Serotonin transporter gene, childhood emotional abuse and cognitive vulnerability to depression

Gender-specific associations between types of childhood maltreatment and major depressive disorder: A matched case-control study

INTRODUCTION

Major depressive disorder (MDD) has been found to be nearly twice as prevalent in females as in males. One hypothesis proposed that abused females were particularly prone to MDD. We aim to examine the sex-specific associations between various types of childhood trauma and MDD.

METHODS

In this study, 290 outpatients diagnosed with MDD were recruited from Beijing Anding Hospital, and 290 healthy volunteers were recruited from neighborhoods nearby the hospital, with sex, age, and family history matched. Childhood Trauma Questionnaire-Short Form (CTQ-SF) developed by Bernstein et al. was used to assess the severity of five different types of childhood abuse and neglect. McNemar's test and conditional logistic regression models with potential confounders (i.e., marital status, educational level, and body mass index) controlled were used to explore the sex-specific associations between different types of childhood maltreatment and MDD.

RESULTS

In the full sample, patients with MDD showed a significant higher rate of any childhood maltreatment (i.e., emotional abuse, sexual abuse, physical abuse, emotional neglect, and physical neglect). Among females, all types of childhood abuse were statistically significant. For males, significant differences were only found in emotional abuse and in emotional neglect.

CONCLUSION

It would appear that MDD in the outpatients is associated with any type of childhood trauma in women and emotional abuse or neglect in men.

Biology of Perseverative Negative Thinking: The Role of Timing and Folate Intake

Past-oriented rumination and future-oriented worry are two aspects of perseverative negative thinking related to the neuroticism endophenotype and associated with depression and anxiety. Our present aim was to investigate the genomic background of these two aspects of perseverative negative thinking within separate groups of individuals with suboptimal versus optimal folate intake. We conducted a genome-wide association study in the UK Biobank database (n = 72,621) on the "rumination" and "worry" items of the Eysenck Personality Inventory Neuroticism scale in these separate groups. Optimal folate intake was related to lower worry, but unrelated to rumination. In contrast, genetic associations for worry did not implicate specific biological processes, while past-oriented rumination had a more specific genetic background, emphasizing its endophenotypic nature. Furthermore, biological pathways leading to rumination appeared to differ according to folate intake: purinergic signaling and circadian regulator gene ARNTL emerged in the whole sample, blastocyst development, DNA replication, and C-C chemokines in the suboptimal folate group, and prostaglandin response and K+ channel subunit gene KCNH3 in the optimal folate group. Our results point to possible benefits of folate in anxiety disorders, and to the importance of simultaneously taking into account genetic and environmental factors to determine personalized intervention in polygenic and multifactorial disorders.

Psychological Mediators of the Association Between Childhood Emotional Abuse and Depression: A Systematic Review

Background: A number of existing meta-analyses and narrative reviews have already addressed the relation between childhood adversity and depression, yet none of them has examined the specific link between emotional abuse and depression highlighted by previous research. It is no longer appropriate to regard childhood maltreatment as a unitary concept when considering its effects on subsequent depression; instead, subtypes of childhood maltreatment need to be scrutinized separately. This review addresses this significant gap by critically evaluating empirical studies examining psychological mediators of the relationship between childhood emotional abuse and subsequent depression. Methods: A systematic search of nine electronic databases was conducted to identify eligible studies published in English between January 1980 and January 2020. Given the heterogeneous outcomes of eligible studies and the inconsistent reporting of indirect effects, a narrative synthesis, rather than a quantitative meta-analysis, was conducted. An appraisal of methodological quality was also included. Results: We identified 34 papers, comprising 18,529 adults and 3,434 adolescents, including 888 clinical participants. Our synthesis suggests that studies on mediators in the emotional abuse-depression link have focused on five clusters of intervening variables: early maladaptive schemas, cognitive-personality variables, emotion dysregulation, interpersonal styles, and stressful negative events. Only 11 studies identified the unique contribution of emotional abuse to depression by controlling for other forms of childhood maltreatment. Conclusions: Our findings support several routes with relative consistency (e.g., early maladaptive schemas, hopelessness, negative cognitive styles, brooding rumination, overall emotion dysregulation). Because psychological mediators function as a complex interrelated system, controlling for the interrelation between them is important. The evidence for the purported mediating role of the factors identified in this review should be considered with caution given the relative dearth of large-scale, adequately powered longitudinal studies. This review proposes a comprehensive multilevel theoretical framework as a basis for future research.

