Does socioeconomic status relate to central serotonergic responsivity in healthy adults?

The association between social class and aggression: A meta-analytic review

RATIONALE

Substantial evidence links social class with aggression. Despite lower social class being recognized as a risk factor for high levels of aggression, the findings of this association have been inconsistent. Some studies have indeed illustrated that a social class level is inversely associated with aggression, while other studies have demonstrated positive or null associations.

OBJECTIVE

To clarify previously inconsistent findings, this meta-analysis assesses the overall magnitude of this relationship and examines the potential moderators.

METHODS

A total of 268 studies met the inclusion criteria, and we used 546 effect sizes in 357 independent samples from these studies. A random-effects meta-analytic model was employed and several moderator analyses were conducted.

RESULTS

Overall, social class shared a small but significant negative relationship with aggression (r = -0.092). Moderator analyses suggested that study-level (e.g., type of study, and national differences), sample-level (e.g., age), class-level (e.g., type, assessment, and source of social class), and aggression-level (e.g., type of aggression) characteristics accounted for heterogeneity in the relationship. Additional analyses also revealed the robustness of these effects with little evidence of publication bias.

CONCLUSIONS

Living in disadvantaged socioecological environments, lower-class individuals may exhibit more aggression to adapt to threats. Moreover, the relationship between social class and aggression is not fixed and can change with specific contexts, and aggression is not an essential feature of a particular social group. This research hopes to inspire future studies to explore the association between social class and aggression more thoroughly. Additionally, it provides insights into how to reduce aggression among lower-class individuals.

Acetylcholine potentiates glutamate transmission from the habenula to the interpeduncular nucleus in losers of social conflict

Switching behaviors from aggression to submission in losers at the end of conspecific social fighting is essential to avoid serious injury or death. We have previously shown that the experience of defeat induces a loser-specific potentiation in the habenula (Hb)-interpeduncular nucleus (IPN) and show here that this is induced by acetylcholine. Calcium imaging and electrophysiological recording using acute brain slices from winners and losers of fighting behavior in zebrafish revealed that the ventral IPN (vIPN) dominates over the dorsal IPN in the neural response to Hb stimulation in losers. We also show that GluA1 α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor subunits on the postsynaptic membrane increased in the vIPN of losers. Furthermore, these loser-specific neural properties disappeared in the presence of an α7 nicotinic acetylcholine receptor (nAChR) antagonist and, conversely, were induced in brain slices of winners treated with α7 nAChR agonists. These data suggest that acetylcholine released from Hb terminals in the vIPN induces activation of α7 nAChR followed by an increase in postsynaptic membrane GluA1. This results in an increase in active synapses on postsynaptic neurons, resulting in the potentiation of neurotransmissions to the vIPN. This acetylcholine-induced neuromodulation could be the neural foundation for behavioral switching in losers. Our results could increase our understanding of the mechanisms of various mood disorders such as social anxiety disorder and social withdrawal.

Education, household income, and depressive symptoms in middle-aged and older Japanese adults

Background

Income inequality has dramatically increased worldwide, and there is a need to re-evaluate the association between socio-economic status (SES) and depression. Relative contributions of household income and education to depression, as well as their interactions, have not been fully evaluated. This study aimed to examine the association between SES and depressive symptoms in Japanese adults, focusing on interactions between education and household income levels.

Methods

This cross-sectional study used data from baseline surveys of two cohort studies. Participants were 38,499 community-dwelling people aged 40–74 years who participated in baseline surveys of the Murakami cohort study (2011–2012) and Uonuma cohort study (2012–2015) conducted in Niigata Prefecture, Japan. Information regarding marital status, education level, household income, occupation, activities of daily living (ADL), and history of cancer, myocardial infarction, stroke, and diabetes was obtained using a self-administered questionnaire. Depressive symptoms were examined using the Center for Epidemiologic Studies Depression Scale (CES-D). Logistic regression analysis was used to obtain odds ratios (ORs). Covariates included age, sex, marital status, education, household income, occupation, ADL, and disease history.

Results

Individuals with higher education levels had lower ORs (adjusted P for trend = 0.0007) for depressive symptoms, independently of household income level. The OR of the university-or-higher group was significantly lower than that of the junior high school group (adjusted OR = 0.79). Individuals with lower household income levels had higher ORs (adjusted P for trend< 0.0001) for depressive symptoms, independently of education level. The type of occupation was not associated with depressive symptoms. In subgroup analyses according to household income level, individuals with higher education levels had significantly lower ORs in the lowest- and lower-income groups (adjusted P for trend = 0.0275 and 0.0123, respectively), but not in higher- and highest-income groups (0.5214 and 0.0915, respectively).

Conclusions

Both education and household income levels are independently associated with the prevalence of depressive symptoms, with household income levels showing a more robust association with depressive symptoms than education levels. This suggests that a high household income level may offset the risk of depressive symptoms from having a low education level.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-021-12168-8.

