STin2 variant and family history of suicide as significant predictors of suicide completion in major depression

Impact of Serotonin Pathway Gene Polymorphisms and Serotonin Levels in Suicidal Behavior

OBJECTIVE

Suicide is a significant public health issue and a major cause of death in all ages worldwide. Previous studies have shown the involvement of genetics in suicidal behaviour. This study aimed to assess the role of the genetic variants of the serotonin transporter genes (5HTTLPR, SLC6A4 intron 2) and receptor gene (5HTR2AT102C) in individuals who died of suicide. The study compares the serum levels of serotonin between the cases and controls.

METHODS

We conducted a case control study with 120 cases and 126 controls. Socio-economic details of the subjects were collected using a semi-structured proforma and psychological autopsy was used to collect details of medical and other clinical conditions. Blood was drawn after taking informed consent and serum levels of serotonin were estimated by ELISA. Genotyping was performed using appropriate primers followed by polymerase chain reaction (PCR) and a restriction fragment length polymorphism (RFLP).

RESULTS

Mean age was 32.59 ± 12.58 for cases and 33.64 ± 9.78 for controls. The risk associated LL genotype of 5HTTLPR was higher among cases. The heterozygous 12/10 genotype of SLC6A4 intron 2 polymorphism was increased among controls. Serum levels of serotonin were lower among cases. Variant genotypes of all the 3 polymorphisms showed significant interaction (OR= 39.26) indicating that this model may increase suicidal tendency.

CONCLUSION

The findings of this study suggest that low serum levels of serotonin and two variants of the serotonin gene may influence suicide behaviour in a south Indian population.

Unraveling the Contribution of Serotonergic Polymorphisms, Prefrontal Alpha Asymmetry, and Individual Alpha Peak Frequency to the Emotion-Related Impulsivity Endophenotype

The unique contribution of the serotonin transporter-linked polymorphic region (5-HTTLPR), intronic region 2 (STin2), and monoamine oxidase A (MAO-A) genes to individual differences in personality traits has been widely explored, and research has shown that certain forms of these polymorphisms relate to impulsivity and impulsivity-related disorders. Humans showing these traits are also described as having an asymmetrical prefrontal cortical activity when compared to others. In this explorative study, we examine the relationship between serotonergic neurotransmission polymorphisms, cortical activity features (prefrontal alpha asymmetry, individual alpha peak frequency [iAPF]), emotion-related and non-emotion-related impulsivity in humans. 5-HTTLPR, MAO-A, and STin2 polymorphisms were assessed in blood taken from 91 participants with high emotion-related impulsivity levels. Sixty-seven participants completed resting electroencephalography and a more comprehensive impulsivity index. In univariate analyses, iAPF correlated with both forms of emotion-related impulsivity. In multiple linear regression models, 5-HTTLPR polymorphism (model 1, adj. R² = 15.2%) and iAPF were significant interacting predictors of emotion-related impulsivity, explaining a large share of the results’ variance (model 2, adj. R² = 21.2%). Carriers of the low transcriptional activity 5-HTTPLR and MAO-A phenotypes obtained higher emotion-related impulsivity scores than others did. No significant results were detected for non-emotion-related impulsivity or for a form of emotion-related impulsivity involving cognitive/motivational reactivity to emotion. Our findings support an endophenotypic approach to impulsivity, showing that tri-allelic 5-HTTLPR polymorphism, iAPF, and their interaction are relevant predictors of one form of emotion-related impulsivity.

Prevalence of suicidality in clinically stable patients with major depressive disorder during the COVID-19 pandemic

BACKGROUND

The COVID-19 pandemic is associated with an increased risk of mental health problems including suicide in many subpopulations, but its influence on stable patients with major depressive disorder (MDD) has been studied fleetingly. This study examined the one-year prevalence of suicidality including suicidal ideation (SI), suicide plans (SP), and suicide attempts (SA) as well as their correlates in clinically stable MDD patients during the COVID-19 pandemic.

METHODS

A cross-sectional, observational study was conducted between October 1, 2020, and October 15, 2021, in six tertiary psychiatric hospitals. Socio-demographic information, clinical data and one-year prevalence of suicidality were recorded.

RESULTS

Altogether, 1718 participants who met the eligibility criteria were included. The overall one-year prevalence of suicidality during the COVID-19 pandemic was 68.04% (95% confidence intervals (CI) =65.84-70.25%), with one-year SI prevalence of 66.4% (95%CI = 64.18-68.65%), SP prevalence of 36.26% (95%CI = 33.99-38.54%), and SA prevalence of 39.35% (95%CI = 37.04-41.66%). Binary logistic regression analyses revealed male gender, married marital status, college education level and above and age were negatively associated with risk of suicidality. Urban residence, unemployed work status, experiences of cyberbullying, a history of suicide among family members or friends, and more severe fatigue, physical pain, and residual depressive symptoms were positively associated with risk of suicidality.

CONCLUSIONS

Suicidality is common among clinically stable MDD patients during the COVID-19 pandemic. Regular suicide screening and preventive measures should be provided to clinically stable MDD patients during the pandemic.

Factors of suicidal behavior among inpatients with major depressive disorder: A retrospective case series

OBJECTIVE

Previous studies indicate that more than half of those who died by suicide had a depressive disorder. When discussing the factors associated to suicidal behavior (SB) among patients with major depressive disorder (MDD), sociocultural contexts should also be carefully considered. This case series study explored the factors correlated to SB among MDD patients in Beijing, China.

METHODS

The patient information sheets were retrieved from an electronic database that comprised patient medical information. Three forms of binary logistic regression equations were conducted to explore the factors associated to SB among patients with MDD. For the inconsistent variables produced by the three regression models, the propensity score matching (PSM) analysis was done for further verification.

RESULTS

In this retrospective study, 1,091 depressed cases were enrolled. The difference between the SB group and non-SB group in gender, impulsivity, the severity of depression, history of major mental trauma, and family history of suicide were statistically significant in univariate comparisons (P < 0.05); the binary logistic regression analysis and the PSM analysis showed that female gender, history of major mental trauma, impulsivity, family history of suicide and severity of depression were factors correlated to SB among patients with MDD (odds ratios >1).

