From nature versus nurture, via nature and nurture, to gene x environment interaction in mental disorders

Diagnostic trajectories of mental disorders in children and adolescents: a cohort study

Mental disorders in children and adolescents may follow different trajectories, such as remission, change of diagnosis, or addition of two or more comorbid diagnoses, showing a heterotypic pattern. This study aims to describe the main diagnostic trajectories across a broad range of mental disorder diagnostic categories, from childhood to adolescence and from adolescence to young adulthood in a clinical population. A prospective study was conducted among a clinical sample of children and adolescents who were aged 3-17 years at the face-to-face baseline interview. Electronic health records of these participants were reviewed 10 years later. The diagnostic stability over time was examined using the kappa coefficient, and factors associated with stability were explored using simple logistic regression. The study included a sample of 691 participants. The kappa coefficient for diagnostic stability across all diagnoses was 0.574 for the transition from childhood to adulthood, 0.614 from childhood to adolescence, and 0.733 from adolescence to adulthood. Neurodevelopmental diagnoses had the highest stability. Factors associated with higher diagnostic stability included family history of mental disorders, receiving psychopharmacological treatment, and symptom severity at baseline. We found a variable diagnostic stability across different diagnoses and age categories. The different life transitions represent complex periods that should not be overlooked from a clinical standpoint. An appropriate transition from child and adolescent mental health services to adult mental health services may have a positive impact on children and adolescents with mental disorders.

Genotype-Environment Interaction in ADHD: Genetic Predisposition Determines the Extent to Which Environmental Influences Explain Variability in the Symptom Dimensions Hyperactivity and Inattention

Although earlier research has shown that individual differences on the spectrum of attention deficit hyperactivity disorder (ADHD) are highly heritable, emerging evidence suggests that symptoms are associated with complex interactions between genes and environmental influences. This study investigated whether a genetic predisposition [Note that the term 'genetic predisposition' was used in this manuscript to refer to an estimate based on twin modeling (an individual's score on the latent trait that resembles additive genetic influences) in the particular population being examined.] for the symptom dimensions hyperactivity and inattention determines the extent to which unique-environmental influences explain variability in these symptoms. To this purpose, we analysed a sample drawn from the Twins Early Development Study (TEDS) that consisted of item-level scores of 2168 16-year-old twin pairs who completed both the Strengths and Difficulties Questionnaire (SDQ; Goodman, in J Child Psychol Psychiatry 38:581-586, 1997) and the Strength and Weaknesses of ADHD Symptoms and Normal Behavior (SWAN; Swanson, in Paper presented at the meeting of the American Psychological Association, Los Angeles, 1981) questionnaire. To maximize the psychometric information to measure ADHD symptoms, psychometric analyses were performed to investigate whether the items from the two questionnaires could be combined to form two longer subscales. In the estimation of genotype-environment interaction, we corrected for error variance heterogeneity in the measurement of ADHD symptoms through the application of item response theory (IRT) measurement models. A positive interaction was found for both hyperactivity (e.g., [Formula: see text] = 2.20 with 95% highest posterior density interval equal to [1.79;2.65] and effect size equal to 3.00) and inattention (e.g., [Formula: see text] = 2.16 with 95% highest posterior density interval equal to [1.56;2.79] and effect size equal to 3.07). These results indicate that unique-environmental influences were more important in creating individual differences in both hyperactivity and inattention for twins with a genetic predisposition for these symptoms than for twins without such a predisposition.

Right frontal cingulate cortex mediates the effect of prenatal complications on youth internalizing behaviors

Prenatal and perinatal complications represent well-known risk factors for the future development of psychiatric disorders. Such influence might become manifested during childhood and adolescence, as key periods for brain and behavioral changes. Internalizing and externalizing behaviors in adolescence have been associated with the risk of psychiatric onset later in life. Both brain morphology and behavior seem to be affected by obstetric complications, but a clear link among these three aspects is missing. Here, we aimed at analyzing the association between prenatal and perinatal complications, behavioral issues, and brain volumes in a group of children and adolescents. Eighty-two children and adolescents with emotional-behavioral problems underwent clinical and 3 T brain magnetic resonance imaging (MRI) assessments. The former included information on behavior, through the Child Behavior Checklist/6-18 (CBCL/6-18), and on the occurrence of obstetric complications. The relationships between clinical and gray matter volume (GMV) measures were investigated through multiple generalized linear models and mediation models. We found a mutual link between prenatal complications, GMV alterations in the frontal gyrus, and withdrawn problems. Specifically, complications during pregnancy were associated with higher CBCL/6-18 withdrawn scores and GMV reductions in the right superior frontal gyrus and anterior cingulate cortex. Finally, a mediation effect of these GMV measures on the association between prenatal complications and the withdrawn dimension was identified. Our findings suggest a key role of obstetric complications in affecting brain structure and behavior. For the first time, a mediator role of frontal GMV in the relationship between prenatal complications and internalizing symptoms was suggested. Once replicated on independent cohorts, this evidence will have relevant implications for planning preventive interventions.

MAOA uVNTR Polymorphism Influence on Older Adults Diagnosed with Diabetes Mellitus/Systemic Arterial Hypertension

Background

Monoamine oxidase (MAO) is involved in several biological processes associated with well-being and mental health, and alterations in its function might directly impact various mental disorders. Some mental disorders concomitantly occur in individuals with clinical characteristics, such as substance abuse and diabetes.

Objective

To analyze the functional MAOA uVNTR polymorphism genotype frequency in an older adult population with diabetes mellitus/arterial hypertension and associate this frequency with clinical characteristics impacting daily life. Methodology. Older adults diagnosed with diabetes mellitus, systemic arterial hypertension, or both (DM/SAH) were selected and had their MAOA gene genotyped for uVNTR polymorphism. The revised Beck Depression Inventory (BDI) and a questionnaire were also applied to determine their mental health and clinical characteristics.

Results

The allelic variants detected among the participants were the 2R, 3R, 4R, and 3R/4R heterozygous genotypes. Genotypes solely containing the 3R allele had patients who marked yes for smoking and alcoholism, and only those with the 3R genotypes (female 3R/3R homozygote or male 3R∗ hemizygote) were significant. Although not statistically significant, only 3R and 3R/4R genotypes presented cases of severe depression per the revised BDI interpretations.

Conclusion

The MAOA uVNTR polymorphism's low-activity 3R allele presence in an older adult population diagnosed with DM/SAH may represent a risk for developing substance use (alcohol and smoking) dependence.

Gene-Environment Interactions in Attention-Deficit/Hyperactivity Disorder Symptom Dimensions: The Role of Unhealthy Food Habits

Background: Dietary habits were investigated as environmental risk factors for Attention-Deficit/Hyperactivity Disorder (ADHD). However, no previous studies explored the effects of dietary factors on modifying the role of genetic factors on ADHD. Methods: Based on a Swedish population-based twin study with 1518 twin pairs aged 20-47 years, we tested whether the importance of genetic and environmental effects on ADHD varied as a function of dietary habits. Self-reported dietary habits and ADHD symptoms were collected. Twin methods were used to test the degree to which high-sugar and unhealthy food intake moderated the genetic and environmental influences on ADHD symptoms. Results: In middle-aged adults, genetic influences on inattention symptoms were statistically significantly higher among individuals with higher levels of high-sugar (45%, 95%CI: 25-54%) and unhealthy food intake (51%, 95%CI: 31-60%), compared with those with lower levels of consumption of high-sugar (36%, 95%CI: 25-47%) and unhealthy foods (30%, 95%CI: 20-41%). Similar patterns were also found for the associations between hyperactivity/impulsivity and high-sugar/unhealthy food intake, even though the moderation effects were not statistically significant. Conclusion The present study suggests that genetic factors play a more prominent role in individual differences of ADHD symptoms in the presence of the high consumption of sugar and unhealthy foods. Future longitudinal studies with multiple assessments of ADHD and dietary habits are needed to replicate our findings.