Probiotic Treatment in Individuals with Euthymic Bipolar Disorder: A Pilot-Study on Clinical Changes and Compliance

The importance of the microbiome for psychological well-being has gained rising interest in the last decade. A strategy to examine the role of the microbiome in different diseases is the intake of supplements that modulate the gut microbiome. Despite promising results in animal studies, research in humans is sparse to date and especially in individuals with psychiatric disorders almost missing. The current report of the ProbioBIP-one pilot study aims at describing general effects of the intake of the probiotic OMNi-BiOTiC Stress repair® on psychological parameters as well as gastrointestinal symptoms and general compliance in a cohort of euthymic individuals with bipolar disorder (BD), receiving daily probiotic treatment over a time period of 3 months. Twenty-seven individuals with BD took part in the present study (mean age = 50.7 years, SD = 12.2; females 40.7%). In sum, there was a high compliance rate with 81.5% of the study participants completing all 3 study visits and 85% of planned probiotic ingestions taken. Gastrointestinal problems were prevalent in more than half of the patients at the time of inclusion (t1). Expectedly, in the whole cohort, a high proportion of study participants experienced changes concerning digestion during probiotic treatment, around one third reported positive changes (reduced flatulence and easier and more frequent bowel movements) after 1 month (t2) and further after 3 months (t3). In contrast, a smaller part of study participants reported gastrointestinal discomfort after 1 and after 3 months (mainly flatulence and obstipation). We found a significantly reduced cognitive reactivity to sad mood between t2 and t3 indicating that participants under probiotic supplementation perceived themselves to be less distracted by ruminative thoughts. Further changes in psychiatric symptoms were small due to the euthymic state and already low scoring at the time of inclusion. Nevertheless, we found a significant symptom reduction in the rating scales measuring manic symptoms. From a clinical point of view, probiotic supplementation might provide a well-tolerated tool to positively influence gastrointestinal quality of life as well as mental and somatic health, cognition and immune response and potentially have effects on psychiatric symptoms.

Adults with Autism and Adults with Depression Show Similar Attentional Biases to Social-Affective Images

Individuals with ASD have increased rates of depression compared to the general population. Repetitive cognition is a core feature of ASD; in typically developing adults, repetitive cognition has been associated with attentional biases to negative emotional material and increased prospective depression risk. We compared adults with ASD to typically developing adults with depression and never-depressed controls, using a paired preference paradigm sensitive to affective biases in the context of repetitive cognition. Both clinical cohorts oriented faster to negative social-emotional material and spent less time overall on positive material, compared to healthy controls. Exploratory analyses within ASD revealed specific influences of repetitive behavior on patterns of affective bias. Findings help pinpoint susceptibilities in ASD that may confer increased risk for depression.

Rumination impairs the control of stimulus-induced retrieval of irrelevant information, but not attention, control, or response selection in general

The aim of the study was to throw more light on the relationship between rumination and cognitive-control processes. Seventy-eight adults were assessed with respect to rumination tendencies by means of the LEIDS-r before performing a Stroop task, an event-file task assessing the automatic retrieval of irrelevant information, an attentional set-shifting task, and the Attentional Network Task, which provided scores for alerting, orienting, and executive control functioning. The size of the Stroop effect and irrelevant retrieval in the event-five task were positively correlated with the tendency to ruminate, while all other scores did not correlate with any rumination scale. Controlling for depressive tendencies eliminated the Stroop-related finding (an observation that may account for previous failures to replicate), but not the event-file finding. Taken altogether, our results suggest that rumination does not affect attention, executive control, or response selection in general, but rather selectively impairs the control of stimulus-induced retrieval of irrelevant information.

