Testosterone reduces generosity through cortical and subcortical mechanisms.

Recent evidence has linked testosterone, a major sex hormone, to selfishness in economic decision-making. Here, we aimed to investigate the neural mechanisms through which testosterone reduces generosity by combining functional MRI with pharmacological manipulation among healthy young males in a double-blind, placebo-controlled, between-subject design. After testosterone or placebo gel administration, participants performed a social discounting task in which they chose between selfish options (benefiting only the participant) and generous options (providing also some benefit to another person at a particular social distance). At the behavioral level, testosterone reduced generosity compared to the placebo. At the neural level (n = 60), the temporoparietal junction (TPJ) encoded the other-regarding value of the generous option during generous choices, and this effect was attenuated by testosterone, suggesting that testosterone reduced the consideration of other's welfare as underpinned by TPJ activity. Moreover, TPJ activity more strongly reflected individual differences in generosity in the placebo than the testosterone group. Furthermore, testosterone weakened the relation between the other-regarding value of generous decisions and connectivity between the TPJ and a region extending from the insula into the striatum. Together, these findings suggest that a network encompassing both cortical and subcortical components underpins the effects of testosterone on social preferences.

Transformative experience and social connectedness mediate the mood-enhancing effects of psychedelic use in naturalistic settings.

Past research suggests that use of psychedelic substances such as LSD or psilocybin may have positive effects on mood and feelings of social connectedness. These psychological effects are thought to be highly sensitive to context, but robust and direct evidence for them in a naturalistic setting is scarce. In a series of field studies involving over 1,200 participants across six multiday mass gatherings in the United States and the United Kingdom, we investigated the effects of psychedelic substance use on transformative experience, social connectedness, and positive mood. This approach allowed us to test preregistered hypotheses with high ecological validity and statistical precision. Controlling for a host of demographic variables and the use of other psychoactive substances, we found that psychedelic substance use was significantly associated with positive mood-an effect sequentially mediated by self-reported transformative experience and increased social connectedness. These effects were particularly pronounced for those who had taken psychedelic substances within the last 24 h (compared to the last week). Overall, this research provides robust evidence for positive affective and social consequences of psychedelic substance use in naturalistic settings.

Intranasal vasopressin expedites dishonesty in women.

As an integral ingredient of human sociality, dishonesty can be both egocentric and altruistic, as well as gradually escalate. Here, we examined the influence of arginine vasopressin (AVP), a neuropeptide associated with human prosocial behaviors, on dishonest behaviors in men and women. In this double-blind and placebo-controlled study, 101 participants were randomized to administration of either 20 IU intranasal AVP or placebo. We used a two-party task to manipulate the incentive structure of dishonesty in the way of self-/other-serving repeatedly. For lies that benefit both themselves and others, women receiving intranasal AVP lied more than women receiving intranasal placebo and men receiving intranasal AVP. The dishonest behavior of women treated with AVP gradually escalated with repetition over time. These results suggest that AVP selectively regulates the escalation of dishonesty in women, contingent on the motivation of dishonesty. Our findings provide insight into gender-specific modulations of AVP on human dishonest behavior.

Risk taking, sensation seeking and personality as related to changes in substance use from adolescence to young adulthood.

INTRODUCTION: This study examined changes in substance use from adolescence to young adulthood as related to adolescents' risk taking, sensation seeking, antisocial activities, and personality traits. METHODS: Chilean youth (N = 890, 52% female) were studied in adolescence (14.5 and 16.2 years) and young adulthood (M age 21.3 years). Risk taking was assessed via a laboratory-based performance task (Balloon Analogue Risk Task), and self-administered questionnaires assessed sensation seeking, antisocial behaviors, personality and substance use. RESULTS: Frequent involvement in sensation seeking and antisocial activities were associated with increased odds of continued marijuana use from adolescence to young adulthood and of illicit substance use at young adulthood. High risk taking was associated with a reduced likelihood of discontinuing marijuana use at young adulthood, and high agreeableness and conscientiousness were associated with reduced likelihood of new onset marijuana use and illicit substance use at young adulthood. CONCLUSIONS: Results highlight specific risk-taking tendencies and personality characteristics that relate to initiating, continuing, or discontinuing substance use at entry into adulthood. Sensation seeking and involvement in antisocial activities were the two foremost risk factors for continued use, which is a forecaster of drug dependence. Findings suggest potential prevention and intervention targets for abstaining from or discontinuing substance use as youth transition to adulthood.