Impact of Tryptophan Depletion on Executive System Function during Menopause is Moderated by Childhood Adversity

Many healthy women with no history of cognitive dysfunction experience subjective executive difficulties during menopause. Preclinical literature suggests latent effects of early life adversity on serotonin function may play a role in this phenomenon. However, evidence in human participants regarding the mechanisms by which loss of estradiol contributes to this vulnerability is lacking. Here we examined the impact of tryptophan depletion (TD) and adverse childhood experiences (ACE) on brain activation during a working memory task in menopausal women. We hypothesized that an interactive effect between ACE and TD would be observed when women were hypogonadal, and that treatment with estradiol would attenuate this effect. Thirty-three women underwent functional imaging at four time points (123 total scans) in this double-blind, placebo controlled, cross-over study. The effects of TD, ACE, and TD × ACE were evaluated using a voxel-wise, mixed-effects, 2 × 2 ANOVA. In the absence of exogenous estradiol, a TD by ACE interaction was observed on BOLD signal in the right DLPFC such that TD increased activation in high ACE subjects but decreased activation in low ACE subjects. While a similar interaction was observed with placebo treatment, treatment with estradiol attenuated the effects of ACE and TD such that no between or within group differences were observed. Together, these results suggest that early life adversity may have a lasting impact on serotonergic circuits underlying executive function that are unmasked by loss of estradiol during menopause.

Anxiety sensitivity explains associations between anxious arousal symptoms and smoking abstinence expectancies, perceived barriers to cessation, and problems experienced during past quit attempts among low-income smokers

Disproportionately more smokers report low-income and mental health problems relative to non-smokers. Low-income smokers may use smoking to alleviate negative emotional states resulting from exposure to multiple stressors. Yet, little work has been devoted to elucidating mechanisms that may explain the association between negative emotional states and smoking-related processes among low-income smokers. The present study sought to address this gap by examining anxiety sensitivity, a transdiagnostic factor related to both anxiety and smoking, as a potential mediator for the influence of anxiety symptoms on smoking-related processes, including threat-related smoking abstinence expectancies (somatic symptoms and harmful consequences), perceived barriers for cessation, and problems experienced during past quit attempts. Participants included treatment-seeking daily cigarette smokers (n=101; 68.3% male; Mage=47.1; SD=10.2). Results indicated that anxiety symptoms exerted a significant indirect effect through anxiety sensitivity for threat-related smoking abstinence expectancies (somatic symptoms and harmful consequences), perceived barriers for cessation, and problems experienced during past quit attempts. The present results provide empirical support that anxiety sensitivity may be an underlying mechanism that partially explains the relation between anxiety symptoms and smoking processes among low-income treatment-seeking smokers. Findings broaden current theoretical understanding of pathways through which anxiety symptoms contribute to maladaptive smoking processes and cognitions among socioeconomically disadvantaged smokers.

Moral responsibility for (un)healthy behaviour

Combatting chronic, lifestyle-related disease has become a healthcare priority in the developed world. The role personal responsibility should play in healthcare provision has growing pertinence given the growing significance of individual lifestyle choices for health. Media reporting focussing on the 'bad behaviour' of individuals suffering lifestyle-related disease, and policies aimed at encouraging 'responsibilisation' in healthcare highlight the importance of understanding the scope of responsibility ascriptions in this context. Research into the social determinants of health and psychological mechanisms of health behaviour could undermine some commonly held and tacit assumptions about the moral responsibility of agents for the sorts of lifestyles they adopt. I use Philip Petit's conception of freedom as 'fitness to be held responsible' to consider the significance of some of this evidence for assessing the moral responsibility of agents. I propose that, in some cases, factors outside the agent's control may influence behaviour in such a way as to undermine her freedom along the three dimensions described by Pettit: freedom of action; a sense of identification with one's actions; and whether one's social position renders one vulnerable to pressure from more powerful others.

Self-reported family socioeconomic status, the 5-HTTLPR genotype, and delinquent behavior in a community-based adolescent population

Twin and adoption studies have demonstrated a significant contribution of both genetic and environmental factors to antisocial and delinquent behavior. Associations have been reported between the serotonin transporter (5-HTT) and aggression, and between socioeconomic status (SES), aggression, and serotonergic functions of the brain. We aimed to investigate associations between the 5-HTTLPR genotype and family SES in relation to delinquent behavior among adolescents. A total of 1,467 17- to 18-year-old students in the county of Västmanland, Sweden, anonymously completed a questionnaire and gave a saliva sample. Family SES had a U-shaped relation to delinquency, where adolescents with low and high family SES were the most delinquent. There were curvilinear interactions between the 5-HTTLPR genotype and family SES in relation to delinquency. Among individuals having high family SES, boys with the LL (homozygous for the long allele) or LS (heterozygous) genotypes and girls with the SS (homozygous for the short allele) or LS (heterozygous) genotypes showed the highest delinquency scores. Among individuals having low family SES, boys with the LL (homozygous for the long allele) genotype and girls with the LS (heterozygous) genotype showed the highest delinquency scores. The present study suggests evidence for an interaction between family SES and the 5-HTTLPR genotype in relation to juvenile delinquency.

