Predicting sensation seeking from dopamine genes. A candidate-system approach

Addiction-Prone Personality and Creative Cognitive Styles: A Moderated Mediation Model of Novelty Seeking and Depression Tendency

This study attempted to examine the mechanism of the impact of Addiction-Prone Personality (APP) on creative cognitive styles (idea generation, idea selection), especially to explore the mediating role of novelty seeking and the moderating role of depression tendency on the relationship between APP and creative cognitive styles. College students (N = 576, 79% female) participated in and completed measures of APP, idea generation and selection, novelty seeking, and depression tendency. Results showed that (1) APP was positively related with idea generation while negatively related with idea selection; (2) novelty seeking played a partial mediating role in the relationship between APP and idea generation and a suppressing effect between APP and idea selection; (3) depression tendency moderated the indirect relationship between APP and creative cognitive styles through novelty seeking. Therefore, APP has different indirect effects on idea generation and idea selection via novelty seeking. When there was a higher depression tendency, there was a stronger indirect effect. The study highlights the significant importance of the underlying processes between APP and creative cognitive styles and offers implications for rethinking the relationship between addiction and creativity.

Exploring the interplay of dopaminergic genotype and parental behavior in relation to executive function in early childhood

Child genotype is an important biologically based individual difference conferring differential sensitivity to the effect of parental behavior. This study explored dopaminergic polygenic composite × parental behavior interactions in relation to young children's executive function. Participants were 135 36-month-old children and their mothers drawn from a prospective cohort followed longitudinally from pregnancy. A polygenic composite was created based on the number of COMT, DAT1, DRD2, and DRD4 alleles associated with increased reward sensitivity children carried. Maternal negative reactivity and responsiveness were coded during a series of structured mother-child interactions. Executive function was operationalized as self-control and working memory/inhibitory control. Path analysis supported a polygenic composite by negative reactivity interaction for self-control. The nature of the interaction was one of diathesis-stress, such that higher negative reactivity was associated with poorer self-control for children with higher polygenic composite scores. This result suggests that children with a higher number of alleles may be more vulnerable to the negative effect of negative reactivity. Negative reactivity may increase the risk for developing behavior problems in this population via an association with poorer self-control. Due to the small sample size, these initial findings should be treated with caution until they are replicated in a larger independent sample.

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.

Current biopsychosocial science on understanding kink

The field of kink (or BDSM) studies has grown significantly in recent years, with several areas of study being initiated. This paper summarizes the current state of kink research, including prevalence rates; marginalization and stigma; key biological, psychological, and social research findings; clinical issues; and recommendations for further research. Theoretical frameworks, such as minority stress, serious leisure, sexual orientation, personal growth, and sensation-seeking theories appear to be useful frameworks outside of approaches that assume psychopathology as an etiological factor. Studies find the following results: higher levels of sensation-seeking; kink activities generating states of flow and transient hypofrontality; notable levels of gender, sexual orientation, and relationship style diversity in kink samples; and higher levels of minority stress-related suicidality.

The dubious precision and utility of heritability estimates

Uchiyama et al. question heritability estimates in a convincing manner. We offer additional arguments to further bolster their claims, highlighting methodological issues in heritability coefficients' derivation, their misuse in various contexts, and their potential contributions to exacerbating common erroneous intuitions that have been shown to lead to deleterious social phenomena. We conclude that science should move away from using them.

When brain stimulation backfires: the effects of prefrontal cortex stimulation on impulsivity

Transcranial direct current stimulation (tDCS) can sometimes cause the opposite of its intended effect. These reverse effects may be related in part to individual differences in personality and neurochemistry. Previous studies have demonstrated that dopamine levels can impact the effects of tDCS. In the present study, 124 healthy participants took the UPPS impulsive behavior scale. Participants then underwent a single, randomized anodal or sham tDCS session on the prefrontal cortex. While the effects of tDCS were still active, they performed the Stop Signal Task, a measure of state impulsivity. tDCS was associated with increased errors on this task in people who had higher scores on the UPPS in two facets of impulsivity that correlate with dopamine levels. tDCS had no effects on people who are low in trait impulsivity. These results suggest that the reverse effects of tDCS could be associated with inter-individual differences in personality and neurochemistry.

Dopamine increases risky choice while D2 blockade shortens decision time

Dopamine is crucially involved in decision-making and overstimulation within dopaminergic pathways can lead to impulsive behaviour, including a desire to take risks and reduced deliberation before acting. These behavioural changes are side effects of treatment with dopaminergic drugs in Parkinson disease, but their likelihood of occurrence is difficult to predict and may be influenced by the individual's baseline endogenous dopamine state, and indeed correlate with sensation-seeking personality traits. We here collected data on a standard gambling task in healthy volunteers given either placebo, 2.5 mg of the dopamine antagonist haloperidol or 100/25 mg of the dopamine precursor levodopa in a within-subject design. We found an increase in risky choices on levodopa. Choices were, however, made faster on haloperidol with no effect of levodopa on deliberation time. Shortened deliberation times on haloperidol occurred in low sensation-seekers only, suggesting a correlation between sensation-seeking personality trait and baseline dopamine levels. We hypothesise that levodopa increases risk-taking behaviour via overstimulation at both D1 and D2 receptor level, while a single low dose of haloperidol, as previously reported (Frank and O'Reilly 2006), may block D2 receptors pre- and post-synaptically and may paradoxically lead to higher striatal dopamine acting on remaining striatal D1 receptors, causing speedier decision without influencing risk tolerance. These effects could also fit with a recently proposed computational model of the basal ganglia (Moeller and Bogacz 2019; Moeller et al. 2021). Furthermore, our data suggest that the actual dopaminergic drug effect may be dependent on the individual's baseline dopamine state, which may influence our therapeutic decision as clinicians in the future.