CONCLUSIONS

Female gender, the history of major mental trauma, impulsivity, the severity of depression, and family history of suicide were independently associated with the appearance of SB among MDD patients in Beijing, China. Inevitably, these findings should be viewed with particular caution due to the inherent drawbacks of a retrospective nature. More prospective longitudinal research should be conducted to examine those dynamic alterations in the corresponding confounders.

Suicide Related Phenotypes in a Bipolar Sample: Genetic Underpinnings

Suicide in Bipolar Disorder (BD) is a relevant clinical concern. Genetics may shape the individual risk for suicide behavior in BD, together with known clinical factors. The lack of consistent replication in BD may be associated with its multigenetic component. In the present contribution we analyzed a sample of BD individuals (from STEP-BD database) to identify the genetic variants potentially associated with three different suicide-related phenotypes: (1) a feeling that the life was not worth living; (2) fantasies about committing a violent suicide; (3) previous attempted suicide. The sample under analysis included 1115 BD individuals. None of the SNPs reached genome-wide significance. However, a trend of association was evidenced for rs2767403, an intron variant of AOPEP gene, in association with phenotype #1 (p = 5.977 × 10⁻⁶). The molecular pathway analysis showed a significant enrichment in all the investigated phenotypes on pathways related to post synaptic signaling, neurotransmission and neurodevelopment. Further, NOTCH signaling or the γ-aminobutyric acid (GABA)-ergic signaling were found to be associated with specific suicide-related phenotypes. The present investigation contributes to the hypothesis that the genetic architecture of suicide behaviors in BD is related to alteration of entire pathways rather than single genes. In particular, our molecular pathway analysis points on some specific molecular events that could be the focus of further research in this field.

Serotonergic sensitivity alleles moderate relations between attachment security at age three and socioemotional competence at age five

Children with higher socioemotional competence are more likely to build constructive relationships with others and experience more positive adjustment outcomes in later periods. Securely attached children are likely to develop better socioemotional competence, but genetic moderation of associations between attachment and later socioemotional competence has received less attention. Using structural equation modeling, this study analyzed data collected from 1,337 children (51% male) born from 1998 to 2000 in the Fragile Families and Child Wellbeing study. The results demonstrated that relations between attachment security at age 3 years and their social competence at age 5 years differed by two serotonin transporter variants (5-HTTLPR, STin2). Effect sizes of these interactions were larger than effect sizes of main effects and the benefit of having sensitive alleles was consistently supported. This implies that having more secure attachment in the early developmental period is advantageous especially for children with minor alleles who have greater environmental sensitivity.

Associations Among Monoamine Neurotransmitter Pathways, Personality Traits, and Major Depressive Disorder

Major depressive disorder (MDD) is a complex psychiatric disease requiring multidisciplinary approaches to identify specific risk factors and establish more efficacious treatment strategies. Although the etiology and pathophysiology of MDD are not clear until these days, it is acknowledged that they are almost certainly multifactorial and comprehensive. Monoamine neurotransmitter system dysfunction and specific personality traits are independent risk factors for depression and suicide. These factors also demonstrate complex interactions that influence MDD pathogenesis and symptom expression. In this review, we assess these relationships with the aim of providing a reference for the development of precision medicine.

Typologies of Suicide: A Critical Literature Review

This review highlights proposed suicide typologies and identifies areas of future research. The current study is an illustrative, rather than exhaustive, qualitative review of theoretical and empirically derived typologies of suicide decedents. Theoretical and empirical typologies of suicide delineate between groups of suicide decedents based on individual, motivational, psychiatric, interpersonal, socio-demographic, and other variables. Certain core themes emerge across theoretical typologies including escape, aggression, intrapsychic pain, and relational concerns. Empirical typologies have identified unique patterns of life stressors, mental health history, health care utilization, and suicide method among suicide decedents. Future research should build on existing typological models of suicide to delineate when, and for whom, particular typologies of suicide may inform targeted prevention efforts. Researchers and clinicians should consider the characteristics and needs of particular high-risk groups when translating typological research into meaningful suicide prevention and intervention.

The influence of the serotonin transporter gene 5-HTTLPR polymorphism on suicidal behaviors: a meta-analysis

Suicidal Behavior (SB) is the second leading cause of death among youths worldwide and the tenth among all age groups. Inherited genetic differences have a role in suicidality with heritability ranging from 30 to 55%. The SLC6A4 5-HTTLPR gene variant has been largely investigated for association with SB, with controversial results. In this work, we sought to determine whether the results of previous meta-analyses were confirmed or modified subsequent to the inclusion of more recent literature data. An electronic literature search was performed to identify relevant studies published until July 2018. Data were analysed through RevMan v5.3. Subgroup and sensitivity meta-analyses were performed considering different SB sub-phenotypes, ethnicity, gender and psychiatric diagnostic categories. Our literature search yielded 1186 articles; among these, we identified 45 pertinent case-control studies (15,341 subjects). No association was found between low-expressing alleles or genotypes (S + L_G alleles or S' carrier genotypes) and SB in the primary analyses. However, low-expressing alleles (S + L_G) were associated with an increased risk of Violent Suicide Attempt (OR = 1.44, C.I. 1.17-1.78, p = .0007). An effect of the same alleles on SB was found in a subpopulation of substance abusers, but this result was not confirmed after the exclusion of healthy subjects from the control group. The other sensitivity meta-analyses did not show any significant effect. Our findings contribute to clarify the conflicting previous evidence by suggesting an association between the 5-HTTLPR and Violent SB. Nonetheless, many other modulators, including environmental factors and epigenetic mechanisms may act to further increase the level of complexity.

Association between serotonin transporter gene polymorphisms and increased suicidal risk among HIV positive patients in Uganda

BACKGROUND

Persons living with HIV/AIDS (PLWHA) are at an increased risk of suicide. Increased suicidal risk is a predictor of future attempted and completed suicides and has been associated with poor quality of life and poor adherence with antiretroviral therapy. Clinical risk factors have low predictive value for suicide, hence the interest in potential neurobiological correlates and specific heritable markers of suicide vulnerability. The serotonin transporter gene has previously been implicated in the aetiology of increased suicidal risk in non-HIV infected study populations and its variations may provide a platform for identifying genetic risk for suicidality among PLWHA. The present cross-sectional study aimed at identifying two common genetic variants of the serotonin transporter gene and their association with increased suicidal risk among human immunodeficiency virus (HIV)-positive adults in Uganda.

