Testing the diathesis-stress model: 5-HTTLPR, childhood emotional maltreatment, and vulnerability to social anxiety disorder

Interactions Between Serotonin Transporter Gene and Adverse Childhood Experience in a Generalized Additive Model: A Pilot Study

BACKGROUND

While most people experience potentially traumatic events (PTEs), including Adverse Childhood Experiences (ACEs), the stress reactions to PTEs on mental health outcomes are highly heterogeneous. Resilience is influenced by a complex biopsychosocial ecological system, including gene serotonin transporter-linked promoter region or 5-HTTLPR /rs25531 by ACEs interactions.

AIMS

This pilot study investigated the gene-by-environment interactions on mental health outcomes in adults enrolled in a health care profession program using a generalized additive model (GAM).

METHODS

Seventy health care college students (mean age = 27.4 years, 67.1% women) participated in this cross-sectional study. Saliva samples were collected from students to analyze 5-HTTLPR/rs25531. Participants completed the ACE Questionnaire and the Mental Health Inventory. GAMs with different interaction terms were built adjusting for age, gender, and race. The value of the effective degree of freedom (EDF) quantifies the curvature of the relationship.

RESULTS

Among participants with the long allele of 5-HTTLPR/rs25531, a linear pattern was found between the total ACE score and mental health outcomes (EDF = 1). Conversely, among participants with the short allele, EDF was approximately 2, indicating a curved association suggesting that mental health worsens in individuals exposed to up to four types of ACEs.

CONCLUSIONS

The impact of up to four ACEs on mental health was stronger among individuals with the short allele of 5-HTTLPR/rs25531 than those with the long allele. Although this study does not claim to provide a definite approach to analyzing gene-by-environment interactions, we offer a different perspective to explore the relationship.

Candidate Biological Markers for Social Anxiety Disorder: A Systematic Review

Social anxiety disorder (SAD) is a common psychiatric condition associated with a high risk of psychiatric comorbidity and impaired social/occupational functioning when not promptly treated. The identification of biological markers may facilitate the diagnostic process, leading to an early and proper treatment. Our aim was to systematically review the available literature about potential biomarkers for SAD. A search in the main online repositories (PubMed, ISI Web of Knowledge, PsychInfo, etc.) was performed. Of the 662 records screened, 61 were included. Results concerning cortisol, neuropeptides and inflammatory/immunological/neurotrophic markers remain inconsistent. Preliminary evidence emerged about the role of chromosome 16 and the endomannosidase gene, as well as of epigenetic factors, in increasing vulnerability to SAD. Neuroimaging findings revealed an altered connectivity of different cerebral areas in SAD patients and amygdala activation under social threat. Some parameters such as salivary alpha amylase levels, changes in antioxidant defenses, increased gaze avoidance and QT dispersion seem to be associated with SAD and may represent promising biomarkers of this condition. However, the preliminary positive correlations have been poorly replicated. Further studies on larger samples and investigating the same biomarkers are needed to identify more specific biological markers for SAD.

Genetics of social anxiety disorder: a systematic review

Social anxiety disorder (SAD) is a common psychiatric disorder, often associated with avoidant temperament. Research studies have implicated a strong genetic architecture of SAD. We have conducted a systematic review on the genetics of SAD and yielded 66 articles. In general, prior research studies have focused on the serotonin transporter, oxytocin receptor, brain-derived neurotrophic factor and catechol-O-methyltransferase genes. Mixed and inconsistent results have been reported. Additional approaches and phenotypes have also been investigated, including pharmacogenetics of treatment response, imaging genetics and gene-environment interactions. Future directions warrant further international collaborative efforts, deep-phenotyping of clinical characteristics including consistent and reliable measurement-based symptom severity, and larger sample sizes to ensure sufficient power for stratification due to the heterogeneity of this chronic and often debilitating condition.

Psychological and social risk factors associated with development of psychopathology, controlling for biological influence

PURPOSE OF REVIEW

To evaluate and summarize recent research investigating psychological, social and environmental risk factors for development of psychopathology in childhood, while controlling for biological (genetic) influences by using a matched sibling, twin or adoptee design.

RECENT FINDINGS

Nineteen studies were included, of which eleven were longitudinal and eight were cohort studies. Included studies used adequate designs and statistical methods, controlled for unmeasured confounders and, in many cases, for other measured risk factors. None of the studies used the framework for environmental factors presented in the International Classification of Functioning, Disability and Health (ICF). The outcome variable psychopathology was rarely assessed using a diagnostic standard. The findings were sorted in five themes based on included exposures: 'Social support, social rejection and perceived identity,' 'Early symptoms of psychopathology,' 'Antibiotic exposure,' 'Factors in the family' and 'Nature versus nurture'.

