Contributions of dopamine-related genes and environmental factors to highly sensitive personality: a multi-step neuronal system-level approach

Dopamine and Serotonin Transporter Genes Regulation in Highly Sensitive Individuals during Stressful Conditions: A Focus on Genetics and Epigenetics

Background: Coping with stress is essential for mental well-being and can be critical for highly sensitive individuals, characterized by a deeper perception and processing of stimuli. So far, the molecular bases characterizing high-sensitivity traits have not been completely investigated and gene × environment interactions might play a key role in making some people more susceptible than others. Methods: In this study, 104 young adult university students, subjects that might face overwhelming experiences more than others, were evaluated for the genetics and epigenetics of dopamine (DAT1) and serotonin (SERT) transporter genes, in addition to the expression of miR-132, miR-491, miR-16, and miR-135. Results: We found an increase in DNA methylation at one specific CpG site at DAT1 5'UTR in highly sensitive students reporting high levels of perceived stress when compared to those less sensitive and/or less stressed. Moreover, considering DAT1 VNTR at 3'UTR, we observed that this effect was even more pronounced in university students having the 9/9 genotype when compared to those with the 9/10 genotype. These data are corroborated by the higher levels of miR-491, targeting DAT1, in highly sensitive subjects with high levels of perceived stress. SERT gene DNA methylation at one specific CpG site was reported to instead be higher in subjects reporting lower perceived stress when compared to more stressed subjects. Consistently, miR-135 expression, regulating SERT, was lower in subjects with higher perceived stress. Conclusions: We here suggest that the correlation of DAT1 and SERT genetic and epigenetic data with the analysis of stress and sensitivity might be useful to suggest possible biomarkers to monitor mental health wellness in vulnerable subjects.

Brain circuits in autonomous sensory meridian response and related phenomena

Autonomous sensory meridian response (ASMR) is characterized by a tingling sensation with a feeling of relaxation and a state of flow. We explore the neural underpinnings and comorbidities of ASMR and related phenomena with altered sensory processing. These phenomena include sensory processing sensitivity (SPS), synaesthesia, Alice in Wonderland syndrome and misophonia. The objective of this article is to uncover the shared neural substrates and distinctive features of ASMR and its counterparts. ASMR, SPS and misophonia exhibit common activations in the brain regions associated with social cognition, emotion regulation and empathy. Nevertheless, ASMR responders display reduced connectivity in the salience network (SN), while individuals with SPS exhibit increased connectivity in the SN. Furthermore, ASMR induces relaxation and temporarily reduces symptoms of depression, in contrast to SPS and misophonia, which are linked to depression. These observations lead us to propose that ASMR is a distinct phenomenon owing to its attention dispatch mechanism and its connection with emotion regulation. We suggest that increased activations in the insula, along with reduction in connectivity within the salience and default mode networks in ASMR responders, may account for their experiences of relaxation and flow states. This article is part of the theme issue 'Sensing and feeling: an integrative approach to sensory processing and emotional experience'.

Higher sensory processing sensitivity: increased cautiousness in attentional processing in conflict contexts

While interest grows in investigating sensory processing sensitivity (SPS), few studies have employed objective behavioural measures to directly explore the underlying attentional processing. The present study utilised two modified versions of the Emotional Attention Networks Test Integration (E-ANTI) to investigate whether and how emotion interacts with three attentional networks associated with SPS when emotion information was target-irrelevant (Experiment 1) and target-relevant (Experiment 2), respectively. Both experiments involved four manipulated within-subject factors: Signal (tone vs. no-tone), Cue Validity (valid vs. invalid), Flanker Congruency (congruent vs. incongruent), and Emotion (fearful vs. happy). Linear mixed models were employed, and three attentional networks were successfully captured in both experiments. In Experiment 1, we observed that as SPS increased, the difference in reaction time between valid and invalid cue conditions decreased, especially in incongruent trials. Participants rated fearful faces as more arousing than happy faces as SPS increased. In Experiment 2, we found that slow responding to fearful faces reduced as SPS increased, particularly in incongruent trials. The observed effects related to SPS in both experiments were particularly pronounced in incongruent conditions, suggesting that SPS may modulate attentional processes in high-conflict situations. Overall, higher SPS may be associated with increased cautiousness in conflict contexts.

Sensory Processing Sensitivity and the Importance of Individuality and Personality in Veterinary Medicine

Sensory processing sensitivity (SPS) is a personality trait described in humans and dogs that mediates how individuals are affected by experiences. It involves being aware of subtle stimuli, high emotional intensity and empathy, and deeper processing of information. Recognizing individuals scoring higher in SPS is likely to help better diagnose, treat, and prevent both psychological (behavioral) and physical problems, leading to increased welfare and quality of life of the animal and its surroundings.

Sensory processing sensitivity and social pain: a hypothesis and theory

Sensory-processing sensitivity (SPS) defined, as a personality trait, seems to be characterized by emotional sensitivity, and stronger reactivity to both external and internal stimuli. SPS can represent a risk factor for developing clinical conditions during childhood and adolescence. This personality trait is not to be considered a pathological clinical condition, however, can expose to greater environmental vulnerability. In particular, the recent studies about SPS can be contextualized to social situations that evoke traumatic and stressful emotional responses such as social exclusion. We hypothesize that highly sensitive people (HSP) are more vulnerable to social exclusion and social pain. This hypothesis could help structure new educational and intervention models designed to improve coping strategies and promote HSP's psychophysical and social well-being.