Express yourself: Individuals with bold personalities exhibit increased behavioral sensitivity to dynamic herbicide exposure.

The majority of ecotoxicological studies performed measure average responses from individuals which do not account for the inter-individual variation in the responses of animals to environmental stimuli (i.e. the personality of individuals). Thus, these designs assume that all individuals will respond to contaminant exposure in a similar manner. Additionally, commonly used constant, static exposure regime designs neglect to recognize the spatial and temporal variation in contaminant plume structures as they move throughout fluid environments. The purpose of this study was to understand the effects of the structural characteristics (concentration, duration, and frequency) of temporally and spatially variant contaminant plumes on the personality of individuals. This experimental design aimed to construct a sensitive definition of exposure by connecting sublethal effects of toxicants and realistic exposure regimes. This study used escape response of Faxonius virilis crayfish from the predatory odor of Micropterus salmoides prior to and following exposure to the herbicide, atrazine. Atrazine was delivered in pulses to flow through exposure arenas for a total of 47 h while manipulating the concentration, frequency, and duration of the herbicide pulses. Escape response of crayfish prior to exposure was used to categorize animals into bold and shy personalities. The change in escape response was analyzed and resulted in a personality-dependent behavioral sensitivity to the polluted environment. Individuals classified as bold showed increased change in response to predatory odor relative to shy animals. Bold animals exhibited decreased activity after exposure where no change was presented in shy individuals. Shifts in individual behavior have impacts on the population level (e.g. resource acquisition/value; interspecies competition) and the ecosystem level (e.g. food web dynamics; trophic cascades). This study demonstrates the importance of sensitive measures in ecological risk assessment methods.

Effects of psilocybin therapy on personality structure.

OBJECTIVE: To explore whether psilocybin with psychological support modulates personality parameters in patients suffering from treatment-resistant depression (TRD). METHOD: Twenty patients with moderate or severe, unipolar, TRD received oral psilocybin (10 and 25 mg, one week apart) in a supportive setting. Personality was assessed at baseline and at 3-month follow-up using the Revised NEO Personality Inventory (NEO-PI-R), the subjective psilocybin experience with Altered State of Consciousness (ASC) scale, and depressive symptoms with QIDS-SR16. RESULTS: Neuroticism scores significantly decreased while Extraversion increased following psilocybin therapy. These changes were in the direction of the normative NEO-PI-R data and were both predicted, in an exploratory analysis, by the degree of insightfulness experienced during the psilocybin session. Openness scores also significantly increased following psilocybin, whereas Conscientiousness showed trend-level increases, and Agreeableness did not change. CONCLUSION: Our observation of changes in personality measures after psilocybin therapy was mostly consistent with reports of personality change in relation to conventional antidepressant treatment, although the pronounced increases in Extraversion and Openness might constitute an effect more specific to psychedelic therapy. This needs further exploration in future controlled studies, as do the brain mechanisms of postpsychedelic personality change.

Personality traits and escitalopram treatment outcome in major depression.

BACKGROUND: Selective serotonin re-uptake inhibitors (SSRI) have proven to be effective in treatment of depression. Still, treatment efficacy varies significantly from patient to patient and about 40% of patients do not respond to initial treatment. Personality traits have been considered one source of variability in treatment outcome. AIM: Current study aimed at identifying specific personality traits that could be predictive of treatment response and/or the dynamics of symptom change in depressive patients. METHOD: In a sample of 132 outpatients with major depressive disorder (MDD) treated with an SSRI-group antidepressant escitalopram, the Swedish universities Scales of Personality (SSP) were used in order to find predictive personality traits. For the assessment of the severity of depressive symptoms and the improvement rates, the Hamilton Depression Scale (HAM-D) and Montgomery-Åsberg Depression Rating Scale (MADRS) were used. RESULTS: Escitalopram-treated MDD patients with higher social desirability achieved more rapid decrease in symptom severity. None of the studied traits predicted the end result of the treatment. CONCLUSION: The findings suggest that specific personality traits may predict the trajectory of symptom change rather than the overall improvement rate.