Maternal depressive and anxiety symptoms and the risk of attention deficit hyperactivity disorder symptoms in offspring aged 17: Findings from the Raine Study

BACKGROUND

While previous studies have suggested that maternal anxiety and depressive symptoms are associated with increased risk of attention-deficit/hyperactivity disorder (ADHD) in their offspring in early and late childhood, studies exploring the risk in late adolescence are however lacking. This study aims to examine the association between maternal anxiety and depressive symptoms and the risk of ADHD symptoms in late adolescence (at age 17).

METHODS

We used data from the Raine Study. Maternal depressive and anxiety symptoms were measured when the child was 10 years of age using the Depression, Anxiety, and Stress Scale (DASS). Offspring ADHD symptoms at age 17 were assessed using the DSM-oriented scales of the child behavior checklist (CBCL). Log-binomial regression was used to explore the associations.

RESULTS

We found an increased risk of ADHD symptoms in offspring of mothers with comorbid anxiety and depressive symptoms when compared with offspring of mothers with no symptoms [RR 5.60 (95%CI 3.02-10.37)]. There was a nearly three-fold increase in the risk of ADHD symptoms in offspring of mothers with increased anxiety symptoms compared with offspring of mothers who were in the normal range [RR 2.84 (95%CI 1.18-6.83)]. No association was observed with maternal depressive symptoms.

CONCLUSION

This study found an increased risk of ADHD symptoms in the offspring of mothers with anxiety as well as comorbid anxiety and depressive symptoms but not among the offspring of mothers with depressive symptoms. Early screening and intervention for ADHD symptoms in offspring with maternal anxiety and comorbid anxiety and depressive symptoms are warranted.

Prenatal and perinatal factors associated with ADHD risk in schoolchildren: EPINED epidemiological study

The aim of this study is to assess the relationship between pre- and perinatal factors and ADHD in a sample of scholars exploring differences between ADHD presentations and spectrum of severity. A total of 6720 scholars (aged 3-4 and 10-11) participated in a double-phase epidemiologic cross-sectional study (Epidemiological Study of Neurodevelopmental Disorders, EPINED), and a sample of 646 scholars (ADHD risk, ASD risk and controls without risk) were individually assessed in the second phase of the study. The ADHD diagnosis, based on DSM-5 criteria, was performed with the Kiddie-Schedule for Affective Disorders & Schizophrenia, Present & Lifetime Version. Associations for the different ADHD presentations between prenatal, perinatal and postnatal factors and ADHD (n = 168), subclinical ADHD (n = 88) and non-ADHD (n = 310) were analysed. Logistic regression models showed that gestational diabetes (p = 0.012), instrumental delivery (p = 0.011), family history of psychopathology (p = 0.033) and maternal ADHD phenotype (p = 0.023) were associated with ADHD. These factors were related to the hyperactive-impulsive and combined presentations, but they were not related to the inattentive presentation. Maternal weight gain was associated with subclinical ADHD. In conclusion, metabolic disorder in the pregnancy, difficulties in childbirth and specific family phenotype were related to ADHD, specifically with hyperactive-impulsive presentation, but not in subclinical ADHD.

Interaction between lead and noradrenergic genotypes affects neurocognitive functions in attention-deficit/hyperactivity disorder: a case control study

BACKGROUND

Lead is known to be associated with attention-deficit/hyperactivity disorder (ADHD) even at low concentrations. We aimed to evaluate neurocognitive functions associated with lead in the blood and the interactions between lead and dopaminergic or noradrenergic pathway-related genotypes in youths with ADHD.

METHODS

A total of 259 youths with ADHD and 96 healthy controls (aged 5-18 years) enrolled in this study. The Korean Kiddie Schedule for Affective Disorders and Schizophrenia-Present and Lifetime version was conducted for psychiatric diagnostic evaluation. Blood lead levels were measured, and their interaction with dopaminergic or noradrenergic genotypes for ADHD; namely, the dopamine transporter (DAT1), dopamine receptor D4 (DRD4), and alpha-2A-adrenergic receptor (ADRA2A) genotypes were investigated. All participants were assessed using the ADHD Rating Scale-IV (ADHD-RS). Participants also completed the continuous performance test (CPT) and Stroop Color-Word Test (SCWT). Analysis of covariance was used for comparison of blood lead levels between ADHD and control groups. A multivariable linear regression model was used to evaluate the associations of blood lead levels with the results of ADHD-RS, CPT, and SCWT; adjusted for intelligence quotient (IQ), age, and sex. A path analysis model was used to identify the mediating effects of neurocognitive functions on the effects of blood lead on ADHD symptoms. To evaluate the effect of the interaction between blood lead and genes on neuropsychological functions, hierarchical regression analyses were performed.

RESULTS

There was a significant difference in blood lead levels between the ADHD and control groups (1.4 ± 0.5 vs. 1.3 ± 0.5 μg/dL, p = .005). Blood lead levels showed a positive correlation with scores on omission errors(r = .158, p = .003) and response time variability (r = .136, p = .010) of CPT. In the multivariable linear regression model, blood lead levels were associated with omission errors (B = 3.748, p = .045). Regarding the effects of lead on ADHD symptoms, hyperactivity-impulsivity was mediated by omission errors. An interaction effect was detected between ADRA2A DraI genotype and lead levels on omission errors (B = 5.066, p = .041).

CONCLUSIONS

Our results indicate that neurocognitive functions at least partly mediate the association between blood lead levels and ADHD symptoms, and that neurocognitive functions are affected by the interaction between blood lead levels and noradrenergic genotype.

Gender-specific differences in white matter microstructure in healthy adults exposed to mild stress

Stress is a powerful moderator of brain plasticity and may affect several physiological functions such as the endocrine and the immune system. The impact of stress can be protective or detrimental according to several factors such as level of the stressor and age of occurrence. Also, the impact may differ in males and females. We aim to analyze the effect of mild levels of early and recent stress on white matter microstructure in healthy volunteers. MRI acquisition of diffusion tensor images with a 3.0 T scanner was performed on 130 healthy subjects (71 males and 59 females). Severity of early and recent stress was rated, respectively, on the Risky Families Questionnaire and on the Schedule of Recent Experiences; subjects were divided into low stress and mild stress groups. Mild early stress associated with lower fractional anisotropy (FA) in the cingulate gyrus compared to low early stress. Females reported reduced FA compared to males in the low-stress group in the internal capsule, posterior corona radiata, posterior thalamic radiation, superior longitudinal fasciculus, and sagittal stratum whereas no difference was observed in the mild stress group. An additive effect of early and recent stress was observed in posterior corona radiata, retrolenticular part of the internal capsule, and superior longitudinal fasciculus. The impact of early stress on WM microstructure in healthy subjects is different in males and females. While males seem to be more sensitive to early stress, an additive effect of early and recent stress manifests itself in females.Layman summaryMild levels of early stress associate with lower white matter integrity measured by fractional anisotropy.Females and males show differences in white matter integrity when exposed to low levels of early stress with females showing lower white matter integrity compared to males.No difference in white matter integrity was observed for males and females exposed to mild levels of stress.Mild stress in females is associated with higher white matter integrity.Males seem to be more sensitive to early stress while females are more affected when early stress is followed by stress in adult life.