A review on the relationship between testosterone and life-course persistent antisocial behavior

Life-course persistent antisocial behavior is 10 to 14 times more prevalent in males and it has been suggested that testosterone levels could account for this gender bias. Preliminary studies with measures of fetal testosterone find inconsistent associations with antisocial behavior, especially studies that use the 2D:4D ratio as a proxy for fetal testosterone. However, circulating testosterone consistently shows positive associations with antisocial behaviors throughout childhood, adolescence, and adulthood, particularly in males. It is suggested that high fetal/circulating testosterone interactively influence the maturation and functionality of mesolimbic dopaminergic circuitry, right orbitofrontal cortex, and cortico-subcortical connectivity, resulting in a strong reward motivation, low social sensitivity, and dampened regulation of strong motivational/emotional processes. The link between these testosterone induced endophenotypes and actual display of antisocial behavior is strongly modulated by different social (e.g., social rejection, low SES) and genetic (e.g., MAOA, 5HTT) risk factors that can disturb socio-, psycho-, and biological development and interact with testosterone in shaping behavior. When these additional risk factors are present, the testosterone induced endophenotypes may increase the risk for a chronic antisocial lifestyle. However, behavioral endophenotypes induced by testosterone can also predispose towards socially adaptive traits such as a strong achievement motivation, leadership, fair bargaining behaviors, and social assertiveness. These adaptive traits are more likely to emerge when the high testosterone individual has positive social experiences that promote prosocial behaviors such as strong and secure attachments with his caregivers, affiliation with prosocial peers, and sufficient socioeconomic resources. A theoretical model is presented, various hypotheses are examined, and future venues for research are discussed.

Where Is Social Structure in Personality Research?

For decades, feminist scholars have argued that to understand a person’s behavior, one must understand not only that individual but also the social structure in which she or he is embedded. Has psychology heeded these calls? The authors investigated this question using the subfield of personality as an exemplar. Based on a systematic analysis of publication trends in nine prominent journals, the authors found that social-structural analyses rarely appear in highly cited journals specifically devoted to personality research. Instead, these analyses appear in journals that focus on certain social structures (gender and race/ethnicity), while still neglecting others (social class and sexual orientation). To illustrate how greater attention to social structure can advance the scientific understanding of individuals, the authors then identified specific research programs that look closely at both personality and structure. The article concludes with specific recommendations for research and teaching in personality psychology, gender and race psychology, and beyond.

Psychological perspectives on pathways linking socioeconomic status and physical health

Low socioeconomic status (SES) is a reliable correlate of poor physical health. Rather than treat SES as a covariate, health psychology has increasingly focused on the psychobiological pathways that inform understanding why SES is related to physical health. This review assesses the status of research that has examined stress and its associated distress, and social and personal resources as pathways. It highlights work on biomarkers and biological pathways related to SES that can serve as intermediate outcomes in future studies. Recent emphasis on the accumulation of psychobiological risks across the life course is summarized and represents an important direction for future research. Studies that test pathways from SES to candidate psychosocial pathways to health outcomes are few in number but promising. Future research should test integrated models rather than taking piecemeal approaches to evidence. Much work remains to be done, but the questions are of great health significance.

Mediation analysis in psychosomatic medicine research

This article presents an overview of statistical mediation analysis and its application to psychosomatic medicine research. The article begins with a description of the major approaches to mediation analysis and an evaluation of the strengths and limits of each. Emphasis is placed on longitudinal mediation models, and an application using latent growth modeling is presented. The article concludes with a description of recent developments in mediation analysis and suggestions for the use of mediation for future work in psychosomatic medicine research.

Neurobiological pathways linking socioeconomic position and health

Across individuals, risk for poor health varies inversely with socioeconomic position (SEP). The pathways by which SEP affects health have been viewed from many epidemiological perspectives. Central to these perspectives is the notion that socioeconomic health disparities arise from an interplay between nested, recursive, and cumulative environmental, social, familial, psychological, behavioral, and physiological processes that unfold over the life span. Epidemiological perspectives on socioeconomic health disparities, however, have not yet formally integrated emerging findings from neuropharmacological, molecular genetic, and neuroimaging studies demonstrating that indicators of SEP relate to patterns of brain neurotransmission, brain morphology, and brain functionality implicated in the etiology of chronic medical conditions and psychological disorders. Here, we survey these emerging findings and consider how future neurobiological studies in this area can enhance our understanding of the pathways by which different dimensions of SEP become embodied by the brain to influence health throughout life.

Subjective socioeconomic status and presence of the metabolic syndrome in midlife community volunteers

OBJECTIVE

Objective indices of socioeconomic status (SES) predict diverse sources of morbidity and mortality as well as numerous biological and behavioral risk factors for disease. Here we examine whether subjective measures of SES may be similarly associated with measured risk factors including the metabolic syndrome and its components of elevated blood pressure, high fasting glucose, dyslipidemia, and central adiposity.