Taking risks to feel excitement: Detailed personality profile and genetic associations

This study mapped the personality and genetics of risky excitement-seekers focusing on skydiving behavior. We compared 298 skydivers to 298 demographically matched controls across the NEO Personality Inventory-3 domains, facets, and 240 items. The most significant item-level effects were aggregated into a poly-item score of skydiving-associated personality markers (Study 1), where higher scores describe individuals who enjoy risky situations but have no self-control issues. The skydiving-associated personality marker score was associated with greater physical activity, higher rate of traumatic injuries, and better mental health in a sample of 3558 adults (Study 2). From genetic perspective, we associated skydiving behavior with 19 candidate variants that have previously been linked to excitement-seeking (Study 1). Polymorphisms in the SERT gene were the strongest predictors of skydiving, but the false discovery rate-adjusted (FDR-adjusted) p-values were non-significant. In Study 2, we predicted the skydiving-associated personality marker score and E5: Excitement-seeking from multiple risk-taking polygenic scores, using publicly available summary data from genome-wide association studies. While E5: Excitement-seeking was most strongly predicted by general risk tolerance and risky behaviors’ polygenic scores, the skydiving-associated personality marker score was most strongly associated with the adventurousness polygenic scores. Phenotypic and polygenic scores associations suggest that skydiving is a specific—perhaps more functional—form of excitement-seeking, which may nevertheless lead to physical injuries.

Dopaminergic Genetic Variation in Young Adolescents: Associations with Sensation-Seeking

Deficient reward functioning, including reward-related personality, is implicated in depression's etiology. A dopaminergic genetic multilocus genetic profile score (MGPS) has previously been associated with neural reward responsivity but, despite theoretical basis, has not been studied with reward-related personality. Such research is needed to elucidate associations between genetic variation and reward-related personality in a developmentally sensitive population. In the present study, we examined associations between dopaminergic MGPS's and self-report reward-related personality in two young adolescent samples aged 10-15 years old (Sample 1: N = 100 girls, 82% White, 18% Other; Sample 2: N = 141, 65 girls, 76 boys, 89.36% White, 10.64% Other) using an established MGPS and an augmented MGPS. A "mini" meta-analysis synthesized results across samples. In Sample 1, an exploratory mediation analysis intended to gauge effect size for future work tested a path between the MGPS and depression through significant reward traits. In each independent sample, both MGPS's showed significant associations with sensation-seeking but not social drive, a pattern that persisted following correction. Effect sizes of novel variants were at least as robust as established variants, suggesting their added utility. Additionally, the exploratory mediation analysis suggested no noteworthy indirect effect, but a small (R² = 0.022), statistically non-significant direct effect of the MGPS predicting prospective depressive symptoms. Results suggest that dopaminergic genetic variation is associated with the reward-related personality trait of sensation seeking but not social drive. Additional work is needed to probe whether sensation seeking may be a path through which this genetic variation confers depression risk.

Threat or thrill? the neural mechanisms underlying the development of anxiety and risk taking in adolescence

Anxiety is common in adolescence and has been linked to a plethora of negative outcomes across development. While previous studies of anxiety have focused on threat sensitivity, less work has considered the concurrent development of threat- and reward-related neural circuitry and how these circuits interact and compete during puberty to influence typical adolescent behaviors such as increased risk taking and exploration. The current review integrates relevant findings from clinical and developmental neuroimaging studies to paint a multidimensional picture of adolescent-onset anxiety against the backdrop of typical adolescent development. Ultimately, this paper argues that longitudinal neuroimaging studies tracking approach and avoidance motivations across development are needed to fully understand the mechanisms underlying the development of anxiety in adolescence and to identify and provide effective interventions for at-risk youth.

Methamphetamine and Cannabis: A Tale of Two Drugs and their Effects on HIV, Brain, and Behavior

HIV infection and drug use intersect epidemiologically, and their combination can result in complex effects on brain and behavior. The extent to which drugs affect the health of persons with HIV (PWH) depends on many factors including drug characteristics, use patterns, stage of HIV disease and its treatment, comorbid factors, and age. To consider the range of drug effects, we have selected two that are in common use by PWH: methamphetamine and cannabis. We compare the effects of methamphetamine with those of cannabis, to illustrate how substances may potentiate, worsen, or even buffer the effects of HIV on the CNS. Data from human, animal, and ex vivo studies provide insights into how these drugs have differing effects on the persistent inflammatory state that characterizes HIV infection, including effects on viral replication, immune activation, mitochondrial function, gut permeability, blood brain barrier integrity, glia and neuronal signaling. Moving forward, we consider how these mechanistic insights may inform interventions to improve brain outcomes in PWH. This review summarizes literature from clinical and preclinical studies demonstrating the adverse effects of METH, as well as the potentially beneficial effects of cannabis, on the interacting systemic (e.g., gut barrier leakage/microbial translocation, immune activation, inflammation) and CNS-specific (e.g., glial activation/neuroinflammation, neural injury, mitochondrial toxicity/oxidative stress) mechanisms underlying HIV-associated neurocognitive disorders.