RESULTS

The prevalence of increased suicidal risk (defined as moderate to high risk suicidality on the suicidality module of the Mini Neuropsychiatric Interview (M.I.N.I) was 3.3% (95% CI, 2.0-5.3). The 5-HTTLPR was found to be associated with increased suicidal risk before Bonferroni correction (p-value = 0.0174). A protective effect on increased suicidal risk was found for the 5-HTTLPR/rs25531 S _A allele (p-value = 0.0046)- which directs reduced expression of the serotonin transporter gene (5-HTT).

CONCLUSION

The S _A allele at the 5-HTTLPR/rs25531 locus is associated with increased suicidal risk among Ugandan PLWHA. Further studies are needed to validate this finding in Ugandan and other sub-Saharan samples.

The Life Span Model of Suicide and Its Neurobiological Foundation

The very incomprehensibility of the suicidal act has been occupying the minds of researchers and health professionals for a long time. Several theories of suicide have been proposed since the beginning of the past century, and a myriad of neurobiological studies have been conducted over the past two decades in order to elucidate its pathophysiology. Both neurobiology and psychological theories tend to work in parallel lines that need behavioral and empirical data respectively, to confirm their hypotheses. In this review, we are proposing a "Life Span Model of Suicide" with an attempt to integrate the "Stress-Diathesis Model" and the "Interpersonal Model of Suicide" into a neurobiological narrative and support it by providing a thorough compilation of related genetic, epigenetic, and gene expression findings. This proposed model comprises three layers, forming the capability of suicide: genetic factors as the predisposing Diathesis on one side and Stress, characterized by epigenetic marks on the other side, and in between gene expression and gene function which are thought to be influenced by Diathesis and Stress components. The empirical evidence of this model is yet to be confirmed and further research, specifically epigenetic studies in particular, are needed to support the presence of a life-long, evolving capability of suicide and identify its neurobiological correlates.

Gender Differences in Somatic Symptoms and Current Suicidal Risk in Outpatients with Major Depressive Disorder

OBJECTIVE

Although somatic symptoms are common complaints of patients with major depressive disorder (MDD), their associations with suicide are still unclear.

METHODS

A total of 811 MDD outpatients of aged between 18 to 64 years were enrolled nationwide in Korea with the suicidality module of the Mini-International Neuropsychiatric Interview (MINI) and the Depression and Somatic Symptom Scale (DSSS).

RESULTS

On stepwise regression analysis, current suicidality scores were most strongly associated with chest pain in men, and neck or shoulder pain in women. Severe chest pain was associated with higher current suicidality scores in men than in women, whereas severe neck or shoulder pain showed no significant differences between the genders. In conclusion, MDD patients of both sexes with suicidal ideation showed significantly more frequent and severe somatic symptoms than those without. Current suicidal risk was associated with chest pain in men, and neck or shoulder pain in women.

CONCLUSION

We suggest that clinicians pay attention to patients' somatic symptoms in real world practice.

Positron Emission Tomographic Imaging of the Serotonergic System and Prediction of Risk and Lethality of Future Suicidal Behavior

IMPORTANCE

Biomarkers that predict suicidal behavior, especially highly lethal behavior, are urgently needed. In cross-sectional studies, individuals with depression who attempt suicide have lower midbrain serotonin transporter binding potential compared with those who do not attempt suicide, and higher serotonin1A binding potential in the raphe nuclei (RN) is associated with greater lethality of past suicide attempts and suicidal intent and ideation.

OBJECTIVES

To determine whether serotonin transporter binding potential in the lower midbrain predicts future suicide attempts and whether higher RN serotonin1A binding potential predicts future suicidal ideation and intent and lethality of future suicide attempts.

DESIGN, SETTING, AND PARTICIPANTS

In this prospective 2-year observational study, a well-characterized cohort of 100 patients presenting for treatment of a major depressive episode of at least moderate severity underwent positron emission tomography using carbon 11-labeled N-(2-(1-(4-(2-methoxyphenyl)-1-piperazinyl)ethyl))-N-(2-pyridyl)-cyclohexanecarboxamide ([11C]WAY-100635), a serotonin1A antagonist; a subset of 50 patients also underwent imaging with carbon 11-labeled 3-amino-4-(2-dimethylaminomethyl-phenylsulfanyl)- benzonitrile ([11C]DASB), a serotonin transporter radioligand. Imaging was performed at Columbia University Medical Center from May 3, 1999, to March 11, 2008. Follow-up was completed on May 28, 2010, and data were analyzed from August 1, 2013, to March 1, 2016.

EXPOSURES

Patients were treated naturalistically in the community and followed up for 2 years with documentation of suicidal behavior, its lethality, and suicidal ideation and intent.

MAIN OUTCOMES AND MEASURES

Suicide attempt or suicide.

RESULTS

Of the 100 patients undergoing follow-up for more than 2 years (39 men; 61 women; mean [SD] age, 40.2 [11.2] years), 15 made suicide attempts, including 2 who died by suicide. Higher RN serotonin1A binding potential predicted more suicidal ideation at 3 (b = 0.02; t = 3.45; P = .001) and 12 (b = 0.02; t = 3.63; P = .001) months and greater lethality of subsequent suicidal behavior (b = 0.08; t = 2.89; P = .01). Exploratory analyses suggest that the serotonin1A binding potential of the insula (t = 2.41; P = .04), anterior cingulate (t = 2.27; P = .04), and dorsolateral prefrontal cortex (t = 2.44; P = .03) were also predictive of lethality. Contrary to our hypotheses, suicidal intent was not predicted by serotonin1A binding potential in any brain region (F1,10 = 0.83; P = .38), and midbrain serotonin transporter binding potential did not predict future attempts (log-rank χ21 = 0.4; P = .54), possibly owing to low power.

CONCLUSIONS AND RELEVANCE

Greater RN serotonin1A binding potential predicted higher suicidal ideation and more lethal suicidal behavior during a 2-year period. This effect may be mediated through less serotonin neuron firing and release, which affects mood and suicidal ideation and thereby decision making.