Associations Among Depressive Symptoms, Childhood Abuse, Neuroticism, Social Support, and Coping Style in the Population Covering General Adults, Depressed Patients, Bipolar Disorder Patients, and High Risk Population for Depression

BACKGROUND

Exposure to childhood abuse has been identified as a salient risk factor for the development of depression. However, the mediating factors between childhood abuse and depressive symptoms have not been sufficiently elucidated. This study aims to investigate the mediating effects of neuroticism, social support, and coping style between childhood abuse and depressive symptoms in population covering general adults, depressed patients, bipolar disorder patients, and high risk population for depression.

METHODS

This is a cross-sectional study. Five validated questionnaires were used to measure the psychological outcomes (Childhood Trauma Questionnaire CTQ-SF, Eysenck Personality Questionnaire EPQR-S, Social Support Rating Scale SSRS, Simplified Coping Style Questionnaire SCSQ, and Patient Health Questionnaire-9 PHQ-9) of 312 participants. Multiple regressions and structural equation modeling (SEM) were used to conduct data analysis.

RESULTS

Multiple regression analysis and SEM showed a significant association between childhood emotional abuse and depression symptoms. Neuroticism, use of social support, and active coping style were important mediating variables of this association. The R 2 for our model was 0.456, indicating that 45.6% of the variability in depressive symptoms can be explained by the model.

CONCLUSION

This study suggested that neuroticism, active coping, and use of social support play important role in mediating the effects of childhood abuse on adult depressive symptoms.

Genome-wide association analysis reveals KCTD12 and miR-383-binding genes in the background of rumination

Ruminative response style is a passive and repetitive way of responding to stress, associated with several disorders. Although twin and candidate gene studies have proven the genetic underpinnings of rumination, no genome-wide association study (GWAS) has been conducted yet. We performed a GWAS on ruminative response style and its two subtypes, brooding and reflection, among 1758 European adults recruited in the general population of Budapest, Hungary, and Manchester, United Kingdom. We evaluated single-nucleotide polymorphism (SNP)-based, gene-based and gene set-based tests, together with inferences on genes regulated by our most significant SNPs. While no genome-wide significant hit emerged at the SNP level, the association of rumination survived correction for multiple testing with KCTD12 at the gene level, and with the set of genes binding miR-383 at the gene set level. SNP-level results were concordant between the Budapest and Manchester subsamples for all three rumination phenotypes. SNP-level results and their links to brain expression levels based on external databases supported the role of KCTD12, SRGAP3, and SETD5 in rumination, CDH12 in brooding, and DPYSL5, MAPRE3, KCNK3, ATXN7L3B, and TPH2 in reflection, among others. The relatively low sample size is a limitation of our study. Results of the first GWAS on rumination identified genes previously implicated in psychiatric disorders underscoring the transdiagnostic nature of rumination, and pointed to the possible role of the dorsolateral prefrontal cortex, hippocampus, and cerebellum in this cognitive process.

Childhood Adversity Moderates the Effects of HTR2A Epigenetic Regulatory Polymorphisms on Rumination

The serotonin system has been suggested to moderate the association between childhood maltreatment and rumination, with the latter in its turn reported to be a mediator in the depressogenic effect of childhood maltreatment. Therefore, we investigated whether the associations of two epigenetic regulatory polymorphisms in the HTR2A serotonin receptor gene with Ruminative Responses Scale rumination and its two subtypes, brooding and reflection, are moderated by childhood adversity (derived from the Childhood Trauma Questionnaire) among 1,501 European white adults. We tested post hoc whether the significant associations are due to depression. We also tested the replicability of the significant results within the two subsamples of Budapest and Manchester. We revealed two significant models: both the association of methylation site rs6311 with rumination and that of miRNA binding site rs3125 (supposed to bind miR-1270, miR-1304, miR-202, miR-539 and miR-620) with brooding were a function of childhood adversity, and both interaction findings were significantly present both in the never-depressed and in the ever-depressed group. Moreover, the association of rs3125 with brooding could be replicated across the separate subsamples, and remained significant even when controlling for lifetime depression and the Brief Symptom Inventory depression score. These findings indicate the crucial importance of involving stress factors when considering endophenotypes and suggest that brooding is a more promising endophenotype than a broader measure of rumination. Transdiagnostic relevance of the brooding endophenotype and the potential of targeting epigenetic regulatory polymorphisms of HTR2A in primary and secondary prevention of depression and possibly of other disorders are also discussed.