METHODS

Observations were based on a community sample of 981 adults (30-54 years of age; 52% female; 84% white, 16% African American). Subjective SES was measured, using the nationally referenced (U.S.) MacArthur Scale of Subjective Social Status, and objective SES was indexed by composite of years of education and family income.

RESULTS

Likelihood of meeting the criteria for presence of the metabolic syndrome varied inversely with subjective SES (odds ratio [OR] = 0.75; 95% Confidence Interval [CI] = 0.64-0.88, for a 1-standard deviation increase in subjective SES, adjusted for age, sex, and race), and this association persisted on further adjustment for objective SES (OR = 0.82; 95% CI = 0.68-0.99). Subjective SES was also associated inversely with blood pressure, waist circumference, and serum triglycerides, and positively with HDL cholesterol. Level of physical activity and smoking status were predicted by subjective SES as well, but adjusting for these health behaviors did not appreciably reduce associations of subjective SES with metabolic syndrome and syndrome components.

CONCLUSIONS

These findings support speculation that perceived social standing is associated with prominent cardiovascular risk factors and may prove a useful adjunct to conventional socioeconomic indicators in epidemiological research.

Powerlessness, anger, and stress in African American women: implications for physical and emotional health

African American women find themselves at a high risk of experiencing feelings of powerlessness associated with socioeconomic disparities rooted in a history of racism and sexism. The authors present a conceptual model that discusses powerlessness as a significant variable that contributes to the experience of anger and stress in African American women, and consequently to the adverse health consequences of such anger and stress. The authors review the current literature as well as census and health statistics to discern critical historical, social, and cognitive aspects of powerlessness and anger in African American women. Implications for practitioners are addressed.

Neurobiology of stress-induced reproductive dysfunction in female macaques

It is now well accepted that stress can precipitate mental and physical illness. However, it is becoming clear that given the same stress, some individuals are very vulnerable and will succumb to illness while others are more resilient and cope effectively, rather than becoming ill. This difference between individuals is called stress sensitivity. Stress sensitivity of an individual appears to be influenced by genetically inherited factors, early life (even prenatal) stress, and by the presence or absence of factors that provide protection from stress. In comparison to other stress-related diseases, the concept of sensitivity versus resilience to stress-induced reproductive dysfunction has received relatively little attention. The studies presented herein were undertaken to begin to identify stable characteristics and the neural underpinnings of individuals with sensitivity to stress-induced reproductive dysfunction. Female cynomolgus macaques with normal menstrual cycles either stop ovulating (stress sensitive) or to continue to ovulate (stress resilient) upon exposure to a combined metabolic and psychosocial stress. However, even in the absence of stress, the stress-sensitive animals have lower secretion of the ovarian steroids, estrogen and progesterone, have higher heart rates, have lower serotonin function, have fewer serotonin neurons and lower expression of pivotal serotonin-related genes, have lower expression of 5HT2A and 2C genes in the hypothalamus, have higher gene expression of GAD67 and CRH in the hypothalamus, and have reduced gonadotropin-releasing hormone transport to the anterior pituitary. Altogether, the results suggest that the neurobiology of reproductive circuits in stress-sensitive individuals is compromised. We speculate that with the application of stress, the dysfunction of these neural systems becomes exacerbated and reproductive function ceases.

Body size at birth and socio-economic status in childhood: implications for Cloninger's psychobiological model of temperament at age 60

Small birth size predicts various psychiatric outcomes, including depression. While biologically based temperamental traits may constitute a vulnerability factor for depression, the extent to which birth size predicts these traits in adulthood is not known. We studied, in 1369 women and men identified from a cohort born in 1934-44 in Helsinki, Finland, whether birth size predicts the temperamental traits measured with Cloninger's Tridimensional Personality Questionnaire at an average age of 63 years. Moreover, we examined whether socio-economic status (SES) in childhood modified the associations. Data on birth size were obtained from birth records, and SES in childhood was obtained from school records. Weight and length at birth showed curvilinear, reverse J-shaped effects on harm avoidance (HA), such that the highest HA scores were most characteristic of those born small. Furthermore, high HA was confined to those belonging to a low SES group in childhood regardless of birth size, and to those belonging to the high SES group in childhood if their birth size was small. The associations were independent of several confounders. Since small birth size as well as high HA in adulthood may associate with subsequent depression, our findings might shed light on understanding the early neurodevelopmental processes that predispose to depression through vulnerability characteristics.