Systematic reviews of the acute effects of amphetamine on working memory and other cognitive performances in healthy individuals, with a focus on the potential influence of personality traits

OBJECTIVES

This research aimed to systematically review the acute effects of amphetamine (AMP), a dopamine-releasing agent, on working memory (WM) and other cognitive performances. The investigation also aimed to review the impact of personality traits on the subjective and objective effects of AMP and possible links between personality traits and effects of AMP.

METHODS

Previous double-blind controlled studies assessing the main effects of AMP on WM and other cognitive performances in healthy volunteers were systematically reviewed. An electronic search was performed in the PUBMED and SCOPUS databases. Narrative reviews of the influence of personality traits on the subjective and objective effects of AMP were included.

RESULTS

Nineteen WM studies were included in the current review. Seven studies found effects of AMP on spatial WM, but only one study found the effect of AMP on verbal WM. Thirty-seven independent studies on other aspects of cognitive performance were identified. Twenty-two reported effects of AMP on cognitive functions. Studies also showed that personality traits are associated with the subjective effects of AMP. However, few studies reported the impacts of personality traits on the objective (such as WM) effects of AMP.

CONCLUSION

Overall, findings indicate that AMP has mixed-effects on spatial WM and other cognitive functions, but it lacks effects on verbal WM. Although there are insufficient studies on objective measures, studies also indicated that the subjective effects of AMP administration are linked to between-person variations in personality traits.

Equipping Youth to Think and Act Responsibly: The Effectiveness of the "EQUIP for Educators" Program on Youths' Self-Serving Cognitive Distortions and School Bullying Perpetration

School bullying is a serious public health concern in many countries worldwide. Over recent decades, several effective anti-bullying prevention programs have been developed. This study aimed to evaluate the effectiveness of an adapted version of the "Equipping Youth to Help One Another (EQUIP) for Educators" (EfE) program in reducing adolescents' engagement in school bullying perpetration by correcting their use of self-serving cognitive distortions (CDs). Furthermore, guided by the vantage sensitivity framework, we investigated whether the intervention effects varied depending on the adolescents' gender and environmental sensitivity. A quasi-experimental pre-test/post-test with a control group design involved 354 Italian middle and high school adolescents (51.7% males; Mage = 14.86, SD = 2.54). Both the control (n = 187) and experimental group (n = 167) completed self-report questionnaires, before and after the intervention. Structural equation modeling revealed a significant moderated mediation effect: highly sensitive males participating in the EfE program decreased their engagement in bullying by reducing CDs, compared to females and those with low- and medium- sensitivity. These findings support the effectiveness of the EfE program in equipping youth to think and act more responsible and shed light on "why" and "for whom" the intervention might work better to counteract school bullying during adolescence.

Relationship between Sensitivity Tendency and Psychological Stress Reactivity in Healthy Students

This study examined the relationship between sensory processing sensitivity and psychological stress reactivity in 69 healthy Japanese university students. The Japanese version of the Highly Sensitive Person Scale and the Japanese version of the Adolescent/Adult Sensory Profile were used for subjective assessment. The Galvanic skin response was measured as an objective measure of stress responses while the participants were completing the Stroop task. The Wilcoxon signed-rank test, the Spearman rank correlation coefficient, and the Mann−Whitney U test were conducted for data analysis. The results demonstrated that there was no significant correlation between the Japanese version of the Highly Sensitive Person Scale and Galvanic skin response. However, there was a marginal trend toward significance between low registration in the Japanese version of the Adolescent/Adult Sensory Profile and Galvanic skin response (rs = 0.231, p < 0.10; rs = 0.219, p < 0.10), suggesting that self-rated sensitivity was not necessarily associated with objective measures. These results indicate that sensory processing sensitivity analyses require the consideration of the traits and characteristics of the participants and multifaceted evaluations using a sensitivity assessment scale other than the Japanese version of the Highly Sensitive Person Scale.

A neural model of vulnerability and resilience to stress-related disorders linked to differential susceptibility

Expert opinion remains divided concerning the impact of putative risk factors on vulnerability to depression and other stress-related disorders. A large body of literature has investigated gene by environment interactions, particularly between the serotonin transporter polymorphism (5-HTTLPR) and negative environments, on the risk for depression. However, fewer studies have simultaneously investigated the outcomes in both negative and positive environments, which could explain some of the inconclusive findings. This is embodied by the concept of differential susceptibility, i.e., the idea that certain common gene polymorphisms, prenatal factors, and traits make some individuals not only disproportionately more susceptible and responsive to negative, vulnerability-promoting environments, but also more sensitive and responsive to positive, resilience-enhancing environmental conditions. Although this concept from the field of developmental psychology is well accepted and supported by behavioral findings, it is striking that its implementation in neuropsychiatric research is limited and that underlying neural mechanisms are virtually unknown. Based on neuroimaging studies that examined how factors mediating differential susceptibility affect brain function, we posit that environmental sensitivity manifests in increased salience network activity, increased salience and default mode network connectivity, and increased salience and central executive network connectivity. These changes in network function may bring about automatic exogenous attention for positive and negative stimuli and flexible attentional set-shifting. We conclude with a call to action; unraveling the neural mechanisms through which differential susceptibility factors mediate vulnerability and resilience may lead us to personalized preventive interventions.

