Impulsive-Aggressive Traits, Serotonin Function, and Alcohol-Enhanced Aggression

Although alcohol consumption is involved in most acts of violence, most people do not become violent when they drink. Individuals also respond differently to alcohol on laboratory measures of aggression. The objective of this study was to determine whether individual differences in the effects of alcohol on a laboratory measure of aggression are related to specific personality traits and/or serotonin function, as measured by prolactin response to pharmacochallenge. Psychometric scales for impulsiveness, aggression, and anger, as well as a probe for suspiciousness, were administered to 10 healthy male social drinkers. Trait serotonin function was determined by citalopram challenge. The effect of alcohol on the Point Subtraction Aggression Paradigm was determined by comparing aggression scores with and without 1 g/kg alcohol. Impulsivity scores were significantly correlated with the change in aggressive responding after alcohol. Aggression, anger, and suspiciousness scores were not. Prolactin response did not predict the effect of alcohol on aggressive responding. The results suggest that trait impulsiveness may mediate the effects of alcohol on aggression in normal males.

Effects of blood lead and cadmium levels on the functioning of children with behaviour disorders in the family environment

INTRODUCTION AND OBJECTIVE

The developing brain of a child is extremely prone to damage resulting from exposure to harmful environmental factors, e.g. heavy metals. Intoxication of children's organisms with lead and cadmium affects their intellectual development. Even a relatively small amount of this metal in children's blood can lead to developmental dysfunctions. The aim of this study was to analyse the correlation between blood lead and cadmium levels in children with behaviour disorders and their functioning in the home.

MATERIAL AND METHODS

This survey-based study was conducted among 78 families with children diagnosed as having behaviour disorders. It was performed using the ADHD-Rating Scale-IV. To determine lead and cadmium levels the laboratory procedure was based on Stoppler and Brandt's method.

RESULTS

The mean blood lead level was 19.71 µg/l and the mean blood cadmium level was 0.215 µg/l. Higher blood lead levels in children correlates positively with incidences of hyperactive and impulsive behaviour in the home, as assessed by parents (p=0.048). Statistically significant effects of cadmium on children's behaviour were not noticed.

CONCLUSIONS

The effect of lead on the developing organism of a child has such behavioural consequences as attention disorders, hyperactivity and impulsive behaviour which, in turn, may interfere with children's functioning in the home. A negative effect of cadmium on the functioning of children with behaviour disorders in the home was not proved.

Low cholesterol is a risk factor for attentional impulsivity in patients with mood symptoms

This study examined the relationship between cholesterol levels and impulsivity in a large sample of patients with mood symptoms. Three hundred and one patients with mood, anxiety, and personality disorders completed a battery of psychometric scales including the Barratt Impulsiveness Scale-Version 11 (BIS-11) and the Profile of Mood States (POMS). On the same day of psychometric assessment, blood samples were analyzed for total cholesterol (TC) and high-density lipoprotein cholesterol (HDL-C). Statistical analysis controlling for the confounding effects of age, gender, diagnosis, and current mood symptoms showed that lower TC levels were associated with increased attentional impulsivity. There was a weak linear correlation between TC and attentional impulsivity across the entire range of TC levels (110-295mg/dL) but a highly significant difference between participants with TC levels lower than 165mg/dL and the rest of the sample. The current study adds to the growing body of evidence pointing to the association between serum cholesterol and mental health. Considering that attentional impulsivity is a demonstrated risk factor for suicide, patients presenting with low cholesterol and mood symptoms may warrant increased clinical attention and surveillance.

Androgen levels and anger and impulsivity measures as predictors of physical, verbal and indirect aggression in boys and girls