Early life stress predicts negative urgency through brooding, depending on 5-HTTLPR genotype: A pilot study with 6-month follow-up examining suicide ideation

The present study examined the interaction between early life stress and 5-HTT genotypes in predicting two risk factors for suicidal behavior - the brooding subtype of rumination and impulsivity, in the form of negative urgency - over time. Furthermore, we examined early life stress, brooding, and impulsivity as predictors of suicidal ideation over time. Participants with and without a history of early life stress were genotyped for the 5-HTTLPR polymorphism and completed assessments assessing brooding and negative urgency at baseline and 6-month follow up. Early life emotional abuse was associated with negative urgency at follow-up. We found an indirect effect of early life emotional abuse on negative urgency through brooding among individuals with 5-HTT low expressing genotypes but not among individuals with 5-HTT high expressing genotypes. Further, a logistic regression analysis revealed that negative urgency was associated with higher odds (O.R. = 16.2) of reporting suicide ideation (versus no ideation) at follow-up. Our findings suggest that brooding and negative urgency may result from the interaction between early life emotional abuse and 5-HTT low expressing genotypes. Further research is necessary to understand how early life stress interacts with 5-HTT genotypes to confer risk for suicidal behavior through psychological mechanisms.

The Serotonin Transporter Promoter Variant, Stress, and Attentional Biases in Middle Childhood

Although evidence suggests that 5-HTTLPR variants may shape risk for depression, the influence is likely complex, and involves effects on endophenotypes. We examined associations between 5-HTTLPR and biases in attention to affective stimuli in a sample of girls and a sample of both boys and girls. Children with at least one short (S) variant of the 5-HTTLPR polymorphism had lower positive attentional bias scores in both samples. This association was qualified by an interaction with stress in one sample, such that links between the S allele and decreased positive attentional bias was significant only when life stress was elevated. This difference in findings between the two samples was explained by sex differences in samples; the GXE interaction was significant only in boys. Findings are discussed in the context of sex differences in GXE.

Cognitive Reactivity: Cultural Adaptation and Psychometric Testing of the Persian Version of the Leiden Index of Depression Sensitivity Revised (LEIDS-R) in an Iranian Sample

Cognitive reactivity (CR) to the experimental induction of sad mood has been found to predict relapse in recovered depressed patients. The Leiden Index of Depression Sensitivity Revised (LEIDS-R) is a self-report measure of CR. The aim of the present study was to establish the validity and reliability of the Persian version of the LEIDS-R. The participants were recovered depressed and non-depressed Iranian individuals (n = 833). The analyses included content validation, factor analysis, construct validity, and reliability testing. Preliminary construct validation analysis confirmed that factor analysis was appropriate for the Persian version of the LEIDS-R. Factor analysis displayed similar factor loadings to the original English version. The total internal consistency of the translated version, which was assessed using Cronbach’s alpha coefficient, was equal to 0.90. The test-retest reliability of the total score was equal to that of the test-retest conducted after a two-week interval at 0.94. Content validity, face validity, and construct validity, as well as reliability analysis were all found to be satisfactory for the Persian version of the LEIDS-R. The Persian version of the LEIDS-R appears to be valid and reliable for use in future studies, and has properties comparable to the original version and to that obtained in previous studies.