SUMMARY

Using twin/sibling/adoptee designs, a number of unique predictors of psychopathology were found, even when controlling for familial confounders and other specified risk factors. Future studies of psychopathology development should benefit from longitudinal, genetically sensitive designs and from use of diagnostic standards for psychopathology outcome, and should also incorporate ICF for classification of risk factors.

Associations of childhood maltreatment with subsequent illicit drug use among Chinese adolescents: The moderating role of the child's sex

Adolescence is a critical period for the onset of illicit drug use. This study aimed to estimate the prevalence of illicit drug use among Chinese adolescents, to assess the associations between different forms of childhood maltreatment and subsequent illicit drug use and to test whether the child's sex plays a moderating role in the associations. A secondary analysis was made of cross-sectional data collected from 10th to 12th graders from China who were sampled in the 2015 School-based Chinese Adolescents Health Survey. A total of 59,518 questionnaires were included in the final analysis. The prevalence estimates and logistic regression analyses were weighted to account for the complex survey design. If the interaction term (between childhood maltreatment and sex) was significantly associated with illicit drug use, we would perform stratification analyses across sex. Of the total sample, 45.2% were boys, and the mean (SD) age was 17.0 (0.9) years. The results of stratification analyses demonstrated that among boys, physical abuse and sexual abuse were independently associated with an increased risk of use during their lifetime of MDMA, methamphetamine, ketamine, and mephedrone; among girls, only emotional abuse and sexual abuse were associated with MDMA use, methamphetamine use, ketamine use, and mephedrone use.

The mediating effects of depressive symptoms on the association of childhood maltreatment with non-medical use of prescription drugs

BACKGROUND

Childhood maltreatment might increase the risk of subsequent drug use behavior, and depressive symptoms have been reported to be associated both childhood maltreatment and non-medical use of prescription drugs (NMUPD). This large-scale study aimed to test the mediating effects of depressive symptoms on the association of childhood maltreatment with NMUPD among Chinese adolescents.

METHODS

A secondary analysis of the cross-sectional data collected from 7th to 12th graders who were sampled using a multistage, stratified cluster, random sampling method in the 2015 School-based Chinese Adolescents Health Survey. There were 24,457 students who were invited to participate and 23,039 students' questionnaires were completed and qualified for our survey (response rate: 94.2%).

RESULTS

In the adjusted models without mediation, the results showed that students who reported that they had experienced emotional abuse were at a higher risk of past year use and past month use of opioids (past year: Adjusted OR [AOR] = 1.07, 95% CI = 1.05-1.10; past month: AOR = 1.08, 95% CI = 1.06-1.10) and sedatives (past year: AOR = 1.06, 95% CI = 1.03-1.08; past month: AOR = 1.15, 95% CI = 1.13-1.16). The results of mediation analyses demonstrated that there were significant standardized indirect effects of emotional abuse on opioids use and sedatives use through depressive symptoms, respectively (P < 0.001).

LIMITATIONS

Our study sample only included school students, and causal inference could not be examined due to the cross-sectional design.

CONCLUSIONS

Depressive symptoms play a significant mediator role on the association of childhood maltreatment with NMUPD. Interventions targeted at adolescents who are involved in NMUPD should pay attention to their histories of childhood maltreatment.

Genetic variants in 5-HTTLPR, BDNF, HTR1A, COMT, and FKBP5 and risk for treated depression after cancer diagnosis

BACKGROUND

The role of gene-environment interactions in the pathogenesis of depression is unclear. Previous studies addressed vulnerability for depression after childhood adversity and stressful life events among carriers of numerous specific genetic variants; however, the importance of individual genetic variants, the environmental exposures with which they interact, and the magnitude of the risk conveyed by these interactions remain elusive.

METHODS

We included 7,320 people with a first primary cancer identified in the prospective Diet, Cancer and Health study in an exposed-only cohort study. The mean age of the individuals was 68 years (5th, 95th percentiles: 58, 78) at cancer diagnosis. Using Cox regression models and cumulative incidence plots, we analyzed the associations between genetic variants in 5-HTTLPR, BDNF, HTR1A, COMT, and FKBP5 and use of antidepressants as well as hospital contact for depression after diagnosis of cancer.

RESULTS

Overall, we observed no statistically significant associations, with nonsignificant hazard ratio estimates for use of antidepressants of 0.95-1.07.

CONCLUSIONS

This study of elderly people indicates that it is unlikely that the investigated genetic variants are clinically relevantly associated with depression after diagnosis of cancer. The mechanisms for gene-environment interactions in younger individuals are probably different, and we advise caution in extrapolating our results to early life stress. However, conclusion from the present study might be generalizable to elderly persons exposed to other stressful life events.

