Val/Met BDNF as a genetic risk for a false sense of security in post-discharge suicide risk

BACKGROUND

The time after discharge from psychiatric inpatient care is one of the most dangerous periods in terms of suicide risk. Predicting who is at higher risk could help with resource allocation to assure patients at high risk of suicide attempts are most closely followed. We previously showed that inpatients who improve their suicide ideation levels faster while in inpatient treatment are the ones with highest rates of post-discharge suicide. Here, we studied the possible genetic underpinnings associated with such risk.

METHOD

We recorded the slope of suicide ideation recovery of 710 psychiatric inpatients from which we studied two genetic variants likely associated with suicide risk: The serotonin transporter variant 5-HTTLPR, and the BDNF gene variant Val66Met.

RESULTS

We found that inpatients carrying the BDNF Met variant (hypothesized as conferring higher suicide risk) improved their suicide ideation scores faster than Val/Val carrying inpatients. No significant association was found for 5-HTTLPR.

LIMITATIONS

The present sample was genetically homogenous, and future research should replicate these findings on a more diverse sample.

CONCLUSIONS

In conclusion, we found a paradoxical result: Carrying the BDNF Met variant allows inpatients to improve faster, which was shown to confer higher risk at the post-discharge period. This may explain some inconsistencies in the literature in terms of the role of BDNF in suicide ideation and attempts.

Genetic and Phenotypic Profiling of Triptan Users in a Swedish Cluster Headache Cohort

Up to 25% of individuals who live with cluster headache (CH), an extremely painful primary headache disorder, do not adequately respond to the first-line treatment, triptans. Studies have indicated that genetic variants can play a role in treatment response. Likewise, differences in clinical characteristics can give clues to mechanisms underlying triptan non-response. Our aim was to investigate five genetic variants previously implicated in triptan response and their relation to triptan usage in our Swedish CH cohort and to investigate potential distinctions in clinical characteristics. 545 CH patients were screened for the genetic variants rs1024905, rs6724624, rs4795541, rs5443, and rs2651899 with a case control design based on triptan usage. Analysis of clinical characteristics was based on self-reported questionnaire data from 893 patients. One genetic variant, rs1024905, was significantly associated with triptan non-usage in CH (Pc = 0.010). In addition, multi-allele effector analysis showed that individuals with a higher number of effector variants were less likely to use triptans (P = 0.007). Analysis of clinical characteristics showed that triptan users were more likely to have alcohol as a trigger (57.4% vs 43.4%, P = 0.002), have autonomic symptoms (95.1% vs 88.1%, P = 0.002), and be current smokers (27.0% vs 21.9%, P = 0.033) compared to non-users. These results support the hypothesis that genetic variants can play a role in triptan usage in CH and that patients with a typical CH phenotype are more likely to use triptans.

Genetic Markers Associated with Postpartum Depression: A Review

Postpartum depression (PPD) is a common illness in mothers after childbirth. PPD negatively affect the mother's quality of life and the bond with the infant, which can interfere with the infant's emotional, social, and cognitive development. PPD is caused by various biological and psychosocial factors. The aim of this review is to summarize the latest evidence of the associations between genetic polymorphisms and PPD. PubMed and Scopus were used as the literature search databases for this review. The keywords used were postpartum depression, postnatal depression, genetic, and polymorphism. Twenty-seven articles were reviewed after screening and applying the inclusion criteria. As results, the serotonin gene (5-HTTLPR) and oxytocin genes (OXTR) have the most significant associations with PPD among other genes. Further research on PPD biomarkers should be conducted to diagnose and treat PPD patients.

Interaction of 5-HTTLPR and SLE disease status on resting-state brain function

BACKGROUND

Neuropsychiatric involvement in systemic lupus erythematosus (SLE) is a common clinical manifestation. In SLE patients, cerebral function is a more sensitive predictor of central nervous system damage, and abnormalities in cerebral function may be apparent before substantial neuropsychiatric symptoms occur. The 5-hydroxynyptamine(5-HT) system has the ability to interact with the majority of the neurochemical systems in the central nervous system (CNS), influencing brain function. Serotonin transporter gene-linked polymorphic region (5-HTTLPR) is an essential element of the 5-HT system gene polymorphism and is directly related to the control of 5-hydroxytryptamine transporter (5-HTT)gene expression. The relationship between 5-HTTLPR and functional brain measurements in SLE patients requires more investigation because it is one of the most attractive imaging genetics targets for shedding light on the pathophysiology of neuropsychiatric lupus.

METHODS

Resting-state functional magnetic resonance imaging (rs-fMRI) images were collected from 51 SLE patients without obvious neuropsychiatric manifestations and 44 healthy volunteers. Regional homogeneity (ReHo), amplitude of low-frequency fluctuations (ALFF), and fractional amplitude of low-frequency fluctuations (fALFF) were selected as indicators for evaluating brain function. In accordance with the Anatomical Automatic Labeling template, the gray matter was divided into 116 regions. The mean ReHo value, mean ALFF value, and mean fALFF value of each brain region were extracted. 5-HTTLPR genotypes of all research objects were tested by polymerase chain reaction and agarose gel electrophoresis. Two-way analysis of covariance was used to investigate whether there is an interaction effect between SLE disease status and 5-HTTLPR genotype on resting-state brain function.

RESULTS

In SLE patients with S/S homozygosity, there were notably lower mean ReHo, mean ALFF, and mean fALFF values observed in the right parietal, inferior angular gyrus, and the right paracentral lobule compared to healthy controls. However, this distinction was not evident among carriers of the L allele. Within the S/S genotype, SLE patients exhibited decreased mean ReHo in the left posterior cingulate gyrus, reduced mean fALFF in the left caudate nucleus, and diminished mean ALFF in the left temporal pole: superior temporal gyrus, in contrast to the HC group. Conversely, no such differences were discerned among carriers of the L allele. Notably, among L allele carriers, SLE patients displayed a higher mean ReHo value in the right hippocampus compared to the HC group, while demonstrating a lower mean ALFF value in the left medial and paracingulate gyrus in contrast to the HC group. Conversely, these differences were not apparent among S/S homozygotes.

CONCLUSIONS

Brain function in the right parietal and inferior angular gyrus and the right paracentral lobule is affected by the interaction effect of SLE disease status and 5-HTTLPR genotype.

The S/S Genotype of the 5-HTTLPR (Serotonin-Transporter-Linked Promoter Region) Variant of the SLC6A4 Gene Decreases the Risk of Pre-Eclampsia

Pre-eclampsia (PE) is a disorder characterized by hypertension in the second trimester of pregnancy that results from abnormal placentation affecting fetal development and maternal health. Previous studies have shown the role of serotonin (5-HT) that leads to poor placental perfusion, where S/S and S/L polymorphisms promote the solute carrier family 6 member 4 (SLC6A4) gene associated with the risk of developing changes in the microvasculature of the placenta. This study looked at the association between the gene variant 5-HTTLPR (serotonin-transporter-linked promoter region) of the SLC6A4 gene and the occurrence of PE. A total of 200 women were included: 100 cases (pregnant with PE) and 100 controls (pregnant without complications). Genotyping of the 5-HTTLPR variant was performed using polymerase chain reaction (PCR). Associations between the presence of the genetic variant of interest and PE and other clinical features were evaluated statistically. The frequencies of S/S, S/L, and L/L genotypes were 32%, 53%, and 15% for the cases and 55%, 25%, and 20% in the control group. Compared to the controls, the genotype frequencies S/S vs. S/L + L/L (recessive model) in the cases group were different (p = 0.002). The S/S genotype decreased the probability of PE (OR = 0.39, 95% IC: 0.22-0.69, p = 0.002) and PE with severity criteria (OR = 0.39, 95% IC: 0.17-0.91, p = 0.045). The 5-HTTLPR gene variant of the SLC6A4 gene modifies the risk of PE development among the studied population.

The long and the short of it: 5-HTTLPR and moral judgement

Differences in moral sentiments are widespread. Increasingly, their biological correlates are investigated to elucidate potential sources of divergent moral attitudes and choices. Serotonin is one such potential modulator. We investigated the effects of a functional serotonergic polymorphism, 5-HTTLPR, which was previously linked to moral choices albeit with inconsistent findings. N = 157 healthy young adults completed a set of congruent and incongruent moral dilemmas. In addition to the traditional moral response score, this set allows by using a process dissociation (PD) approach an estimation a deontological and a utilitarian parameter. While there was no main effect of 5-HTTLPR on any of the three moral judgement parameters, there was an interaction effect between 5-HTTLPR and endocrine status on PD parameters, which was mainly due to the deontological but not the utilitarian parameter. In men and free cycling women, LL homozygotes showed reduced deontological tendencies compared to S allele carriers. Contrariwise, in women using oral contraceptives, LL homozygotes had increased deontology parameter scores. Furthermore, LL genotypes in general reported less difficulty in making harmful choices, which were in addition associated with less negative emotions. The findings suggest that 5-HTTLPR might be involved in modulating cognitive and emotional processes contributing to moral decisions.