Perigenual anterior cingulate morphology covaries with perceived social standing

Low socioeconomic status (SES) increases the risk for developing psychiatric and chronic medical disorders. A stress-related pathway by which low SES may affect mental and physical health is through the perception of holding a low social standing, termed low subjective social status. This proposal implicates overlapping brain regions mediating stress reactivity and socioemotional behaviors as neuroanatomical substrates that could plausibly link subjective social status to health-related outcomes. In a test of this proposal, we used a computational structural neuroimaging method (voxel-based morphometry) in a healthy community sample to examine the relationships between reports of subjective social status and regional gray matter volume. Results showed that after accounting for potential demographic confounds, subclinical depressive symptoms, dispositional forms of negative emotionality and conventional indicators of SES, self-reports of low subjective social status uniquely covaried with reduced gray matter volume in the perigenual area of the anterior cingulate cortex (pACC)-a brain region involved in experiencing emotions and regulating behavioral and physiological reactivity to psychosocial stress. The pACC may represent a neuroanatomical substrate by which perceived social standing relates to mental and physical health.

Methamphetamine use, impulsivity, and sexual risk behavior among HIV-positive men who have sex with men

This study examined impulsivity as a moderator of the relationship between meth use and sexual risk behavior in a sample of HIV-positive meth-using Men who have Sex with Men (MSM). Higher impulsivity was associated with less education, lower income, being unemployed, psychiatric diagnosis, and higher Beck depression scores. Intensity of meth use and sexual risk behavior were significantly correlated. In a multiple regression analysis, more education, greater intensity of meth use and higher levels of impulsivity predicted more unprotected sex. To test for moderating effects of impulsivity, an interaction term was added to the regression. The interactive effects model was statistically significant. A plot of the interaction revealed that the relationship between intensity of meth use and total unprotected sex was strongest among participants who had higher levels of impulsivity. This suggests that targeting impulsivity in interventions may help reduce sexual risk behaviors in high intensity meth-using HIV-positive MSM.

Plasma serotonin levels in young violent offenders: Aggressive responding and personality correlates

70 young male violent offenders and 30 normal controls in Hunan, China were interviewed and assessed by the Minnesota Multiphasic Personality Inventory (MMPI), Point Subtraction Aggression Paradigm (PSAP) and plasma serotonin (5-HT) level. Compared to the normal controls, the violent offenders had significantly higher plasma 5-HT levels; higher scores on the MMPI subscale Pd (P < 0.01), Pa (P < 0.05); and higher PSAP-B responding and lower PSAP-C responding (P < 0.05). There was a positive correlation between the MMPI Pd score and the PSAP B response, but no significant correlation was found between Pd score and plasma 5-HT level, or between PSAP B response and plasma 5-HT level. Our data suggest that the young violent offenders are more aggressive than the normal control. But this study did not demonstrate that the plasma 5-HT level had a correlation with the PSAP aggressive response. The relationship between the aggressiveness and impulsivity in the violent behavior needs further study.

Polymorphism in the serotonin transporter gene and moderators of prolactin response to meta-chlorophenylpiperazine in African-American cocaine abusers and controls

Serotonin (5-HT) function is altered in several psychiatric disorders, including cocaine dependence (CD), and its role in impulsive-aggressive behaviors has been widely studied. However, the relationship between psychopathological and behavioral dimensions and mechanisms of 5-HT alterations remains unclear. We investigated the relationship of a polymorphism in the 5' promoter region of the serotonin transporter gene (5-HTTLPR) with prolactin (PRL) response to meta-chlorophenylpiperazine (m-CPP) in a sample of 68 African-American individuals, 35 CD subjects and 33 controls. We also examined whether measures of impulsivity, hostility and sensation seeking influenced the relationship between the 5-HTTLPR polymorphism and PRL response to m-CPP in this sample. Individuals with the SS genotype showed significantly heightened PRL response to the challenge compared with the LL and LS genotypes. No influence of gender or substance abuse condition was observed. Hostility was associated with blunted PRL response in the total sample. Cocaine abuse was the most significant moderator of DeltaPRL (peak PRL-baseline PRL), and the interaction of genetic, behavioral and psychopathological measures helped predict most of the observed DeltaPRL (62.5%). Although these results need replication, variation in the 5-HTTLPR gene appears to influence measures of 5-HT function and interact with disease state and personality dimensions to account for 5-HT disturbances in African-American populations.

Individual versus neighborhood socioeconomic status and race as predictors of adolescent ambulatory blood pressure and heart rate

Socioeconomic status (SES) disparities are linked to increased cardiovascular disease risk. Although typically considered an individual or family indicator, SES alternatively can be derived from neighborhood characteristics. Previous research has found both family and neighborhood SES predict laboratory blood pressure responses in youth. The question remains as to whether this SES gradient predicts blood pressure during daily living situations. We evaluated individual versus neighborhood SES and race as predictors of ambulatory blood pressure and heart rate. Participants were recruited from two schools in Pittsburgh, diverse in terms of both race and SES. Adolescents' (N=212, 14.5 years, 50% black) cardiovascular responses were measured at school and home. Individual (parent education, household income) and neighborhood SES indices (derived from 78 census tracts: percentage with high school degree or less, percentage below poverty) were assessed. A neighborhood index of race based on the proportion of blacks in the census tract was also derived as a counterpart to individuals' race. Multi-level modeling indicated neighborhood income predicted systolic blood pressure. Individual race predicted diastolic blood pressure. Individual income and education, and neighborhood race each predicted heart rate. These results have important public health implications as they suggest individual and neighborhood SES and race are linked to cardiovascular risk disparities as early as adolescence.