Influence of 5-HTT variation, childhood trauma and self-efficacy on anxiety traits: a gene-environment-coping interaction study

Environmental vulnerability factors such as adverse childhood experiences in interaction with genetic risk variants, e.g., the serotonin transporter gene linked polymorphic region (5-HTTLPR), are assumed to play a role in the development of anxiety and affective disorders. However, positive influences such as general self-efficacy (GSE) may exert a compensatory effect on genetic disposition, environmental adversity, and anxiety traits. We, thus, assessed childhood trauma (Childhood Trauma Questionnaire, CTQ) and GSE in 678 adults genotyped for 5-HTTLPR/rs25531 and their interaction on agoraphobic cognitions (Agoraphobic Cognitions Questionnaire, ACQ), social anxiety (Liebowitz Social Anxiety Scale, LSAS), and trait anxiety (State-Trait Anxiety Inventory, STAI-T). The relationship between anxiety traits and childhood trauma was moderated by self-efficacy in 5-HTTLPR/rs25531 LALA genotype carriers: LALA probands maltreated as children showed high anxiety scores when self-efficacy was low, but low anxiety scores in the presence of high self-efficacy despite childhood maltreatment. Our results extend previous findings regarding anxiety-related traits showing an interactive relationship between 5-HTT genotype and adverse childhood experiences by suggesting coping-related measures to function as an additional dimension buffering the effects of a gene-environment risk constellation. Given that anxiety disorders manifest already early in childhood, this insight could contribute to the improvement of psychotherapeutic interventions by including measures strengthening self-efficacy and inform early targeted preventive interventions in at-risk populations, particularly within the crucial time window of childhood and adolescence.

Diagnosed thyroid disorders are associated with depression and anxiety

PURPOSE

Associations between thyroid diseases and depression have been described since the 1960s but there is a lack of population-based studies investigating associations of thyroid diseases with depression and anxiety defined by gold-standard methods. Thus, the aim was to investigate the association of diagnosed thyroid disorders, serum thyroid-stimulating hormone (TSH) levels, and anti-thyroid-peroxidase antibodies (TPO-abs) with depression and anxiety.

METHODS

We used data from 2142 individuals, who participated in the first follow-up of the Study of Health in Pomerania (SHIP-1) and in the Life-Events and Gene-Environment Interaction in Depression (LEGEND). DSM-VI diagnoses of major depression disorder and anxiety were defined using the Munich-Composite International Diagnostic Interview; the Beck depression inventory (BDI-II) was used for the assessment of current depressive symptoms. Thyroid diseases were assessed by interviews and by biomarkers and were associated with depression and anxiety using Poisson regression adjusted for age, sex, marital status, educational level, smoking status, BMI, and the log-transformed time between SHIP-1 and LEGEND.

RESULTS

Untreated diagnosed hypothyroidism was positively associated with the BDI-II-score and with anxiety, while untreated diagnosed hyperthyroidism was significantly related to MDD during the last 12 months. Serum TSH levels and TPO-Abs were not significantly associated with depression and anxiety. In sub-analyses, distinct interactions were found between childhood maltreatment and thyroid disorders in modifying the association on depression and anxiety disorders.

CONCLUSIONS

Our results substantiate evidence that diagnosed untreated hypothyroidism is associated with depression and anxiety, and that diagnosed untreated hyperthyroidism is associated with depression.

Are there associations between early emotional trauma and anxiety disorders? Evidence from a systematic literature review and meta-analysis

BACKGROUND

Previous studies indicate a possible association between early emotional trauma (EET) and the development of anxiety disorders (ADs) in adult life. However, no previous studies have compiled the findings of such studies and analyzed their statistical significance. Therefore, the objective of this study was to conduct a systematic literature review and meta-analysis to determine possible associations between EET and three ADs (panic, generalized anxiety, and social anxiety disorders).

METHODS

A systematic search was conducted in PubMed, PsycInfo, and Scielo with no publication date limitations. A total of 2127 studies were found, 32 studies of which were selected for the systematic review and 13 studies of which were selected for the meta-analysis.

RESULTS

High prevalence rates of different EETs were observed among the individuals with ADs (median: 18%-45%). The results of the meta-analysis indicated that individuals with EETs were 1.9- to 3.6-fold more likely to develop ADs compared with a control group of healthy individuals. Emotional traumas were the main risk factor for social anxiety disorder. However, no specific associations were found for the other ADs.

CONCLUSIONS

EET is a risk factor for ADs, underscoring the importance of preventive measures to combat the development of these disorders. Moreover, the identification of EETs among patients with ADs is essential for implementing remedial measures to minimize the impact and damage arising from this association by decreasing the risk and severity of symptoms and to improve the response rate to treatment of ADs.