Empathy as a "risky strength": a multilevel examination of empathy and risk for internalizing disorders

Learning to respond to others' distress with well-regulated empathy is an important developmental task linked to positive health outcomes and moral achievements. However, this important interpersonal skill set may also confer risk for depression and anxiety when present at extreme levels and in combination with certain individual characteristics or within particular contexts. The purpose of this review is to describe an empirically grounded theoretical rationale for the hypothesis that empathic tendencies can be "risky strengths." We propose a model in which typical development of affective and cognitive empathy can be influenced by complex interplay among intraindividual and interindividual moderators that increase risk for empathic personal distress and excessive interpersonal guilt. These intermediate states in turn precipitate internalizing problems that map onto empirically derived fear/arousal and anhedonia/misery subfactors of internalizing disorders. The intraindividual moderators include a genetically influenced propensity toward physiological hyperarousal, which is proposed to interact with genetic propensity to empathic sensitivity to contribute to neurobiological processes that underlie personal distress responses to others' pain or unhappiness. This empathic personal distress then increases risk for internalizing problems, particularly fear/arousal symptoms. In a similar fashion, interactions between genetic propensities toward negative thinking processes and empathic sensitivity are hypothesized to contribute to excess interpersonal guilt in response to others' distress. This interpersonal guilt then increases the risk for internalizing problems, especially anhedonia/misery symptoms. Interindividual moderators, such as maladaptive parenting or chronic exposure to parents' negative affect, further interact with these genetic liabilities to amplify risk for personal distress and interpersonal guilt as well as for consequent internalizing problems. Age-related increases in the heritability of depression, anxiety, and empathy-related constructs are consistent with developmental shifts toward greater influence of intraindividual moderators throughout childhood and adolescence, with interindividual moderators exerting their greatest influence during early childhood. Efforts to modulate neurobiological and behavioral expressions of genetic dysregulation liabilities and to promote adaptive empathic skills must thus begin early in development.

[The specificity of cognitive reactivity in recurrent major depressive episodes]

The present study examined cognitive vulnerability to relapses of depression by clarifying the characteristics of "cognitive reactivity" in people with recurrent major depressive episodes. Study 1-1 and 1-2 developed a Japanese version of the Leiden Index of Depression Sensitivity-Revised (LEIDS-R), which assessed cognitive reactivity, and evaluated the reliability and validity of the scale. Study 2 examined the characteristics of cognitive reactivity which differentiate people with recurrent major depressive episodes from people with a single episode or none. The Japanese version of the LEIDS-R was shown to have reasonable reliability and validity. Participants with recurrent major depressive episodes showed more repetitive thoughts about negative issues and avoidance from internal and external aversive events when depressive mood was induced, compared to participants with only a single episode of depression. These results suggest that the characteristics of cognitive reactivity are important considerations for preventing relapse of depression.

Associations between the SS variant of 5-HTTLPR and PTSD among adults with histories of childhood emotional abuse: results from two African American independent samples

BACKGROUND

Prior studies have found that the 5-HTTLPR polymorphism in the promoter region of the serotonin transporter gene (SLC6A4) interacts with stressful life events to increase general risk for PTSD, but this association has not extended to African American samples. Further, little is known about the effects of this interaction on specific PTSD symptom clusters, despite indications that clusters may have different biological substrates. The current study examined the interaction between exposure to childhood emotional abuse and 5-HTTLPR genotype on risk for PTSD symptom severity and severity of specific PTSD symptom clusters in two African American samples.

METHODS

Participants were 136 African American household residents from Detroit, MI and 546 African American patients recruited from waiting rooms in primary care clinics in Atlanta, GA. Participants reported emotional abuse exposure and PTSD symptom severity, and provided DNA for triallelic 5-HTTLPR genotyping. Analysis of covariance (ANCOVA) was used to examine main effects and interactions.

RESULTS

In both African American samples, 5-HTTLPR genotype modified the effect of emotional abuse on PTSD symptom severity. Participants with the low-expression SS genotype who were exposed to emotional abuse had significantly lower reexperiencing and arousal symptom severity scores.