Cumulative Influence of Inflammatory Response Genetic Variation on Long-Term Neurobehavioral Outcomes after Pediatric Traumatic Brain Injury Relative to Orthopedic Injury: An Exploratory Polygenic Risk Score

The addition of genetic factors to prognostic models of neurobehavioral recovery following pediatric traumatic brain injury (TBI) may account for unexplained heterogeneity in outcomes. The present study examined the cumulative influence of candidate genes involved in the inflammatory response on long-term neurobehavioral recovery in children with early childhood TBI relative to children with orthopedic injuries (OI). Participants were drawn from a prospective, longitudinal study evaluating outcomes of children who sustained TBI (n = 67) or OI (n = 68) between the ages of 3 and 7 years. Parents completed ratings of child executive function and behavior at an average of 6.8 years after injury. Exploratory unweighted and weighted polygenic risk scores (PRS) were constructed from single nucleotide polymorphisms (SNPs) across candidate inflammatory response genes (i.e., angiotensin converting enzyme [ACE], brain-derived neurotrophic factor [BDNF], interleukin-1 receptor antagonist [IL1RN], and 5'-ectonucleotidase [NT5E]) that showed nominal (p ≤ 0.20) associations with outcomes in the TBI group. Linear regression models tested the PRS × injury group (TBI vs. OI) interaction term and post-hoc analyses examined the effect of PRS within each injury group. Higher inflammatory response PRS were associated with more executive dysfunction and behavior problems in children with TBI but not in children with OI. The cumulative influence of inflammatory response genes as measured by PRS explained additional variance in long-term neurobehavioral outcomes, over and above well-established predictors and single candidate SNPs tested individually. The results suggest that some of the unexplained heterogeneity in long-term neurobehavioral outcomes following pediatric TBI may be attributable to a child's genetic predisposition to a greater or lesser inflammatory response to TBI.

Neural activity moderates the association between sleep and risky driving behaviors in adolescence

The biological, environmental, and psychosocial changes that occur in adolescence engender an increase in risk taking often linked to the high rates of motor vehicle crashes amongst young drivers. Most U.S. adolescents suffer from poor sleep, which is known to exacerbate the risk of driving crashes; however, research has yet to uncover a neurobiological link between sleep and risky driving in adolescence. Here, we examined potential moderators of the sleep-risk relation in fifty-six adolescents (14-18y/o) as they completed a driving task during fMRI. While poor sleep was associated with increased risky driving (i.e., running more yellow lights), good sleep emerged as a novel buffer against risky driving in lower sensation-seeking adolescents. Neural activity in the ventral striatum (VS), a key node of the risk-taking circuit, also moderated the sleep-risk association: sleep was related to risk-taking in individuals demonstrating high, but not low, VS response during risky decision-making, suggesting that reward-related neural response may underly the connection between sleep and risk-taking in adolescence. This study sheds light on the risk of driving crashes in youth by highlighting sleep as both an exacerbator and a buffer of risky driving in adolescence. Taken together, these results underscore the importance of improving adolescent sleep.

Gene set enrichment analysis to create polygenic scores: a developmental examination of aggression

Previous approaches for creating polygenic risk scores (PRSs) do not explicitly consider the biological or developmental relevance of the genetic variants selected for inclusion. We applied gene set enrichment analysis to meta-GWAS data to create developmentally targeted, functionally informed PRSs. Using two developmentally matched meta-GWAS discovery samples, separate PRSs were formed, then examined in time-varying effect models of aggression in a second, longitudinal sample of children (n = 515, 49% female) in early childhood (2-5 years old), and middle childhood (7.5-10.5 years old). Functional PRSs were associated with aggression in both the early and middle childhood models.

Assessing the interplay between multigenic and environmental influences on adolescent to adult pathways of antisocial behaviors

The current investigation utilized a developmental psychopathology approach to test the hypothesis that multigenic (i.e., dopaminergic and serotonergic genes) and multienvironmental factors interactively contribute to developmental pathways of antisocial behavior (ASB). A sample of 8,834 Caucasian individuals from the National Longitudinal Study of Adolescent to Adult Health (Add Health) were used to (a) examine the developmental pathways of ASB from age 13 to 32 using growth mixture modeling, (b) compute weighted multigenic risk scores (Add Health MRS) for ASB from six well-characterized polymorphisms in dopamine and serotonin genes, and (c) test the interaction between the Add Health MRS and a measures of support (incorporating indicators of both positive and negative support from parents and schools). Four pathways of adolescent to adult ASB emerged from the growth mixture models: low, adolescence-peaked, high decline, and persistent. Add Health MRS predicted the persistent ASB pathway, but not other ASB pathways. Males with high Add Health MRS, but not low MRS, had significantly greater odds of being in the adolescence-peaked pathway relative to the low pathway at low levels of school connectedness. Nonfamilial environmental influences during adolescence may have a cumulative impact on the development of ASB, particularly among males with greater underlying genetic risks.