Individual Differences and Susceptibility to Burnout Syndrome: Sensory Processing Sensitivity and Its Relation to Exhaustion and Disengagement

The aim of the study is to analyze the relationship between sensory processing sensitivity and occupational burnout. This analysis makes it possible to explore the problem of sensitivity as a predictor of burnout syndrome and to discuss adequate coping strategies in the work environment to improve employee well-being. The sample consists of 516 employees (236 women; M_age = 28.97, SD = 6.62 years). The Highly Sensitive Person Scale (HSPS; 27 items) was used to measure sensory processing sensitivity; the Oldenburg Burnout Inventory (OLBI; 16 items) was used to measure exhaustion and disengagement from work. The analysis of sensitivity is based on the ‘DOES’ model of a highly sensitive person, which includes depth of processing (D), overstimulation (O), emotional reactivity and empathy (E), and sensing the subtle (S). Burnout due to exhaustion and disengagement is analyzed. The factor analysis of the HSPS confirms its three-factor structure. The results indicate significant relationships between sensory processing sensitivity and burnout symptoms. However, the influence of specific aspects of sensitivity on the burnout problem varies: the results indicate that higher emotional reactivity is linked to worse burnout symptoms, but sensing the subtle shows the opposite effect and may be a protective factor against exhaustion. Significant gender differences were observed [F(511,1) = 136.63, p < 0.001; η² = 0.21]; women revealed a significantly higher level of general sensitivity (M_women = 4.66, SD = 0.62) as compared to men (M_men = 4.01; SD = 0.64). Awareness of one’s high sensory-processing sensitivity and its potential outcomes in the work environment may be essential in order to implement appropriate regulatory strategies. Proactive strategies aimed at reducing prolonged emotional overload may be critical for highly sensitive employees. Recognizing high sensitivity may reduce burnout symptoms and improve well-being at work.

Sensory Processing Sensitivity Predicts Individual Differences in Resting-State Functional Connectivity Associated with Depth of Processing

BACKGROUND

Sensory processing sensitivity (SPS) is a biologically based temperament trait associated with enhanced awareness and responsivity to environmental and social stimuli. Individuals with high SPS are more affected by their environments, which may result in overarousal, cognitive depletion, and fatigue.

METHOD

We examined individual differences in resting-state (rs) brain connectivity (using functional MRI) as a function of SPS among a group of adults (M age = 66.13 ± 11.44 years) immediately after they completed a social affective "empathy" task. SPS was measured with the Highly Sensitive Person (HSP) Scale and correlated with rs brain connectivity.

RESULTS

Results showed enhanced rs brain connectivity within the ventral attention, dorsal attention, and limbic networks as a function of greater SPS. Region of interest analyses showed increased rs brain connectivity between the hippocampus and the precuneus (implicated in episodic memory); while weaker connectivity was shown between the amygdala and the periaqueductal gray (important for anxiety), and the hippocampus and insula (implicated in habitual cognitive processing).

CONCLUSIONS

The present study showed that SPS is associated with rs brain connectivity implicated in attentional control, consolidation of memory, physiological homeostasis, and deliberative cognition. These results support theories proposing "depth of processing" as a central feature of SPS and highlight the neural processes underlying this cardinal feature of the trait.

Unravelling selection signatures in a single dog breed suggests recent selection for morphological and behavioral traits

Strong selection has resulted in substantial morphological and behavioral diversity across modern dog breeds, which makes dogs interesting model animals to study the underlying genetic architecture of these traits. However, results from between-breed analyses may confound selection signatures for behavior and morphological features that were coselected during breed development. In this study, we assess population genetic differences in a unique resource of dogs of the same breed but with systematic behavioral selection in only one population. We exploit these different breeding backgrounds to identify signatures of recent selection. Selection signatures within populations were found on chromosomes 4 and 19, with the strongest signals in behavior-related genes. Regions showing strong signals of divergent selection were located on chromosomes 1, 24, and 32, and include candidate genes for both physical features and behavior. Some of the selection signatures appear to be driven by loci associated with coat color (Chr 24; ASIP) and length (Chr 32; FGF5), while others showed evidence of association with behavior. Our findings suggest that signatures of selection within dog breeds have been driven by selection for morphology and behavior. Furthermore, we demonstrate that combining selection scans with association analyses is effective for dissecting the traits under selection.

A psychometric evaluation of the Highly Sensitive Person Scale in ethnically and culturally heterogeneous South African samples

Sensory Processing Sensitivity (SPS) is a personality trait that describes highly neurosensitive individuals who, for better and for worse, are permeable to their environmental context. Recently, these individuals have been noted for their amenability to positive intervention efforts - an observation that may have important psychosocial value. SPS is currently assessed through the 27-item Highly Sensitive Person Scale (HSPS). However, this instrument has not been adequately scrutinised in cross-cultural samples, and has generated varied factor solutions that lack consistent support. We assessed the HSPS in South African university student samples which were ethno-culturally diverse, across four academic years (n = 750). The HSPS demonstrated strong reliability across samples (α > .84). Factor analysis revealed a novel five-factor solution (Negative Affect, Neural Sensitivity, Propensity to Overwhelm, Careful Processing and Aesthetic Sensitivity). As per previous reports, latent class analysis suggested a three class solution. We validated these findings in a general population sample that was part of the longitudinal Birth to Twenty Plus cohort (n = 1400). In conclusion, we found the HSPS to be reliable in culturally diverse samples. The instrument remains a robust tool for identifying sensitive individuals and may be an important addition to psychosocial studies in low-to-middle income countries.