Altered DNA Methylation of the Serotonin Transporter Gene Associated with Early Life Stress and White Matter Microalterations in Korean Patients with Panic Disorder

INTRODUCTION

Changes in the DNA methylation of 5-HTTLPR are associated with the pathophysiology of panic disorder (PD). This study was conducted to investigate the association between stressful life events and the level of 5-HTTLPR methylation in patients with PD. We also examined whether these factors were associated with white matter alterations in psychological trauma-related regions.

METHODS

The participants comprised 232 patients with PD and 93 healthy adults of Korean descent. DNA methylation levels of five cytosine-phosphate-guanine (CpG) sites in the 5-HTTLPR region were analyzed. Voxel-wise statistical analysis of diffusion tensor imaging data was performed within the trauma-related regions.

RESULTS

PD patients showed significantly lower levels of the DNA methylation at 5-HTTLPR 5 CpG sites than healthy controls. In patients with PD, the DNA methylation levels at 5-HTTLPR 5 CpG sites showed significant negative association with the parental separation-related psychological distress, and positive correlations with the fractional anisotropy values of the superior longitudinal fasciculus (SLF) which might be related to trait anxiety.

CONCLUSION

Early life stress was significantly associated with DNA methylation levels at 5-HTTLPR related to the decreased white matter integrity in the SLF region in PD. Decreased white matter connectivity in the SLF might be related to trait anxiety and is vital to the pathophysiology of PD.

The Relationship between Maternal Antibodies to Fetal Brain and Prenatal Stress Exposure in Autism Spectrum Disorder

Environmental and genetic factors contribute to the etiology of autism spectrum disorder (ASD), but their interaction is less well understood. Mothers that are genetically more stress-susceptible have been found to be at increased risk of having a child with ASD after exposure to stress during pregnancy. Additionally, the presence of maternal antibodies for the fetal brain is associated with a diagnosis of ASD in children. However, the relationship between prenatal stress exposure and maternal antibodies in the mothers of children diagnosed with ASD has not yet been addressed. This exploratory study examined the association of maternal antibody response with prenatal stress and a diagnosis of ASD in children. Blood samples from 53 mothers with at least one child diagnosed with ASD were examined by ELISA. Maternal antibody presence, perceived stress levels during pregnancy (high or low), and maternal 5-HTTLPR polymorphisms were examined for their interrelationship in ASD. While high incidences of prenatal stress and maternal antibodies were found in the sample, they were not associated with each other (p = 0.709, Cramér's V = 0.051). Furthermore, the results revealed no significant association between maternal antibody presence and the interaction between 5-HTTLPR genotype and stress (p = 0.729, Cramér's V = 0.157). Prenatal stress was not found to be associated with the presence of maternal antibodies in the context of ASD, at least in this initial exploratory sample. Despite the known relationship between stress and changes in immune function, these results suggest that prenatal stress and immune dysregulation are independently associated with a diagnosis of ASD in this study population, rather than acting through a convergent mechanism. However, this would need to be confirmed in a larger sample.

Insights into the molecular genetic basis of individual differences in metacognition

There is a striking lack of studies on the molecular genetic basis of metacognition, i.e., the higher-order ability to monitor mental processes. Here, an initial step toward resolving this issue was undertaken by investigating functional polymorphisms from three genes of the dopaminergic or serotonergic systems (DRD4, COMT, and 5-HTTLPR) in relation to behaviorally assessed metacognition in six paradigms across three cognitive domains. We report evidence for a task-dependent higher average confidence level (metacognitive bias) in carriers of at least one S or L_G-allele in the 5-HTTLPR genotype and integrate these findings within a differential susceptibility framework.

Association Study of BDNF, SLC6A4, and FTO Genetic Variants with Schizophrenia Spectrum Disorders

Schizophrenia spectrum disorders (patients with a diagnosis of schizophrenia, schizotypal, and delusional disorders: F20-F29 according to International Classification of Diseases 10th revision (ICD-10)) are considered highly heritable heterogeneous psychiatric conditions. Their pathophysiology is multifactorial with involved dysregulated serotonergic neurotransmission and synaptic plasticity. The present study aimed to evaluate the association of SLC6A4 (5-HTTLPR), FTO (rs9939609), and BDNF (rs6265, rs962369) polymorphisms with schizophrenia spectrum disorders in Slovak patients. We analyzed the genotypes of 150 patients with schizophrenia, schizotypal, and delusional disorders and compared them with genotypes from 178 healthy volunteers. We have found a marginally protective effect of LS + SS genotypes of 5-HTTLPR variant of the serotonin transporter SLC6A4 gene against the development of schizophrenia spectrum disorders, but the result failed to remain significant after Bonferroni correction. Similarly, we have not proven any significant association between other selected genetic variants and schizophrenia and related disorders. Studies including a higher number of subjects are warranted to reliably confirm the presence or absence of the studied associations.

Effects of serotonin transporter and receptor polymorphisms on depression

INTRODUCTION

Serotonin is highly implicated in the regulation of emotional state and the execution of cognitive tasks, so much so that the serotonin transporter genes (5-HTT, SLC6A4) and the serotonin receptor genes (HTR1A, HTR1B, HTR2A) have become the perfect candidates when studying the effects that these genes and their polymorphic variations have on depression characteristics.

OBJECTIVE

A review of research reports that have studied the effects of variations in the serotonin transporter and receptor genes on different clinical features of depression.

METHODS

A search of the Scopus, Web of Science and PubMed databases was conducted using the keywords ("depression" AND "polymorphism").

CONCLUSIONS

According to the review of 54 articles, the short allele of the 5-HTTLPR polymorphism was found to be the most reported risk factor related to the development of depression and its severity. Variations in the genes studied (SLC6A4, HTR1A, HTR2A) can generate morphological alterations of brain structures.

Meta-Analysis of the Association Between 5-Hydroxytryptamine Transporter Gene-Linked Polymorphic Region and Functional Dyspepsia and its Subtypes

Background: Association studies of variations in the 5-hydroxytryptamine (5-HT, serotonin) transporter gene-linked polymorphic region (5-HTTLPR) and functional dyspepsia (FD) have yielded contradictory results. Hence, we performed a meta-analysis to clarify inconsistencies between the 5-HTTLPR polymorphism with FD and it subtypes. Methods: We performed a literature search in PubMed, Embase, Web of Science, Cochrane Library, and CNKI, including articles published until March 2022. We calculated and pooled odds ratios (ORs) with their 95% confidence intervals (CIs) in Stata 15.0. Data extraction was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and Cochrane Handbook for Systematic Reviews of Interventions. Results: The meta-analysis included six studies, comprising 488 cases and 1513 healthy controls. We did not observe a significant association between the 5-HTTLPR polymorphism and FD in the overall population. In subgroup analyses, the 5-HTTLPR polymorphism was significantly associated with FD-subtype epigastric pain syndrome (EPS) (SS vs. LL+LS, OR = 0.620, 95% CI: 0.414-0.930; SS vs. LS, OR = 0.640, 95% CI: 0.417-0.980; S vs. L, OR = 0.655, 95% CI: 0.471-0.911). However, no association was observed with the other subtype, postprandial distress syndrome (PDS). Conclusion: While the 5-HTTLPR polymorphism had no relationship with FD overall, splitting the disease into its subtypes revealed a clear association with EPS.

COMT but Not 5HTTLPR Gene Is Associated with Depression in First-Episode Psychosis: The Role of Stressful Life Events

Serotonergic and dopaminergic systems are involved in the regulation of mood and reactivity to psychological stress. This study explores, in a sample of first episode psychosis (FEP) patients, whether more severe depressive symptoms were found in those who: (1) experienced a major stressful event in the 6 months preceding illness onset; and (2) were homozygous for the COMT Val158 allele or carrying the S allele of 5-HTTLPR. A total of 186 FEP patients recruited were assessed using the Hamilton Rating Scale for Depression (HAMD) for depressive symptoms. Stressful life events (SLEs) were collected by the List of Events Scale. The genotypes of 5-HTTLPR, rs25531, and COMT Val158 Met were performed. It has been found that higher levels of depression is associated with the presence of SLEs (p = 0.019) and with COMT Val158 allele homozygosity (p = 0.029), but not with carrying the S allele of 5-HTTLPR. The COMT gene moderates the association between depression and SLEs as Val158 allele homozygote patients experiencing SLEs had the highest level of depressive symptoms compared to the others (p = 0.002). The present study provides initial evidence for an effect of the COMT Val158 homozygosity and severe stressful life events on the severity of depressive symptoms in first episode psychosis.

Hypermethylation of the serotonin transporter gene and paternal parenting styles in untreated anorexia nervosa patients: A pilot study

Purpose

It has been reported that serotonergic systems and parenting styles are involved in the pathogenesis of anorexia nervosa (AN). The present study made attempts to examine the DNA methylation profiles in the promoter region of serotonin transporter (5-HTT) encoding gene SLC6A4, and explore the association between the methylation level and severity of symptoms, 5-HTT linked polymorphic region (5-HTTLPR) genotypes and parenting styles in untreated Chinese Han AN patients.