Dynamic Brains and the Changing Rules of Neuroplasticity: Implications for Learning and Recovery

A growing number of research publications have illustrated the remarkable ability of the brain to reorganize itself in response to various sensory experiences. A traditional view of this plastic nature of the brain is that it is predominantly limited to short epochs during early development. Although examples showing that neuroplasticity exists outside of these finite time-windows have existed for some time, it is only recently that we have started to develop a fuller understanding of the different regulators that modulate and underlie plasticity. In this article, we will provide several lines of evidence indicating that mechanisms of neuroplasticity are extremely variable across individuals and throughout the lifetime. This variability is attributable to several factors including inhibitory network function, neuromodulator systems, age, sex, brain disease, and psychological traits. We will also provide evidence of how neuroplasticity can be manipulated in both the healthy and diseased brain, including recent data in both young and aged rats demonstrating how plasticity within auditory cortex can be manipulated pharmacologically and by varying the quality of sensory inputs. We propose that a better understanding of the individual differences that exist within the various mechanisms that govern experience-dependent neuroplasticity will improve our ability to harness brain plasticity for the development of personalized translational strategies for learning and recovery following brain injury or disease.

Using a Systems-Based Risk Score Approach to Examine Genetic Predisposition to Novelty Seeking

Abstract. Previous research is mixed regarding the relation between dopamine and Novelty Seeking. The goals of the current study were to support the hypotheses that Novelty Seeking is associated with dopamine genes and that modeling genetic risk score increases the utility of genetic information in hypothesis-driven research. The results showed that higher hypodopaminergic genetic risk score positively predicted higher Novelty Seeking score, F(1, 115) = 5.76, p < .01, R2 = 0.06. The findings support study hypotheses and, in combination with previous studies, show the utility of empirically validated system-based risk scores as a means of modeling genetic predisposition in neurobiological systems. This approach provides a mechanism for incorporating genetic predisposition into theory-driven multivariate etiological models of psychological constructs such as personality and mental illness.

Affiliation with substance-using peers: Examining gene-environment correlations among parent monitoring, polygenic risk, and children's impulsivity

Parental monitoring can buffer the effect of deviant peers on adolescents' substance use by reducing affiliation with substance-using peers. However, children's genetic predispositions may evoke poorer monitoring, contributing to negative child outcomes. We examined evocative genotype-environment correlations underlying children's genetic predisposition for behavioral undercontrol and parental monitoring in early adolescence via children's impulsivity in middle childhood, and the influence of parental monitoring on affiliation with substance-using peers a year and a half later (n = 359). Genetic predisposition for behavioral undercontrol was captured using a polygenic risk score, and a portion of passive rGE was controlled by including parents' polygenic risk scores. Children's polygenic risk predicted poorer parental monitoring via greater children's impulsivity, indicating evocative rGE, controlling for a portion of passive rGE. Poorer parental monitoring predicted greater children's affiliation with substance-using peers a year and a half later. Results are discussed with respect to gene-environment correlations within developmental cascades.

Environmental risks outweigh dopaminergic genetic risks for alcohol use and abuse from adolescence through early adulthood

BACKGROUND

Alcohol use is a primary public health concern, particularly among adolescents and young adults. Based on the rapidly growing field of gene-environment models, this study assessed the combined role of environmental and dopamine-related genetic correlates of early alcohol use and abuse.

METHODS

Multilevel growth models assessed trajectories of alcohol use and intoxication and ordered logistic regressions assessed alcohol use disorder among a sample of 12,437 youth from the nationally representative Add Health study who were followed from mid-adolescence through early adulthood.

RESULTS

Endogenous and exogenous stressful life events and social norms supportive of alcohol use from parents and peers were significant predictors of alcohol use, intoxication, and alcohol use disorder, with consistent patterns across males and females. In contrast, a dopamine-system genetic risk score (GRS) was not associated with alcohol use trajectories nor alcohol use disorder in early adulthood, although weak connections emerged between the GRS and growth trajectories of intoxication, indicating that higher GRS predicted more frequent episodes of intoxication during the transition to adulthood but not during adolescence or later 20s. No evidence of gene-environment interactions emerged.

CONCLUSIONS

Results extend a substantial body of prior research primarily assessing single genetic polymorphisms in the dopamine system, suggesting that dopaminergic GRSs may be associated with more problematic alcohol behaviors at some developmental periods, but further, that social norms and stressful life experiences are more consistent correlates of early and problematic alcohol use among youth. These environmental factors present potential targets for research manipulating contexts to identify causal pathways.

Polygenic Risk, Personality Dimensions, and Adolescent Alcohol Use Problems: A Longitudinal Study

OBJECTIVE

Alcohol use problems are common during adolescence and can predict serious negative outcomes in adulthood, including substance dependence and psychopathology. The current study examines the notion that alcohol use problems are driven by polygenic influences and that genetic influences may indirectly affect alcohol use problems through multiple pathways of risk, including variations in personality.

METHOD

We used a genome-wide approach to examine associations between genetic risk for alcohol use problems, personality dimensions, and adolescent alcohol use problems in two separate longitudinal population-based samples, the Finnish Twin Cohort (FinnTwin12) and the Avon Longitudinal Study of Parents and Children (ALSPAC). Participants were 1,035 young adults from FinnTwin12 and 3,160 adolescents from ALSPAC. Polygenic risk scores (PRS) were calculated for ALSPAC using genome-wide association results (on alcohol dependence symptoms as defined by the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition) from FinnTwin12. A parallel multiple mediator model was tested to examine whether the association between PRS and alcohol use problems assessed at age 16 could be explained by variations in personality dimensions assessed at age 13, including sensation seeking and negative emotionality.