Investigating Causality Between Blood Metabolites and Emotional and Behavioral Responses to Traumatic Stress: a Mendelian Randomization Study

To investigate the causal relationship between blood metabolites and traits related to trauma-response, we combined genome-wide and metabolome-wide datasets generated from large-scale cohorts. Five trauma-response traits ascertained in the UK Biobank (52,816 < N < 117,900 individuals) were considered: (i) "Avoided activities/situations because of previous stressful experience" (Avoidance); (ii) "Felt distant from other people" (Distant); (iii) "Felt irritable/had angry outbursts" (Irritable); (iv) "Felt very upset when reminded of stressful experience" (Upset); (v) "Repeated disturbing thoughts of stressful experience". These were investigated with respect to 52 blood metabolites tested in a previous genome-wide-association study (N = 24,925 European-ancestry individuals). Linkage disequilibrium score regression, polygenic risk scoring (PRS), and Mendelian randomization were applied to the datasets. We observed that 14 metabolites were genetically correlated with trauma-response traits (p < 0.05). High-resolution PRS of 4 metabolites (citrate; glycoprotein acetyls; concentration of large very-low-density lipoproteins (VLDL) particles (LVLDLP); total cholesterol in medium particles of VLDL (MVLDLC)) were associated with trauma-response traits (false discovery rate Q < 10%). These genetic associations were partially due to causal relationships (Citrate→Upset β = - 0.058, p = 9.1 × 10^-4; Glycoproteins→Avoidance β = 0.008, p = 0.003; LVLDLP→Distant β = 0.008, p = 0.022; MVLDLC→Avoidance β = 0.019, p = 3 × 10^-4). No reverse associations were observed. In conclusion, our study supports causal relationships between certain blood metabolites and emotional and behavioral responses to traumatic experiences.

Impact of autism-associated genetic variants in interaction with environmental factors on ADHD comorbidities: an exploratory pilot study

Attention-deficit/hyperactivity disorder (ADHD) is determined by genetic and environmental factors, and shares genetic risk with ASD. Functional single-nucleotide polymorphisms of the metabotropic glutamatergic signaling pathway are reported to increase the risk for ASD. The aim of this pilot study was to explore the main effects of respective ASD variants as well as their interaction effects with well-replicated ADHD environmental risk factors on the risk for ADHD, ADHD symptom severities, and comorbidities. We included 318 children with ADHD, aged 5-13 years, and their parents (N = 164 trios, N = 113 duos, N = 41 singletons). Interaction of ASD risk variants CYFIP1-rs7170637, CYFIP1-rs3693, CAMK4-rs25925, and GRM1-rs6923492 with prenatal biological and lifetime psychosocial risk factors was explored in a subsample with complete environmental risk factors (N = 139 trios, N = 83 duos, two singletons) by transmission disequilibrium test and stepwise regression analyses. We identified nominally significant (alpha < 0.05) GxE interactions of acute life events with CYFIP1-rs3693 on ADHD diagnosis (p = 0.004; fdr = 0.096) but no significant association of any single marker. Further results suggest that the risk for comorbid disruptive disorders was significantly modulated by GxE interactions between familial risk factors and CAMK4-rs25925 (p = 0.001; fdr = 0.018) and prenatal alcohol exposure with CYFIP1-rs3693 (p = 0.003; fdr = 0.027); both findings survived correction for multiple testing (fdr value < 0.05). Nominal significant GxE interactions moderating the risk for anxiety disorders have also been identified, but did not pass multiple testing corrections. This pilot study suggests that common ASD variants of the glutamatergic system interact with prenatal and lifetime psychosocial risk factors influencing the risk for ADHD common comorbidities and thus warrants replication in larger samples.

Maternal stress in Shank3ex4-9 mice increases pup-directed care and alters brain white matter in male offspring

Gene-environment interactions contribute to the risk for Autism Spectrum Disorder (ASD). Among environmental factors, prenatal exposure to stress may increase the risk for ASD. To examine if there is an interaction between exposure to maternal stress and reduced dosage or loss of Shank3, wild-type (WT), heterozygous (HET) and homozygous (HOM) female mice carrying a deletion of exons four through nine of Shank3 (Shank3^ex4-9) were exposed to chronic unpredictable mild stress (CUMS) from prior to conception throughout gestation. This study examined maternal care of these dams and the white matter microstructure in the brains of their adult male offspring. Overall, our findings suggest that maternal exposure to CUMS increased pup-directed care for dams of all three genotypes. Compared to WT and HET dams, HOM dams also exhibited increased maternal care behaviors with increased time spent in the nest and reduced cage exploration, regardless of exposure to CUMS. Diffusion tensor imaging showed higher mean fractional anisotropy in the hippocampal stratum radiatum of WT and HOM male offspring from dams exposed to CUMS and HOM offspring from unexposed dams, compared to WT male offspring from unexposed dams. These data support that CUMS in Shank3-mutant dams results in subtle maternal care alterations and long-lasting changes in the white matter of the hippocampus of their offspring.

Children's DAT1 Polymorphism Moderates the Relationship Between Parents' Psychological Profiles, Children's DAT Methylation, and Their Emotional/Behavioral Functioning in a Normative Sample

Parental psychopathological risk is considered as one of the most crucial features associated with epigenetic modifications in offspring, which in turn are thought to be related to their emotional/behavioral profiles. The dopamine active transporter (DAT) gene is suggested to play a significant role in affective/behavioral regulation. On the basis of the previous literature, we aimed at verifying whether children’s DAT1 polymorphisms moderated the relationship between parents’ psychological profiles, children’s emotional/behavioral functioning, and DAT1 methylation in a normative sample of 79 families with school-age children (Ntot = 237). Children’s biological samples were collected through buccal swabs, while Symptom Check-List-90 item Revised, Adult Self Report, and Child Behavior Check-List/6–18 was administered to assess parental and children’s psychological functioning. We found that higher maternal externalizing problems predicted the following: higher levels of children’s DAT1 methylation at M1, but only among children with 10/10 genotype; higher levels of methylation at M2 among children with 10/10 genotype; while lower levels for children with a 9-repeat allele. There was also a positive relationship between fathers’ externalizing problems and children’s externalizing problems, only for children with a 9-repeat allele. Our findings support emerging evidence of the complex interplay between genetic and environmental factors in shaping children’ emotional/behavioral functioning, contributing to the knowledge of risk variables for a child’s development and psychological well-being.

LPHN3 gene variations and susceptibility to ADHD in Chinese Han population: a two-stage case-control association study and gene-environment interactions

Polymorphisms in latrophilin 3 (LPHN3) were recently reported to be associated with attention-deficit/hyperactivity disorder (ADHD), and subsequently other researchers tried to replicate the findings in different populations. This study was aimed to confirm the role of the LPHN3 in ADHD and explore the potential interactions with environmental risk factors in Chinese Han population. We examined the association of LPHN3 with ADHD in a population of 473 ADHD children and 585 controls. As a supplement of ADHD diagnosis, Conners Parent Symptom Questionnaire (PSQ) was used to evaluate ADHD symptoms. Blood lead levels (BLLs) were measured by atomic absorption spectrophotometry and other potential environmental risk factors were determined via a questionnaire filled out by the parents. Finally, after validation in an independent sample (284 cases and 390 controls), we observed significant associations between LPHN3 variants rs1868790 and ADHD risk in combined stage within codominant model [TA/AA: OR (95% CI) = 1.636 (1.325-2.021)], dominant model [OR (95% CI) = 1.573 (1.288-1.922)], and additive model [OR (95% CI) = 1.535 (1.266-1.862)]. Furthermore, rs1868790 significantly interacted with BLLs and maternal stress to modify ADHD susceptibility (P < 0.05), and rs1868790 was found to be related with ADHD symptoms (P < 0.05). Expression quantitative trait loci analysis further indicated that rs1868790 took part in the regulation of LPHN3 gene expression. As the first study to comprehensively explore the role of LPHN3 in ADHD in Chinese children, our research suggests that LPHN3 gene has a significant effect on the ADHD in a Chinese population.