Methods

Ninety-one untreated female AN patients (ANs) and eighty-seven matched healthy controls (HCs) were analyzed for DNA methylation status at CpG islands in the promoter region of SLC6A4 using MassARRY EpiTYPER, and genotypes of 5-HTTLPR using PCR-RFLP. The severity of eating disorder (ED) symptoms was evaluated by body mass index (BMI) and Questionnaire Version of the Eating Disorders Examination (EDE-Q 6.0), and part of participants were assessed parenting styles using the short Chinese Egna Minnen av Barndoms Uppfostra (s-EMBU-C).

Results

ANs had greater methylation levels at CpG26.27.28, CpG 31.32, and CpG 37 than HCs (P = 0.039, 0.042, 0.018 respectively). A positive association of methylation level at CpG26.27.28 with ED symptoms detected by EDEQ-6.0 was discovered in AN group (r = 0.216, P = 0.047). Methylation level at CpG26.27.28 was showed to be or tend to be positively correlated with the parenting styles of paternal rejection (r = 0.425, P = 0.038) and paternal overprotection (r = 0.362, P = 0.062) in ANs. No significant differences were found in SLC6A4 promoter region methylation levels among 5-HTTLPR genotypes in our samples (P > 0.05) and no interaction effect between 5-HTTLPR genotypes and parenting styles on SLC6A4 promoter region methylation was observed (P > 0.05).

Conclusions

This study suggested that hypermethylation of SLC6A4 promoter region may be implicated in the pathological mechanisms of untreated Chinese Han female ANs, which is possibly associated with poor parenting styles. This finding may provide a direction for the epigenetic and family treatments for ANs and further investigation with larger samples is warranted.

Deciphering the Effect of Different Genetic Variants on Hippocampal Subfield Volumes in the General Population

The aim of this study was to disentangle the effects of various genetic factors on hippocampal subfield volumes using three different approaches: a biologically driven candidate gene approach, a hypothesis-free GWAS approach, and a polygenic approach, where AD risk alleles are combined with a polygenic risk score (PRS). The impact of these genetic factors was investigated in a large dementia-free general population cohort from the Study of Health in Pomerania (SHIP, n = 1806). Analyses were performed using linear regression models adjusted for biological and environmental risk factors. Hippocampus subfield volume alterations were found for APOE ε4, BDNF Val, and 5-HTTLPR L allele carriers. In addition, we were able to replicate GWAS findings, especially for rs17178139 (MSRB3), rs1861979 (DPP4), rs7873551 (ASTN2), and rs572246240 (MAST4). Interaction analyses between the significant SNPs as well as the PRS for AD revealed no significant results. Our results confirm that hippocampal volume reductions are influenced by genetic variation, and that different variants reveal different association patterns that can be linked to biological processes in neurodegeneration. Thus, this study underlines the importance of specific genetic analyses in the quest for acquiring deeper insights into the biology of hippocampal volume loss, memory impairment, depression, and neurodegenerative diseases.

Genome-wide gene-gene interaction of the 5-HTTLPR promoter polymorphism emphasizes the important role of neuroplasticity in depression

Recent genome-wide association studies (GWAS) have identified numerous single nucleotide polymorphisms affecting depressive disorders. GWAS results support the heterogeneity of depression as a disorder affected by a large number of genetic variants with mainly small effect sizes. However, not much is known about the interplay of different genetic risk factors. Moreover, recent studies are questioning the role of common candidate genes in the development of depressive disorders. One such candidate variant is the serotonin-transporter-promoter-polymorphism 5-HTTLPR in the SLC6A4 gene. We hypothesize that 5-HTTLPR exerts its effect on depressive disorders in interaction with other genetic variants. In the present study we test this hypothesis using a genome-wide gene-gene interaction approach on a large sample from the UK Biobank (N = 127,558). We identified a region in the DPF1 gene that displayed a genome-wide significant (p = 3.31 × 10^-7) interaction effect with the biallelic version of 5-HTTLPR on lifetime depression. DPF1 has not previously been described as risk factor for depressive disorders but is exclusively expressed in the brain as a major regulator of neuronal development and neuroplasticity. This study stresses the need for further analyses that take into consideration the fact that genetic variants do operate in biological networks.

Emotional valence of self-defining memories in older adults: A longitudinal study

The present study aimed to evaluate the pleasantness bias and fading affect bias in self-defining memories (SDMs) and to examine the relationship between their emotional valence of SDMs and cognitive function and serotonin transporter polymorphisms (5-HTTLPR) with a prospective longitudinal method. Ninety-two older adults recalled SDMs twice at an interval of one year (T1 and T2). The results showed a pleasantness bias and a fading affect bias in SDMs. The higher the working memory was, the higher the vividness of SDMs and the higher the concordance rate of SDMs between T1 and T2. Meanwhile, cognitive performance had no effect on the emotional valence of SDMs. Additionally, the repeatedly recalled SDMs in the S/S allele carriers of the 5-HTTLPR polymorphism changed with a lower negative valence at T2 than at T1. The 5-HTTLPR polymorphism may be a plasticity factor that predicts positive outcomes in positive situations.

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.

Respiratory Sinus Aarrhythmia (RSA) stress response in preschool age varies by serotonin transporter polymorphism (5-HTTLPR): A preliminary report

The serotonin transporter promoter region polymorphism (5-HTTLPR) has been implicated in stress regulation, with increased stress reactivity often being found in carriers of the low-expressing short (S) allele. Nevertheless, the role of the 5-HTTLPR in influencing parasympathetic stress reactivity, as indexed by Respiratory Sinus Arrhythmia (RSA), is still unknown. This study examined, for the first time, whether the 5-HTTLPR was associated with variations in RSA response to maternal separation in a sample of 69 healthy 5-year-old children. Preschoolers' RSA was measured during an age-adapted version of the Strange Situation Procedure (SSP). The 5-HTTLPR polymorphism was tested as a predictor of RSA dynamic response to the SSP through multilevel models. A significant interaction between 5-HTTLPR and SSP episodes was found. In particular, whereas a significant decrease in RSA levels was observed during the stranger episode in the whole sample, S allele carriers showed a significant decrease in RSA levels from the stranger episode to the first separation episode, followed by an increase for the rest of the procedure. Albeit preliminary, data support the view that the 5-HTTLPR may contribute to individual differences in RSA stress reactivity from preschool age.

The Influence of 5-HTTLPR, BDNF Rs6265 and COMT Rs4680 Polymorphisms on Impulsivity in Bipolar Disorder: The Role of Gender

Impulsivity has been proposed as an endophenotype for bipolar disorder (BD); moreover, impulsivity levels have been shown to carry prognostic significance and to be quality-of-life predictors. To date, reports about the genetic determinants of impulsivity in mood disorders are limited, with no studies on BD individuals. Individuals with BD and healthy controls (HC) were recruited in the context of an observational, multisite study (GECOBIP). Subjects were genotyped for three candidate single-nucleotide polymorphisms (SNPs) (5-HTTLPR, COMT rs4680, BDNF rs6265); impulsivity was measured through the Italian version of the Barratt Impulsiveness Scale (BIS-11). A mixed-effects regression model was built, with BIS scores as dependent variables, genotypes of the three polymorphisms as fixed effects, and centers of enrollment as random effect. Compared to HC, scores for all BIS factors were higher among subjects with euthymic BD (adjusted β for Total BIS score: 5.35, p < 0.001). No significant interaction effect was evident between disease status (HC vs. BD) and SNP status for any polymorphism. Considering the whole sample, BDNF Met/Met homozygosis was associated with lower BIS scores across all three factors (adjusted β for Total BIS score: −10.2, p < 0.001). A significant 5-HTTLPR x gender interaction was found for the SS genotype, associated with higher BIS scores in females only (adjusted β for Total BIS score: 12.0, p = 0.001). Finally, COMT polymorphism status was not significantly associated with BIS scores. In conclusion, BD diagnosis did not influence the effect on impulsivity scores for any of the three SNPs considered. Only one SNP—the BDNF rs6265 Met/Met homozygosis—was independently associated with lower impulsivity scores. The 5-HTTLPR SS genotype was associated with higher impulsivity scores in females only. Further studies adopting genome-wide screening in larger samples are needed to define the genetic basis of impulsivity in BD.

5-HTT genotype and inertia of negative affect in adolescents and young adults from the general population

The study aims to replicate the previous found association of 5-HTTLPR and inertia of negative affect in daily life of adolescents and young adults. Data of 877 adolescents (aged 14–21 years) of the Behavior and Mind Health (BeMIND) study (epidemiological cohort study, Dresden, Germany) were genotyped for 5-HTTLPR/rs25531, grouped into SS/SL_G/SL_A/L_GL_A/L_GL_G vs. L_AL_A, and provided ratings on negative affect items, depression and anxiety (Patient-Reported Outcomes Measurement Information System) eight times a day over 4 days. Multilevel regression models did not reveal an association of 5-HTTLPR genotype and inertia of negative affect, nor associations with inertia of anxiety or depression. Inertia of negative affect seems not to be a psychological mechanism through which 5-HTTLPR acts on psychopathology.