RESULTS

PRS were marginally predictive of age 16 alcohol use problems; this association was partially mediated by sensation seeking. Polygenic variation underlying risk for alcohol use problems may directly influence the effects of sensation seeking, which in turn influence the development of alcohol use problems in later adolescence.

CONCLUSIONS

These findings contribute to the increasing evidence regarding the salience of sensation seeking during early adolescence as a potential constituent in the risk pathway underlying the development of alcohol use problems.

Differences in Pre-Attentive Processes of Sound Intensity Change Between High- and Low-Sensation Seekers

Abstract. High-sensation seekers are prone to search for changing stimuli. Pre-attentive processes reveal the earliest cortical change detection in response to external stimulus changes. This study recorded the mismatch negativity (MMN) to intensity increments and decrements in a repetitive tone in high- and low-sensation seekers. It was found that the MMN amplitude for intensity-decrement deviants was larger in high- than low-sensation seekers. However, with regard to deviant-increment stimulation, the difference between the two groups was not significant. Consequently, the sensitivity of high-sensitivity seekers to pre-attentively detect a decrease in sound intensity is higher than that of low-sensation seekers.

Striatal Dopamine, Externalizing Proneness, and Substance Abuse: Effects on Wanting and Learning during Reward-Based Decision Making

We examined whether striatal dopamine moderates the impact of externalizing proneness (disinhibition) on reward-based decision-making. Participants completed disinhibition and substance abuse subscales of the brief form Externalizing Spectrum Inventory, and then performed a delay discounting task to assess preference for immediate rewards along with a dynamic decision-making task that assessed long-term reward learning (i.e., inclination to choose larger delayed versus smaller immediate rewards). Striatal tonic dopamine levels were operationalized using spontaneous eyeblink rate. Regression analyses revealed that high disinhibition predicted greater delay discounting among participants with lower levels of striatal dopamine only, while substance abuse was associated with poorer long-term learning among individuals with lower levels of striatal dopamine, but better long-term learning in those with higher levels of striatal dopamine. These results suggest that disinhibition is more strongly associated with the wanting component of reward-based decision-making, whereas substance abuse behavior is associated more with learning of long-term action-reward contingencies.

Predicting substance use in emerging adulthood: A genetically informed study of developmental transactions between impulsivity and family conflict

Deviance proneness models propose a multilevel interplay in which transactions among genetic, individual, and family risk factors place children at increased risk for substance use. We examined bidirectional transactions between impulsivity and family conflict from middle childhood to adolescence and their contributions to substance use in adolescence and emerging adulthood (n = 380). Moreover, we examined children's, mothers', and fathers' polygenic risk scores for behavioral undercontrol, and mothers' and fathers' interparental conflict and substance disorder diagnoses as predictors of these transactions. The results support a developmental cascade model in which children's polygenic risk scores predicted greater impulsivity in middle childhood. Impulsivity in middle childhood predicted greater family conflict in late childhood, which in turn predicted greater impulsivity in late adolescence. Adolescent impulsivity subsequently predicted greater substance use in emerging adulthood. Results are discussed with respect to evocative genotype-environment correlations within developmental cascades and applications to prevention efforts.

Attentional biases to emotional stimuli: Key components of the RDoC constructs of sustained threat and loss

Biased attention to emotional stimuli plays a key role in the RDoC constructs of Sustained Threat and Loss. In this article, we review approaches to assessing these biases, their links with psychopathology, and the underlying neural influences. We then review evidence from twin and candidate gene studies regarding genetic influences on attentional biases. We also discuss the impact of developmental and environmental influences and end with a number of suggestions for future research in this area.

Sibling genes as environment: Sibling dopamine genotypes and adolescent health support frequency dependent selection

While research consistently suggests siblings matter for individual outcomes, it remains unclear why. At the same time, studies of genetic effects on health typically correlate variants of a gene with the average level of behavioral or health measures, ignoring more complicated genetic dynamics. Using National Longitudinal Study of Adolescent Health data, we investigate whether sibling genes moderate individual genetic expression. We compare twin variation in health-related absences and self-rated health by genetic differences at three locations related to dopamine regulation and transport to test sibship-level cross-person gene-gene interactions. Results suggest effects of variation at these genetic locations are moderated by sibling genes. Although the mechanism remains unclear, this evidence is consistent with frequency dependent selection and suggests much genetic research may violate the stable unit treatment value assumption.