LIMITATIONS

The DNHS genetic sample size was small, and abuse data were assessed retrospectively.

CONCLUSIONS

The SS variant of 5-HTTLPR appears to buffer against developing the reexperiencing and arousal symptoms of PTSD in two independent African American samples exposed to childhood emotional abuse. Findings also highlight the importance of considering emotional abuse experiences in patients with suspected PTSD.

A Preliminary Examination of the Relationship Between the 5-HTTLPR and Childhood Emotional Abuse on Depressive Symptoms in 10-12-Year-Old Youth

Childhood emotional abuse (CEA) is a pervasive problem associated with negative sequelae such as elevated depressive symptoms. Key stress-related genes, such as the 5-HTTLPR polymorphism, interact with childhood abuse to produce elevated depressive symptoms in older adolescent girls, but not in older adolescent boys. To date, studies have not examined this relationship as a function of CEA specifically or among younger adolescents. To extend prior work, we examined the effects of the 5-HTTLPR and CEA on depressive symptoms among 10-12-year-old youth. Based on previous findings, we expected a main effect of CEA on depressive symptoms among all youth, but only expected an interactive effect between the 5-HTTLPR and CEA on depressive symptoms in girls. In the current study, 222 youth (mean age 11.02 years, 44.1% girls, 51.6% Caucasian, 33.0% African American, 2.7% Latino, and 12.7% other) and their parent(s)/guardian(s) completed the Revised Child Anxiety and Depression Scale and the Emotional Abuse subscale of the Childhood Trauma Questionnaire and provided saliva samples for genotyping the 5-HTTLPR. Results indicate that CEA, but not the 5-HTTLPR, was related to elevated depressive symptoms among boys. Among girls, each copy of the s allele of the 5-HTTLPR was related to increased depressive symptoms, but only for those who had experienced CEA. Our results extend prior findings by specifically examining CEA and by focusing on 10-12-year-old youth. These results, although preliminary, suggest that focusing on the interplay between putative genetic markers and a broader range of environmental events, such as CEA, might allow researchers to determine factors differentially influencing the later emergence of sex differences in depressive symptoms.

Cognitive reactivity, implicit associations, and the incidence of depression: a two-year prospective study

BACKGROUND

Cognitive reactivity to sad mood is a vulnerability marker of depression. Implicit self-depressed associations are related to depression status and reduced remission probability. It is unknown whether these cognitive vulnerabilities precede the first onset of depression.

AIM

To test the predictive value of cognitive reactivity and implicit self-depressed associations for the incidence of depressive disorders.

METHODS

Prospective cohort study of 834 never-depressed individuals, followed over a two-year period. The predictive value of cognitive reactivity and implicit self-depressed associations for the onset of depressive disorders was assessed using binomial logistic regression. The multivariate model corrected for baseline levels of subclinical depressive symptoms, neuroticism, for the presence of a history of anxiety disorders, for family history of depressive or anxiety disorders, and for the incidence of negative life events.

RESULTS

As single predictors, both cognitive reactivity and implicit self-depressed associations were significantly associated with depression incidence. In the multivariate model, cognitive reactivity was significantly associated with depression incidence, together with baseline depressive symptoms and the number of negative life events, whereas implicit self-depressed associations were not.

CONCLUSION

Cognitive reactivity to sad mood is associated with the incidence of depressive disorders, also when various other depression-related variables are controlled for. Implicit self-depressed associations predicted depression incidence in a bivariate test, but not when controlling for other predictors.

Stressful life events and depression symptoms: the effect of childhood emotional abuse on stress reactivity

OBJECTIVE

Stressful life events are associated with an increase in depressive symptoms and the onset of major depression. Importantly, research has shown that the role of stress changes over the course of depression. The present study extends the current literature by examining the effects of early life stress on emotional reactivity to current stressors.

METHOD

In a multiwave study (N = 281, mean age = 18.76; 68% female), we investigated the proximal changes that occur in depressive symptoms when individuals are faced with life stress and whether a history of childhood emotional abuse moderates this relationship.