You are what you eat: diet shapes body composition, personality and behavioural stability.

BACKGROUND: Behavioural phenotypes vary within and among individuals. While early-life experiences have repeatedly been proposed to underpin interactions between these two hierarchical levels, the environmental factors causing such effects remain under-studied. We tested whether an individual's diet affected both its body composition, average behaviour (thereby causing among-individual variation or 'personality') and within-individual variability in behaviour and body weight (thereby causing among-individual differences in residual within-individual variance or 'stability'), using the Southern field cricket Gryllus bimaculatus as a model. We further asked whether effects of diet on the expression of these variance components were sex-specific. METHODS: Manipulating both juvenile and adult diet in a full factorial design, individuals were put, in each life-stage, on a diet that was either relatively high in carbohydrates or relatively high in protein. We subsequently measured the expression of multiple behavioural (exploration, aggression and mating activity) and morphological traits (body weight and lipid mass) during adulthood. RESULTS: Dietary history affected both average phenotype and level of within-individual variability: males raised as juveniles on high-protein diets were heavier, more aggressive, more active during mating, and behaviourally less stable, than conspecifics raised on high-carbohydrate diets. Females preferred more protein in their diet compared to males, and dietary history affected average phenotype and within-individual variability in a sex-specific manner: individuals raised on high-protein diets were behaviourally less stable in their aggressiveness but this effect was only present in males. Diet also influenced individual differences in male body weight, but within-individual variance in female body weight. DISCUSSION: This study thereby provides experimental evidence that dietary history explains both heterogeneous residual within-individual variance (i.e., individual variation in 'behavioural stability') and individual differences in average behaviour (i.e., 'personality'), though dietary effects were notably trait-specific. These findings call for future studies integrating proximate and ultimate perspectives on the role of diet in the evolution of repeatedly expressed traits, such as behaviour and body weight.

Association between personality traits and Escitalopram treatment efficacy in panic disorder.

BACKGROUND: There is strong evidence to suggest that personality factors may interact with the development and clinical expression of panic disorder (PD). A greater understanding of these relationships may have important implications for clinical practice and implications for searching reliable predictors of treatment outcome. AIMS: The study aimed to examine the effect of escitalopram treatment on personality traits in PD patients, and to identify whether the treatment outcome could be predicted by any personality trait. METHOD: A study sample consisting of 110 outpatients with PD treated with 10-20 mg/day of escitalopram for 12 weeks. The personality traits were evaluated before and after 12 weeks of medication by using the Swedish universities Scales of Personality (SSP). RESULTS: Although almost all personality traits on the SSP measurement were improved after 12 weeks of medication in comparison with the baseline scores, none of these changes reached a statistically significant level. Only higher impulsivity at baseline SSP predicted non-remission to 12-weeks treatment with escitalopram; however, this association did not withstand the Bonferroni correction in multiple comparisons. LIMITATIONS: All patients were treated in a naturalistic way using an open-label drug, so placebo responses cannot be excluded. The sample size can still be considered not large enough to reveal statistically significant findings. CONCLUSIONS: Maladaptive personality disposition in patients with PD seems to have a trait character and shows little trend toward normalization after 12-weeks treatment with the antidepressant, while the association between impulsivity and treatment response needs further investigation.

LSD-induced entropic brain activity predicts subsequent personality change.