Previous studies indicate that androgen levels and certain psychological characteristics such as anger and impulsivity are related to the development and maintenance of aggression. Further studies are required to analyze the potential predictor role of the interaction of said factors on aggressive behavior. 90 nine-year-old children (44 boys and 46 girls) were assessed in relation to their levels of physical, verbal and indirect aggression, using a peer-rating technique. Testosterone and androstenedione levels were analyzed using an enzymoimmunoassay technique in saliva samples. Anger (state and trait) and anger control were measured using the STAXI-NA, and impulsivity was measured through the MFF-20. A General Linear Model revealed that sex was the best predictor for aggression measures, with boys scoring higher than girls in physical, verbal and indirect aggression; after sex, testosterone was found to be the best predictor (in a positive sense) of all three types of aggressive behavior studied. In addition to observing a main effect of androstenedione on physical and verbal aggression, a 'state anger*androstenedione' interaction was found to predict these types of aggression, with androstenedione acting as a moderator (inhibitor) of the effects of anger on these behaviors; also, a 'state anger*testosterone' interaction was found to predict verbal aggression. The results support the idea that, after sex, androgens constitute a biological marker to be taken into consideration in relation to individual differences in aggressive behavior. It is possible that at the age of 9, testosterone tends to increase aggression, while androstenedione tends to moderate (inhibit) the effects of anger on aggression.

High impulsivity predicting vulnerability to cocaine addiction in rats: some relationship with novelty preference but not novelty reactivity, anxiety or stress

RATIONALE

Impulsivity is a vulnerability marker for drug addiction in which other behavioural traits such as anxiety and novelty seeking ('sensation seeking') are also widely present. However, inter-relationships between impulsivity, novelty seeking and anxiety traits are poorly understood.

OBJECTIVE

The objective of this paper was to investigate the contribution of novelty seeking and anxiety traits to the expression of behavioural impulsivity in rats.

METHODS

Rats were screened on the five-choice serial reaction time task (5-CSRTT) for spontaneously high impulsivity (SHI) and low impulsivity (SLI) and subsequently tested for novelty reactivity and preference, assessed by open-field locomotor activity (OF), novelty place preference (NPP), and novel object recognition (OR). Anxiety was assessed on the elevated plus maze (EPM) both prior to and following the administration of the anxiolytic drug diazepam, and by blood corticosterone levels following forced novelty exposure. Finally, the effects of diazepam on impulsivity and visual attention were assessed in SHI and SLI rats.

RESULTS

SHI rats were significantly faster to enter an open arm on the EPM and exhibited preference for novelty in the OR and NPP tests, unlike SLI rats. However, there was no dimensional relationship between impulsivity and either novelty-seeking behaviour, anxiety levels, OF activity or novelty-induced changes in blood corticosterone levels. By contrast, diazepam (0.3-3 mg/kg), whilst not significantly increasing or decreasing impulsivity in SHI and SLI rats, did reduce the contrast in impulsivity between these two groups of animals.

CONCLUSIONS

This investigation indicates that behavioural impulsivity in rats on the 5-CSRTT, which predicts vulnerability for cocaine addiction, is distinct from anxiety, novelty reactivity and novelty-induced stress responses, and thus has relevance for the aetiology of drug addiction.

[The effect of lead and cadmium on the lipid profile and psychosocial functioning of children with developmental disorders]

INTRODUCTION

Impulsiveness, hyperactivity, and attention deficit are the most frequent neurocognitive disorders of childhood. Leaving aside the putative role of environmental and nutritive factors, the etiology and pathogenesis of these disorders remains unknown. The aim of this study was to examine the relationship between the concentration of lead, cadmium, and polyunsaturated fatty acids, and functioning of the child with developmental disorders.

MATERIAL AND METHODS

The study enrolled 78 children with behavioral disorders. The mean age of the children was eight years. Standardized tools were used: Manfred Cierpka Family Assessment Measures, Children's Health Questionnaire Parent Form-28, and ADHD-Rating Scale-IV. Concentrations of lead and cadmium in venous blood, lipid profile, and the percentage of some omega-3 and omega-6 fatty acids in the erythrocyte membrane were measured.

RESULTS

A correlation between higher levels of lead in blood of the child and impulsive and hyperactive behaviors at home was observed. Concentrations of cadmium correlated with increased incidence of attention deficit at school. Analysis of the health profile revealed that lead and cadmium correlate with some of the elements that make up the image of a properly functioning child. Reduced levels of AA and EPA positively correlated with the incidence of hyperactive and impulsive behaviors. Reduced levels of GLA impaired the acceptance of norms and values. Levels of EPA and DHA had an impact on the overall state of health of the child, as well as on physical activity and feeling of loneliness.