Possible Association between Serotonin Transporter Gene Polymorphism and Suicide Behavior in Major Depressive Disorder

OBJECTIVE

The serotonin transporter (5-HTT) genes are major candidate genes for modulating the suicidal behavior. We investigated the association between serotonin transporter polymorphisms and suicidal behavior in patients with major depressive disorder (MDD).

METHODS

Serotonin transporter intron 2 VNTR polymorphism (5-HTTVNTR) and serotonin transporter linked polymorphic region polymorphism (5-HTTLPR) were analyzed in 132 depressed patients with suicidal attempt as well as in 122 normal controls. Hamilton's 17-item Depression Rating Scale (HDRS), the Risk-Rescue rating system (RRR) and the Lethality Suicide Attempt Rating Scale updated (LSARS-II) were assessed for the depressed patients.

RESULTS

Although not statistically significant, a trend was found such that the 10/10 and 10/12 alleles of 5-HTTVNTR were more common in suicidal subjects than in control subjects. Comparing allele frequency, those with a 10 allele or 10 allele carriers were higher in suicidal subjects than in control subjects. No difference was noted in 5-HTTLPR genotypes and haplotype distribution between the suicidal subjects and control subjects. The RRR scores in subjects with the 10/10 5-HTTVNTR genotype or 10 5-HTTVNTR allele were significantly lower than those in subjects with other genotypes.

CONCLUSION

These results show the possibility that 10 allele of 5-HTTVNTR is related to suicidal behavior in the suicidal subjects with MDD and suggest that 12 allele of 5-HTTVNTR might be related to more lethality in the suicidal subjects with MDD.

Toward a biosignature for suicide

OBJECTIVE

Suicide, a major cause of death worldwide, has distinct biological underpinnings. The authors review and synthesize the research literature on biomarkers of suicide, with the aim of using the findings of these studies to develop a coherent model for the biological diathesis for suicide.

METHOD

The authors examined studies covering a large range of neurobiological systems implicated in suicide. They provide succinct descriptions of each system to provide a context for interpreting the meaning of findings in suicide.

RESULTS

Several lines of evidence implicate dysregulation in stress response systems, especially the hypothalamic-pituitary-adrenal axis, as a diathesis for suicide. Additional findings related to neuroinflammatory indices, glutamatergic function, and neuronal plasticity at the cellular and circuitry level may reflect downstream effects of such dysregulation. Whether serotonergic abnormalities observed in individuals who have died by suicide are independent of stress response abnormalities is an unresolved question.

CONCLUSIONS

The most compelling biomarkers for suicide are linked to altered stress responses and their downstream effects, and to abnormalities in the serotonergic system. Studying these systems in parallel and in the same populations may elucidate the role of each and their interplay, possibly leading to identification of new treatment targets and biological predictors.

Serotonergic genes and suicidal ideation 2 weeks and 1 year after stroke in Korea

OBJECTIVES

Serotonergic genes are associated with suicidal behavior; this association has not been tested in stroke survivors, however. In this study, we investigated whether serotonin transporter (5-HTT) and serotonin 2a receptor (5-HTR2a) genes were associated with suicidal ideation at 2 weeks and at 1 year after stroke.

METHODS

A total of 286 patients were evaluated 2 weeks after stroke, and 222 (78%) participated in a follow-up evaluation one year later. Suicidal ideation was ascertained using the "suicidal thoughts" item of the Montgomery and Asberg Depression Rating Scale. Associations between suicidal ideation and 5-HTTLPR, STin2 VNTR, 5-HTR2a 1438A/G, and 5-HTR2a 102T/C genotypes were estimated using logistic regression models, and gene-gene interactions were investigated using the generalized multifactor dimensionality reduction method after adjustment for potential covariates, including depression.

RESULTS

The 5-HTR2a 1438 A/A genotype was significantly associated with suicidal ideation 2 weeks after stroke, before and after statistical adjustment. The 5-HTTLPR short allele was associated with suicidal ideation 2 weeks after stroke, although the significance of this finding was not evident after adjustment. No significant associations were observed between any genotype and suicidal ideation one year after stroke. No significant gene-gene interactions were detected.

CONCLUSIONS

Individuals with the 5-HTR2a 1438 A/A genotype were more susceptible to suicidal ideation 2 weeks after stroke. Careful evaluation and management are indicated for those with increased genetic vulnerability, particularly during the acute phase of stroke.

Feelings of worthlessness, traumatic experience, and their comorbidity in relation to lifetime suicide attempt in community adults with major depressive disorder

BACKGROUND

Major depressive disorder (MDD) and traumatic experience are independent risk factors for lifetime suicide attempt (LSA). However, the relationships between trauma history and depressive symptomatology as they relate to LSA are not fully understood.

METHODS

A total of 12,532 adults, randomly selected through one-person-per-household method, completed a face-to-face interview using the Korean version of Composite International Diagnostic Interview (K-CIDI) and a questionnaire for LSA (response rate 80.2%).

RESULTS

Among 825 subjects with MDD, 141 subjects reported an LSA (17.1%). LSAs were significantly greater in those who had experienced any trauma than in those who had not (χ(2)=34.66, p<0.0001). Multivariate logistic regression showed that only feelings of worthlessness were significantly associated with LSA among 20 depression symptoms in individuals with MDD (AOR=3.08, 95% CI 1.70-5.60). Feelings of worthlessness was associated with LSA in those who had experienced serious trauma (AOR=5.02, 95% CI 3.35-7.52), but not in those who had not. Serious traumas associated with LSA included military combat, witnessing a violent crime, rape or sexual assault, a bad beating, being threatened by others, and learning about traumas to others. Serious trauma showed no significant association with LSA in those who did not have feelings of worthlessness. PTSD was a comorbidity that showed the highest odds ratio with LSA in individuals with MDD.

CONCLUSIONS

Feelings of worthlessness are more strongly associated with LSA than other depression symptoms in individuals with MDD, and it is significantly associated with LSA in those who experienced serious trauma but not in those who did not.

Risk factors for suicide in individuals with depression: a systematic review

BACKGROUND

Depression is the most common psychiatric disorder in people who die by suicide. Awareness of risk factors for suicide in depression is important for clinicians.