Personality is known to be relatively stable throughout adulthood. Nevertheless, it has been shown that major life events with high personal significance, including experiences engendered by psychedelic drugs, can have an enduring impact on some core facets of personality. In the present, balanced-order, placebo-controlled study, we investigated biological predictors of post-lysergic acid diethylamide (LSD) changes in personality. Nineteen healthy adults underwent resting state functional MRI scans under LSD (75µg, I.V.) and placebo (saline I.V.). The Revised NEO Personality Inventory (NEO-PI-R) was completed at screening and 2 weeks after LSD/placebo. Scanning sessions consisted of three 7.5-min eyes-closed resting-state scans, one of which involved music listening. A standardized preprocessing pipeline was used to extract measures of sample entropy, which characterizes the predictability of an fMRI time-series. Mixed-effects models were used to evaluate drug-induced shifts in brain entropy and their relationship with the observed increases in the personality trait openness at the 2-week follow-up. Overall, LSD had a pronounced global effect on brain entropy, increasing it in both sensory and hierarchically higher networks across multiple time scales. These shifts predicted enduring increases in trait openness. Moreover, the predictive power of the entropy increases was greatest for the music-listening scans and when "ego-dissolution" was reported during the acute experience. These results shed new light on how LSD-induced shifts in brain dynamics and concomitant subjective experience can be predictive of lasting changes in personality. Hum Brain Mapp 37:3203-3213, 2016. © 2016 Wiley Periodicals, Inc.

Psychological and neuropsychological assessment of regular hoasca users.

BACKGROUND: Hoasca (also called ayahuasca) is a N,N-dimethyltryptamine (DMT) - containing psychedelic brew originally used for magico-religious purposes by Amerindian populations of the Amazon Basin. Recently, Brazilian syncretic churches have helped spread the ritual use of hoasca to Western societies. The aim of this study was to evaluate substance use, and neuropsychological and psychological functioning of regular hoasca users within a religious setting. METHODS: Assessment of socio-economic status, mood, personality traits, impulsiveness, drug use, quality of life, extrinsic and intrinsic religiosity, and neuropsychological function was performed on 30 volunteers from a U.S. branch of União do Vegetal (UDV), a Brazilian religion which uses hoasca ritually. We also assessed 27 non-hoasca-using control subjects matched by socio-demographic profile and church attendance. Mann-Whitney U, chi-squared and Fisher tests were used to analyze differences between groups. Spearman's association and simple logistic regression tests were used to analyze the impact of frequency of hoasca use on dependent variables. RESULTS: Relative to the control group, the UDV group demonstrated lower scores for depression (p=0.043, r=.27) and confusion (p=0.032, r=.29) as assessed by the Profile of Mood States (POMS); higher scores on the instrument Big Five Inventory (BFI) for the personality traits agreeableness (p=0.028, r=.29) and openness (p=0.037, r=.28); higher scores on the quality life domain role limitations due to physical health as determined by the instrument Medical Outcomes Study Short Form-36 - SF-36 (p=0.035, r=.28); less recent use of alcohol (p<0.001, φc=.57), greater past use of alcohol to intoxication (p=0.007, φc=.36) and past use of cannabis (p=0.001, φc=.45) as measured by the Addiction Severity Index (ASI), 5th edition; better score on a measure of memory vulnerability to proactive interference as measured by the California Verbal Learning Test - CVLT (p=0.040, r=.27). Lifetime use of hoasca was positively correlated with role limitations due to physical health (p=0.032, rs=.39) and negatively associated with lifetime heavy alcohol use (p=0.034, OR=0.979). CONCLUSIONS: The findings indicate that religious use of hoasca does not adversely affect neuropsychological functioning and may have positive effects on substance abuse and mood.

Differential Effects of Oxytocin on Agency and Communion for Anxiously and Avoidantly Attached Individuals.

Oxytocin promotes prosocial behavior, especially in those individuals who are low in affiliation (e.g., avoidantly attached individuals), but can exacerbate interpersonal insecurities in those preoccupied with closeness (e.g., anxiously attached individuals). One explanation for these opposing observations is that oxytocin induces a communal, other-orientation. Becoming more other oriented should help those people who focus on the self to the exclusion of others, but could be detrimental to those who are other focused but have little sense of an agentic self. Using a within-subjects design, we administered intranasal oxytocin and placebo to 40 males and measured their agency (self-orientation) and communion (other-orientation). Oxytocin produced a slight increase in communion for the average participant; however, as predicted, avoidantly attached individuals were especially likely to perceive themselves as more communal ("kind," "warm," "gentle," etc.) after receiving oxytocin than after receiving the placebo. There was no main effect of oxytocin on agency for the average participant; however, anxiously attached individuals showed a selective decrease in agency ("independent," "self-confident," etc.) following administration of oxytocin. These data help explain the complex social effects of oxytocin.