CONCLUSIONS

1. Developmental disorders at school and difficulties in functioning at home may be the consequence of dysfunctions caused by lead and cadmium. 2. Deficiencies of AA, GLA, DHA, and EPA fatty acids or a disorder of their metabolism affect the behavior of the child in the form of hyperactivity, impulsiveness, and attention deficit.

High neuroticism and low conscientiousness are associated with interleukin-6

BACKGROUND

High Neuroticism and low Conscientiousness are frequently implicated in health-risk behaviors, such as smoking and overeating, as well as health outcomes, including mortality. Their associations with physiological markers of morbidity and mortality, such as inflammation, are less well documented. The present research examines the association between the five major dimensions of personality and interleukin-6 (IL-6), a pro-inflammatory cytokine often elevated in patients with chronic morbidity and frailty.

METHOD

A population-based sample (n=4923) from four towns in Sardinia, Italy, had their levels of IL-6 measured and completed a comprehensive personality questionnaire, the NEO-PI-R. Analyses controlled for factors known to have an effect on IL-6: age; sex; smoking; weight; aspirin use; disease burden.

RESULTS

High Neuroticism and low Conscientiousness were both associated with higher levels of IL-6. The findings remained significant after controlling for the relevant covariates. Similar results were found for C-reactive protein, a related marker of chronic inflammation. Further, smoking and weight partially mediated the association between impulsivity-related traits and higher IL-6 levels. Finally, logistic regressions revealed that participants either in the top 10% of the distribution of Neuroticism or the bottom 10% of conscientiousness had an approximately 40% greater risk of exceeding clinically relevant thresholds of IL-6.

CONCLUSIONS

Consistent with the literature on personality and self-reported health, individuals high on Neuroticism or low on Conscientiousness show elevated levels of this inflammatory cytokine. Identifying critical medical biomarkers associated with personality may help to elucidate the physiological mechanisms responsible for the observed connections between personality traits and physical health.

Speed of exploration and risk-taking behavior are linked to corticosterone titres in zebra finches

The existence of consistent individual differences in behavioral strategies ("personalities" or coping styles) has been reported in several animal species. Recent work in great tits has shown that such traits are heritable and exhibit significant genetic variation. Free-living birds respond to environmental stresses by up-regulating corticosterone production. Behavior during mild stress can occur in accordance to two types of coping styles, i.e. active and passive. Using artificially selected lines of zebra finches that vary in the amount of corticosterone produced in response to a manual restraint stressor we ran three "personality" experiments. We show that birds in the different corticosterone lines differ in their exploratory and risk-taking behaviors. There was an increase in exploratory behavior as corticosterone titre increased but only in the low corticosterone line. Birds in high corticosterone line showed greater risk-taking behavior than birds in the other lines. Thus, in general, higher levels of circulating corticosterone following a mild stress result in greater exploratory behavior and greater risk taking. This study shows that lines of animals selected for endocrine hormonal responses differ in their "coping" styles or "personalities".

Serum omega-3 fatty acids are associated with variation in mood, personality and behavior in hypercholesterolemic community volunteers

Low dietary intake of omega-3 polyunsaturated fatty acids has been linked to several features of psychiatric symptomatology, including depression, disorders of impulse control, and hostility. Preliminary intervention trials of omega-3 fatty acid supplementation for clinical depression and other disorders have reported benefit. However, few studies have investigated the relationships between these fatty acids and normative variability in mood, behavior and personality. Participants were 105 hypercholesterolemic, but otherwise healthy, non-smoking adults. Fasting serum alpha-linolenic (alpha-LNA), eicosapentaenoic (EPA) and docosahexaenoic acid (DHA) were assayed with gas chromatography. Participants completed the Beck Depression Inventory (BDI), the NEO Five Factor Personality Inventory (NEO-FFI) and the Barratt Impulsiveness Scale (BIS). In multivariate analyses, higher levels of the long chain omega-3 PUFAs, EPA and DHA, were associated with significantly reduced odds of scoring >or=10 on the BDI. Similarly, DHA and EPA covaried inversely with NEO-Neuroticism scores, whereas DHA was positively associated with NEO-Agreeableness. On the BIS, DHA was inversely related to cognitive impulsivity and alpha-LNA was inversely related to motor and total impulsivity. These findings suggest that omega-3 fatty acid status is associated with variability in affect regulation, personality and impulse control.