Homo- and Heterotypic Trajectories in a Preschool to Primary-School Clinical Sample: A Prospective Study Related to Maternal Psychopathology

Background: Most longitudinal or follow-up mental health studies describe developmental pathways using dimensional measures of psychopathology, but seldom using pathways described by clinical disorders. Objective: We aim to describe diagnostic pathways by homotypic (within the disorder continuity) and heterotypic development (between the disorder continuity), with maternal psychopathology as moderator for both trajectories. Methods: Clinically referred children (0-7 years; N = 83) were assessed at preschool age and at primary-school age through a clinical interview. We built a disorder cluster of emotional disorders (ED; F32, F40, F42, F43, F93.0, F93.1, F93.2, F93.8, F95), behavioral disorders (BD; F68.8, F90, F91, F91.3, F93.3, F93.9, F94), and specific early onset disorders (SEO; F50, F51, F70, F98.0, F98.1, F98.2, F98.8, F98.9). We describe the prevalence, comorbidity, and clinical trajectories of various types of homotypic and heterotypic development. Results: We observed a high rate of comorbidity throughout the study (62.6% at admission and 67.5% at follow-up) and in general, a high continuity of mental health problems from preschool to primary-school age children (69.9% of the sample showed continuity), with 50.6% of the sample showing homotypic and 44.6% showing heterotypic development. Hierarchical multiple regression analyses suggest that heterotypic development may be influenced by maternal psychopathology. Conclusion: Currently, evidence-based mental health guidelines for preschool populations are designed and evaluated assuming a homotypic development. However, our findings indicate that treatment interventions and outcome measures should also be designed and evaluated for heterotypic development especially in case of increased maternal psychopathology.

Lost in translation: how to upgrade fear memory research

We address some of the current limitations of translational research in fear memory and suggest alternatives that might help to overcome them. Appropriate fear responses are adaptive, but disruption of healthy fear memory circuits can lead to anxiety and fear-based disorders. Stress is one of the main environmental factors that can disrupt memory circuits and constitutes as a key factor in the etiopathology of these psychiatric conditions. Current therapies for anxiety and fear-based disorders have limited success rate, revealing a clear need for an improved understanding of their neurobiological basis. Although animal models are excellent for dissecting fear memory circuits and have driven tremendous advances in the field, translation of these findings into the clinic has been limited so far. Animal models of stress-induced pathological fear combined with powerful cutting-edge techniques would help to improve the translational value of preclinical studies. We also encourage combining animal and human research, including psychiatric patients in order to find new pharmacological targets with real therapeutic potential that will improve the extrapolation of the findings. Finally, we highlight novel neuroimaging approaches that improve our understanding of anxiety and fear-based disorders.

ADHD, CD, and ODD: Systematic review of genetic and environmental risk factors

This review aims to analyze the relationships between Attention-Deficit Hyperactivity Disorder (ADHD), Oppositional Defiant Disorder (ODD), and Conduct Disorder (CD), particularly regarding the relative importance of genetic and environmental factors in the development of these disorders. Studies that examined at least two of these disorders were obtained from multiple databases, following the procedures of the Cochrane Collaboration initiative. Of the 279 documents obtained, nine were retained for in-depth analysis and were considered eligible for inclusion. In addition, eight studies from the manual search were included. The objectives, methodological aspects (sample and instruments), and the main conclusions were extracted from each study. Overall, the results suggest that (a) the causes for the onset and maintenance of these disorders are more associated with genetic factors than environmental factors, although the importance of the latter is recognized, and (b) children with ADHD have a predisposition to manifest behaviors that are common to ODD and CD, including the antisocial behavior that these children often display.

Oxytocin receptors (OXTR) and early parental care: An interaction that modulates psychiatric disorders

Oxytocin plays an important role in the modulation of social behavior in both typical and atypical contexts. Also, the quality of early parental care sets the foundation for long-term psychosocial development. Here, we review studies that investigated how oxytocin receptor (OXTR) interacts with early parental care experiences to influence the development of psychiatric disorders. Using Pubmed, Scopus and PsycInfo databases, we utilized the keyword "OXTR" before subsequently searching for specific OXTR single nucleotide polymorphisms (SNPs), generating a list of 598 studies in total. The papers were catalogued in a database and filtered for gene-environment interaction, psychiatric disorders and involvement of parental care. In particular, rs53576 and rs2254298 were found to be significantly involved in gene-environment interactions that modulated risk for psychopathology and the following psychiatric disorders: disruptive behavior, depression, anxiety, eating disorder and borderline personality disorder. These results illustrate the importance of OXTR in mediating the impact of parental care on the emergence of psychopathology.

Effects of Interaction Between DRD4 Methylation and Prenatal Maternal Stress on Methylphenidate-Induced Changes in Continuous Performance Test Performance in Youth with Attention-Deficit/Hyperactivity Disorder

OBJECTIVES

Environmental factors may interact with genetic factors via the epigenetic process, and this interaction can contribute to inter-individual variability in the treatment response. The purpose of this study was to investigate the interaction effects between dopamine receptor D4 (DRD4) methylation and prenatal maternal stress on the methylphenidate (MPH) response of youth with attention-deficit/hyperactivity disorder (ADHD).

METHODS

This study was an 8-week open-label trial of MPH that included 74 ADHD youth. We investigated the associations between MPH treatment response, which was defined as a score ≤2 on the Clinical Global Impressions-Improvement (CGI-I) scale, and the methylation of 28 cytosine-guanine dinucleotide (CpG) sites of DRD4. Additionally, the interaction effects between DRD4 methylation and prenatal maternal stress on changes in Continuous Performance Test (CPT) scores after MPH treatment were investigated.

RESULTS

Although there were no significant sites that showed significant association with treatment response, there was a significant interaction effect of the methylation of CpG7 and prenatal maternal stress on changes in omission errors of the CPT following treatment (p = 0.0001).

CONCLUSIONS

The present findings indicate that the interaction between methylation of CpG7 of DRD4 and prenatal maternal stress may be predictive of the treatment response to MPH in youth with ADHD.

SLC6A3 polymorphism and response to methylphenidate in children with ADHD: A systematic review and meta-analysis

Methylphenidate (MPH) is the most commonly used treatment for attention-deficit hyperactivity disorder (ADHD) in children. However, the response to MPH is not similar in all patients. This meta-analysis investigated the potential role of SLC6A3 polymorphisms in response to MPH in children with ADHD. Clinical trials or naturalistic studies were selected from electronic databases. A meta-analysis was conducted using a random-effects model. Cohen's d effect size and 95% confidence intervals (CIs) were determined. Sensitivity analysis and meta-regression were performed. Q-statistic and Egger's tests were conducted to evaluate heterogeneity and publication bias, respectively. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) system was used to assess the quality of evidence. Sixteen studies with follow-up periods of 1-28 weeks were eligible. The mean treatment acceptability of MPH was 97.2%. In contrast to clinical trials, the meta-analysis of naturalistic studies indicated that children without 10/10 repeat carriers had better response to MPH (Cohen's d: -0.09 and 0.44, respectively). The 9/9 repeat polymorphism had no effect on the response rate (Cohen's d: -0.43). In the meta-regression, a significant association was observed between baseline severity of ADHD, MPH dosage, and combined type of ADHD in some genetic models. Sensitivity analysis indicated the robustness of our findings. No publication bias was observed in our meta-analysis. The GRADE evaluations revealed very low levels of confidence for each outcome of response to MPH. The results of clinical trials and naturalistic studies regarding the effect size between different polymorphisms of SLC6A3 were contradictory. Therefore, further research is recommended.

Prenatal stress and genetic risk: How prenatal stress interacts with genetics to alter risk for psychiatric illness

Risk for neuropsychiatric disorders is complex and includes an individual's internal genetic endowment and their environmental experiences and exposures. Embryonic development captures a particularly complex period, in which genetic and environmental factors can interact to contribute to risk. These environmental factors are incorporated differently into the embryonic brain than postnatal one. Here, we comprehensively review the human and animal model literature for studies that assess the interaction between genetic risks and one particular environmental exposure with strong and complex associations with neuropsychiatric outcomes-prenatal maternal stress. Gene-environment interaction has been demonstrated for stress occurring during childhood, adolescence, and adulthood. Additional work demonstrates that prenatal stress risk may be similarly complex. Animal model studies have begun to address some underlying mechanisms, including particular maternal or fetal genetic susceptibilities that interact with stress exposure and those that do not. More specifically, the genetic underpinnings of serotonin and dopamine signaling and stress physiology mechanisms have been shown to be particularly relevant to social, attentional, and internalizing behavioral changes, while other genetic factors have not, including some growth factor and hormone-related genes. Interactions have reflected both the diathesis-stress and differential susceptibility models. Maternal genetic factors have received less attention than those in offspring, but strongly modulate impacts of prenatal stress. Priorities for future research are investigating maternal response to distinct forms of stress and developing whole-genome methods to examine the contributions of genetic variants of both mothers and offspring, particularly including genes involved in neurodevelopment. This is a burgeoning field of research that will ultimately contribute not only to a broad understanding of psychiatric pathophysiology but also to efforts for personalized medicine.