Association of Serotonin Transporter Gene (5-HTTLPR/rs25531) Polymorphism with Comorbidities of Panic Disorder

INTRODUCTION

Panic disorder (PD) has many comorbidities such as depression, bipolar disorder (BPD), and agoraphobia (AG). PD is a moderately heritable anxiety disorder whose pathogenesis is not well understood. Recently, a tri-allelic serotonin transporter (5-HTTLPR/rs25531) polymorphism was reported to be more sensitive to personality traits compared to the bi-allelic 5-HTTLPR polymorphism. We hypothesized that the 5-HTTLPR/rs25531 polymorphism may lead to a pathological anxious state depending on the presence or absence of a comorbidity in PD.

METHODS

In this study, we investigated the relationship between comorbidities in PD and tri-allelic 5-HTTLPR polymorphisms. A total of 515 patients with PD (148 males, 367 females) were genotyped, and the Revised NEO Personality Inventory as well as anxiety-related psychological tests were administered. Depression, BPD, and AG were diagnosed as comorbidities.

RESULTS

For the tri-allele 5-HTTLPR genotype, a significant interaction effect was found between openness to experience and comorbid depression. Examination of the interaction between AG and the tri-allelic 5-HTTLPR genotype revealed that L' allele carriers are associated with higher trait anxiety than the S'S' genotype group in PD without AG.

CONCLUSION

Some anxiety and personality traits can be characterized by the tri-allelic gene effect of 5-HTTLPR. These results suggest that tri-allelic 5-HTTLPR genotypes have genetic effects on the presence of comorbidities of PD.

Serotonin Transporter Genetic Variation and Antidepressant Response and Tolerability: A Systematic Review and Meta-Analysis

Antidepressants are used to treat several psychiatric disorders; however, a large proportion of patients do not respond to their first antidepressant therapy and often experience adverse drug reactions (ADR). A common insertion–deletion polymorphism in the promoter region (5-HTTLPR) of the serotonin transporter (SLC6A4) gene has been frequently investigated for its association with antidepressant outcomes. Here, we performed a systematic review and meta-analysis to assess 5-HTTLPR associations with antidepressants: (1) response in psychiatric disorders other than major depressive disorder (MDD) and (2) tolerability across all psychiatric disorders. Literature searches were performed up to January 2021, yielding 82 studies that met inclusion criteria, and 16 of these studies were included in the meta-analyses. Carriers of the 5-HTTLPR LL or LS genotypes were more likely to respond to antidepressant therapy, compared to the SS carriers in the total and European ancestry-only study populations. Long (L) allele carriers taking selective serotonin reuptake inhibitors (SSRIs) reported fewer ADRs relative to short/short (SS) carriers. European L carriers taking SSRIs had lower ADR rates than S carriers. These results suggest the 5-HTTLPR polymorphism may serve as a marker for antidepressant outcomes in psychiatric disorders and may be particularly relevant to SSRI treatment among individuals of European descent.

Effects of Serotonin Transporter and Receptor Polymorphisms on Depression

INTRODUCTION

Serotonin is highly implicated in the regulation of emotional state and the execution of cognitive tasks, so much so that the serotonin transporter genes (5-HTT, SLC6A4) and the serotonin receptor genes (HTR1A, HTR1B, HTR2A) have become the perfect candidates when studying the effects that these genes and their polymorphic variations have on depression characteristics.

OBJECTIVE

A review of research reports that have studied the effects of variations in the serotonin transporter and receptor genes on different clinical features of depression.

METHODS

A search of the Scopus, Web of Science and PubMed databases was conducted using the keywords ("depression" AND "polymorphism").

CONCLUSIONS

According to the review of 54 articles, the short allele of the 5-HTTLPR polymorphism was found to be the most reported risk factor related to the development of depression and its severity. Variations in the genes studied (SLC6A4, HTR1A, HTR2A) can generate morphological alterations of brain structures.

Associations of the MAOA uVNTR genotype and 5-HTTLPR/rs25531 haplotype with psychopathic traits

Previous studies have linked polymorphisms of the monoamine oxidase A (MAOA uVNTR) and serotonin transporter gene (5-HTTLPR) to individual differences in the expression of psychopathic traits, but findings remain inconsistent. One possible reason is that these studies have treated psychopathy as a unitary construct when there is accumulating evidence that there are variants or subtypes. We used a variable-centered and a person-centered approach by (a) examining putative genetic correlates of psychopathy across individuals and (b) comparing the frequencies of the MAOA uVNTR genotype and 5-HTTLPR/rs25531 haplotype between empirically derived subtypes of psychopathy, respectively. Notably, we included the often neglected rs25531 polymorphism, which is closely connected to the 5-HTTLPR. Based on data from male offenders and community volunteers, structural equation modeling indicated that the 5-HTTLPR/rs25531 haplotype was specifically associated with interpersonal deficits beyond the overarching psychopathy construct. Latent profile analysis revealed four clusters that were labeled non-psychopaths, sociopaths, callous-conning, and psychopaths. The low-activity variant of the 5-HTTLPR/rs25531 haplotype was significantly more frequent in the callous-conning compared to the non-psychopathic subtype. There were no effects for the MAOA uVNTR. The results illustrate that psychopathy should not be treated as a unitary construct but that there are variants with specific profiles of psychopathic traits, and that the 5-HTTLPR/rs25531 haplotype plays a role in the manifestation of interpersonal deficits from a variable-centered as well as from a person-centered view.

Maternal serotonin transporter genotype and offsprings' clinical and cognitive measures of ADHD and ASD

Serotonin (5-HT) is an important factor for prenatal neurodevelopment whereby its neurotrophic actions can be regulated through maternal-fetal interactions. We explored if maternal 5-HTTLPR genotype is associated with clinical and cognitive measures of attention-deficit/hyperactivity disorder (ADHD) and comorbid autism spectrum disorder (ASD) in typically-developing and ADHD-diagnosed offspring, beyond classical inheritance and environmental- and comorbidity-mediators/confounders. Family-based variance decomposition analyses were performed incorporating 6-31 year-old offsprings' as well as parental genotypes of 462 ADHD and control families from the NeuroIMAGE cohort. Dependent measures were offsprings' ADHD symptom- and ASD trait-scores and cognitive measures including executive functioning (including response inhibition and cognitive flexibility), sustained attention, reward processing, motor control, and emotion recognition. Offsprings' stereotyped behavior was predicted by an interaction between maternal 5-HTTLPR genotype and offsprings' sex. Furthermore, offspring of mothers with low-expressing genotypes demonstrated larger reward-related reductions in reaction time. While specifically adult male offspring of these mothers reported a faster reversal learning with less errors, specifically young female offspring of these mothers were more accurate in identifying happy faces. Adult offspring from the mothers with low-expressing 5-HTTLPR genotypes were also slower in identifying happy faces. However, this association seemed to be mediated by offsprings' high anxiety levels. In sum, we found some support for a role of the maternal 5-HT system in modulating fetal brain development and behavior. Offsprings' cognitive measures might be more sensitive to small alterations within the maternal 5-HT system than their ADHD and ASD clinical phenotypes. Further studies are needed to specify the association between maternal genotype and risk for neurodevelopmental disorders.

The association of the 5-HTTLPR polymorphism and the response to different stressors in healthy males

The experience of stress is related to individual wellbeing and vulnerability to psychopathology. Therefore, understanding the determinants of individual differences in stress reactivity is of great concern from a clinical perspective. The functional promotor polymorphism of the serotonin transporter gene (5-HTTLPR/rs25531) is such a factor, which has been linked to the acute stress response as well as the adverse effect of life stressors. In the present study, we compared the impact of two different stress induction protocols (Maastricht Acute Stress Test and ScanSTRESS) and the respective control conditions on affective ratings, salivary cortisol levels and cognitive performance. To this end, 156 healthy young males were tested and genotyped for the 5-HTTLPR/rs25531 polymorphism. While combined physiological and psychological stress in the MAST led to a greater cortisol increase compared to control conditions as well as the psychosocial ScanSTRESS, subjective stress ratings were highest in the ScanSTRESS condition. Stress induction in general affected working memory capacity but not response inhibition. Subjective stress was also influenced by 5-HTTLPR/rs25531 genotype with the high expression group showing lower stress ratings than lower expression groups. In line with previous research, we identified the low expression variant of the serotonin transporter gene as a risk factor for increased stress reactivity. While some dimensions of the human stress response may be stressor specific, cognitive outcomes such as working memory performance are influenced by stress in general. Different pathways of stress processing and possible underlying mechanisms are discussed.