RESULTS

Results support the stress sensitivity hypothesis for early emotional abuse history. Individuals with greater childhood emotional abuse severity experienced greater increases in depressive symptoms when confronted with current dependent stressors, controlling for childhood physical and sexual abuse.

CONCLUSIONS

This study highlights the importance of emotional abuse as an indicator for reactivity to stressful life events.

The effects of MAOA genotype, childhood trauma, and sex on trait and state-dependent aggression

Monoamine oxidase A (MAOA) genotypic variation has been associated with variation in aggression, especially in interaction with childhood trauma or other early adverse events. Male carriers of the low-expressing variant (MAOA-L) with childhood trauma or other early adverse events seem to be more aggressive, whereas female carriers with the high-expressing variant (MAOA-H) with childhood trauma or other early adverse events may be more aggressive. We further investigated the effects of MAOA genotype and its interaction with sex and childhood trauma or other early adverse events on aggression in a young adult sample. We hypothesized that the association between genotype, childhood trauma, and aggression would be different for men and women. We also explored whether this association is different for dispositional (trait) aggression versus aggression in the context of dysphoric mood. In all, 432 Western European students (332 women, 100 men; mean age 20.2) were genotyped for the MAOA gene. They completed measures of childhood trauma, state and trait measures of aggression-related behaviors (STAXI), and cognitive reactivity to sad mood (LEIDS-R), including aggression reactivity. Women with the MAOA-H had higher aggression reactivity scores than women with the MAOA-L. This effect was not observed in men, although the nonsignificant findings in men may be a result of low power. Effects on the STAXI were not observed, nor were there gene by environment interactions on any of the aggression measures. A protective effect of the low-expression variant in women on aggression reactivity is consistent with previous observations in adolescent girls. In females, the MAOA-H may predispose to aggression-related problems during sad mood.

Toward an integration of cognitive and genetic models of risk for depression

There is growing interest in integrating cognitive and genetic models of depression risk. We review two ways in which these models can be meaningfully integrated. First, information-processing biases may represent intermediate phenotypes for specific genetic influences. These genetic influences may represent main effects on specific cognitive processes or may moderate the impact of environmental influences on information-processing biases. Second, cognitive and genetic influences may combine to increase reactivity to environmental stressors, increasing risk for depression in a gene×cognition×environment model of risk. There is now growing support for both of these ways of integrating cognitive and genetic models of depression risk. Specifically, there is support for genetic influences on information-processing biases, particularly the link between 5-HTTLPR and attentional biases, from both genetic association and gene×environment (G×E) studies. There is also initial support for gene×cognition×environment models of risk in which specific genetic influences contribute to increased reactivity to environmental influences. We review this research and discuss important areas of future research, particularly the need for larger samples that allow for a broader examination of genetic and epigenetic influences as well as the combined influence of variability across a number of genes.

Serotonin transporter gene polymorphism and psychiatric disorders: is there a link?

Though still in infancy, the field of psychiatric genetics holds great potential to contribute to the development of new diagnostic and therapeutic options to treat these disorders. Among a large number of existing neurotransmitter systems, the serotonin system dysfunction has been implicated in many psychiatric disorders and therapeutic efficacy of many drugs is also thought to be based on modulation of serotonin. Serotonin transporter gene polymorphism is one of the most extensively studied polymorphisms in psychiatric behavioral genetics. In this article, we review the status of evidence for association between the serotonin gene polymorphism and some common mental disorders like affective disorders, post-traumatic stress disorder, obsessive-compulsive disorder, suicide, autism, and other anxiety and personality disorders. Going beyond traditional association studies, gene-environment interaction, currently gaining momentum, is also discussed in the review. While the existing information of psychiatric genetics is inadequate for putting into practice genetic testing in the diagnostic work-up of the psychiatric patient, if consistent in future research attempts, such results can be of great help to improve the clinical care of a vast majority of patients suffering from such disorders.