Social support and the serotonin transporter genotype (5-HTTLPR) moderate levels of resilience, sense of coherence, and depression

Gene x environment interactions have mainly been investigated in models of psychopathology. However, the putative interplay between genes and beneficial environmental conditions on positive outcomes has rarely been addressed. We therefore examined the interaction between the serotonin transporter linked polymorphic region (5-HTTLPR) and social support on the sense of coherence (SOC), resilience, and depressive symptoms. Furthermore, we scrutinized our examinations by differentiating between individuals with and without childhood abuse. The sample included 1,811 participants from the general population (Study of Health in Pomerania, Germany). The triallelic genotype of 5-HTTLPR was determined and longitudinal data of social support were used. Among individuals with high social support no significant differences between 5-HTTLPR genotypes regarding all outcome variables were found. However, among those with low social support, carriers of at least one short allele reported significantly increased levels of SOC and resilience, as well as less depressive symptoms than carriers of the l/l genotype. This result was not modified by differentiating between those with childhood abuse and those without. In less supportive social environments the impact of distinct genotypes on behavioral outcomes might be more relevant than in supportive environments where social compensation might take place. Our findings indicate that both alleles of 5-HTTLPR contribute to the adaptability to different environmental conditions.

Epigenetic regulation in biopsychosocial pathways

Theory and empirical evidence suggest that psychological stress and other adverse psychosocial experiences can contribute to cancer progression. Research has begun to explore the potential role of epigenetic changes in these pathways. In basic, animal and human models, exposure to stressors or to the products of the physiological stress response (e.g., cortisol) has been associated with epigenetic changes, such as DNA methylation and microRNA (miR) expression, which may influence tumor growth, progression, metastasis, or chemoresistance. However, the specific biological pathways linking stress, epigenetic changes, and cancer outcomes remain unclear. Numerous opportunities exist to extend the preliminary evidence for the role of epigenetic mechanisms in the biopsychosocial pathways contributing to cancer progression. Such work will improve our understanding of how the psychosocial environment influences cancer risk and survival, potentially leading to improved prevention and treatment strategies.

High social support buffers the effects of 5-HTTLPR genotypes within social anxiety disorder

An interaction between genetic aspects and environmental stressors has been suggested with regard to the etiology of social anxiety disorder (SAD). However, potential protective interplays which might decrease the risk of SAD have not been considered so far. Thus, we analyzed the interaction between 5-HTTLPR and differing levels of social support regarding SAD. The sample was based on participants of the Study of Health in Pomerania, Germany. We used the triallelic genotype of 5-HTTLPR and longitudinal data of social support. Final analyses were conducted in 79 individuals with SAD and 1,708 without. The diagnosis of SAD was derived from diagnostic interviews in accordance with DSM-IV. Considering the risk of SAD, a general protective effect of high social support was shown independent of variation in 5-HTTLPR genotype. In contrast, the risk of SAD was increased for both genotypes within those individuals with low social support. Additionally, the odds ratio for suffering from SAD was about two times higher for carriers of the l/l genotype compared to those with at least one short allele in those perceiving less-supportive social environments. The findings suggest that SAD is influenced by a protective and a contributing gene × environment interaction. High social support might act in a protective and low social support in an increasing manner on the risk of SAD especially within carriers of the l/l genotype. Therefore, effects of 5-HTTLPR might be buffered by high social support with respect to the risk of SAD.

The 5-HTTLPR genotype modulates heart rate variability and its adjustment by pharmacological panic challenge in healthy men

Abnormal serotonin transporter (5-HTT) function and autonomic nervous system (ANS) dysregulation has been proposed in panic disorder. However, in contrast to hypothalamo-pituitary-adrenocortical (HPA) functioning, ANS reactivity during panic response has yet not been investigated in humans with respect to the 5-HTT genotype. The present study assessed the influence of challenging by cholecystokinin tetrapeptide (CCK-4) on heart rate variability (HRV) measures, to monitor autonomic reactivity and its relationship to 5-HTT-linked polymorphic region (5-HTTLPR) genotypes. We hypothesized substantial effects of the 5-HTTLPR genotype on autonomic reactivity. We studied 30 healthy young men, 15 of each with the long/long (l/l) or short/short (s/s) genotype for the 5-HTTLPR. All participants received an intravenous application of 50 μg CCK-4. HRV measures were assessed in both groups at baseline and immediately after CCK-4 application. Our results indicated lower parasympathetic activity in s/s carriers during baseline, time and frequency domain measures. CCK-4 application significantly enhanced the sympathetic tone in both groups, leading to diminished group differences. A significant treatment by genotype effect indicated reduced autonomic reactivity to CCK-4 challenge in the s/s compared to l/l carriers. Our findings show enhanced sympathetic and/or diminished cardiac vagal activity under basal conditions and blunted autonomic reactivity in s/s vs. l/l carriers. Our study provides novel data supporting claims that the s/s genotype represents a genetic vulnerability factor associated with inadequate hyporeactivity to stress and extends current knowledge on the impact of the central serotonergic activity on the sympathoadrenal pathway.