[Reduced serotonin levels in platelet-free plasma of adolescents with externalizing behaviour problems]

OBJECTIVES

A serotonergic dysfunction, in particular a reduced serotonergic neurotransmission in the frontal cortex and limbic brain regions, has been discussed in connection with the aetiology of aggressive and impulsive behaviour. Assessment of the activity in the central serotonergic system in children and adolescents is limited due to its technical complexity and ethical restrictions. Therefore, peripheral serotonergic parameters have been used as a model to obtain deeper insight into central serotonergic functions. The aim of this investigation is to examine the significance of plasma serotonin measurement with regard to behavioural problems in adolescents at risk for psychopathology.

METHODS

Within the framework of a prospective longitudinal study of children at risk, serotonin levels in platelet-free blood plasma were measured in a group of n = 10 adolescents aged 15 years with persistent externalizing behaviour (T-score > or = 60 on the "Externalizing Problems" scale of the CBCL) and in a control group of n = 20 mentally undisturbed adolescents. Groups were matched according to age and gender. Externalizing behaviour was assessed by means of a parent questionnaire, the Achenbach Child Behavior Checklist (CBCL).

RESULTS

Significantly lower levels of plasma serotonin were found in adolescents with persistent behaviour problems than in the control group. Significant negative correlations between serotonin levels and the CBCL scales "Aggressive Behavior" and "Externalizing Problems" were obtained for the total sample.

CONCLUSIONS

Earlier findings that described a serotonergic deficit as a key mechanism in the manifestation of aggressive and antisocial behaviour are confirmed for adolescents at risk taken from a community sample.

Psychosocial stress and cardiovascular diseases

Fifty five years after the first finding relating mood disturbances and cardiovascular diseases, there is still debate on the formation of a cogent conception embracing all the fragments of insight within the various aspects relating psychosocial stress to cardiovascular diseases. The clinical comorbidity is empirically evident, but there are ambiguous research results limiting the value of the proposed pathophysiological mechanisms. Psychosocial stress represents here any event that relates psychological phenomena to the social environment and to the associated pathophysiological changes. Stress denotes the external or environmental factors to which people are exposed, as well as the behavioural or biological reaction to it (response that some authors call "distress"). Cardiovascular diseases will be considered here only when being the consequence of chronic inflammatory disease of arteries (atherosclerosis). The question is: are there pathophysiological reliable mechanisms relating psychosocial stress to the development of cardiovascular diseases?

Impulsivity and methamphetamine use

The purpose of this study was to explore the relationship between methamphetamine (meth) use and impulsivity in a sample of 385 HIV-negative heterosexually identified meth users. Participants who scored highest on a self-report measure of impulsivity were compared with those who scored lower in terms of background characteristics, meth use patterns, use of alcohol and other illicit drugs, sexual risk behavior, and psychiatric health variables. Methamphetamine users in the high impulsivity group were younger, less educated, used larger quantities of meth, were more likely to be binge users, had a larger number of sexual partners, engaged in more unprotected vaginal and oral sex, and scored higher on the Beck Depression Inventory as compared with those in the low impulsivity group. In a logistic regression analysis, Beck depression was the factor that best distinguished between meth users who scored high and those who scored low on impulsivity. Neurophysiological pathways that may underlie the relationship between impulsivity and meth use are discussed.

Sensitivity to stress-induced reproductive dysfunction linked to activity of the serotonin system

OBJECTIVE

To use a nonhuman primate model and determine whether individuals sensitive to stress-induced reproductive dysfunction have lower activity of central serotonergic neurons under nonstressed conditions.

DESIGN

The activity of the central serotonergic system was assessed by measuring responsiveness to a fenfluramine challenge (5 mg/kg, IV) in sedated monkeys previously categorized as highly stress resistant (HSR; n = 4; normal menstrual cyclicity through two stress cycles), medium stress resistant (MSR; n = 5; ovulatory in the first stress cycle but anovulatory in the second stress cycle), or low stress resistant (i.e., stress sensitive, SS; n = 4; anovulatory as soon as stress is initiated). To control for differences in pituitary stores of prolactin or ACTH, the animals were subsequently administered a bolus of thyrotropin-releasing hormone (3 microg/kg) plus corticotropin releasing factor (CRF), (3 microg/kg).

SETTING

Oregon National Primate Research Center, Animal Services Building.

PATIENT(S)

Female cynomolgus macaques exhibiting normal menstrual cycles.

INTERVENTION(S)

Administration of fenfluramine, a serotonin-releasing drug.

MAIN OUTCOMES MEASURE(S)

Serum concentrations of prolactin (PRL) and cortisol (F).