Blunted neural responses to monetary risk in high sensation seekers

The sensation-seeking trait is a valid predictor of various risk-taking behaviors. However, the neural underpinnings of risk processing in sensation seeking are yet unclear. The present event-related potential (ERP) study examined electrophysiological correlates associated with different stages of risky reward processing in sensation seeking. Twenty-one high sensation seekers (HSS) and 22 low sensation seekers (LSS) performed a simple two-choice gambling task. Behaviorally, whereas LSS exhibited a risk-averse pattern, HSS showed a risk-neutral pattern. During the anticipation stage, an increased stimulus-preceding negativity was elicited by high-risk compared to low-risk choices in LSS but not in HSS. During the outcome-appraisal stage, the feedback-related negativity, when calculated as the difference between losses and gains, was enhanced in response to the high-risk versus low-risk outcomes, which appeared for LSS but not for HSS. Further, HSS as compared to LSS exhibited a diminished P300 to both gains and losses. These findings suggest that risk-taking behavior in sensation seeking is expressed as blunted neural responses to risk in the anticipation stage and in the outcome-appraisal stage, which represents a candidate target for drug prevention.

Childhood Sexual Abuse and Impulsive Personality Traits: Mixed Evidence for Moderation by DRD4 Genotype

This project examines associations between childhood sexual abuse (CSA) and two dimensions of impulsivity (sensation seeking and premeditation), and tests whether CSA-personality associations are moderated by the DRD4 exon III VNTR polymorphism. Sample 1 is from a longitudinal study of university students measured at 10 waves over ages 18-24 years (n = 500). Sample 2 is from a national sample of young adult sibling pairs, ages 18-24, from the National Longitudinal Study of Adolescent Health (n = 2,559). In both samples, CSA was associated with elevated sensation seeking. In Sample 1, the association between CSA and sensation seeking was moderated by DRD4 genotype; this gene × environment interaction effect, however, was not replicated in Sample 2. Results suggest new avenues for research on CSA in the area of normal-range personality variation.

Genetics of alcoholism

Alcohol use and alcohol use disorders are substantially heritable. Variants in genes coding for alcohol metabolic enzymes have long been known to influence consumption. More recent studies in family-based samples have implicated GABRA2, nicotinic receptor genes such as CHRNB3, and a number of other specific single genes as associated with alcohol use disorders. The growing use of genetic analyses, in particular studies using polygenic risk scores; neurobiologic pathways; and methods for quantifying gene × gene and gene × environment interactions have also contributed to an evolving understanding of the genetic architecture of alcohol use disorders. Additionally, the study of behavioral traits associated with alcohol dependence such as impulsivity and sensation seeking, and the influences of demographic factors (i.e., sex and ethnicity) have significantly enhanced the genetics of alcoholism literature. This article provides a brief overview of the current topically relevant findings in the field to date and includes areas of research still requiring attention.

Genetic, psychosocial, and demographic factors associated with social disinhibition in Mexican-origin youth

INTRODUCTION

The genetic heritability for sensation-seeking tendencies ranges from 40 to 60%. Sensation-seeking behaviors typically manifest during adolescence and are associated with alcohol and cigarette experimentation in adolescents. Social disinhibition is an aspect of sensation-seeking that is closely tied to cigarette and alcohol experimentation.

METHODS

We examined the contribution of candidate genes to social disinhibition among 1132 Mexican origin youth in Houston, Texas, adjusting for established demographic and psychosocial risk factors. Saliva samples were obtained at baseline in 2005-06, and social disinhibition and other psychosocial data were obtained in 2008-09. Participants were genotyped for 672 functional and tagging SNPs potentially related to sensation-seeking, risk-taking, smoking, and alcohol use.

RESULTS

Six SNPs were significantly associated with social disinhibition scores, after controlling for false discovery and adjusting for population stratification and relevant demographic/psychosocial characteristics. Minor alleles for three of the SNPs (rs1998220 on OPRM1; rs9534511 on HTR2A; and rs4938056 on HTR3B) were associated with increased risk of social disinhibition, while minor alleles for the other three SNPs (rs1003921 on KCNC1; rs16116 downstream of NPY; and rs16870286 on LINC00518) exhibited a protective effect. Age, linguistic acculturation, thrill and adventure-seeking, and drug and alcohol-seeking were all significantly positively associated with increased risk of social disinhibition in a multivariable model (P < 0.001).

CONCLUSIONS

These results add to our knowledge of genetic risk factors for social disinhibition. Additional research is needed to verify whether these SNPs are associated with social disinhibition among youth of different ethnicities and nationalities, and to elucidate whether and how these SNPs functionally contribute to social disinhibition.

Variants in the dopamine-4-receptor gene promoter are not associated with sensation seeking in skiers

Sensation seeking is a personality trait that has been associated with disinhibited behaviours including substance use and gambling, but also with high-risk sport practices including skydiving, paragliding, and downhill skiing. Twin studies have shown that sensation seeking is moderately heritable, and candidate genes encoding components involved in dopaminergic transmission have been investigated as contributing to this type of behaviour. To determine whether variants in the regulatory regions of the dopamine-4-receptor gene (DRD4) influenced sport-specific sensation seeking, we analyzed five polymorphisms (−1106T/C, −906T/C, −809G/A, −291C/T, 120-bp duplication) in the promoter region of the gene in a cohort of skiers and snowboarders (n = 599) that represented a broad range of sensation seeking behaviours. We grouped subjects by genotype at each of the five loci and compared impulsive sensation seeking and domain-specific (skiing) sensation seeking between groups. There were no significant associations between genotype(s) and general or domain-specific sensation seeking in the skiers and snowboarders, suggesting that while DRD4 has previously been implicated in sensation seeking, the promoter variants investigated in this study do not contribute to sensation seeking in this athlete population.