Personality traits explain the relationship between psychedelic use and less depression in a comparative study.

Interest in psychedelics is increasing due to the potential for improved mental health and quality of life. However, adverse effects on mental health are still a concern. Personality traits have been suggested to both influence the psychedelic experience and mental health, and even be changed by psychedelic use. The present study describes for the first time a national sample of Swedish psychedelic users (n = 400) compared to a sex and age-matched control-group of non-users (n = 400) regarding mental health variables (depression, insomnia, problematic alcohol and drug use, and dissociation) and personality (Big Five). Data was collected in an online survey including individuals from 16 years of age who had at least one psychedelic experience. The main results reported psychedelic users as less depressed (Patient Health Questionnaire-9; PHQ-9) (d = - 0.29) and having more use of drugs (Drug Use Disorders Identification Test; DUDIT) (d = 1.27). In the Big Five personality traits, openness differed notably (d = 1.72), and the between-group effects in PHQ-9 were explained by lower neuroticism. Our findings reveal that psychedelic users report less depression and higher drug use, and this is partly due to personality traits. These results have implications on how we view psychedelic users and the use of psychedelic drugs.

In for a penny, in for a pound: methylphenidate reduces the inhibitory effect of high stakes on persistent risky choice.

Methylphenidate (MPH) is a stimulant that increases extracellular levels of dopamine and noradrenaline. It can diminish risky decision-making tendencies in certain clinical populations. MPH is also used, without license, by healthy adults, but the impact on their decision-making is not well established. Previous work has found that dopamine receptor activity of healthy adults can modulate the influence of stake magnitude on decisions to persistently gamble after incurring a loss. In this study, we tested for modulation of this effect by MPH in 40 healthy human adults. In a double-blind experiment, 20 subjects received 20 mg of MPH, while 20 matched controls received a placebo. All were provided with 30 rounds of opportunities to accept an incurred loss from their assets or opt for a "double-or-nothing" gamble that would either avoid or double it. Rounds began with a variable loss that would double with every failed gamble until it was accepted, recovered, or reached a specified maximum. Probability of recovery on any gamble was low and ambiguous. Subjects receiving placebo gambled less as the magnitude of the stake was raised and as the magnitude of accumulated loss escalated over the course of the task. In contrast, subjects treated with MPH gambled at a consistent rate, well above chance, across all stakes and trials. Trait reward responsiveness also reduced the impact of high stakes. The findings suggest that elevated catecholamine activity by MPH can disrupt inhibitory influences on persistent risky choice in healthy adults.

Dopamine-d2-receptor blockade reverses the association between trait approach motivation and frontal asymmetry in an approach-motivation context.

Individual differences in the behavioral approach system (BAS)-referred to as trait approach motivation or trait BAS)-have been linked to both frontal electroencephalogram (EEG) alpha asymmetry between left and right hemispheres (frontal alpha asymmetry) and brain dopamine. However, evidence directly linking frontal alpha asymmetry and dopamine is scarce. In the present study, female experimenters recorded EEG data in 181 male participants after double-blind administration of either a placebo or a dopamine D2 blocker. As expected, trait BAS was associated with greater left- than right-frontal cortical activity (i.e., greater right- than left-frontal EEG alpha) in the placebo group, but a reversed association emerged in the dopamine-blocker group. Furthermore, frontal alpha asymmetry was associated with a genetic variant known to modulate prefrontal dopamine levels (the catechol-O-methyltransferase Val158Met polymorphism). Finally, each of these effects was significant only in the subgroup of male participants interacting with female experimenters rated as most attractive; this finding suggests that associations between frontal alpha asymmetry and both dopamine and trait BAS are detectable only in approach-motivation contexts.

Association of five-factor model personality domains and facets with presence, onset, and treatment outcomes of major depression in older adults.