Serotonin transporter gene (SLC6A4) variation and sensory processing sensitivity-Comparison with other anxiety-related temperamental dimensions

Background

The short (s) allele of the 5‐HTTLPR polymorphism in the promoter region of the human serotonin transporter (5‐HTT) gene SLC6A4 has previously been associated with anxiety‐related personality dimensions. However, this relationship has not been confirmed in all studies and may be modified by environmental circumstances and/or psychiatric illness. This study examined whether the temperamental trait sensory processing sensitivity (SPS), characterized by increased responsivity to environmental stimuli, is related to 5‐HTTLPR/rs25531 genotype.

Methods

5‐HTTLPR and rs25531 genotypes, level of SPS, self‐reported Revised NEO Personality Inventory (NEO‐PI‐R) and Temperament and Character Inventory (TCI) personality profiles, and symptoms of psychological distress (SCL‐90R Global Severity Index) were determined for 405 healthy volunteers.

Results

Sensory processing sensitivity was highly correlated with the anxiety‐related dimensions of the NEO‐PI‐R and the TCI models of personality, Neuroticism, and Harm Avoidance, respectively. However, the level of SPS was not associated with the combined 5‐HTTLPR and rs25531 s′/s′ genotype. Neuroticism and Harm Avoidance were also not associated with 5‐HTTLPR/rs25531 s′/s′ genotype. Correcting for symptoms of psychological distress had no effect on the relationships between personality and genotype.

Conclusion

The level of SPS was not associated with serotonin transporter gene variation. Further, combined 5‐HTTLPR and rs25531 genotype was not associated with other anxiety‐related dimensions.

Inter-individual maternal care received and genotype interactions affect dopaminergic phenotypes in female rat offspring

Rat mothers exhibit natural variations in care and can shape offspring adult behaviour and their maternal care by affecting the dopaminergic system. We explored whether genotype and gene × environment interactions are involved in these processes in nulliparous female offspring. We assessed maternal licking/grooming toward individual female pups during the first week postpartum and dopamine-related behaviour of the offspring in adulthood. Behaviours explored included strategy shifting, impulsive action and sucrose preference. Single nucleotide polymorphisms in the dopamine receptor 2, dopamine transporter and catechol-O-methyltransferase genes were examined in relation to offspring behaviour and baseline dopamine turnover in select brain regions. Dopamine receptor 2 (RS107017253) variation moderated, or interacted with, the relationship between early-life licking received and behaviour. Specifically, offspring with the A/A genotype showed a significant correlation between early-life licking received and behaviour. Offspring with the A/G and G/G genotypes did not show this relationship. Dopamine transporter gene variation affected offspring behaviour regardless of early-life licking received. Our findings suggest that genotype can directly affect dopamine-related behaviours and alter the sensitivity of offspring to the maternal environment. This could be informative on how maternal care is transmitted between generations of female offspring.

Dispositional Mindfulness Mediates the Relationship Between Sensory-Processing Sensitivity and Trait Anxiety, Well-Being, and Psychosomatic Symptoms

Recent studies have suggested that sensory-processing sensitivity correlates to poor psychological and physical health. However, it remains unclear how this occurs. Sensory-processing sensitivity can be understood as sensitivity to sensations without the presence of intentional awareness and a nonreactive attitude, which are the components of mindfulness. We tested the hypothesis that dispositional mindfulness mediates the relationship between sensory-processing sensitivity and trait anxiety, well-being and psychosomatic symptoms. We analyzed data from 563 participating young adults living in Japan. Multiple mediation analysis showed that the four facets (nonreactivity, nonjudging, describing, and acting with awareness) of mindfulness partially mediated the effects of sub-factors of sensory-processing sensitivity (low sensory threshold and ease of excitation) on trait anxiety. Nonreactivity, describing, and acting with awareness partially mediated the effect of low sensory threshold on well-being and fully mediated the effect of ease of excitation. Nonjudging and acting with awareness partially mediated the effects of low sensory threshold and ease of excitation on psychosomatic symptoms. As a whole, the mediation hypotheses were supported, and it was determined that the improvement of dispositional mindfulness may prove effective for the psychological and physical problems of people with high sensory-processing sensitivity.

Catechol-O-Methyltransferase Genotypes and Parenting Influence on Long-Term Executive Functioning After Moderate to Severe Early Childhood Traumatic Brain Injury: An Exploratory Study

OBJECTIVES

To examine catechol-O-methyltransferase (COMT) rs4680 genotypes as moderators of the effects of parenting style on postinjury changes in parent behavior ratings of executive dysfunction following moderate to severe early childhood traumatic brain injury.

SETTING

Research was conducted in an outpatient setting.

PARTICIPANTS

Participants included children admitted to hospital with moderate to severe traumatic brain injury (n = 55) or orthopedic injuries (n = 70) between ages 3 and 7 years.

DESIGN

Prospective cohort followed over 7 years postinjury.

MAIN MEASURES

Parenting Practices Questionnaire and the Behavior Rating Inventory of Executive Functioning obtained at baseline, 6, 12, and 18 months, and 3.5 and 6.8 years postinjury. DNA was collected from saliva samples, purified using the Oragene (DNA Genotek, Ottawa, Ontario, Canada) OG-500 self-collection tubes, and analyzed using TaqMan (Applied Biosystems, Thermo Fisher Scientific, Waltham, Massachusetts) assay protocols to identify the COMT rs4680 polymorphism.