Cognition and motor control as a function of Delta9-THC concentration in serum and oral fluid: limits of impairment

Cannabis use has been associated with increased risk of becoming involved in traffic accidents; however, the relation between THC concentration and driver impairment is relatively obscure. The present study was designed to define performance impairment as a function of THC in serum and oral fluid in order to provide a scientific framework to the development of per se limits for driving under the influence of cannabis. Twenty recreational users of cannabis participated in a double-blind, placebo-controlled, three-way cross-over study. Subjects were administered single doses of 0, 250 and 500 microg/kg THC by smoking. Performance tests measuring skills related to driving were conducted at regular intervals between 15 min and 6h post smoking and included measures of perceptual-motor control (Critical tracking task), motor impulsivity (Stop signal task) and cognitive function (Tower of London). Blood and oral fluid were collected throughout testing. Results showed a strong and linear relation between THC in serum and oral fluid. Linear relations between magnitude of performance impairment and THC in oral fluid and serum, however, were low. A more promising way to define threshold levels of impairment was found by comparing the proportion of observations showing impairment or no impairment as a function of THC concentration. The proportion of observations showing impairment progressively increased as a function of serum THC in every task. Binomial tests showed an initial and significant shift toward impairment in the Critical tracking task for serum THC concentrations between 2 and 5 ng/ml. At concentrations between 5 and 10 ng/ml approximately 75-90% of the observations were indicative of significant impairment in every performance test. At THC concentrations >30 ng/ml the proportion of observations indicative of significant impairment increased to a full 100% in every performance tests. It is concluded that serum THC concentrations between 2 and 5 ng/ml establish the lower and upper range of a THC limit for impairment.

Blunted hormone responses to Ipsapirone are associated with trait impulsivity in personality disorder patients

Impulsive aggression is associated with central serotonergic dysfunction. Animal models particularly implicate the 5-HT(1A) receptor in this behavior. We tested the hypothesis that central 5-HT(1A) receptor function is impaired in impulsive aggressive personality disorder patients. A total of 52 individuals with DSM-III-R personality disorders, all medically healthy adult outpatients without concurrent psychiatric medication treatment, underwent serial plasma cortisol, prolactin, and temperature measurements before and after ipsapirone 20 mg oral administration. Subjects completed self-report measures of impulsivity, hostility, depression and anxiety, and childhood maltreatment. Stepwise regression analysis revealed impulsivity alone among symptom measures to be associated with significantly decreased peak cortisol and prolactin responses. Diagnoses of borderline personality disorder (BPD) and intermittent explosive disorder-revised (IED-R) were associated with significantly increased and decreased cortisol responses, respectively. However, post hoc analyses indicated that impulsivity was significantly negatively correlated with cortisol responses in the BPD group, and may mediate the association of both BPD and IED-R with altered cortisol responses. Temperature response was associated with neither diagnostic nor symptom measures. Neither diagnostic nor dimensional measures of depression or anxiety, nor severity of childhood maltreatment, were significantly associated with cortisol, prolactin, or temperature responses. Impulsivity is related to impaired function at (or downstream to) postsynaptic 5-HT(1A) receptors, and this relationship may be partly responsible for the association of impaired serotonergic function with diagnoses such as BPD and IED-R. In addition, D(2) receptor dysfunction may play a role in impulsivity, whereas 5-HT(1A) cell-body autoreceptor function may be spared in these disorders.

Association of the promoter polymorphism -1438G/A of the 5-HT2A receptor gene with behavioral impulsiveness and serotonin function in women with bulimia nervosa