OBJECTIVES: To assess the relationship of multiple domains and facets of the five-factor model of personality with presence, onset, and severity of late-life depression. DESIGN: Cross-sectional analysis of depression status, and age of onset. Retrospective analysis of baseline severity. Longitudinal analysis of severity after 3 and 12 months of psychiatric treatment. SETTING: Private university-affiliated medical center in the Southeastern United States. PARTICIPANTS: One hundred twelve psychiatric patients with a current episode of unipolar major depression, and 104 nondepressed comparison subjects, age 60 and older (mean: 70, SD: 6). MEASUREMENTS: Revised NEO Personality Inventory, Diagnostic Interview Schedule, and Montgomery-Åsberg Depression Rating Scale. RESULTS: Binary logistic regression found that depression was related to higher neuroticism (and all its facets) and to lower extraversion (and facets of assertiveness, activity, and positive emotionality) and conscientiousness (and facets of competence, order, dutifulness, and self-discipline). Multinomial logistic regression found some of these relationships held only for depression with onset before age 50 (hostility, self-consciousness, extraversion, assertiveness, positive emotions, order, and dutifulness). Linear regression found that personality was unrelated to depression severity at the beginning of treatment, but improvement after 3 months was related to lower neuroticism (and facets depressiveness and stress-vulnerability) and higher warmth and competence. Improvement after 12 months was related to lower neuroticism, depressiveness, and stress-vulnerability. CONCLUSIONS: Specific personality facets are related with depression and treatment outcomes. Screening for certain personality traits at the start of treatment may help identify patients at risk of worse response to treatment after 3 months.

Psychobiological model of personality and psychopharmacotherapy outcomes in treatment of depression and schizophrenia.

In distinguishing why some patients respond and other do not respond to treatments arraised the clinically very important body of research considering weather patients' personality characteristics might predict outcomes of pharmacotherapeutic treatment. Personality can be a predictor of a psychiatric disorder either owing to their common genetic background or because it enhances exposure of the subject to environmental risk factors. The results of the studies using psychobiological model are reviewed. The studies show that personality temperament dimension Harm Avoidance and character dimension Self-directedness predict outcomes of the pharmacological treatment of depression, but the result for other psychiatric disorders are sparse. The studies are not straightforward in recommendations for treatment choice dependent of personality dimensions.

Bipolar disorder - from endophenotypes to treatment.

INTRODUCTION: There are a lot of unresolved issues associated with the classification, diagnosis, clinical management and understanding of the underlying pathogenic mechanisms of bipolar affective disorder. AIM: To search for discrete endophenotypes in BAD. SUBJECTS AND METHODS: We studied various bipolar I and II and recurrent depression patient samples and healthy controls using descriptive data, self and clinician-rated scales for neurological and psychopathological symptoms, neurocognitive instruments, and inventories for temperamental and characterological features. We also looked into the efficacy, tolerability and cost/benefit ratio of sodium valproate in the treatment of acute mania. RESULTS: BAD patients display deficits in the domains of memory, selective attention, working memory and psychomotor speed. Sensory, motor and complex neurological soft signs can be considered part and parcel of the symptomatology of BAD. The evidence linking hyperthymic temperament to the bipolar spectrum is not supported, while cyclothymia seems to be a marker of vulnerability to affective psychopathology. In contrast to others, we found significantly lower self-transcendence in BAD patients compared to controls. Early age of onset, abrupt onset, lability of mood and energy with late-day brightening and activation, discriminate bipolar from unipolar depression. Sodium valproate (especially if started intravenously) is a highly efficacious, cost-effective treatment approach for acute mania. CONCLUSION: The discovery of BAD endophenotypes can enhance early diagnosis, prevent errors in treatment and help elucidate the genetic vulnerability for this grave disease.

[Substance use risk personality trait for adolescents].

The prevention and treatment of substance use for youth are important issues in Japan. Substance use have significant risks of adverse psychological, social and physical health consequences. Personality factors in order to understand individual differences for substance use and misuse particularly were the much promise, and several personality factors have been demonstrated to be associated with risk for substance use. Conrod and Woicik (2002) developed Substance Use Risk Profile Scale (SURPS) that measures four substance use risk personalities: anxiety sensitivity, hopelessness, sensation-seeking, impulsivity being closely relevant to substance use/misuse and abuse. There are only a few studies focusing the relationship between personality factors and substance use among Japanese adolescents. Thus, this paper aimed to review the previous studies on these issues, and introduce studies regarding SURPS including our studies.