METHODS

In a systematic review of the international literature we identified cohort and case-control studies of people with depression in which suicide was an outcome, and conducted meta-analyses of potential risk factors.

RESULTS

Nineteen studies (28 publications) were included. Factors significantly associated with suicide were: male gender (OR=1.76, 95% CI=1.08-2.86), family history of psychiatric disorder (OR=1.41, 95% CI=1.00-1.97), previous attempted suicide (OR=4.84, 95% CI=3.26-7.20), more severe depression (OR=2.20, 95% CI=1.05-4.60), hopelessness (OR=2.20, 95% CI=1.49-3.23) and comorbid disorders, including anxiety (OR=1.59, 95% CI=1.03-2.45) and misuse of alcohol and drugs (OR=2.17, 95% CI=1.77-2.66).

LIMITATIONS

There were fewer studies than suspected. Interdependence between risk factors could not be examined.

CONCLUSIONS

The factors identified should be included in clinical assessment of risk in depressed patients. Further large-scale studies are required to identify other relevant factors.

Clinical implications of genetic variation in the serotonin transporter promoter region: a review

OBJECTIVE

To determine the state of the art in understanding the role of genetic variation in the serotonin transporter (5-HTT) promoter region (5-HTTLPR) in the development of a depressive episode and in its response to treatment.

DATA SOURCES

PubMed and Ovid were used to search for articles published prior to December 2007 utilizing the key words serotonin transporter, 5-HTT, 5-HTTLPR, serotonin transporter gene, and SLC6A4.

STUDY SELECTION

All studies were reviewed, but case reports and small case series were excluded.

DATA EXTRACTION

All relevant articles were read by at least 2 of the coauthors and notes regarding study design, measures, data analysis, and findings were later used to construct the review.

DATA SYNTHESIS

A common genetic variant, the short allele, in which 44 base pairs are missing from the promoter of SLC6A4, is associated with a greater risk for developing a major depressive disorder in patients following exposure to adversity. This association appears to be most important in the early stages of the depressive disorder. Additionally, the likelihood of a positive response to antidepressant treatment may be reduced in these patients in terms of delayed response, greater adverse event load, or, in bipolar patients, mania induction and rapid cycling.

CONCLUSIONS

Selected genetic testing of patients with a recent history of significant adversity may be a reasonable tool that can enlighten treatment options and the course of illness. Ongoing work with the short allele of 5-HTT may also inform clinical guidelines of long-term treatment with antidepressants.

Peripheral SLC6A4 DNA methylation is associated with in vivo measures of human brain serotonin synthesis and childhood physical aggression

The main challenge in addressing the role of DNA methylation in human behaviour is the fact that the brain is inaccessible to epigenetic analysis in living humans. Using positron emission tomography (PET) measures of brain serotonin (5-HT) synthesis, we found in a longitudinal sample that adult males with high childhood-limited aggression (C-LHPA) had lower in vivo 5-HT synthesis in the orbitofrontal cortex (OBFC). Here we hypothesized that 5-HT alterations associated with childhood aggression were linked to differential DNA methylation of critical genes in the 5-HT pathway and these changes were also detectable in peripheral white blood cells. Using pyrosequencing, we determined the state of DNA methylation of SLC6A4 promoter in T cells and monocytes isolated from blood of cohort members (N = 25) who underwent a PET scan, and we examined whether methylation status in the blood is associated with in vivo brain 5-HT synthesis. Higher levels of methylation were observed in both T cells and monocytes at specific CpG sites in the C-LHPA group. DNA methylation of SLC6A4 in monocytes appears to be associated more reliably with group membership than T cells. In both cell types the methylation state of these CpGs was associated with lower in vivo measures of brain 5-HT synthesis in the left and right lateral OBFC (N = 20) where lower 5-HT synthesis in C-LHPA group was observed. Furthermore, in vitro methylation of the SLC6A4 promoter in a luciferase reporter construct suppresses its transcriptional activity supporting a functional role of DNA methylation in SLC6A4 promoter regulation. These findings indicate that state of SLC6A4 promoter methylation is altered in peripheral white blood cells of individuals with physical aggression during childhood. This supports the relevance of peripheral DNA methylation for brain function and suggests that peripheral SLC6A4 DNA methylation could be a marker of central 5-HT function.

Interactions between serotonin transporter gene haplotypes and quality of mothers' parenting predict the development of children's noncompliance

The LPR and STin2 polymorphisms of the serotonin transporter gene (SLC6A4) were combined into haplotypes that, together with quality of maternal parenting, were used to predict initial levels and linear change in children's (N = 138) noncompliance and aggression from age 18-54 months. Quality of mothers' parenting behavior was observed when children were 18 months old, and nonparental caregivers' reports of noncompliance and aggression were collected annually from 18 to 54 months of age. Quality of early parenting was negatively related to the slope of noncompliance only for children with the LPR-S/STin2-10 haplotype and to 18-month noncompliance only for children with haplotypes that did not include LPR-S. The findings support the notion that SLC6A4 haplotypes index differential susceptibility to variability in parenting quality, with certain haplotypes showing greater reactivity to both supportive and unsupportive environments. These different genetic backgrounds likely reflect an evolutionary response to variation in the parenting environment.

AVPR1A and SLC6A4 polymorphisms in choral singers and non-musicians: a gene association study

Amateur choral singing is a common pastime and worthy of study, possibly conferring benefits to health and social behaviour. Participants might be expected to possess musical ability and share some behavioural characteristics. Polymorphisms in genes concerned with serotonergic neurotransmission are associated with both behaviour and musical aptitude. Those investigated previously include the variable number tandem repeats RS1, RS3 and AVR in the AVPR1A (arginine vasopressin receptor 1a) gene and STin2 in the SLC6A4 (solute carrier family 6 [neurotransmitter transporter, serotonin], member 4) gene, as well as the SLC6A4 promoter region polymorphism, 5-HTTLPR. We conducted a genetic association study on 523 participants to establish whether alleles at these polymorphisms occur more commonly in choral singers than in those not regularly participating in organised musical activity (non-musicians). We also analysed tagging single nucleotide polymorphisms (SNPs) for AVPR1A and SLC6A4 to determine whether other variants in these genes were associated with singer/non-musician status. At the STin2 polymorphism, overall association with singer/non-musician status was evident at P = 0.006. The 9-repeat (P = 0.04) and 12-repeat (P = 0.04) alleles were more common in singers and the 10-repeat allele less so (P = 0.009). Odds ratios were 0.73 (95% CI 0.57–0.94) for the 10-repeat allele and 2.47 (95% CI 0.88–6.94) for the rarer 9-repeat allele. No overall association was detected at P<0.05 between any other polymorphism and singer/non-musician status. Our null findings with respect to RS3, RS1 and AVR, polymorphisms associated with musical ability by other authors, suggest that choir membership may depend partly on factors other than musical ability. In a related musical project involving one participating choir, a new 40-part unaccompanied choral work, “Allele”, was composed and broadcast on national radio. In the piece, each singer's part incorporated their personal RS3 genotype.