5-HTTLPR polymorphism and depression risk in Parkinson's disease: an updated meta-analysis

The relationship between the 5-hydroxytryptamine transporter gene-linked polymorphic region (5-HTTLPR) and depression in Parkinson's disease (PD) has remained controversial. Therefore, we conducted this meta-analysis to evaluate the relationship between 5-HTTLPR polymorphisms and depression in PD. Relevant online databases were searched for cross-sectional, case-control or cohort studies examining relations between 5-HTTLPR polymorphisms (S/L) and the risk of developing depression of PD using a meta-analysis. Odd ratios (ORs) of 5-HTTLPR polymorphisms (S/L allele genotype) were calculated between depression in PD and PD for each study. Five observational studies were identified. Overall ORs for 5-HTTLPR S-Allele genotype was 1.98 (95% CI 0.92-4.26) in the dominant model, 1.43 (95% CI 1.08-1.90) in the recessive model, 2.64 (95% CI 1.01-6.88) in the additive model, independently. The overall ORs of S-Allele genotype was 1.51 (95% CI 0.63-3.64) for the Caucasian subgroup, and 1.44 (95% CI 1.05-1.98) for the non-Caucasian subgroup in the recessive model. This meta-analysis indicates that the 5-HTTLPR genotype (S/S-Allele) is correlated with an increased depression risk in PD, and this highlights the needs for these people to take some effective approaches (if any) in prevention of depression of PD before its onset.

Genetic risk factors for autism-spectrum disorders: a systematic review based on systematic reviews and meta-analysis

BACKGROUND

Based on recent evidence, more than 200 susceptibility genes have been identified to be associated with autism until now. Correspondingly, cytogenetic abnormalities have been reported for almost every chromosome. While the results of multiple genes associated with risk factors for autism are still incomplete, this paper systematically reviews published meta-analyses and systematic reviews of evidence related to autism occurrence.

METHOD

Literature search was conducted in the PubMed system, and the publication dates were limited between January 2000 and July 2020. We included a meta-analysis and systematic review that assessed the impact of related gene variants on the development of autism. After screening, this comprehensive literature search identified 31 meta-analyses and ten systematic reviews. We arranged the genes related to autism in the published studies according to the order of the chromosomes, and based on the results of a meta-analysis and systematic review, we selected 6 candidate genes related to ASD, namely MTHFR C677T, SLC25A12, OXTR, RELN, 5-HTTLPR, SHANK, including basic features and functions. In addition to these typical genes, we have also listed candidate genes that may exist on almost every chromosome that are related to autism.

RESULTS

We found that the results of several literature reviews included in this study showed that the MTHFR C667T variant was a risk factor for the occurrence of ASD, and the results were consistent. The results of studies on SLC25A12 variation (rs2056202 and rs2292813) and ASD risk were inconsistent but statistically significant. No association of 5-HTTLPR was found with autism, but when subgroup analysis was performed according to ethnicity, the association was statistically significant. RELN variants (rs362691 and rs736707) were consistent with ASD risk studies, but some of the results were not statistically significant.

CONCLUSION

This review summarized the well-known ASD candidate genes and listed some new genes that need further study in larger sample sets to improve our understanding of the genetic basis of ASD, but sample size and heterogeneity remain major limiting factors in some genome-wide association studies. We also found that common genetic variants in some genes may be co-risk factors for autism or other neuropsychiatric disorders when we collated these results. It is worth considering screening for these mutations in clinical applications.

Effects of Polymorphisms in the Serotonin Transporter Promoter-Linked Polymorphic Region on Postthoracotomy Pain Severity

Purpose

Serotonin (5-HT) is highly associated with pain modulation. The human 5-HT transporter (5-HTT) gene (SLC6A4) features several polymorphisms in its promoter region (5-HTTLPR) that affect the 5-HTT expression. The S allele of 5-HTTLPR induces low 5-HT tone, and it may influence the modulation of chronic pain. Meanwhile, pain occurs in 40–50% of patients after thoracic surgery, and its mechanism remains under investigation. This study assessed the role of 5-HTTLPR polymorphisms in postthoracotomy pain severity.

Patients and Methods

A total of 178 patients undergoing pneumonectomy were enrolled. The genotypes of 5-HTTLPR were divided into two groups: S/S group and S/L or L/L group. Linear mixed-effects models were used to assess the association between 5-HTTLPR genotypes and the numerical rating scale (NRS) score change over time.

Results

Among the participants, data were obtained for 162 patients. The genotype distribution was as follows: S/S, 67.3%; S/L or L/L, 32.7%. No significant difference in patient characteristics was found between the genotype groups. There was no significant interaction between the 5-HTTLPR genotypes and the NRS score change over time (p = 0.842).

Conclusion

Polymorphisms in 5-HTTLPR were not associated with postthoracotomy pain severity.

Developmental Antecedents of Adult Macaque Neurogenesis: Early-Life Adversity, 5-HTTLPR Polymorphisms, and Adolescent Hippocampal Volume

INTRODUCTION

Attenuated adult hippocampal neurogenesis may manifest in affective symptomatology and/or resistance to antidepressant treatment. While early-life adversity and the short variant ('s') of the serotonin transporter gene's long polymorphic region (5-HTTLPR) are suggested as interacting risk factors for affective disorders, no studies have examined whether their superposed risk effectuates neurogenic changes into adulthood. Similarly, it is not established whether reduced hippocampal volume in adolescence, variously identified as a marker and antecedent of affective disorders, anticipates diminished adult neurogenesis. We investigate these potential developmental precursors of neurogenic alterations using a bonnet macaque model.

METHODS

Twenty-five male infant bonnet macaques were randomized to stressed [variable foraging demand (VFD)] or normative [low foraging demand (LFD)] rearing protocols and genotyped for 5-HTTLPR polymorphisms. Adolescent MRI brain scans (mean age 4.2y) were available for 14 subjects. Adult-born neurons were detected post-mortem (mean age 8.6y) via immunohistochemistry targeting the microtubule protein doublecortin (DCX). Models were adjusted for age and weight.

RESULTS

A putative vulnerability group (VG) of VFD-reared 's'-carriers (all 's/l') exhibited reduced neurogenesis compared to non-VG subjects. Neurogenesis levels were positively predicted by ipsilateral hippocampal volume normalized for total brain volume, but not by contralateral or raw hippocampal volume.

LIMITATIONS

No 's'-carriers were identified in LFD-reared subjects, precluding a 2×2 factorial analysis.

CONCLUSION

The 's' allele (with adverse rearing) and low adolescent hippocampal volume portend a neurogenic deficit in adult macaques, suggesting persistent alterations in hippocampal plasticity may contribute to these developmental factors' affective risk in humans.

Factors related to age at depression onset: the role of SLC6A4 methylation, sex, exposure to stressful life events and personality in a sample of inpatients suffering from major depression

BACKGROUND

An early onset of depression is associated with higher chronicity and disability, more stressful life events (SLEs), higher negative emotionality as described by the primary emotion SADNESS and more severe depressive symptomatology compared to depression onset later in life. Additionally, methylation of the serotonin transporter gene (SLC6A4) is associated with SLEs and depressive symptoms.

METHODS

We investigated the relation of SLEs, SLC6A4 methylation in peripheral blood, the primary emotions SADNESS and SEEKING (measured by the Affective Neuroscience Personality Scales) as well as depressive symptom severity to age at depression onset in a sample of N = 146 inpatients suffering from major depression.

RESULTS

Depressed women showed higher SADNESS (t (91.05) = - 3.17, p = 0.028, d = - 0.57) and higher SLC6A4 methylation (t (88.79) = - 2.95, p = 0.02, d = - 0.55) compared to men. There were associations between SLEs, primary emotions and depression severity, which partly differed between women and men. The Akaike information criterion (AIC) indicated the selection of a model including sex, SLEs, SEEKING and SADNESS for the prediction of age at depression onset. SLC6A4 methylation was not related to depression severity, age at depression onset or SLEs in the entire group, but positively related to depression severity in women.

CONCLUSIONS

Taken together, we provide further evidence that age at depression onset is associated with SLEs, personality and depression severity. However, we found no associations between age at onset and SLC6A4 methylation. The joint investigation of variables originating in biology, psychology and psychiatry could make an important contribution to understanding the development of depressive disorders by elucidating potential subtypes of depression.

The interaction of 5-HTT variation, recent stress, and resilience on current anxiety levels in adolescents and young adults from the general population

BACKGROUND

Previous work on gene-environment (GxE) interplay concerning anxiety has focused on the interaction of 5-HTTLPR with childhood adversities or traumatic events whereas the impact of recent stressors is understudied, as is the integration of resilience. The current study aimed to investigate the interactive effect of 5-HTTLPR and recent stress on anxiety in adolescents considering resilience as buffer of a GxE risk constellation.

METHOD

In a random population-based sample of 14-21 years old from Dresden, Germany, (N = 1180; genotyped = 942) recent stress (Daily Hassles [DH] Scale, Perceived Stress Scale, Screening Scale of the Trier Inventory for the Assessment of Chronic Stress), resilience (Connor-Davidson resilience scale) and anxiety (Patient Reported Outcome Measurement Information System Anxiety Short Form) were assessed via questionnaire in 2015 or 2016.