Ventral striatal dopamine synthesis capacity is associated with individual differences in behavioral disinhibition

Pathological gambling, alongside addictive and antisocial disorders, forms part of a broad psychopathological spectrum of externalizing disorders, which share an underlying genetic vulnerability. The shared externalizing propensity is a highly heritable, continuously varying trait. Disinhibitory personality traits such as impulsivity and novelty seeking (NS) function as indicators of this broad shared externalizing tendency, which may reflect, at the neurobiological level, variation in the reactivity of dopaminergic (DAergic) brain reward systems centered on the ventral striatum (VS). Here, we examined whether individual differences in ventral striatal dopamine (DA) synthesis capacity were associated with individual variation in disinhibitory personality traits. Twelve healthy male volunteers underwent 6-[¹⁸F]Fluoro-L-DOPA (FDOPA) positron emission tomography (PET) scanning to measure striatal DA synthesis capacity, and completed a measure of disinhibited personality (NS). We found that levels of ventral, but not dorsal, striatal DA synthesis capacity were significantly correlated with inter-individual variation in disinhibitory personality traits, particularly a propensity for financial extravagance and irresponsibility. Our results are consistent with preclinical models of behavioral disinhibition and addiction proneness, and provide novel insights into the neurobiology of personality based vulnerability to pathological gambling and other externalizing disorders.

A brief history of research on the genetics of alcohol and other drug use disorders

OBJECTIVE

This article reviews developments in research on genetic influences on alcohol and other drug use and disorders over the past 7 decades.

METHOD

The author began with a review of the flow and content of articles published in the three iterations of the journal since 1940 and then used a PubMed search of genetics of alcohol and other drug-related topics to gain a broad overview of developments in this field.

RESULTS

The literature demonstrates the rapid metamorphosis of genetic research from the ideas of Mendel to an understanding that the substance use disorders are complex, genetically influenced conditions where genes explain up to 60% of the picture. Most genes operate through additional intermediate characteristics, such as impulsivity and a low sensitivity to alcohol, some of which are substance specific and others related to substances in general. Using linkage, association, genome-wide association, and other modern methods, investigators have identified a diverse range of genetic variations that affect substance-related phenomena.

CONCLUSIONS

Genetic studies regarding alcohol and other drug use and problems have grown dramatically in the past 75 years. We currently have a much more sophisticated understanding of these influences, and the rapid development of new methods has the promise of continuing what has been a solid contribution of important findings in recent years.

Are there reciprocal relationships between substance use risk personality profiles and alcohol or tobacco use in early adolescence?

AIM

We examined whether reciprocal relationships were present between the SURPS personality profiles and substance use in early adolescence.

METHODS

Longitudinal data of four-waves of a broader effectiveness study were used from 1068 early adolescents.

RESULTS

Our cross-lagged models indicated that sensation seeking and impulsivity show strongest reciprocal associations with substance use during early adolescence. In contrast, no reciprocity was present between substance use and anxiety sensitivity and only one reciprocal relationship was present between substance use and hopelessness.

CONCLUSIONS

In trying to prevent early adolescents from alcohol and tobacco use, it might be of key importance to acknowledge the mutual influence between certain personality profiles and substance use. Specifically, sensation seeking and impulsivity are relevant during early adolescence and awareness of early adolescents' vulnerability for these personality predispositions is warranted.

Dopamine modulates risk-taking as a function of baseline sensation-seeking trait

Trait sensation-seeking, defined as a need for varied, complex, and intense sensations, represents a relatively underexplored hedonic drive in human behavioral neuroscience research. It is related to increased risk for a range of behaviors including substance use, gambling, and risky sexual practice. Individual differences in self-reported sensation-seeking have been linked to brain dopamine function, particularly at D2-like receptors, but so far no causal evidence exists for a role of dopamine in sensation-seeking behavior in humans. Here, we investigated the effects of the selective D2/D3 agonist cabergoline on performance of a probabilistic risky choice task in healthy humans using a sensitive within-subject, placebo-controlled design. Cabergoline significantly influenced the way participants combined different explicit signals regarding probability and loss when choosing between response options associated with uncertain outcomes. Importantly, these effects were strongly dependent on baseline sensation-seeking score. Overall, cabergoline increased sensitivity of choice to information about probability of winning; while decreasing discrimination according to magnitude of potential losses associated with different options. The largest effects of the drug were observed in participants with lower sensation-seeking scores. These findings provide evidence that risk-taking behavior in humans can be directly manipulated by a dopaminergic drug, but that the effectiveness of such a manipulation depends on baseline differences in sensation-seeking trait. This emphasizes the importance of considering individual differences when investigating manipulation of risky decision-making, and may have relevance for the development of pharmacotherapies for disorders involving excessive risk-taking in humans, such as pathological gambling.

Pitfalls of predicting complex traits from SNPs

The success of genome-wide association studies (GWASs) has led to increasing interest in making predictions of complex trait phenotypes, including disease, from genotype data. Rigorous assessment of the value of predictors is crucial before implementation. Here we discuss some of the limitations and pitfalls of prediction analysis and show how naive implementations can lead to severe bias and misinterpretation of results.