Associations of monoamine oxidase A gene first exon methylation with sexual abuse and current depression in women

Childhood physical abuse (PA) and sexual abuse (SA) interact with monoamine oxidase A (MAOA) gene polymorphism to modify risk for mental disorders. In addition, PA and SA may alter gene activity through epigenetic mechanisms such as DNA methylation, thereby further modifying risk for disorders. We investigated whether methylation in a region spanning the MAOA first exon and part of the first intron was associated with PA and/or SA, MAOA genotype, alcohol dependence, drug dependence, depression disorders, anxiety disorders, and conduct disorder. 114 Swedish women completed standardized diagnostic interviews and questionnaires to report PA and SA, and provided saliva samples for DNA extraction. DNA was genotyped for MAOA-uVNTR polymorphisms, and methylation of a MAOA region of interest (chrX: 43,515,544–43,515,991) was measured. SA, not PA, was associated with hypermethylation of the MAOA first exon relative to no-abuse, and the association was robust to adjustment for psychoactive medication, alcohol and drug dependence, and current substance use. SA and MAOA-uVNTR genotype, but not their interaction, was associated with MAOA methylation. SA associated with all measured mental disorders. Hypermethylation of MAOA first exon mediated the association of SA with current depression, and both methylation levels and SA independently predicted lifetime depression. Much remains to be learned about the independent effects of SA and MAOA-uVNTR genotypes on methylation of the MAOA first exon.

The role of emotion regulation in childhood obesity: implications for prevention and treatment

Stress and negative emotions pose a major threat to public health, by increasing the risk of obesity. Since the management process for emotions (emotion regulation; ER) is developed in childhood, we present a novel conceptual framework model for the role of ER in the prevention and treatment of childhood obesity. A narrative review of the literature by electronic database search (MEDLINE, Web of Knowledge and Scopus) was conducted of observational and interventional/experimental literature on ER and obesity and the underlying concepts. We also present an overview of ER intervention techniques. Our model indicates that childhood ER is a link between stress and obesity. Stress along with ineffective ER leads to abnormal cortisol patterns, emotional eating, sedentary lifestyle, reduction of physical activity, and sleep problems. Simultaneously, a healthy lifestyle could show benefits on ER and in developing adaptive ER strategies. In the development of obesity and ER, parents also play a role. By contrast, effective ER skills decrease obesity-related unhealthy behaviour and enhance protective factors, which boost health. The literature contains some observational studies of children but very few intervention studies, most of which are pilot or on-going studies. In conclusion, encouraging effective ER could be a useful new approach for combating and treating childhood obesity. Future ER intervention studies are needed to confirm the validity of this model in children.

A Concept Analysis of Resilience Integrating Genetics

Although clinicians and researchers are interested in the phenomenon of resilience, there is no agreed-upon definition of resilience. Scientific evidence suggests that resilience is influenced by intrapersonal (e.g. personality traits) and environmental (e.g. social support) variables. A concept analysis was conducted to better understand the meaning of resilience. In this analysis, the antecedent of resilience was a potentially traumatic event; the defining attributes were ego-resiliency, emotion regulation, social support, and heredity; and the consequences were none to mild psychopathological symptoms and positive adaptation. This analysis can help nurses better understand resilience and its relationships to both intrapersonal and environmental variables.

Attention, cognitive control and motivation in ADHD: Linking event-related brain potentials and DNA methylation patterns in boys at early school age

In order to better understand the underpinnings of attention-deficit/hyperactivity disorder (ADHD), we targeted the relationship of attentional, cognitive control and motivational processes with DNA methylation patterns of 60 candidate genes in boys at early school age. Participants (6 to 8 years; N = 82) were selected from a German longitudinal cohort (FRANCES). ADHD-related behaviour was assessed via maternal ratings. Performance and event-related potential measures (inter alia Cue-P3 and Nogo-P3), which were recorded in a motivational go/nogo task, indicated diminished attentional orienting, reduced inhibitory response control and a larger motivational effect on performance in ADHD already at this relatively young age. Methylation patterns were analysed in buccal cell DNA with the Illumina HumanMethylation 450K array. For CpG sites at genes of the dopaminergic (COMT, ANKK1) and the neurotrophic (BDNF, NGFR) system, associations with the Nogo-P3 as well as ADHD symptom severity were found suggesting that these systems are involved in response control deficits in ADHD. Methylation effects related to both functional aspects and ADHD behaviour were also observed for DPP10 and TPH2. Epigenetic mechanisms may play a role in ADHD-associated deficits but findings need to be replicated in larger samples and are limited by the fact that only peripheral methylation could be considered.

RNA-binding proteins, neural development and the addictions

Transcriptional and post-transcriptional regulation of gene expression defines the neurobiological mechanisms that bridge genetic and environmental risk factors with neurobehavioral dysfunction underlying the addictions. More than 1000 genes in the eukaryotic genome code for multifunctional RNA-binding proteins (RBPs) that can regulate all levels of RNA biogenesis. More than 50% of these RBPs are expressed in the brain where they regulate alternative splicing, transport, localization, stability and translation of RNAs during development and adulthood. Dysfunction of RBPs can exert global effects on their targetomes that underlie neurodegenerative disorders such as Alzheimer's and Parkinson's diseases as well as neurodevelopmental disorders, including autism and schizophrenia. Here, we consider the evidence that RBPs influence key molecular targets, neurodevelopment, synaptic plasticity and neurobehavioral dysfunction underlying the addictions. Increasingly well-powered genome-wide association studies in humans and mammalian model organisms combined with ever more precise transcriptomic and proteomic approaches will continue to uncover novel and possibly selective roles for RBPs in the addictions. Key challenges include identifying the biological functions of the dynamic RBP targetomes from specific cell types throughout subcellular space (e.g. the nuclear spliceome vs. the synaptic translatome) and time and manipulating RBP programs through post-transcriptional modifications to prevent or reverse aberrant neurodevelopment and plasticity underlying the addictions.

Sexual dimorphism of the cerebellar vermis in schizophrenia

Converging lines of evidence implicate structural and functional abnormalities in the cerebellum in schizophrenia (SCZ). The cerebellar vermis is of particular interest given its association with clinical symptoms and cognitive deficits in SCZ and its known connections with cortical regions such as the prefrontal cortex. Prior neuroimaging studies have shown structural and functional abnormalities in the vermis in SCZ. In this study, we examined the cerebellar vermis in 50 individuals with SCZ and 54 healthy controls (HC) using a quantitative volumetric approach. All participants underwent high-resolution structural magnetic resonance imaging (MRI). The vermis was manually traced for each participant, and vermis volumes were computed using semiautomated methods. Volumes for total vermis and vermis subregions (anterior and posterior vermis) were analyzed in the SCZ and HC groups. Significant diagnosis-by-sex interaction effects were found in total vermis and vermis subregion analyses. These effects appeared to be driven by significantly decreased posterior vermis volumes in males with SCZ. Exploratory analyses did not reveal significant effects of clinical variables (FEP status, illness duration, and BPRS total score and subscores) on vermis volumes. The findings herein highlight the presence of neural sex differences in SCZ and the need for considering sex-related factors in studying the disorder.