RESULTS

Fractional regression models revealed that resilience interacted with recent stress in form of DH as well as recent chronic stress and 5-HTTLPR regarding anxiety. Participants carrying the more active L_A L_A genotype reported consistently higher levels of anxiety when experiencing more DH or more recent chronic stress and having low levels of resilience. When the resilience scores were high, L_A L_A carriers reported the lowest anxiety scores despite DH or recent chronic stress.

CONCLUSION

Findings revealed an interactive relationship between 5-HTTLPR genotype and recent stress suggesting resilience to function as an additional dimension buffering the impact of a GxE risk constellation. Early interventions to build resilience may be useful to prevent an escalation of distress and associated unfavorable health outcomes.

The effects of 5-HTTLPR/rs25531 serotonin transporter gene polymorphisms on antisocial personality disorder among criminals in a sample of the Turkish population

Antisocial personality disorder (ASPD) is a cluster B personality disorder characterized by a disposition for criminal behaviors. It has been determined by previous studies that ASPD may have a genetic origin and the human serotonin transporter gene (SLC6A4) is one of the two serotonergic genes expected to be associated with this disorder. 5-HTT-linked polymorphic promoter region (5-HTTLPR) is a degenerate repeat polymorphic region in SLC6A4, the gene that codes for the serotonin transporter. Among many polymorphisms in SLC6A4, 5-HTTLPR an insertion/deletion (indel) polymorphism and rs25531 single nucleotide polymorphism (SNP) in the 5-HTTLPR polymorphic region contribute to the regulation of SLC6A4 expression. In this study, we aimed to reveal the relationship between frequencies of 5-HTTLPR variants and ASPD among criminals in the Turkish population. Moreover, it was also attempted to figure out the SLC6A4 gene expression level differences regarding these polymorphisms. The 5-HTTLPR/rs25531 genotypes were determined by PCR and restriction length polymorphism (RFLP) analyses and quantitative real-time-PCR was done for measuring the gene expression levels in the case and control groups. Although no significant difference was observed in the distributions of the 5-HTTLPR/rs25531 polymorphisms between the case and control groups, SLC6A4 expression level in the control group was found significantly higher than the case group (p < 0.0001). There was also no significant difference between genotypes in terms of mRNA expression levels in either the control or the case group. According to our results, ASPD in Turkish society is associated with the SLC6A4 gene expression levels, though the distributions of 5-HTTLPR polymorphisms are not different. This study sheds light on future relevant studies as the first study which is conducted in criminals with ASPD in the Turkish community.

Polymorphism of the Serotonin Transporter Gene and the Peripheral 5-Hydroxytryptamine in Obstructive Sleep Apnea: What Do We Know and What are We Looking for? A Systematic Review of the Literature

BACKGROUND

Obstructive sleep apnea (OSA) is a highly prevalent disease with substantial public health burden. In most of the cases, there is a genetic predisposition to OSA. Serotonin/T-HydroxyTriptamine (5-HT) plays a key role in ventilatory stimulation, while the polymorphism of the serotonin transporter gene (STG) leads to alterations in serotonin level, making it important in OSA.

OBJECTIVE

To examine whether the 5-HydroxyTriptamine and the genetic predisposition influence the incidence and evolution of OSA, we reviewed randomized, controlled trials and observational studies on the selected topic. The secondary objective was to determine the metabolic effects of the circulating serotonin in other tissues (liver, pancreas, gut, brown adipose tissue, and white adipose tissue) and its role in the development of obesity.

DATA SOURCES

A systematic review of English articles was performed based on PubMed and the Cochrane Library databases. Search filters included randomized controlled trial, controlled clinical trial, random allocation, double-blind method, and case-control studies and used the following keywords: Brain Serotonin OR Serotonin Transporter Gene Polymorphism OR Peripheral 5-HydroxyTryptamine AND Obstructive Sleep Apnea OR Sleep Disorder Breathing OR brain serotonin AND OSA OR serotonin transporter gene OR Peripheral 5-Hydroxytryptamine AND Sleep.

STUDY ELIGIBILITY CRITERIA

The inclusion criteria for the current review were previous diagnosis of OSA, age above 18 years, and articles including quantitative data about serotonin transporter gene or peripheral serotonin. Language and time criteria were added - English articles published in the last 15 years. Studies that were not included were reviews and case reports.

STUDY APPRAISAL AND SYNTHESIS METHODS

In order to study the serotonin function, a literature research was conducted in the databases Pubmed and Cochrane Library. The following search terms were used: serotonin, 5-hydroxytryptamine, serotonin transporter gene. A critical appraisal of the included studies was performed with the Newcastle-Ottawa scale (NOS) and Delphi list.

RESULTS

The search yielded 1210 articles, from which 43 were included. The included studies suggest that the two polymorphisms of serotonin transporter gene (5HTT) - variable number of tandem repeats (VNTR) and linked polymorphic region (LPR) - are strong candidates in the pathogenesis of OSA. The allele 10 of 5HTTVNTR and the long/long (L/L) allele genotype were associated with a higher prevalence of OSA and the L allele with a higher apnea-hypopnea index and a longer time during sleep with oxygen desaturation.

LIMITATIONS

The main limitation of the present study consists of heterogeneity of the information. Being a less studied subject, randomized trials are not widely available and most data were obtained from case-control trials. Moreover, the included material indirectly approached the subject by demonstrating the effects of serotoninergic system over the metabolism, the connection between serotonin and obesity, factors which are implied in the pathogenesis of OSA.

CONCLUSION AND IMPLICATIONS OF KEY FINDINGS

The two polymorphisms of serotonin gene can be considered important factors in the diagnosis and management of OSA.

A Biopsychosocial Approach to Understanding Panic Buying: Integrating Neurobiological, Attachment-Based, and Social-Anthropological Perspectives

The global COVID-19 pandemic has focused the attention of researchers, civil authority and the general public on the phenomenon of "panic buying," characterized by the excessive purchase of specific materials-particularly food and hygiene-related products-in anticipation of an expected shortage. This phenomenon has been well-documented in response to several natural and man-made disasters, but its global scope and severity in the context of COVID-19 are unprecedented. This response can negatively impact health, food security, and disease prevention efforts. Attempts to modify such behaviors are more likely to succeed if they are based on insights from both the biomedical and the social sciences. From a biological perspective, the phenomenological overlap between panic buying and psychological disorders such as hoarding disorder and compulsive buying raises the possibility of a shared neurobiological underpinning. Evolutionary models suggest that these behaviors represent an attempt to enhance individual and group survival in the face of a threatened scarcity of resources. These phenomena may be influenced by specific genetic variants which are also implicated in hoarding-related psychological disorders. From a psychological perspective, attachment theory provides a conceptual framework that serves as a bridge between prior life adversity, current deprivation, and an increased attachment to material objects. Such a framework is of relevance when considering panic buying during the COVID-19 pandemic, which has been associated with significant disruptions in attachment bonds. From a social-anthropological perspective, hoarding and related behaviors have been associated with social exclusion and rejection, as well a lack of social support. These risk factors have affected large sections of the general population in the context of the COVID-19 pandemic and the governmental responses to it. This perspective also emphasizes the symbolic significance of the hoarded objects themselves. In this paper, an attempt is made to integrate these three perspectives and thereby formulate a biopsychosocial model of panic buying in response to this global health crisis. The existing scientific literature on panic buying is examined in the light of this model. Finally, suggestions are proposed as to how this model might inform social strategies aimed at preventing or reducing panic buying.

Association of 5-HTTLPR/rs25531 with depressive symptoms in patients with coronary heart disease: A prospective study

BACKGROUND

5-HTTLPR/rs25531 is suspected to be involved in the pathogenesis of both coronary heart disease (CHD)¹ and depression. We aimed to investigate the role of 5-HTTLPR/rs25531 in the development of depressive symptoms among CHD patients in a longitudinal design.

METHODS

N = 265 participants with CHD diagnosis were included while hospitalized in a department of cardiology and genotyped for the 5-HTTLPR/rs25531. Depressive symptoms were measured using the Patient Health Questionnaire (PHQ-9)⁷ at baseline and after 6 and 12 months. Binary logistic regression models were used to analyze the association of 5-HTTLPR/rs25531 with the prevalence of depressive symptoms at each time point as well as with the incidence and persistence of depressive symptoms at follow-up.

RESULTS

"L_AL_A" genotype was associated with a higher prevalence of depressive symptoms 12 months after study inclusion. "L_AL_A" genotype was associated with a higher incidence of depressive symptoms 6 and 12 months after study inclusion. There was no association of 5-HTTLPR/rs25531 with the persistence of depressive symptoms.

LIMITATIONS

Inclusion criteria did not demand a particular cardiac event at baseline, which aggravated the interpretation of the time-specific results. The majority of the participants was of male gender which could cause bias. The present study only vaguely differentiated between ethnical groups which might cause bias regarding nationality-dependent allele distributions.

CONCLUSION

The present study suggests a time-dependent association of the "L_AL_A" genotype with depressive symptoms in CHD patients. 5-HTTLPR/rs25531 might be an important marker to detect risk groups for later onset depressive symptoms among CHD patients.