Addictive behaviors and addiction-prone personality traits: associations with a dopamine multilocus genetic profile

The purpose of this study was to examine reward-related genetic risk for addictive behaviors in a healthy community sample (n=217) of men and women. We tested a mediation model predicting that a quantitative multilocus genetic profile score - reflecting the additive effects of alleles known to confer relatively increased dopamine signaling in the ventral striatum - would relate positively to a composite measure of addictive behaviors, and that this association would be mediated by personality traits consistently associated with addiction disorders. Our model was strongly supported by the data, and accounted for 24% of the variance in addictive behaviors. These data suggest that brain reward processes tend to exert their influence on addiction risk by their role in the development of relatively stable personality traits associated with addictive behaviors.

Sensation seeking in major depressive patients: relationship to sub-threshold bipolarity and cyclothymic temperament

BACKGROUND

High levels of sensation seeking (SS) have been traditionally reported for lifetime bipolar disorder (BD) and/or substance use disorder (SUD) rather than major depressive disorder (MDD). Nonetheless, a renewed clinical attention toward the burden of sub-threshold bipolarity in MDD, solicits for a better assessment of "unipolar" major depressive episodes (MDEs) via characterization of putative differential psychopathological patterns, including SS and predominant affective temperament.

METHODS

Two hundred and eighty currently depressed cases of MDD and 87 healthy controls were screened using the Zuckerman's sensation seeking scale-Form-V, the Hypomania Check List-32-item (HCL-32), the Temperament Evaluation of Memphis, Pisa, Paris and San Diego Auto-questionnaire-110-item, the Barratt Impulsivity Scale-11-item, the State-Trait Anxiety Inventory modules and the Structured Clinical Interview for DSM-IV axis-I disorders. Cases were divided into HCL-32(+)(sub-threshold bipolar)/HCL-32(-)("true" unipolar depressed) depending on the HCL-32 total score.

RESULTS

Upon correlation and multivariate regression analyses, the HCL-32(+) patients showed the highest levels of SS, higher prevalence of cyclothymic temperament, and higher rates of multiple lifetime axis-I co-morbidities, including SUD.

LIMITS

Recall bias on some diagnoses, including BD, grossly matched healthy control group, lack of ad-hoc validated measures for ADHD, SUD, or axis-II disorders.

CONCLUSIONS

In our sample, the occurrence of higher levels of SS in "sub-threshold" bipolar cases outlined a differential psychopathological profile compared to DSM-defined "true unipolar" cases of MDE. If confirmed by replication studies, these findings may aid clinicians in delivering a more accurate diagnosis and a safer use of antidepressants in some MDD cases.

A neurogenetics approach to understanding individual differences in brain, behavior, and risk for psychopathology

Neurogenetics research has begun to advance our understanding of how genetic variation gives rise to individual differences in brain function, which, in turn, shapes behavior and risk for psychopathology. Despite these advancements, neurogenetics research is currently confronted by three major challenges: (1) conducting research on individual variables with small effects, (2) absence of detailed mechanisms, and (3) a need to translate findings toward greater clinical relevance. In this review, we showcase techniques and developments that address these challenges and highlight the benefits of a neurogenetics approach to understanding brain, behavior and psychopathology. To address the challenge of small effects, we explore approaches including incorporating the environment, modeling epistatic relationships and using multilocus profiles. To address the challenge of mechanism, we explore how non-human animal research, epigenetics research and genome-wide association studies can inform our mechanistic understanding of behaviorally relevant brain function. Finally, to address the challenge of clinical relevance, we examine how neurogenetics research can identify novel therapeutic targets and for whom treatments work best. By addressing these challenges, neurogenetics research is poised to exponentially increase our understanding of how genetic variation interacts with the environment to shape the brain, behavior and risk for psychopathology.

Ventral striatal dopamine synthesis capacity predicts financial extravagance in Parkinson's disease

Impulse control disorders (ICDs), including disordered gambling, can occur in a significant number of patients with Parkinson’s disease (PD) receiving dopaminergic therapy. The neurobiology underlying susceptibility to such problems is unclear, but risk likely results from an interaction between dopaminergic medication and a pre-existing trait vulnerability. Impulse control and addictive disorders form part of a broader psychopathological spectrum of disorders, which share a common underlying genetic vulnerability, referred to as externalizing. The broad externalizing risk factor is a continuously varying trait reflecting vulnerability to various impulse control problems, manifested at the overt level by disinhibitory symptoms and at the personality level by antecedent traits such as impulsivity and novelty/sensation seeking. Trait “disinhibition” is thus a core endophenotype of ICDs, and a key target for neurobiological investigation. The ventral striatal dopamine system has been hypothesized to underlie individual variation in behavioral disinhibition. Here, we examined whether individual differences in ventral striatal dopamine synthesis capacity predicted individual variation in disinhibitory temperament traits in individuals with PD. Eighteen early-stage male PD patients underwent 6-[¹⁸F]Fluoro-l-DOPA (FDOPA) positron emission tomography scanning to measure striatal dopamine synthesis capacity, and completed a measure of disinhibited personality. Consistent with our predictions, we found that levels of ventral, but not dorsal, striatal dopamine synthesis capacity predicted disinhibited personality, particularly a propensity for financial extravagance. Our results are consistent with recent preclinical models of vulnerability to behavioral disinhibition and addiction proneness, and provide novel insights into the neurobiology of potential vulnerability to impulse control problems in PD and other disorders.