Leadership, Literacy, and Translational Expertise in Genomics: Challenges and Opportunities for Social Work

The transdisciplinary field of genomics is revolutionizing conceptualizations of health, mental health, family formation, and public policy. Many professions must rapidly acquire genomic expertise to maintain state-of-the-art knowledge in their practice. Calls for social workers to build genomic capacity come regularly, yet social work education has not prepared practitioners to join the genomics workforce in providing socially just, ethically informed care to all clients, particularly those from vulnerable and marginalized groups. The authors suggest a set of action steps for bringing social work skills and practice into the 21st century. They propose that good genomic practice entails bringing social work values, skills, and behaviors to genomics. With education and training, social workers may facilitate socially just dissemination of genomic knowledge and services across practice domains. Increased genomic literacy will support the profession's mission to address disparities in health, health care access, and mortality.

Mediating and Moderating Role of Depression, Conduct Disorder or Attention-Deficit/Hyperactivity Disorder in Developing Adolescent Substance Use Disorders: A Population-Based Study

Objective

To evaluate the mediating/moderating effects of common internalizing /externalizing disorders on the association between ADHD and adolescent substance use disorders (SUD) in a population-based birth cohort.

Methods

Among 5718 children in the birth cohort, 343 ADHD incident cases and 712 matched controls were identified. Psychiatric diagnoses prior to age 19 were classified into DSM-IV categories. The association between ADHD and SUD was summarized (hazard ratios (HR), 95% CI). The effect of depression, CD/ODD, anxiety was evaluated separately.

Results

Assessment of the joint effects of ADHD and each psychiatric disorder did not support a moderating effect of these disorders on SUD on additive scale. However, the association between ADHD and SUD was partially explained by a mediating role of these psychiatric disorders.

Conclusion

For clinicians our results emphasize that depression (or CD/ODD) confers greater risk for SUD than ADHD alone. Early detection/treatment of SUD among adolescents with depression (or CD/ODD) is crucial regardless of ADHD.

Are fetal growth impairment and preterm birth causally related to child attention problems and ADHD? Evidence from a comparison between high-income and middle-income cohorts

Background

Cross-cohort comparison is an established method for improving causal inference. This study compared 2 cohorts, 1 from a high-income country and another from a middle-income country, to (1) establish whether birth exposures may play a causal role in the development of childhood attention problems; and (2) identify whether confounding structures play a different role in parent-reported attention difficulties compared with attention deficit hyperactivity disorder (ADHD) diagnoses.

Methods

Birth exposures included low birth weight (LBW), small-for-gestational age (SGA), small head circumference (HC) and preterm birth (PTB)). Outcomes of interest were attention difficulties (Strengths and Difficulties Questionnaire, SDQ) and ADHD (Development and Well-Being Assessment, DAWBA). Associations between exposures and outcomes were compared between 7-year-old children from the Avon Longitudinal Study of Parents and Children (ALSPAC) in the UK (N=6849) and the 2004 Pelotas cohort in Brazil (N=3509).

Results

For attention difficulties (SDQ), the pattern of association with birth exposures was similar between cohorts: following adjustment, attention difficulties were associated with SGA (OR=1.59, 95% CI 1.20 to 2.19) and small HC (OR=1.64, 95% CI 1.11 to 2.41) in ALSPAC and SGA (OR=1.35, 95% CI 1.04 to 1.75) in Pelotas. For ADHD, however, the pattern of association following adjustment differed markedly between cohorts. In ALSPAC, ADHD was associated with LBW (OR=2.29, 95% CI 1.09 to 4.80) and PTB (OR=2.33, 95% CI 1.23 to 4.42). In the Pelotas cohort, however, ADHD was associated with SGA (OR=1.69, 95% CI 1.02 to 2.82).

Conclusions

The findings suggest that fetal growth impairment may play a causal role in the development of attention difficulties in childhood, as similar associations were identified across both cohorts. Confounding structures, however, appear to play a greater role in determining whether a child meets the full diagnostic criteria for ADHD.

Adverse childhood experiences influence the detrimental effect of bipolar disorder and schizophrenia on cortico-limbic grey matter volumes

BACKGROUND

Adverse childhood experiences (ACE) can lead to several negative consequences in adult life, are highly prevalent in psychiatric disorders where they associate with clinical and brain morphological features. Grey matter volume loss is a central characteristic of bipolar disorder (BD) and schizophrenia (SCZ). The aim of this study is to measure the effect of diagnosis and ACE on GM volume in a sample of patients with BD or SCZ compared with healthy controls (HC).

METHODS

We studied 206 depressed BD patients, 96 SCZ patients and 136 healthy subjects. GM volumes were estimated with 3.0 Tesla MRI and analyzed with VBM technique. The effect of diagnosis was investigated in the whole sample and separately exposed to high and low ACE subjects.

RESULTS

An effect of diagnosis was observed in orbitofrontal cortex encompassing BA 47 and insula, and in the thalamus. HC had the highest volume and SCZ patients the lowest with BD patients showing an intermediate volume. This pattern persisted only in subjects with high ACE. No differences were observed for low ACE subjects.

LIMITATIONS

The three diagnostic groups differ for age and education, previous and current medications, and treatment periods.

CONCLUSIONS

Our results underline the importance of ACE on the neural underpinnings of psychiatric psychopathology and suggest a major role of exposure to ACE for the GM deficits to reveal in clinical populations. Exposure to early stress is a crucial factor that must be taken in to account when searching for biomarkers of BD and SCZ.

“What about FH of my child?” parents’ opinion on family history collection in preventive primary pediatric care

Objective: Family history (FH) in Preventive Primary Pediatric Care is to identify children at risk for complex diseases and provide personal preventive strategies. This study was to assess parents’ opinion on FH collection. Methods: Semi-structured interviews were conducted. Among issues addressed were: former experiences with FH, knowledge about FH, family definition and sharing information about FH. Results: The importance of FH for participants depended on their knowledge, perceived family health status and former experiences. After insight into FH, parents shift to believing it to be important, but certain barriers exist in reporting FH. Conclusion: Parents suggest that the importance of FH should be more emphasized and more trusting relationship with Preventive Primary Pediatric Care should be invested in.

Differential susceptibility to maternal expressed emotion in children with ADHD and their siblings? Investigating plasticity genes, prosocial and antisocial behaviour

The differential susceptibility theory states that children differ in their susceptibility towards environmental experiences, partially due to plasticity genes. Individuals carrying specific variants in such genes will be more disadvantaged in negative but, conversely, more advantaged in positive environments. Understanding gene-environment interactions may help unravel the causal mechanisms involved in multifactorial psychiatric disorders such as Attention-Deficit/Hyperactivity Disorder (ADHD). The differential susceptibility theory was examined by investigating the presence of interaction effects between maternal expressed emotion (EE; warmth and criticism) and the solitary and combined effects of plasticity genes (DAT1, DRD4, 5-HTT) on prosocial and antisocial behaviour (measured with parent- and self-reports) in children with ADHD and their siblings (N = 366, M = 17.11 years, 74.9% male). Maternal warmth was positively associated with prosocial behaviour and negatively with antisocial behaviour, while maternal criticism was positively associated with antisocial behaviour and negatively with prosocial behaviour. No evidence of differential susceptibility was found. The current study found no evidence for differential susceptibility based on the selected plasticity genes, in spite of strong EE-behaviour associations. It is likely that additional factors play a role in the complex relationship between genes, environment and behaviour.

The prevalence of psychopathology in siblings of children with mental health problems: a 20-year systematic review

While the importance of looking at the entire family system in the context of child and adolescent mental health is well recognised, siblings of children with mental health problems (MHPs) are often overlooked. The existing literature on the mental health of these siblings needs to be reviewed. A systematic search located publications from 1990 to 2011 in four electronic databases. Thirty-nine relevant studies reported data on the prevalence of psychopathology in siblings of target children with MHPs. Siblings of target children had higher rates of at least one type of psychopathology than comparison children. Risk of psychopathology varied across the type of MHP in the target child. Other covariates included sibling age and gender and parental psychopathology. Significant variations and limitations in methodology were found in the existing literature. Methodological guidelines for future studies are outlined. Implications for clinicians, parents, and for future research are discussed.