Threat-Avoidance Tendencies Moderate the Link Between Serotonin Transporter Genetic Variation and Reactive Aggression

The short (S) allele of the serotonin transporter-linked promoter region (5-HTTLPR) polymorphism has been linked to reactive aggression in men, but this association is less consistent in females. Reactive aggression has been particularly described as a result of fear-driven defense to threat, but how this interaction between defensive behavior and aggression is expressed in S-allele carriers remains unknown. In order to explore this interplay between 5-HTTLPR genotype, defensive behavior and reactive aggression, we combined genotyping with objective measures of action tendencies toward angry faces in an approach-avoidance task (AAT) and reactive aggression in the Taylor aggression paradigm (TAP) in healthy females, N = 95. This study shows that female S-allele carriers in general display increased implicit reactive aggression (administering aversive white noise) toward opponents. Furthermore, we found that threat-avoidance tendencies moderate the association between 5-HTTLPR genotype and aggression displayed on the TAP. Together, these findings indicate a positive correlation between avoidance of angry faces in the AAT and reactive aggression in the TAP exclusively present in S-allele carriers.

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.

Socioemotional Mechanisms of Children's Differential Response to the Effects of Maternal Sensitivity on Child Adjustment

OBJECTIVE

Children differ in the extent to which they reap the benefits of maternal sensitive care or suffer the adverse consequences of insensitive care, and these differences can be accounted for by biological characteristics. However, how susceptible children adapt to maternal sensitivity in ways that either maximize positive development or lead to maladjustment has yet to be determined. Here, we propose a novel model of socioemotional mechanisms by which the joint influences of maternal sensitivity and child biological characteristics influence child adjustment.

DESIGN

We propose a theoretical model, in which children's vagal functioning and polymorphisms in serotonin transporter (5-HTTLPR) and dopamine receptor D4 (DRD4) genes confer susceptibility to the effects of maternal sensitivity on internalizing, externalizing, prosocial and moral behavior via changes in interpersonal strategies for emotion regulation, the threat response system, and empathy.

RESULTS

Theoretical and empirical support for the proposed mechanisms are provided.

CONCLUSIONS

The proposed mechanistic model of susceptibility to maternal sensitivity offers a novel framework of for whom and how children are affected by early maternal care, highlighting multiple reciprocal, interacting influences across genes, physiology, behavior, and the environment.

Childhood maltreatment, serotonin transporter gene, and risk for callous and unemotional traits: A prospective investigation

Previous studies have reported associations between the serotonin transporter 5-HTTLPR genotype and antisocial and aggressive traits and between child maltreatment and antisocial traits. However, few studies have examined whether 5-HTTLPR moderates the influence of childhood maltreatment on callous and unemotional traits, a hallmark of psychopathy. Using a prospective cohort design, children with documented cases of maltreatment and matched controls were followed up and interviewed in adulthood. DNA was extracted from blood and saliva (N = 414) and callous-unemotional (CU) traits were assessed. Childhood maltreatment predicted higher CU scores in adulthood, whereas the effect of 5-HTTLPR was not significant. The effect of child maltreatment on CU traits did not differ by genetic risk (high or low activity 5-HTTLPR), whereas controls with the LL genotype had higher CU scores than controls with the SS genotype. Similar results were found for females and White, non-Hispanics, but not for males and Blacks. Variations in 5-HTTLPR did not affect the impact of child maltreatment on CU traits in adulthood. Genetic risk had a stronger effect on adults with lower environmental risk (controls). Having a history of child maltreatment or the LL genotype placed participants at risk for higher levels of callous and unemotional trait scores.

Severity of self-reported depressive symptoms in a healthy sample is modulated by trait Harm Avoidance, not by 5-HTTLPR polymorphism

BACKGROUND

The length of the serotonin transporter polymorphic region (5-HTTLPR) has been suggested to be associated with risk for developing depression, though with inconsistent evidence. Likewise, the personality trait Harm Avoidance (HA) has been linked to vulnerability for developing depression. However, no study has investigated whether there is an interaction effect between 5-HTTLPR and trait HA on depressive symptoms in healthy individuals.

METHODS

A total of 319 healthy individuals were included in this cross-sectional study. All participants were genotyped for the 5-HTTLPR polymorphism and completed self-reported measures of personality trait HA with the Temperament and Character Inventory (TCI), and of depression with the Major Depression Inventory (MDI). Linear regression analyses were used to test interaction effects between 5-HTTLPR and HA on MDI. Post hoc analyses were further performed to investigate main effects of HA and possible interaction effects between 5-HTTLPR and HA sub-scales on MDI.

RESULTS

No significant interaction effect between 5-HTTLPR and HA on MDI was found. A significant main effect of trait HA on MDI was found, indicating that personality trait HA is a viable vulnerability factor for even sub-clinical depressive symptoms.

CONCLUSION

This study finds a strong significant relationship between HA and MDI. Moreover, the present study supports the line of research indicating that candidate gene-by-interactions does not increase vulnerability for developing depression even at a sub-clinical level.

Pharmacogenetic association of bi- and triallelic polymorphisms of SLC6A4 with antidepressant response in major depressive disorder

BACKGROUND

Antidepressants (ADs) are the main clinical therapy for depression, but approximately half of users do not get adequate response. The biallelic (5-HTTLPR) and triallelic (5-HTTLPR/rs25531) polymorphisms in SLC6A4 have been frequently investigated, but their associations with ADs response are in controversy. Here, we performed a meta-analysis to assess their modulation effect to ADs response in major depressive disorder (MDD).

METHODS

We performed literature search in PubMed, Web of Science and EMBASE before June 2019. Pooled analysis of genetic associations with response and remission, meta-regression and sensitivity analysis were performed, and publication bias was assessed.

RESULTS

Literature search yielded 49 eligible studies with 46 and 10 studies for biallelic and triallelic polymorphism, respectively. L allele of 5-HTTLPR was associated with both of response and remission rates. In the Caucasians using SSRIs only, carriers of LL/LS or LL genotype were more likely to be responders compared to SS carriers (LL/LS vs. SS: OR=1.55, 95%CI 1.20-2.00, p=0.001; LL vs. SS: OR=1.97, 95%CI 1.45-2.67, p<0.001). Similar associations were also found with remission rate. However, no effects on response or remission were found in the Asians or mixed/other antidepressant subgroups. Additionally, the 5-HTTLPR/rs25531 triallelic polymorphism may not associate with ADs response. Meta-regression showed that percent of female in participants, year of publication and treatment duration modulated the association in Caucasians.

CONCLUSION

5-HTTLPR, instead of 5-HTTLPR/rs25531 triallelic polymorphism, may exert as a marker for the prediction of response to SSRIs in Caucasians with MDD.

Common HTR2A variants and 5-HTTLPR are not associated with human in vivo serotonin 2A receptor levels

The serotonin 2A receptor (5‐HT2AR) is implicated in the pathophysiology and treatment of various psychiatric disorders. [¹⁸F]altanserin and [¹¹C]Cimbi‐36 positron emission tomography (PET) allow for high‐resolution imaging of 5‐HT2AR in the living human brain. Cerebral 5‐HT2AR binding is strongly genetically determined, though the impact of specific variants is poorly understood. Candidate gene studies suggest that HTR2A single nucleotide polymorphisms including rs6311/rs6313, rs6314, and rs7997012 may influence risk for psychiatric disorders and mediate treatment response. Although known to impact in vitro expression of 5‐HT2AR or other serotonin (5‐HT) proteins, their effect on human in vivo brain 5‐HT2AR binding has as of yet been insufficiently studied. We thus assessed the extent to which these variants and the commonly studied 5‐HTTLPR predict neocortex in vivo 5‐HT2AR binding in healthy adult humans. We used linear regression analyses and likelihood ratio tests in 197 subjects scanned with [¹⁸F]altanserin or [¹¹C]Cimbi‐36 PET. Although we observed genotype group differences in 5‐HT2AR binding of up to ~10%, no genetic variants were statistically significantly predictive of 5‐HT2AR binding in what is the largest human in vivo 5‐HT2AR imaging genetics study to date. Thus, in vitro and post mortem results suggesting effects on 5‐HT2AR expression did not carry over to the in vivo setting. To any extent these variants might affect clinical risk, our findings do not support that 5‐HT2AR binding mediates such effects. Our observations indicate that these individual variants do not significantly contribute to genetic load on human in vivo 5‐HT2AR binding.

