified genes with significant roles in its aetiology. Application of this understanding to patient care has been slower. Until very recently, the health risks of obesity were thought to be well understood, with a straightforward correlation between increasing obesity and increasing risk of health problems such as type 2 diabetes, coronary heart disease, hypertension, arthritis and cancer. It is becoming clear, however, that the location of fat deposition, variation in the secretion of adipokines and other factors govern whether a particular obese person develops such complications. Prediction of the health risks of obesity for individual patients is not straightforward, but continuing advances in understanding of genetic factors influencing obesity risk and improved diagnostic technologies mean that the future for such prediction is looking increasingly bright.