Association between autoimmune thyroiditis and depressive disorder in psychiatric outpatients

Thyroid diseases are often associated with psychiatric disorders. The prevalence of autoimmune thyroiditis in the general population is estimated to be at about 5-14 %. A clinical study was conducted to evaluate the association between autoimmune thyroiditis and depression in psychiatric outpatients. Fifty-two patients with depression and nineteen patients with schizophrenia (serving as control group), attending a psychiatric outpatient unit, were included. In addition to the measurement of thyroid-stimulating hormone (TSH), free triiodothyronine, free thyroxine, antithyroid peroxidase (anti-TPO) antibodies, and anti-thyroglobulin antibodies, ultrasound examination of the thyroid gland was performed. The proportion of pathologically increased anti-TPO levels in patients with depression was high. Furthermore, the distribution of pathologically increased anti-TPO levels was significantly (χ (2) = 5.5; p = 0.019) different between patients with depression (32.7 %) and patients with schizophrenia (5.3 %). In a gender- and age-adjusted logistic regression, the odds ratio of uni- or bipolar patients with depression for an autoimmune thyroiditis was ten times higher (95 % CI = 1.2-85.3) when compared with schizophrenia patients. TSH basal level did not differ between patients with depression and patients with schizophrenia. Our study demonstrates a strong association between anti-TPO levels, which are considered to be of diagnostic value for autoimmune thyroiditis (in combination with a hypoechoic thyroid in ultrasonography) with uni- or bipolar depression. It should be noted that the routinely measured TSH level is not sufficient in itself to diagnose this relevant autoimmune comorbidity.

Attention-deficit hyperactivity disorder (ADHD): an updated review of the essential facts

Attention-deficit hyperactivity disorder (ADHD) is a complex disorder that can affect individuals across the lifespan. It is associated with substantial heterogeneity in terms of aetiology, clinical presentation and treatment outcome and is the subject of extensive research. Because of this, it can be difficult for clinicians to stay up to date with the most relevant findings and know how best to respond to parents' questions and concerns about the disorder and interventions. This is a narrative review that aims to summarize key findings from recent research into ADHD and its treatment that clinicians can share with families in order to increase their knowledge about ADHD and intervention options. ADHD develops as a result of complex interplay between interdependent genetic and non-genetic factors. The disorder is associated with substantial impairments in functioning and poor long-term outcomes. Pharmacological and non-pharmacological treatment options are available for symptom management and to improve function, but functioning outcomes often fail to normalize in children with ADHD. Despite extensive advances in understanding this complex disorder, it is clear that there is still a long way to go. In particular, we address the need for future non-pharmacological interventions to be more specifically targeted for ADHD symptoms and its commonly associated functioning deficits in order to ensure the best long-term outcomes for children with ADHD.

[The role of genotype in the intergenerational transmission of experiences of childhood adversity]

The prevalence of childhood abuse and maltreatment is estimated to lie at about 15% in the overall German population. Previous research suggested that about one third of all individuals who had experienced childhood adversity subsequently maltreated their own children or responded insensitively to their children's needs. Empirical studies imply that interindividual differences in the responsiveness to childhood adversity can partially be explained by gene-environment interactions. This article discusses the potential interplay of genes and environment in the context of transmitting maltreating behavior and (in)sensitive parenting against the background of current challenges in genetic research. Selected studies on gene × environment interactions are presented and relevant gene polymorphisms are identified. Overall, previous studies reported interactions between polymorphisms of the serotonergic, dopaminergic, oxytocin-related, and arginine vasopressin-related systems and childhood experiences of care and abuse in the prediction of social behaviors during mother-child interactions. The results indicate a differential susceptibility toward both negative and positive environments which is dependent on genetic characteristics. Future research should thus investigate the effects of children's presumed risk gene variants toward negative as well as positive parenting. This could contribute to a deeper understanding of the underlying mechanisms of the intergenerational transmission of abusive and beneficial parenting behavior and help to avoid false stigmatizations.

The rare DAT coding variant Val559 perturbs DA neuron function, changes behavior, and alters in vivo responses to psychostimulants

Despite the critical role of the presynaptic dopamine (DA) transporter (DAT, SLC6A3) in DA clearance and psychostimulant responses, evidence that DAT dysfunction supports risk for mental illness is indirect. Recently, we identified a rare, nonsynonymous Slc6a3 variant that produces the DAT substitution Ala559Val in two male siblings who share a diagnosis of attention-deficit hyperactivity disorder (ADHD), with other studies identifying the variant in subjects with bipolar disorder (BPD) and autism spectrum disorder (ASD). Previously, using transfected cell studies, we observed that although DAT Val559 displays normal total and surface DAT protein levels, and normal DA recognition and uptake, the variant transporter exhibits anomalous DA efflux (ADE) and lacks capacity for amphetamine (AMPH)-stimulated DA release. To pursue the significance of these findings in vivo, we engineered DAT Val559 knock-in mice, and here we demonstrate in this model the presence of elevated extracellular DA levels, altered somatodendritic and presynaptic D2 DA receptor (D2R) function, a blunted ability of DA terminals to support depolarization and AMPH-evoked DA release, and disruptions in basal and psychostimulant-evoked locomotor behavior. Together, our studies demonstrate an in vivo functional impact of the DAT Val559 variant, providing support for the ability of DAT dysfunction to impact risk for mental illness.

Adverse childhood experiences influence white matter microstructure in patients with bipolar disorder

BACKGROUND

Bipolar disorder (BD) is associated with adverse childhood experiences (ACE), which worsen the lifetime course of illness, and with signs of widespread disruption of white matter (WM) integrity in adult life. ACE are associated with changes in WM microstructure in healthy humans.

METHOD

We tested the effects of ACE on diffusion-tensor imaging (DTI) measures of WM integrity in 80 in-patients affected by a major depressive episode in the course of BD. We used whole-brain tract-based spatial statistics in the WM skeleton with threshold-free cluster enhancement of DTI measures of WM microstructure: axial, radial and mean diffusivity, and fractional anisotropy.

RESULTS

ACE hastened the onset of illness. We observed an inverse correlation between the severity of ACE and DTI measures of axial diffusivity in several WM fibre tracts contributing to the functional integrity of the brain and including the corona radiata, thalamic radiations, corpus callosum, cingulum bundle, superior longitudinal fasciculus, inferior fronto-occipital fasciculus and uncinate fasciculus.

CONCLUSIONS

Axial diffusivity reflects the integrity of axons and myelin sheaths, and correlates with functional connectivity and with higher-order abilities such as reasoning and experience of emotions. In patients with BD axial diffusivity is increased by lithium treatment. ACE might contribute to BD pathophysiology by hampering structural connectivity in critical cortico-limbic networks.

Effect of early stress on hippocampal gray matter is influenced by a functional polymorphism in EAAT2 in bipolar disorder

Current views on the pathogenesis of psychiatric disorders focus on the interplay between genetic and environmental factors, with individual variation in vulnerability and resilience to hazards being part of the multifactorial development of illness. The aim of the study is to investigate the effect of glutamate transporter polymorphism SLC1A2-181A>C and exposure to Adverse Childhood Experiences (ACE) on hippocampal gray matter volume of patients with bipolar disorder (BD). Patients exposed to higher levels of ACE reported lower gray matter volume. The effect of SLC1A2-181A>C revealed itself only among patients exposed to lower levels of ACE, with T/T homozygotes showing the lowest, and G/G the highest, gray matter volume. The greatest difference between high and low exposures to ACE was observed in carriers of the G allele. Since the mutant G allele has been associated with a reduced transcriptional activity and expression of the transporter protein, we could hypothesize that after exposure to highest levels of ACE G/G homozygotes are more vulnerable to stress reporting the highest brain damage as a consequence of an excess of free glutamate.