RESULTS

Linear mixed models revealed a significant genotype × parenting style × time interaction (F = 5.72, P = .02), which suggested that the adverse effects of authoritarian parenting on postinjury development of executive functioning were buffered by the presence of the COMT AA genotype (lower enzyme activity, higher dopamine levels). There were no significant associations of executive functioning with the interaction between genotype and authoritative or permissive parenting ratings.

CONCLUSION

The lower activity COMT rs4680 genotype may buffer the negative effect of authoritarian parenting on long-term executive functioning following injury in early childhood. The findings provide preliminary evidence for associations of parenting style with executive dysfunction in children and for a complex interplay of genetic and environmental factors as contributors to decreases in these problems after traumatic injuries in children. Further investigation is warranted to understand the interplay among genetic and environmental factors related to recovery after traumatic brain injury in children.

Influence of Catechol-O-methyltransferase on Executive Functioning Longitudinally After Early Childhood Traumatic Brain Injury: Preliminary Findings

OBJECTIVE

To elucidate the association of a functional catechol-O-methyltransferase (COMT) genotype (rs4680) with recovery of executive functions up to 18 months after early childhood traumatic brain injury (TBI) compared with an orthopedic injury (OI) group.

SETTING

Outpatient.

PARTICIPANTS

A total of 134 children with a moderate to severe TBI (n = 63) or OI (n = 71) between the ages of 3 and 6 years who were followed 18 months postinjury.

DESIGN

Case-comparison, longitudinal cohort

MAIN MEASURES

: The Behavior Rating Inventory of Executive Function, developmental NEuroPSYchological Assessment (NEPSY) of Verbal Fluency, and a modified Stroop Test for young children (Shape School).

RESULTS

The low-activity COMT enzyme genotype (AA) was associated with better scores on the developmental NEPSY of Verbal Fluency (F = 3.80; P = .02) and the Shape School (F = 2.89; P = .06) in all participants when controlling for injury type (TBI vs OI) over the first 18 months after injury. Injury type (TBI vs OI) did not significantly moderate the effect of the COMT genotypes on executive function recovery.

CONCLUSION

This study provides preliminary evidence for a role of COMT genotypes in long-term recovery of executive function after pediatric TBI and OI. Larger studies are needed to determine the exact link between genetic variation in the COMT gene and TBI recovery in children.

Dopamine genes are linked to Extraversion and Neuroticism personality traits, but only in demanding climates

Cross-national differences in personality have long been recognized in the behavioural sciences. However, the origins of such differences are debated. Building on reinforcement sensitivity theories and gene-by-environment interactions, we predict that personality trait phenotypes linked to dopaminergic brain functions (centrally involved in reward processing) diverge most strongly in climatically stressful environments, due to shifts in perceived rewards vs risks. Individuals from populations with a highly efficient dopamine system are biased towards behavioural approach traits (Extraversion and Emotional Stability) due to higher perceived reward values, whereas individuals from populations with a less efficient dopaminergic system are biased towards risk avoidance. In temperate climates, we predict smaller phenotypic differences due to overall weakened reward and risk ratios. We calculated a population-level index of dopamine functioning using 9 commonly investigated genetic polymorphisms encoding dopamine transporters and receptors, derived from a meta-analysis with data from 805 independent samples involving 127,685 participants across 73 societies or territories. We found strong support for the dopamine gene by climatic stress interaction: Population genetic differences in dopamine predicted personality traits at the population level in demanding climates, but not in temperate, less demanding climates, even when controlling for known correlates of personality including wealth and parasite stress.

Sweet and Sensitive: Sensory Processing Sensitivity and Type 1 Diabetes

OBJECTIVE

Sensory processing sensitivity (SPS) is a recently proposed construct that refers to a genetically influenced tendency to more strongly and deeply process a variety of information. The aim of the study was to examine whether SPS is associated with an autoimmune disease such as type 1 diabetes (T1D).

RESEARCH DESIGN AND METHODS

Participants were 128 adolescents (62 with T1D and 66 comparisons [without autoimmune disease]) and their parents who completed the Highly Sensitive Person Scale (HSPS) questionnaire, assessing SPS level.

RESULTS

Higher levels of SPS were found in the T1D group than in the comparison group. Furthermore, the frequency of SPS trait was significantly higher in the T1D group than in the comparison group.

CONCLUSIONS

T1D is associated with higher levels of SPS. Hence, there is a need to develop interventions, treatments, and care focused on the needs of T1D patients with SPS temperament, aimed at better treatment adherence. Furthermore, longitudinal research is needed to evaluate whether SPS is a risk factor in the development of T1D.