RESULT(S)

Prolactin release in response to fenfluramine was significantly greater in the HSR group compared with the MSR or SS groups. In contrast, cortisol was higher in the SS group compared with the other two groups. Similar responses were not evident after thyrotropin-releasing hormone + CRF stimulation.

CONCLUSION(S)

The lower PRL response to fenfluramine in the stress-sensitive animals suggests that stress-sensitive individuals have decreased activity in central serotonergic neurons. However, the F data suggest that the hypothalamic-pituitary-adrenal axis in stress-sensitive individuals is highly responsive to even small increases in serotonin.

Interactions between anxiety, social support, health status and buspirone efficacy in elderly patients

Psychosocial factors are among the etiological factors of anxiety, and have been shown to affect the anxiolytic efficacy of buspirone in laboratory rodents. Disparate human studies suggest that a similar interaction may be valid for anxious patients. However, this interaction is poorly known at present. It was hypothesized that social support and health status are especially relevant psychosocial problems in elderly, and as such, have a large impact on both anxiety and the efficacy of anxiolytic treatment with buspirone. The hypothesis was assessed by three independent studies performed in a total number of 384 elderly in-patients (109 males, 275 females, age approximately 80 years). A low number of social contacts associated with a large number of diseases proved to be a strong risk factor for anxiety, whereas the reverse condition (many contacts/few diseases) was associated with considerably lower Hamilton Rating Scale for Anxiety (HAM-A) scores. Buspirone ameliorated anxiety significantly in general, but the "many contacts/many diseases" condition was associated with twice as much improvement as the "few contacts/few diseases" condition. The patient's self-evaluation of health status was predicted strongly by the disease score used in the above two studies. Taken conjointly, data suggest that the major Axis-IV problems faced by the age class studied (social support and health status) have a strong effect on both anxiety and buspirone responsiveness in elderly patients. Thus, drug responses appear to be modulated by nonpharmacological factors, and research directed towards identifying such factors would provide information important to a more appropriate patient targeting of certain medications.

Socio-economic status covaries with central nervous system serotonergic responsivity as a function of allelic variation in the serotonin transporter gene-linked polymorphic region

It was reported recently that exposure to an adverse rearing environment lowers central nervous system (CNS) serotonergic activity in a nonhuman primate (rhesus monkeys), but only among animals having the shorter variant of a functional, biallelic repeat polymorphism in the regulatory region of the serotonin transporter (5-HTT) gene. Because repeat variants of the same core sequence affect transcriptional efficiency of the 5-HTT gene in humans, we examined whether biallelic variation in the 5-HTT gene-linked polymorphic region (5-HTTLPR) acts analogously to modulate a previously described association between socio-economic status (SES) and CNS serotonergic function. The 5-HTTLPR was genotyped in 139 adult men and women (n = 75 and 64) who were administered a standard neuroendocrine challenge to assess central serotonergic responsivity (plasma prolactin (PRL) response to the serotonin releasing agent, fenfluramine). Socio-economic status was estimated from reported income and years of education. Hierarchical linear regression showed serotonergic responsivity to be predicted by the interaction of 5-HTTLPR genotype and SES (p = 0.018). Individuals of lower income and less education had lower peak PRL concentrations following administration of fenfluramine than did subjects ranking higher on these dimensions, but only among persons possessing at least one 5-HTTLPR short allele. Within genotype, SES covaried moderately with the PRL response to fenfluramine among subjects who were homozygous for the short allele (r18 = 0.50, p < 0.03). A similar association was present at lesser magnitude in heterozygotes (r70 = 0.24, p < 0.05) and absent among subjects homozygous for the long allele (r45 = -0.04, n.s.). Findings were comparable for men and women and persisted on re-analysis restricted to persons without current Axis I psychopathology. We conclude that allelic variation at 5-HTTLPR moderates the influence of social position on CNS serotonergic responsivity.

Understanding the association between socioeconomic status and physical health: do negative emotions play a role?

In this article, the authors evaluate the possible roles of negative emotions and cognitions in the association between socioeconomic status (SES) and physical health, focusing on the outcomes of cardiovascular diseases and all-cause mortality. After reviewing the limited direct evidence, the authors examine indirect evidence showing that (a) SES relates to the targeted health outcomes, (b) SES relates to negative emotions and cognitions, and (c) negative emotions and cognitions relate to the targeted health outcomes. The authors present a general framework for understanding the roles of cognitive-emotional factors, suggesting that low-SES environments are stressful and reduce individuals' reserve capacity to manage stress, thereby increasing vulnerability to negative emotions and cognitions. The article concludes with suggestions for future research to better evaluate the proposed model.