ADHD pharmacogenetics across the life cycle: New findings and perspectives

Attention-deficit/hyperactivity disorder (ADHD) is a complex and heterogeneous disorder, affecting individuals across the life cycle. Although its etiology is not yet completely understood, genetics plays a substantial role. Pharmacological treatment is considered effective and safe for children and adults, but there is considerable inter-individual variability among patients regarding response to medication, required doses, and adverse events. We present here a systematic review of the literature on ADHD pharmacogenetics to provide a critical discussion of the existent findings, new approaches, limitations, and recommendations for future research. Our main findings are: first, the number of studies continues to grow, making ADHD one of the mental health areas with more pharmacogenetic studies. Second, there has been a focus shift on ADHD pharmacogenetic studies in the last years. There is an increasing number of studies assessing gene-gene and gene-environment interactions, using genome-wide association approaches, neuroimaging, and assessing pharmacokinetic properties. Third and most importantly, the heterogeneity in methodological strategies employed by different studies remains impressive. The question whether pharmacogenetics studies of ADHD will improve clinical management by shifting from trial-and-error approach to a pharmacological regimen that takes into account the individual variability remains unanswered. © 2014 Wiley Periodicals, Inc.

Role of 5-HTTLPR polymorphism in the development of the inward/outward personality organization: a genetic association study

Reciprocity with primary caregivers affects subjects' adaptive abilities toward the construction of the most useful personal meaning organization (PMO) with respect to their developmental environment. Within cognitive theory the post-rationalist approach has outlined two basic categories of identity construction and of regulation of cognitive and emotional processes: the Outward and the Inward PMO. The presence of different, consistent clinical patterns in Inward and Outward subjects is paralleled by differences in cerebral activation during emotional tasks on fMRI and by different expression of some polymorphisms in serotonin pathways. Since several lines of evidence support a role for the 5-HTTLPR polymorphism in mediating individual susceptibility to environmental emotional stimuli, this study was conducted to investigate its influence in the development of the Inward/Outward PMO.

PMO was assessed and the 5-HTTLPR polymorphism investigated in 124 healthy subjects who were subdivided into an Inward (n = 52) and an Outward (n = 72) group.

Case-control comparisons of short allele (S) frequencies showed significant differences between Inwards and Outwards (p = 0.036, χ2 test; p = 0.026, exact test). Genotype frequencies were not significantly different although values slightly exceeded p≤0.05 (p = 0.056, χ2 test; p = 0.059, exact test). Analysis of the 5-HTTLPR genotypes according to the recessive inheritance model showed that the S/S genotype increased the likelihood of developing an Outward PMO (p = 0.0178, χ2 test; p = 0.0143, exact test; OR = 3.43, CI (95%) = 1.188–9.925). A logistic regression analysis confirmed the association between short allele and S/S genotypes with the Outward PMO also when gender and age were considered. However none of the differences remained significant after correction for multiple testing, even though using the recessive model they approach significance.

Overall our data seem to suggest a putative genetic basis for interindividual differences in PMO development.

Genetics of eating disorders

Disordered eating behavior is the core symptom of the complex disorders anorexia nervosa and bulimia nervosa. Twin and family studies derive high heritability estimates. Hence, substantial genetic influences on the etiology can be assumed for both. Initially, candidate gene studies pertaining to the monoaminergic neurotransmitter systems and to body weight regulation comprised the core of the genetic analyses. Unfortunately, confirmed, solid findings substantiated in meta-analyses are rare, so that eventually none of these associations is unequivocal. Thus, systematic, genome-wide approaches emerged to identify genes with no a priori evidence for their involvement in eating disorders. Genome-wide association studies have hinted to formerly unknown genetic regions. However, significant genome-wide findings have not yet been reported.

Gene-environment interactions in genome-wide association studies: current approaches and new directions

BACKGROUND

Complex psychiatric traits have long been thought to be the result of a combination of genetic and environmental factors, and gene-environment interactions are thought to play a crucial role in behavioral phenotypes and the susceptibility and progression of psychiatric disorders. Candidate gene studies to investigate hypothesized gene-environment interactions are now fairly common in human genetic research, and with the shift toward genome-wide association studies, genome-wide gene-environment interaction studies are beginning to emerge.

METHODS

We summarize the basic ideas behind gene-environment interaction, and provide an overview of possible study designs and traditional analysis methods in the context of genome-wide analysis. We then discuss novel approaches beyond the traditional strategy of analyzing the interaction between the environmental factor and each polymorphism individually.

RESULTS

Two-step filtering approaches that reduce the number of polymorphisms tested for interactions can substantially increase the power of genome-wide gene-environment studies. New analytical methods including data-mining approaches, and gene-level and pathway-level analyses, also have the capacity to improve our understanding of how complex genetic and environmental factors interact to influence psychologic and psychiatric traits. Such methods, however, have not yet been utilized much in behavioral and mental health research.

CONCLUSIONS

Although methods to investigate gene-environment interactions are available, there is a need for further development and extension of these methods to identify gene-environment interactions in the context of genome-wide association studies. These novel approaches need to be applied in studies of psychology and psychiatry.

Gene-environment interactions affect long-term depression (LTD) through changes in dopamine receptor affinity in Snap25 deficient mice

Genes and environmental conditions interact in the development of cognitive capacities and each plays an important role in neuropsychiatric disorders such as attention deficit/hyperactivity disorder (ADHD) and schizophrenia. Multiple studies have indicated that the gene for the SNARE protein SNAP-25 is a candidate susceptibility gene for ADHD, as well as schizophrenia, while maternal smoking is a candidate environmental risk factor for ADHD. We utilized mice heterozygous for a Snap25 null allele and deficient in SNAP-25 expression to model genetic effects in combination with prenatal exposure to nicotine to explore genetic and environmental interactions in synaptic plasticity and behavior. We show that SNAP-25 deficient mice exposed to prenatal nicotine exhibit hyperactivity and deficits in social interaction. Using a high frequency stimulus electrophysiological paradigm for long-term depression (LTD) induction, we examined the roles of dopaminergic D2 receptors (D2Rs) and cannabinoid CB1 receptors (CB1Rs), both critical for LTD induction in the striatum. We found that prenatal exposure to nicotine in Snap25 heterozygote null mice produced a deficit in the D2R-dependent induction of LTD, although CB1R regulation of plasticity was not impaired. We also show that prenatal nicotine exposure altered the affinity and/or receptor coupling of D2Rs, but not the number of these receptors in heterozygote null Snap25 mutants. These results refine the observations made in the coloboma mouse mutant, a proposed mouse model of ADHD, and illustrate how gene×environmental influences can interact to perturb neural functions that regulate behavior.

Serotonin transporter genotype and mild traumatic brain injury independently influence resilience and perception of limitations in veterans

Evidence indicates that individuals with the 5-HTTLPR variant short/short genotype have increased sensitivity to both positive and negative perceptions of perceived social support. The aim of this study was to evaluate this association among Veterans in the context of mild traumatic brain injury (TBI). As part of a larger TBI center, we performed a cross-sectional study of 67 OEF/OIF/OND Veterans (41 with TBI and 26 controls without TBI) who completed the questionnaires and consented to genetic testing. The primary measures included the Connor-Davidson Resilience Scale (CDRISC) and the Perceived Limitations in community participation subscale of the Community Reintegration of Service Members Instrument (CRIS-PL). Both 5-HTTLPR genotype and TBI status were independently associated with the CRIS-PL (p = .009 for genotype, p = .001 for TBI) and the CDRISC (p = .015 for genotype, p = .003 for TBI) scores. This study suggests that both the 5-HTTLPR genotype and TBI status independently, in an almost equal but opposite direction, influence resilience and perceived limitations to social participation. Further, resilience appears more sensitive to perceived limitations in Veterans carrying an S'S' genotype than in L' carriers, but only in the context of having sustained a TBI. While having a TBI appeared to increase a Veteran's sensitivity to social stress, the Veteran's who were L' allele carriers with a TBI fared the worst, with lower resilience and more perceived limitations for community participation compared to L' carrier Veterans without a TBI or Veterans with the S'S' genotype regardless of TBI status.