Development of the "Highly Sensitive Dog" questionnaire to evaluate the personality dimension "Sensory Processing Sensitivity" in dogs

In humans, the personality dimension 'sensory processing sensitivity (SPS)', also referred to as "high sensitivity", involves deeper processing of sensory information, which can be associated with physiological and behavioral overarousal. However, it has not been studied up to now whether this dimension also exists in other species. SPS can influence how people perceive the environment and how this affects them, thus a similar dimension in animals would be highly relevant with respect to animal welfare. We therefore explored whether SPS translates to dogs, one of the primary model species in personality research. A 32-item questionnaire to assess the "highly sensitive dog score" (HSD-s) was developed based on the "highly sensitive person" (HSP) questionnaire. A large-scale, international online survey was conducted, including the HSD questionnaire, as well as questions on fearfulness, neuroticism, "demographic" (e.g. dog sex, age, weight; age at adoption, etc.) and "human" factors (e.g. owner age, sex, profession, communication style, etc.), and the HSP questionnaire. Data were analyzed using linear mixed effect models with forward stepwise selection to test prediction of HSD-s by the above-mentioned factors, with country of residence and dog breed treated as random effects. A total of 3647 questionnaires were fully completed. HSD-, fearfulness, neuroticism and HSP-scores showed good internal consistencies, and HSD-s only moderately correlated with fearfulness and neuroticism scores, paralleling previous findings in humans. Intra- (N = 447) and inter-rater (N = 120) reliabilities were good. Demographic and human factors, including HSP score, explained only a small amount of the variance of HSD-s. A PCA analysis identified three subtraits of SPS, comparable to human findings. Overall, the measured personality dimension in dogs showed good internal consistency, partial independence from fearfulness and neuroticism, and good intra- and inter-rater reliability, indicating good construct validity of the HSD questionnaire. Human and demographic factors only marginally affected the HSD-s suggesting that, as hypothesized for human SPS, a genetic basis may underlie this dimension within the dog species.

Applying Systems Biology Methodology To Identify Genetic Factors Possibly Associated with Recovery after Traumatic Brain Injury

Traumatic brain injury (TBI) is one of the leading causes of morbidity and mortality worldwide. It is linked with a number of medical, neurological, cognitive, and behavioral sequelae. The influence of genetic factors on the biology and related recovery after TBI is poorly understood. Studies that seek to elucidate the impact of genetic influences on neurorecovery after TBI will lead to better individualization of prognosis and inform development of novel treatments, which are considerably lacking. Current genetic studies related to TBI have focused on specific candidate genes. The objectives of this study were to use a system biology-based approach to identify biologic processes over-represented with genetic variants previously implicated in clinical outcomes after TBI and identify unique genes potentially related to recovery after TBI. After performing a systematic review to identify genes in the literature associated with clinical outcomes, we used the genes identified to perform a systems biology-based integrative computational analysis to ascertain the interactions between molecular components and to develop models for regulation and function of genes involved in TBI recovery. The analysis identified over-representation of genetic variants primarily in two biologic processes: response to injury (cell proliferation, cell death, inflammatory response, and cellular metabolism) and neurocognitive and behavioral reserve (brain development, cognition, and behavior). Overall, this study demonstrates the use of a systems biology-based approach to identify unique/novel genes or sets of genes important to the recovery process. Findings from this systems biology-based approach provide additional insight into the potential impact of genetic variants on the underlying complex biological processes important to TBI recovery and may inform the development of empirical genetic-related studies for TBI. Future studies that combine systems biology methodology and genomic, proteomic, and epigenetic approaches are needed in TBI.

Sensory processing sensitivity and serotonin gene variance: Insights into mechanisms shaping environmental sensitivity

Current research supports the notion that the apparently innate trait Sensory Processing Sensitivity (SPS) may act as a modulator of development as function of the environment. Interestingly, the common serotonin transporter linked polymorphic region (5-HTTLPR) does the same. While neural mechanisms underlying SPS are largely unknown, those associated with the 5-HTTLPR have been extensively investigated. We perform a comparative analysis of research findings on sensory processing facets associated with the trait and polymorphism to: 1. detect shared phenotypes and frame a hypothesis towards neural mechanisms underlying SPS; 2. increase the understanding of 5-HTTLPR-associated behavioral patterns. Trait and polymorphism are both associated with differential susceptibility to environmental stimuli; additionally, both involve 1. having stronger emotional reactions, 2. processing of sensory information more deeply, 3. being more aware of environmental subtleties, and 4. being easily overstimulated. We discuss neural mechanisms and environmental conditions that may underlie these four facets. Besides urging the actual assessment of the link between the two, the conclusions of our analyses may guide and focus future research strategies.

Differential Susceptibility of the Developing Brain to Contextual Adversity and Stress

A swiftly growing volume of literature, comprising both human and animal studies and employing both observational and experimental designs, has documented striking individual differences in neurobiological sensitivities to environmental circumstances within subgroups of study samples. This differential susceptibility to social and physical environments operates bidirectionally, in both adverse and beneficial contexts, and results in a minority subpopulation with remarkably poor or unusually positive trajectories of health and development, contingent upon the character of environmental conditions. Differences in contextual susceptibility appear to emerge in early development, as the interactive and adaptive product of genetic and environmental attributes. This paper surveys what is currently known of the mechanisms or mediators of differential susceptibility, at the levels of temperament and behavior, physiological systems, brain circuitry and neuronal function, and genetic and epigenetic variation. It concludes with the assertion that differential susceptibility is inherently grounded within processes of biological moderation, the complexities of which are at present only partially understood.