Soy and social stress affect serotonin neurotransmission in primates

Stress and sex steroidal milieu can each influence mood in women. The purpose of this study was to compare the effect of long-term conjugated equine estrogen (CEE), soy phytoestrogen (SPE), and social subordination stress on dorsal raphe serotonin neurotransmission of ovariectomized cynomolgus monkeys. Tryptophan hydroxylase (TPH) and serotonin reuptake transporter (SERT) protein content were determined, and the in vitro degradation of macaque SERT protein was examined in the presence and absence of protease inhibitors, serotonin (5-HT), and citalopram. Like CEE, SPE increased TPH protein levels. Social subordinates had markedly lower TPH protein levels than dominants regardless of hormone replacement. Therefore, these two variables had independent and additive effects. CEE and SPE increased SERT, and social status had no effect. Thus, the hormone-induced increase in SERT was accompanied by increased 5-HT synthesis and neuronal firing, which appears biologically reasonable as 5-HT prevented SERT degradation in vitro.

Covariation of psychosocial characteristics associated with cardiovascular disease: genetic and environmental influences

OBJECTIVE

Three psychosocial characteristics associated with cardiovascular disease (CVD)-depression, hostility, and social support-tend to correlate with one another. However, the causes of each characteristic and why they tend to co-occur are not completely understood. Therefore, the current study used a twin design to examine the relative contributions of genetic and environmental influences to the variation and covariation of these three psychosocial characteristics.

METHODS

The sources of variation and covariation among the Beck Depression Inventory, the Cook-Medley Hostility Scale, and the Interpersonal Support Evaluation List were examined in a young adult community sample of 157 monozygotic and 75 dizygotic twin pairs.

RESULTS

Phenotypic confirmatory factor analysis indicated that a single latent factor could account for their moderate intercorrelations. Twin analyses indicated that the Beck Depression Inventory and Interpersonal Support Evaluation List were each influenced by genetic and nonshared environmental factors, whereas the Cook-Medley Hostility Scale was influenced by familial (genetic and/or shared environmental) and nonshared environmental factors. Bivariate associations between these scales were largely determined by common genetic effects and, to a lesser degree, common nonshared environmental effects. Covariation among the three scales could be explained by a single common genetic factor and a common nonshared environmental factor. Environmental factors shared within families did not contribute to covariation among the psychosocial characteristics.

CONCLUSIONS

The results challenge the conventional approach of examining these psychosocial variables as independent risk factors for cardiovascular disease and argue for the importance of investigating specific causes for their covariation.

The Japanese version of the Barratt Impulsiveness Scale, 11th version (BIS-11): its reliability and validity

No instrument for assessing impulsiveness has been developed in Japan. After translating the Barratt Impulsiveness Scale 11th version (BIS-11) into Japanese, we investigated reliability and validity in student (n = 34) and worker (n = 416) samples. To assess test-retest reliability, the intraclass coefficient between test and retest was calculated in the student sample. Internal consistency was examined by calculating Cronbach's alpha in the worker sample. To see factor validity, we examined by confirmatory factor analysis whether the three-factor model, proposed by a previous report, fit the data. The results showed that the Japanese version of the BIS-11 had excellent test-retest reliability and acceptable internal consistency reliability. In addition, the Japanese version was judged to have similar factor structure to the original one. The Japanese version of the BIS-11 is a reliable and valid measure and has possible utility for assessing impulsiveness.

Central nervous system serotonin function and cardiovascular responses to stress

OBJECTIVE

The objective of this study was to evaluate the impact of indices of central nervous system (CNS) serotonin function on cardiovascular reactivity to mental stress.

METHODS

Lumbar puncture was performed on 54 healthy volunteers to obtain cerebrospinal fluid (CSF) for determination of 5-hydroxyindoleacetic acid (5HIAA) levels. Genotypes were determined with respect to a functional polymorphism of the serotonin transporter gene promoter region (5HTTLPR). Subjects then underwent mental stress testing.

RESULTS

Persons with one or two long (l) 5HTTLPR alleles had CSF levels of the major serotonin metabolite, 5HIAA, that were 50% higher than those of persons with the s/s 5HTTLPR genotype. Persons with one or two l alleles or higher CSF 5HIAA levels also exhibited greater blood pressure and heart rate responses to a mental stress protocol.

CONCLUSIONS

These findings suggest the 5HTTLPR polymorphism affects CNS serotonin function, and they are consistent with the general hypothesis that CNS serotonin function is involved in the regulation of potentially health-damaging biobehavioral characteristics. In particular, the l allele could contribute, through its association with increased cardiovascular reactivity to stress, to increased risk of cardiovascular disease.

The neuropsychopharmacology of criminality and aggression

Although the idea that aggression has biological components is not a new one, recent research in genetics, neuropsychopharmacology, and neuroimaging has helped clarify the biological contributions to aggression. Studies to date have focused on serotonergic function and impulsive aggression. Reduced levels of cerebrospinal fluid (CSF) 5-hydroxyindoleacetic acid (5-HIAA) are associated with impulsive aggression. Pharmacochallenge studies have found decreased serotonergic responsiveness associated with impulsive aggression. Neuroimaging studies suggest a role for the prefrontal cortex, along with other regions of the brain, in the expression of aggression. Serotonin is not the only aspect of brain function implicated in impulsive aggression, and further work is being done on other neurotransmitters and neuropeptides.