Life stressors and 5-HTTLPR interaction in relation to midpregnancy depressive symptoms among African-American women

OBJECTIVE

In earlier analyses of nonHispanic White women we found a stronger relation between abuse history and midpregnancy elevated depressive symptoms in women with the serotonin transporter (5-HTTLPR) S/S genotype. Here, we focus on African-American women (N=698). Our inquiry is motivated by racial differences in depression diagnosis/treatment, stressors, and frequency of major 5-HTTLPR alleles (S, LA, LG).

MATERIALS AND METHODS

Stressful life events (lifetime) and depressive symptoms (current) were ascertained at 15-27 weeks gestation. A Center for Epidemiological Studies Depression Score of more than or equal to 18 was considered 'elevated'. Life events were scored together and separated into six subconstructs. 5-HTTLPR genotypes were grouped as follows: (i) L and S alleles, (ii) S-LG equivalence ('triallelic to biallelic'), and (iii) LA/LA, all others, S/S ('high/intermediate/low'). Odds ratios (OR) for 'elevated' depressive symptoms-life events (total and subconstructs) relations were calculated for each genotype grouping.

RESULTS

The prevalence of 'elevated' depressive symptoms did not vary by genotype. The relation between stressful life events and 'elevated' depressive symptoms was stronger in S/S compared with LA/LA genotype (interaction P=0.11). Of the six subconstructs, only abuse showed a statistically significant gene-environment interaction. The OR for the abuse-'elevated' depressive symptoms association was greater for S/S vs. LA/LA genotype (interaction P=0.03) and in the 'triallelic to biallelic' grouping (interaction P=0.04). In the 'high/intermediate/low' grouping, 'low' (S/S) had a higher OR (5.5) than both 'intermediate' and 'high' (ORs≤2.3) (interaction P=0.10).

CONCLUSIONS

These results show the importance of examining racial groups, specific stressful events, and different 5-HTTLPR genotype groupings when exploring gene-environment interactions in depression.

Acute and posttraumatic stress symptoms in a prospective gene x environment study of a university campus shooting

CONTEXT

The serotonin transporter (SLC6A4) has been associated with several stress-related syndromes including posttraumatic stress disorder (PTSD). The ability to detect meaningful associations is largely dependent on reliable measures of preexisting trauma.

OBJECTIVE

To study the association of genetic variants within SLC6A4 with acute and posttraumatic stress symptoms in a civilian cohort with known levels of preexisting trauma and PTSD symptoms collected prior to a shared index traumatic event.

DESIGN

Ongoing longitudinal study.

SETTING

On February 14, 2008, a lone gunman shot multiple people on the campus of Northern Illinois University in DeKalb, Illinois, killing 5 and wounding 21. As part of an ongoing longitudinal study on that campus, a cohort of female undergraduate students, interviewed prior to the shooting, completed follow-up trauma-related measures including PTSD symptom severity (follow-up survey was launched 17 days postshooting; n = 691). To obtain DNA, salivary samples were collected from a subset of the original study population based on willingness to participate (n = 276).

PARTICIPANTS

Two hundred four undergraduate women.

MAIN OUTCOME MEASURES

SLC6A4 polymorphisms STin2, 5-HTTLPR, and rs25531 were genotyped in 235 individuals.

RESULTS

We found that although the STin2 variant and 5-HTTLPR alone did not associate with increased PTSD symptoms, rs25531 and the 5-HTTLPR multimarker genotype (combined 5-HTTLPR and rs25531) were associated with significantly increased acute stress disorder symptoms at 2 to 4 weeks postshooting (n = 161; P < .05). This association remained significant when controlling for race and for level of shooting exposure (n = 123; P < .007). The association was most robust with the 5-HTTLPR multimarker genotype and avoidance symptoms (P = .003).

CONCLUSION

These data suggest that differential function of the serotonin transporter may mediate differential response to a severe trauma. When examined in a relatively homogenous sample with shared trauma and known prior levels of child and adult trauma, the 5-HTTLPR multimarker genotype may serve as a useful predictor of risk for PTSD-related symptoms in the weeks and months following the trauma.

Incomplete coverage of candidate genes: a poorly considered bias

Current genetic investigations are performed both on the basis of a rational and biologically based choice of candidate genes and through genome wide scans. Nonetheless, lack of replication is a common problem in psychiatric genetics as well as in other genetic fields. There are a number of reasons for this inconsistency, among them a well known but poorly considered issue is gene coverage. The aim of the present paper is to focus on this well known and defectively deemed bias, especially when a candidate gene approach is chosen. The rational and the technical feasibility of this proposal are discussed as well as a survey of current investigations. The known consistent methodology to fix this bias is also discussed.