Regional Homogeneity of Resting-State Brain Activity Suppresses the Effect of Dopamine-Related Genes on Sensory Processing Sensitivity

Sensory processing sensitivity (SPS) is an intrinsic personality trait whose genetic and neural bases have recently been studied. The current study used a neural mediation model to explore whether resting-state brain functions mediated the effects of dopamine-related genes on SPS. 298 healthy Chinese college students (96 males, mean age = 20.42 years, SD = 0.89) were scanned with magnetic resonance imaging during resting state, genotyped for 98 loci within the dopamine system, and administered the Highly Sensitive Person Scale. We extracted a “gene score” that summarized the genetic variations representing the 10 loci that were significantly linked to SPS, and then used path analysis to search for brain regions whose resting-state data would help explain the gene-behavior association. Mediation analysis revealed that temporal homogeneity of regional spontaneous activity (ReHo) in the precuneus actually suppressed the effect of dopamine-related genes on SPS. The path model explained 16% of the variance of SPS. This study represents the first attempt at using a multi-gene voxel-based neural mediation model to explore the complex relations among genes, brain, and personality.

The Dopamine D2 Receptor Polymorphism (DRD2 TaqIA) Interacts with Maternal Parenting in Predicting Early Adolescent Depressive Symptoms: Evidence of Differential Susceptibility and Age Differences

Most gene-environment interaction research on depression has largely focused on negative environment and to a lesser extent on positive environment. Moreover, to date few studies have directly examined G × E at different periods in development, particularly during early adolescence. The present study addressed these issues by examining the concurrent and prospective longitudinal effects of maternal parenting, DRD2 TaqIA polymorphism, and their interaction on adolescent depressive symptoms in a sample of 1026 Chinese adolescents (Mage = 11.33 ± 0.47 years at T1, 50.3% girls) in a three-wave longitudinal study from age 11 to 13. Results indicated that maternal positive and negative parenting significantly concurrently predicted adolescent depressive symptoms at all three waves, whereas TaqIA polymorphism had no main effect on depressive symptoms. TaqIA polymorphism interacted with negative parenting in predicting concurrent depressive symptoms at age 11 and 12. A1 carriers were more susceptible to negative parenting compared to A2A2 homozygotes, such that adolescents carrying A1 alleles experiencing high negative parenting reported more depressive symptoms but fared better when experiencing low negative parenting. However, the interaction became nonsignificant at age 13, indicating the interaction of TaqIA polymorphism and maternal parenting may vary with development. Also, there was no G × E effect on longitudinal change in depression. The findings provided evidence in support of the differential susceptibility hypothesis and shed light on the potential for dynamic change in gene-environment interactions over development.

Genetic variations in the serotoninergic system and environmental factors contribute to aggressive behavior in Chinese adolescents

Aggressive behavior is a major public health problem worldwide and has been associated with many gene variants, especially those related to the serotonin (5-hydroxytryptamine, 5-HT) system, and environmental factors. However, the overall contribution of serotonin-related genes to aggressive behavior is not well understood. With a sample of 478 healthy Chinese volunteers, this study investigated the relation between aggressive behavior and genetic variations of the serotoninergic system (as characterized by 129 representative polymorphisms) interacting with environmental factors (parental warmth and acceptance; stressful life events). We adopted a system-level approach to identify SNPs and environmental factors associated with aggressive behavior, and estimated their overall contribution to aggressive behavior using multiple regression, which was then verified by permutation analysis. We identified 12 SNPs that made statistically significant contributions to aggressive behavior. Next, main effects, interactions among these SNPs, and interactions between these SNPs and environmental factors were assessed using multiple regression. The final model accounted for approximately 19% of the variance for aggressive behavior. Permutation analysis confirmed that the probability of obtaining these findings by chance was low (p=0.045, permuted for 1000 times). These results showed that genetic variations in the serotoninergic system, combined with environmental risk factors, made a moderate contribution to individual differences in aggressive behavior among a healthy population sample.

The highly sensitive brain: an fMRI study of sensory processing sensitivity and response to others' emotions

BACKGROUND

Theory and research suggest that sensory processing sensitivity (SPS), found in roughly 20% of humans and over 100 other species, is a trait associated with greater sensitivity and responsiveness to the environment and to social stimuli. Self-report studies have shown that high-SPS individuals are strongly affected by others' moods, but no previous study has examined neural systems engaged in response to others' emotions.

METHODS

This study examined the neural correlates of SPS (measured by the standard short-form Highly Sensitive Person [HSP] scale) among 18 participants (10 females) while viewing photos of their romantic partners and of strangers displaying positive, negative, or neutral facial expressions. One year apart, 13 of the 18 participants were scanned twice.

RESULTS

Across all conditions, HSP scores were associated with increased brain activation of regions involved in attention and action planning (in the cingulate and premotor area [PMA]). For happy and sad photo conditions, SPS was associated with activation of brain regions involved in awareness, integration of sensory information, empathy, and action planning (e.g., cingulate, insula, inferior frontal gyrus [IFG], middle temporal gyrus [MTG], and PMA).

CONCLUSIONS

As predicted, for partner images and for happy facial photos, HSP scores were associated with stronger activation of brain regions involved in awareness, empathy, and self-other processing. These results provide evidence that awareness and responsiveness are fundamental features of SPS, and show how the brain may mediate these traits.