The Multifaceted Effects of Serotonin Transporter Polymorphism (5-HTTLPR) on Anxiety, Implicit Moral Attitudes, and Harmful Behaviors

Morality is fundamentally human in nature. Regardless, and even when moral norms seem to work toward the common goal of human cooperation, which morally contentious behaviors are permitted and which are prohibited vary across populations. Because of this occurrence, much scientific debate has revolved around the notion that this phenomenon might be explained by the interaction between genes and environment. Alongside, whether the principles cementing the bases of morality are intuition- or reason-based is another question that has been raised. However, previous research addressing these topics used explicit measures to probe moral attitudes, thus being the participants able to intentionally modify or disguise their honest responses. What's more, while the 5-HTT gene was found to be associated with anxiety, morality, and even cultural structures, a single genotype-phenotype linkage cannot be established without considering the multifaceted effects of the 5-HTT gene on gene-behavior interactions. In order to explore the role of genetics on modeling moral attitudes and behaviors, we genotyped the 5-HTTLPR in 114 healthy volunteers and subsequently assessed their explicit justice sensitivity (Justice Sensitivity Inventory) and moral permissibility judgments, as well as their implicit moral attitudes [moral implicit association task (mIAT)]. Results revealed that 5-HTTLPR short-allele carriers had significantly lower mIAT reaction times when answering correctly and were less compliant on harming another person even when harm or death would inevitably occur anyway to this other individual. With these preliminary results, we can first see how it does not have to be a matter of vouching for a rationalist versus an intuitionist model of moral judgment, but rather being moral judgment an outcome of the different variants of the 5-HTTLPR polymorphism affecting the way in which individuals engage contrastingly with moral issues.

Promoter Activity-Based Case-Control Association Study on SLC6A4 Highlighting Hypermethylation and Altered Amygdala Volume in Male Patients With Schizophrenia

Associations between altered DNA methylation of the serotonin transporter (5-HTT)-encoding gene SLC6A4 and early life adversity, mood and anxiety disorders, and amygdala reactivity have been reported. However, few studies have examined epigenetic alterations of SLC6A4 in schizophrenia (SZ). We examined CpG sites of SLC6A4, whose DNA methylation levels have been reported to be altered in bipolar disorder, using 3 independent cohorts of patients with SZ and age-matched controls. We found significant hypermethylation of a CpG site in SLC6A4 in male patients with SZ in all 3 cohorts. We showed that chronic administration of risperidone did not affect the DNA methylation status at this CpG site using common marmosets, and that in vitro DNA methylation at this CpG site diminished the promoter activity of SLC6A4. We then genotyped the 5-HTT-linked polymorphic region (5-HTTLPR) and investigated the relationship among 5-HTTLPR, DNA methylation, and amygdala volume using brain imaging data. We found that patients harboring low-activity 5-HTTLPR alleles showed hypermethylation and they showed a negative correlation between DNA methylation levels and left amygdala volumes. These results suggest that hypermethylation of the CpG site in SLC6A4 is involved in the pathophysiology of SZ, especially in male patients harboring low-activity 5-HTTLPR alleles.

Influence of psychosocial stress on activation in human brain regions: moderation by the 5-HTTLPR genetic locus

Variants of the serotonin transporter linked polymorphic region (5-HTTLPR) of the serotonin transporter gene SLC6A4 have been related with the onset of depression, anxiety, and other mental disorders. Homozygotes for the short 5-HTTLPR variant, referred to as the SS genotype, have greater cortisol responses to experimentally induced psychosocial stress. In the current study, we used functional magnetic resonance imaging (fMRI) to compare regional brain activations across 5-HTTLPR genotypes in subjects performing the Montreal Imaging Stress Task (MIST). Subjects with an SS genotype had significant greater increases in cortisol concentrations after the task than subjects with at least one long 5-HTTLPR allele. Additionally, relative to L carriers, the SS group had greater activation in the dorsomedial prefrontal cortex(dmPFC), dorsal anterior cingulate cortex, anterior insula.

The relationships among MAOA, COMT Val158Met, and 5-HTTLPR polymorphisms, newborn stress reactivity, and infant temperament

INTRODUCTION

Variance in hypothalamic-pituitary-adrenal (HPA) axis reactivity is considered to be one of the sources of differences in infant temperament. The cortisol enters into interactions with dopamine and serotonin, so it is expected that polymorphisms in genes coding monoamine metabolism influence both HPA axis reactivity and temperament.

METHODS

We therefore explore the relationship among 5-HTTLPR S/L, MAOA H/L, and COMT Val158Met polymorphisms, the stress reaction of newborn infants after a heel stick blood draw (measured by determining salivary cortisol at three time points), and temperament assessed at the age of 3 months using Rothbart's Infant Behavior Questionnaire-Revised (IBQ-R) with a sample of 84 infants.

RESULTS

The decrease in the salivary cortisol correlated with nine primary scales and all three secondary scales of IBQ-R. Children with a greater cortisol decrease were assessed as less susceptible to negative emotions, more extraverted, and more regulated. The polymorphisms that were observed were related both to the course of the stress reaction and to temperament. The 5-HTTLPR S allele was connected to higher scores for Negative Emotionality and lower scores for Orienting/Regulatory Capacity. The presence of the MAOA L allele predisposed its carriers to higher scores for Negative Emotionality, lower scores for Orienting/Regulatory Capacity, and a lower decrease in cortisol. The Met allele of COMT Val158Met polymorphism was connected to a higher Positive Affectivity/Surgency and Orienting/Regulatory Capacity and a greater cortisol decrease.

CONCLUSIONS

Contrary to previous studies referring mainly basal cortisol and its increase, the results of our study emphasize the importance of cortisol elimination in infant temperament. Another interesting finding was a higher cortisol increase, higher Distress to Limitations, Negative Emotionality, and Approach in MAOA LL homozygotes which are traditionally understood as more vulnerable toward early stress in developing later externalizing behavior.

"Out, out, brief candle! Life's but a walking shadow": 5-HTTLPR Is Associated With Current Suicidal Ideation but Not With Previous Suicide Attempts and Interacts With Recent Relationship Problems

BACKGROUND

Suicide is an unresolved psychiatric and public health emergency, claiming 800,000 lives each year, however, its neurobiological etiology is still not understood. In spite of original reports concerning the involvement of 5-HTTLPR in interaction with recent stress in the appearance of suicidal ideation and attempts, replication studies have yielded contradictory results. In our study, we analyzed the association between 5-HTTLPR and lifetime suicide attempts, current suicidal ideation, hopelessness and thoughts of death as main effects, and in interaction with childhood adversities, recent stress, and different types of recent life events in a general population sample.

METHODS

Two thousand and three hundred fifty-eight unrelated European volunteers were genotyped for 5-HTTLPR, provided phenotypic data on previous suicide attempts, and current suicidal ideation, hopelessness and thoughts about death, and information on childhood adversities and recent life events. Logistic and linear regression models were run with age, gender, and population as covariates to test for the effect of 5-HTTLPR as a main effect and in interaction with childhood adversities and recent life events on previous suicide attempts and current suicidal ideation. Benjamini-Hochberg FDR Q values were calculated to correct for multiple testing.

RESULTS

5-HTTLPR had no significant effect on lifetime suicide attempts either as a main effect on in interaction with childhood adversities. 5-HTTLPR had a significant main effect on current suicidal ideation in the dominant model (Q=0.0344). 5-HTTLPR did not interact with childhood adversities or total number of recent life events on any phenotypes related to current suicidal risk, however, a significant interaction effect between 5-HTTLPR and current relationship problems emerged in the case of current suicidal ideation in the dominant model (Q=0.0218) and in the case of thoughts about death and dying in the dominant (Q=0.0094) and additive models (Q=0.0281).

CONCLUSION

While 5-HTTLPR did not influence previous suicide attempts or interacted with childhood adversities, it did influence current suicidal ideation with, in addition, an interaction with recent relationship problems supporting the involvement of 5-HTTLPR in suicide. Our findings that 5-HTTLPR impacts only certain types of suicide risk-related behaviors and that it interacts with only distinct types of recent stressors provides a possible explanation for previous conflicting findings.

Smoking moderates association of 5-HTTLPR and in vivo availability of serotonin transporters

Although preclinical studies clearly indicate an effect of 5-HTTLPR genotype on 5-HT transporter (5-HTT) expression, studies in humans provided inconclusive results, hypothetically due to environmental factors and differences in individual behavior. For example, nicotine and other constituents of tobacco smoke elevate serotonin (5-HT) levels in the brain and may thereby cause homeostatic adaptations in 5-HTT availability that moderate effects of 5-HTTLPR genotype. To test whether 5-HTT availability in the midbrain is affected by smoking status and 5-HTTLPR genotype, we pooled data from prior studies on in vivo 5-HTT availability (BP_ND) measured with positron emission tomography (PET) and [¹¹C]DASB. In total, we reanalyzed 5-HTT availability in 116 subjects using ANCOVA statistics. ROI analysis revealed that current smokers and non-smokers do not differ in midbrain BP_ND. Interestingly, smoking status significantly interacted with 5-HTTLPR genotype: active smoking was associated with reduced 5-HTT availability only in LL subjects but not in carriers of the S-allele. From the perspective of genotype effects, non-smokers showed the expected association with 5-HTTLPR, i.e. higher 5-HTT availability in LL subjects compared to carriers of the S-allele, whereas this pattern was actually reversed for active smokers. Our study indicates that smoking status moderates the association of 5-HTTLPR genotype and 5-HTT expression, which may help to explain inconsistent findings in previous studies. Regarding the mechanism, we suggest that smoking may induce epigenetic processes such as methylation of SLC6A4, which can differ depending on its genetic constitution.