P2RX7 gene is associated consistently with mood disorders and predicts clinical outcome in three clinical cohorts

We investigated the effect of nine candidate genes on risk for mood disorders, hypothesizing that predisposing gene variants not only elevate the risk for mood disorders but also result in clinically significant differences in the clinical course of mood disorders. We genotyped 178 DSM-IV bipolar I and II and 272 major depressive disorder patients from three independent clinical cohorts carefully diagnosed with semistructured interviews and prospectively followed up with life charts for a median of 60 (range 6-83) months. Healthy control subjects (n = 1322) were obtained from the population-based national Health 2000 Study. We analyzed 62 genotyped variants within the selected genes (BDNF, NTRK2, SLC6A4, TPH2, P2RX7, DAOA, COMT, DISC1, and MAOA) against the presence of mood disorder, and in post-hoc analyses, specifically against bipolar disorder or major depressive disorder. Estimates for time ill were based on life charts. The P2RX7 gene variants rs208294 and rs2230912 significantly elevated the risk for a familial mood disorder (OR = 1.35, P = 0.0013, permuted P = 0.06, and OR = 1.44, P = 0.0031, permuted P = 0.17, respectively). The results were consistent in all three cohorts. The same risk alleles predicted more time ill in all cohorts (OR 1.3, 95% CI 1.1-1.6, P = 0.0069 and OR 1.7, 95% CI 1.3-2.3, P = 0.0002 with rs208294 and rs2230912, respectively), so that homozygous carriers spent 12 and 24% more time ill. P2RX7 and its risk alleles predisposed to mood disorders consistently in three independent clinical cohorts. The same risk alleles resulted in clinically significant differences in outcome of patients with major depressive and bipolar disorder.

Pharmacogenetics of antidepressants

Up to 60% of depressed patients do not respond completely to antidepressants (ADs) and up to 30% do not respond at all. Genetic factors contribute for about 50% of the AD response. During the recent years the possible influence of a set of candidate genes as genetic predictors of AD response efficacy was investigated by us and others. They include the cytochrome P450 superfamily, the P-glycoprotein (ABCB1), the tryptophan hydroxylase, the catechol-O-methyltransferase, the monoamine oxidase A, the serotonin transporter (5-HTTLPR), the norepinephrine transporter, the dopamine transporter, variants in the 5-hydroxytryptamine receptors (5-HT1A, 5-HT2A, 5-HT3A, 5-HT3B, and 5-HT6), adrenoreceptor beta-1 and alpha-2, the dopamine receptors (D2), the G protein beta 3 subunit, the corticotropin releasing hormone receptors (CRHR1 and CRHR2), the glucocorticoid receptors, the c-AMP response-element binding, and the brain-derived neurotrophic factor. Marginal associations were reported for angiotensin I converting enzyme, circadian locomotor output cycles kaput protein, glutamatergic system, nitric oxide synthase, and interleukin 1-beta gene. In conclusion, gene variants seem to influence human behavior, liability to disorders and treatment response. Nonetheless, gene × environment interactions have been hypothesized to modulate several of these effects.

Investigation of serotonin transporter gene promoter (5-HTTLPR) and intron 2 (variable number of tandem repeats) polymorphisms with suicidal behavior in a Turkish population

The serotonin (5-hydroxytryptamine) transporter (5HTt) gene has been reported to be associated with suicidal behavior. In this study, we have investigated the 5' promoter region (i.e., 5HTt gene-linked polymorphic region [5-HTTLPR]) and a 17-base pair variable number of tandem repeats polymorphism in the 5HTt gene for potential association with suicidal behavior in a Turkish population. Genotypes were determined for 182 subjects of suicide (86 attempted suicide and 96 completed suicide) and 181 healthy control subjects. Our results showed that allele frequencies at individual loci were not significantly different in the two groups. This absence of altered individual locus haplotype (allele) frequency suggests the lack of a significant genetic contribution by the 5-HTTLPR or variable number of tandem repeats variations to the expression of suicidal tendencies. However, our linkage disequilibrium analyses indicated that there may be a greater risk for suicidal behavior in carriers of the S10 and L12 alleles of 5-HTTLPR.

The interpersonal theory of suicide

Suicidal behavior is a major problem worldwide and, at the same time, has received relatively little empirical attention. This relative lack of empirical attention may be due in part to a relative absence of theory development regarding suicidal behavior. The current article presents the interpersonal theory of suicidal behavior. We propose that the most dangerous form of suicidal desire is caused by the simultaneous presence of two interpersonal constructs-thwarted belongingness and perceived burdensomeness (and hopelessness about these states)-and further that the capability to engage in suicidal behavior is separate from the desire to engage in suicidal behavior. According to the theory, the capability for suicidal behavior emerges, via habituation and opponent processes, in response to repeated exposure to physically painful and/or fear-inducing experiences. In the current article, the theory's hypotheses are more precisely delineated than in previous presentations (Joiner, 2005), with the aim of inviting scientific inquiry and potential falsification of the theory's hypotheses.

Family history of suicidal behavior predicts impulsive-aggressive behavior levels in psychiatric outpatients

OBJECTIVES

Impulsive-aggressive traits have been proposed as mediators of the transmission of suicidal behavior in families. Our aim was to investigate the association between family history of suicidal behavior, and expressions of impulsivity and aggressive behavior, in a clinical population.

METHODS

A sample of n=474 psychiatric outpatient subjects were assessed by means of standardized interviews for Axis I and II psychopathology, history of suicidal behavior in subjects and their family, and measures of impulsive-aggressive behaviors (IAB).

RESULTS

A total of n=38 (8%) probands had a family history of suicidal behavior. This was three times more frequent in patients with a personal history of suicidality, irrespective of their own psychopathology (p<0.001), and four times more frequent in suicide attempters with depression vs. depressed non-attempters (p<0.005). A family history of suicidal behavior was associated with higher impulsive (p<0.005) and aggressive behavior measures (p<0.01) in probands.

LIMITATIONS

Retrospective design and family-history methodology; Limited sample; Contagion and imitation effects could not be assessed based on available data.

CONCLUSIONS

Impulsive-aggressive behaviors are significantly elevated in persons who have a familial loading of suicidal behavior.

How the serotonin story is being rewritten by new gene-based discoveries principally related to SLC6A4, the serotonin transporter gene, which functions to influence all cellular serotonin systems

Discovered and crystallized over sixty years ago, serotonin's important functions in the brain and body were identified over the ensuing years by neurochemical, physiological and pharmacological investigations. This 2008 M. Rapport Memorial Serotonin Review focuses on some of the most recent discoveries involving serotonin that are based on genetic methodologies. These include examples of the consequences that result from direct serotonergic gene manipulation (gene deletion or overexpression) in mice and other species; an evaluation of some phenotypes related to functional human serotonergic gene variants, particularly in SLC6A4, the serotonin transporter gene; and finally, a consideration of the pharmacogenomics of serotonergic drugs with respect to both their therapeutic actions and side effects. The serotonin transporter (SERT) has been the most comprehensively studied of the serotonin system molecular components, and will be the primary focus of this review. We provide in-depth examples of gene-based discoveries primarily related to SLC6A4 that have clarified serotonin's many important homeostatic functions in humans, non-human primates, mice and other species.