Mood-linked responses in medial prefrontal cortex predict relapse in patients with recurrent unipolar depression

BACKGROUND

Altered cognitive processing following mood challenge is associated with elevated relapse risk in remitted unipolar depressed patients, but little is known about the neural basis of this reactivity and its link to depressive relapse and prophylaxis.

METHODS

Remitted unipolar depressed participants (n = 16) and healthy control subjects (n = 16) underwent functional magnetic resonance imaging (fMRI) while viewing sad and neutral film clips. Correlations were determined between emotional reactivity (neural responses to sad vs. neutral films) in remitted patients and subsequent relapse status over an 18 month follow-up period. A receiver operating characteristic analysis was used to determine signal cutoffs for predicting relapse. Emotional reactivity in relapse prognostic areas was compared between groups.

RESULTS

Within the remitted group, relapse was predicted by medial prefrontal cortical (mPFC; Brodmann's area 32) activity and contraindicated by visual cortical activity (Brodmann's area 17). mPFC reactivity predicted rumination, whereas visual cortical reactivity predicted distress tolerance (acceptance). Compared with control participants, remitted depressed patients demonstrated a more pronounced tradeoff between mPFC and visual cortex reactivity. The difference score between mPFC and visual reactivity yielded excellent prediction of depressive relapse.

CONCLUSIONS

Medial prefrontal cortical reactivity to mood provocation in remitted unipolar depressed patients serves as a marker of relapse risk rather than successful emotion regulation. Enduring remission is characterized by normalization of the mPFC to that of healthy control subjects. Furthermore, visual cortex reactivity predicts resilience against depressive relapse, indicating a prophylactic role for sensory rather than ruminative cognitive reactivity in the processing of negative emotion.

5-HTTLPR and BDNF Val66Met polymorphisms moderate effects of stress on rumination

This study examined whether polymorphisms in the serotonin transporter (SLC6A4, 5-HTTLPR) and brain-derived neurotropic factor (BDNF Val66Met, rs6265) genes moderate the relationship between life stress and rumination. Participants were a large homogenous group of healthy, unmedicated, never depressed individuals with few current symptoms of depression (N = 273). Results indicate that individuals with two short (S) alleles of the 5-HTTLPR polymorphism or two Met alleles of the BDNF Val66Met polymorphism ruminate more under conditions of life stress, compared to the other genotypes. Moreover, the accumulation of risk alleles (i.e. S and Met alleles) across genes is associated with significantly greater rumination in the context of life stress. These results suggest that both 5-HTTLPR and BDNF Val66Met moderate the relationship between life stress and rumination. These findings support the notion that variation in these genes is associated with biological sensitivity to the negative effects of stress.

Dopamine D4 receptor and serotonin transporter gene effects on the longitudinal development of infant temperament

Existing studies of the effect on infant temperament of the 48 base pair variable number of tandem repeats polymorphism in exon 3 of the dopamine D4 receptor gene, DRD4 VNTR, and the serotonin transporter-linked polymorphic region, 5-HTTLPR, have provided contradictory results, and age seems to be an important factor. The present study investigated the effect of these two polymorphisms on the stability of infant temperament between 4 and 9 months of age. Furthermore, the effect of a recently discovered single nucleotide polymorphism which modulates the 5-HTTLPR (rs25531) was investigated in relation to infant temperament. The study sample consisted of 90 infants, who were assessed by parental report at the two ages under consideration using the Revised Infant Behavior Questionnaire. It was found that infants carrying the 7-repeat allele of the DRD4 VNTR had higher levels of Negative Affect. Furthermore, there was an interaction between DRD4 VNTR and 5-HTTLPR genotype such that infants with the DRD4 VNTR 7-repeat allele and the highest expressing 5-HTTLPR genotype (L(A) L(A) ) had the highest level of Negative Affect. These effects were largely driven by scores on the Falling Reactivity scale. Genetic effects were stable across age. The results emphasize the need for developmental studies of genetic effects on temperament.