Child dopamine active transporter 1 genotype and parenting: evidence for evocative gene-environment correlations

The dopamine active transporter 1 (DAT1) gene is implicated in psychopathology risk. Although the processes by which this gene exerts its effects on risk are poorly understood, a small body of research suggests that the DAT1 gene influences early emerging negative emotionality, a marker of children's psychopathology risk. As child negative emotionality evokes negative parenting practices, the DAT1 gene may also play a role in gene-environment correlations. To test this model, children (N = 365) were genotyped for the DAT1 gene and participated in standardized parent-child interaction tasks with their primary caregiver. The DAT1 gene 9-repeat variant was associated with child negative affect expressed toward the parent during parent-child interactions, and parents of children with a 9-repeat allele exhibited more hostility and lower guidance/engagement than parents of children without a 9-repeat allele. These gene-environment associations were partially mediated by child negative affect toward the parent. The findings implicate a specific polymorphism in eliciting negative parenting, suggesting that evocative associations play a role in elevating children's risk for emotional trajectories toward psychopathology risk.

Web-based cognitive bias modification for problem drinkers: protocol of a randomised controlled trial with a 2x2x2 factorial design

BACKGROUND

The automatic tendency to attend to, positively evaluate and approach alcohol related stimuli has been found to play a causal role in problematic alcohol use and can be retrained by computerised Cognitive Bias Modification (CBM). In spite of CBMs potential as an internet intervention, little is known about the efficacy of web-based CBM. The study described in this protocol will test the effectiveness of web-based CBM in a double blind randomised controlled trial with a 2 (attention bias retraining: real versus placebo) x 2 (alcohol/no-go training: real versus placebo) x 2 (approach bias retraining: real versus placebo) factorial design.

METHODS/DESIGN

The effectiveness of 12 sessions of CBM will be examined among problem drinkers aged 18-65 who are randomly assigned to one of the eight CBM conditions, after completing two modules of a validated cognitive behavioural intervention, DrinkingLess. The primary outcome measure is the change in alcohol use. It is expected that, for each of the CBM interventions, participants in the real CBM conditions will show a greater decrease in alcohol use than participants in the placebo conditions. Secondary outcome measures include the percentage of participants drinking within the limits for sensible drinking. Possible mediating (change in automatic biases) and moderating (working memory, inhibition) factors will be examined, as will the comparative cost-effectiveness of the various CBM strategies.

DISCUSSION

This study will be the first to test the relative efficacy of various web-based CBM strategies in problem drinkers. If proven effective, CBM could be implemented as a low-cost, low-threshold adjuvant to CBT-based online interventions for problem drinkers.

TRIAL REGISTRATION

Netherlands Trial register: NTR3875.

Genetic variations in the serotoninergic system contribute to body-mass index in Chinese adolescents

OBJECTIVE

Obesity has become a worldwide health problem in the past decades. Human and animal studies have implicated serotonin in appetite regulation, and behavior genetic studies have shown that body mass index (BMI) has a strong genetic component. However, the roles of genes related to the serotoninergic (5-hydroxytryptamine,5-HT) system in obesity/BMI are not well understood, especially in Chinese subjects.

SUBJECTS AND DESIGN

With a sample of 478 healthy Chinese volunteers, this study investigated the relation between BMI and genetic variations of the serotoninergic system as characterized by 136 representative polymorphisms. We used a system-level approach to identify SNPs associated with BMI, then estimated their overall contribution to BMI by multiple regression and verified it by permutation.

RESULTS

We identified 12 SNPs that made statistically significant contributions to BMI. After controlling for gender and age, four of these SNPs accounted for 7.7% additional variance of BMI. Permutation analysis showed that the probability of obtaining these findings by chance was low (p = 0.015, permuted for 1000 times).

CONCLUSION

These results showed that genetic variations in the serotoninergic system made a moderate contribution to individual differences in BMI among a healthy Chinese sample, suggesting that a similar approach can be used to study obesity.

Measurable Like Temperature or Mereological like Flocking? on the Nature of Personality Traits

Some commentators wholeheartedly disagreed with the central tenet of the network perspective on personality, namely that traits are the result of mutual interactions between thoughts, feelings and behaviours. In this rejoinder, we primarily focus on these commentaries by (i) clarifying the main differences between the latent versus the network view on traits; (ii) discussing some of the arguments in favour of the latent trait views that were put forward by these commentators; and by (iii) comparing the capacity of both views to explain thoughts, feelings and behaviours. Some commentators were by and large positive about the network perspective, and we discuss their excellent suggestions for defining components and linking these to genes and other biological mechanisms. We conclude that no doors should be closed in the study of personality and that, as such, alternative theories such as the network perspective should be welcomed, formalised and tested. Copyright © 2012 John Wiley & Sons, Ltd.

Sensory processing sensitivity: a review in the light of the evolution of biological responsivity

This article reviews the literature on sensory processing sensitivity (SPS) in light of growing evidence from evolutionary biology that many personality differences in nonhuman species involve being more or less responsive, reactive, flexible, or sensitive to the environment. After briefly defining SPS, it first discusses how biologists studying animal personality have conceptualized this general environmental sensitivity. Second, it reviews relevant previous human personality/temperament work, focusing on crossover interactions (where a trait generates positive or negative outcomes depending on the environment), and traits relevant to specific hypothesized aspects of SPS: inhibition of behavior, sensitivity to stimuli, depth of processing, and emotional/physiological reactivity. Third, it reviews support for the overall SPS model, focusing on development of the Highly Sensitive Person (HSP) Scale as a measure of SPS then on neuroimaging and genetic studies using the scale, all of which bears on the extent to which SPS in humans corresponds to biological responsivity.