Association of the STin2 polymorphism of the serotonin transporter gene with a neurocognitive endophenotype in major depressive disorder

BACKGROUND

The aim of our study was to investigate the association of STin2 polymorphism and cognitive dysfunction in major depression.

METHODS

71 patients with major depression and 99 controls were genotyped for STin2. All depressive subjects and 30 controls also completed tests measuring neurocognitive performance.

RESULTS

We found a significantly higher frequency of the STin2.10/Stin2.10 homozygous genotype in the depressed group compared to controls. In the depressed group subjects with at least one copy of the 10-repeat allele showed decreased interference threshold in Stroop III compared to patients without the 10-repeat allele. Average performance of the depressed group without the 12-repeat allele was significantly weaker in the Rey Auditory Verbal Learning Test working memory and recall tasks compared to patients having at least one copy of the 12-repeat allele.

CONCLUSION

Our results suggest that the presence of STin2.10 and absence of STin2.12 allele may be related to a possible genetic endophenotype for characteristic cognitive dysfunctions detected in MDD.

The genetics of suicide: a critical review of molecular studies

Genetic epidemiology research has shown that genes contribute to suicide risk. Unfortunately, the first 30 years of candidate-based association studies have provided little information about the specific genetic contributors. This article reviews genetic association studies of suicidal phenotypes published to date. Possible theoretical, methodological, and operational challenges accounting for the modest success of association studies in the field are also discussed. The authors conclude that future research may benefit from using a more systematic and comprehensive selection of candidate genes and variants, examining gene-environment and gene-gene interactions, and investigating higher-order moderators.

Serotonin transporter gene polymorphisms: effect on serotonin transporter availability in the brain of suicide attempters

The efficacy of serotonin reuptake inhibitors in depression and anxiety disorders suggests the gene coding for the serotonin transporter (5-HTT), SLC6A4, as a candidate of importance for these conditions. Positive findings regarding associations between polymorphisms in SLC6A4 have been reported, indicating that these polymorphisms may influence anxiety-related personality traits, as well as the risk of developing depression and suicidality. Serotonin 5-HTT availability was assessed with single photon emission computed tomography (SPECT), using (123)I-beta-CIT as ligand, in a population of unmedicated male suicide attempters (n=9) and in matched controls (n=9). Two polymorphisms in SLC6A4 were assessed, including the 5-HTTLPR located in the promoter region and a variable number of tandem repeats (VNTR) polymorphism in intron 2 (STin2). In suicide attempters, but not in controls, low 5-HTT availability was associated with the S allele of 5-HTTLPR and with the 12 repeat allele of STin2. Data suggest that polymorphisms in SLC6A4 may influence the expression of the brain serotonin transporter in suicide attempters.

Effect of tryptophan hydroxylase-2 gene variants on suicide risk in major depression

BACKGROUND

Suicide and depressive disorders are strongly associated, yet not all depressed patients commit suicide. Genetic factors may partly explain this difference. We investigated whether variation at the tryptophan hydroxylase-2 (TPH2) gene and its 5' upstream region may predispose to suicide in major depressive disorder (MDD) and whether this predisposition is mediated by impulsive-aggressive behaviors (IABs).

METHODS

We genotyped 14 single nucleotide polymorphisms (SNPs) in 259 depressed subjects, 114 of which committed suicide while depressed. Phenotypic assessments were carried out by means of proxy-based interviews. Single-marker and haplotype association analyses were conducted. Differences in behavioral and personality traits according to genotypic variation were investigated, as well as genetic and clinical predictors of suicide.

RESULTS

We found two upstream and two intronic SNPs associated with suicide. No direct effect of these variants was observed on IABs. However, a slight association with reward dependence scores was found. Controlling for suicide risk factors, two SNPs (rs4448731 and rs4641527) significantly predicted suicide, along with cluster B personality disorders and family history of suicide.

CONCLUSIONS

The TPH2 gene and its 5' upstream region variants may be involved in the predisposition to suicide in MDD; however, our findings do not support the role of IABs as mediators.

The serotonin transporter gene: polymorphism and haplotype analysis in Russian suicide attempters

The focus on gender-specific genes associated with female suicide is justified by the possible dimorphic nature of the serotonergic system and by the greater number of suicide attempts in females. We performed analysis of the promoter (5-HTTLPR) and intron 2 (STin2 VNTR) polymorphisms and haplotypes of the serotonin transporter gene in Russian suicide attempters, separately in men and women. Our findings indicate the contribution of the SLC6A4 gene to susceptibility for suicidal behavior in women, but not in men. The L/L genotype (p = 0.013, OR = 2.09) and L10 haplotype (p = 0.04, OR = 1.77) were associated with suicide in Russian women only. Further investigations of this gene in different phenotypic groups are necessary.

Genetics of suicide

The concept that genetic factors contribute to the complex trait of suicidal behaviour has stimulated much work aimed at identifying susceptibility genes. So far molecular genetic studies focused on the serotonergic pathway as the intent to die and the lethality of suicide acts were related to the serotonergic system. Two genes have so far emerged as being involved in the vulnerability for suicidality: first, the intronic polymorphisms (A218C or A779C) of the tryptophan hydroxylase 1 (TPH1) gene, which was suggested as a quantitative risk factor for suicidal behaviour; second, the insertion/deletion polymorphism of the serotonin transporter gene (5-HTTLPR), which does not seem to be involved in general suicidal behaviour, but in violent and repeated suicide attempts. The data have further shown that the MAOA gene, which is consistently associated with impulsive-aggressive personality traits, is not related to suicide but might induce violent methods in subjects with other suicide risk factors. Predominantly negative were the findings with any type of the serotonin receptors and inconsistent with catecholamine-synthesizing and -metabolizing enzymes or with the dopaminergic receptors. This paper reviews the status of current knowledge in this area, points to the weakness of the investigations and presents new approaches beyond the serotonergic system.