Separate lines of research suggest that the functional alterations in the serotonin (5-HT) 2A receptor are associated with 5-HT tone, behavioral impulsiveness, and bulimia nervosa (BN). We explored the effect of allelic variations within the 5-HT2A receptor gene promoter polymorphism -1438G/A on trait impulsiveness and serotonin function in women with BN. Participants included women with BN having the A allele (i.e., AA homozygotes and AG heterozygotes, BNA+, N = 21); women with BN but without the A allele (i.e., GG homozygotes, BNGG, N = 12), and normal eater control women having the A allele (NEA+, N = 19) or without the A allele (NEGG; N = 9). The women were assessed for psychopathological tendencies and eating disorder symptoms, and provided blood samples for measurement of serial prolactin responses following oral administration of the post-synaptic partial 5-HT agonist meta-chlorophenylpiperazine (m-CPP). The BNGG group had higher scores than the other groups on self-report measures of non-planning and overall impulsiveness and had blunted prolactin response following m-CPP. The bulimic groups did not differ from each other on current eating symptoms or on frequencies of other Axis I mental disorders. Findings indicate that women with BN who are GG homozygotes on the -1438G/A promoter polymorphism are characterized by increased impulsiveness and lower sensitivity to post-synaptic serotonin activation. These findings implicate the GG genotype in the co-aggregation of impulsive behaviors and alterations of post-synaptic 5-HT functioning in women with BN.

Relationship between platelet serotonin uptake sites and measures of impulsivity, aggression, and craving among African-American cocaine abusers

We investigated whether platelet-tritiated paroxetine binding, a measure of serotonin uptake sites, and behavioral measures of impulsivity, aggression, and craving differed between cocaine-dependent subjects and controls and whether paroxetine binding was related to these behavioral measures. One hundred and five African-American cocaine-dependent outpatients and 44 African-American controls were studied. Tritiated paroxetine binding sites on platelets were assayed, and standardized assessments of impulsivity, aggression, and craving were performed. The Bmax values of paroxetine binding were significantly reduced among cocaine patients compared to controls. Cocaine patients showed significantly higher scores on certain measures of sensation seeking, impulsivity, and aggression as compared to controls. Furthermore, paroxetine binding showed a significant negative correlation with most measures of sensation seeking, impulsivity, and aggression--though not craving--among cocaine patients. Our findings indicate that densities of serotonin uptake sites may be reduced among cocaine abusers and related to impulsive-aggressive behavioral dimensions.

Physiological correlates of aggression and impulsivity in free-ranging female primates

We examined the relations among cerebrospinal fluid (CSF) monoamine metabolite concentrations, plasma hormone concentrations, aggression, and impulsive risk-taking behavior in a free-ranging population of female rhesus macaques. We selected 44 juvenile female rhesus macaques as subjects from a population of approximately 3000 macaques that inhabit a 475-acre Sea Island. We obtained CSF and blood samples, and recorded behavioral observations over a subsequent 18-month period. Our results indicate an inverse correlation between CSF concentrations of the major serotonin metabolite 5-hydroxyindoleacetic acid (5-HIAA), and the frequency of low-intensity restrained aggression typically associated with matrilineal defense of social status. In contrast, previous research with males has shown an inverse correlation between CSF 5-HIAA concentrations and levels of violent unstrained aggression typically associated with traumatic injury and death. We also noted a negative correlation between plasma concentrations of the stress hormone cortisol and the frequency of low-intensity aggressive acts, a finding not reported in our previous studies with males. Further examination revealed a negative correlation between CSF 5-HIAA concentrations and the rate of long dangerous leaps through the forest canopy, suggesting that the relation between low serotonergic functioning and impulsivity may generalize to both female and male primates. These results indicate that females with low CSF 5-HIAA concentrations, like their male counterparts, are at increased risk for impulsive temperament, but that unlike males, females may be buffered from this risk through intersexual differences in life history patterns and social affiliation.

The role of cortisol suppression on craving for and satisfaction from nicotine in high and low impulsive subjects

The rewarding properties of drug self-administration have been shown to depend on mesolimbic dopamine release but also on the availability of corticosterone, as shown in rats. Since this became particularly evident when tested in rat strains bred for high (HR) and low (LR) reactivity to novel stimuli, the role of cortisol and personality in drug craving was investigated in 60 male nicotine-deprived smokers divided according to questionnaire scores into high and low impulsives, a dimension considered to represent HR/LR rats. They either received the peripheral cortisol blocker metyrapone (MET) or the centrally blocking substance dexamethasone (DEX) or placebo (n=20 each) and were then allowed to smoke. MET more than DEX reduced craving for cigarettes during deprivation. This was only observed in low impulsives while high impulsives developed low craving unmodified by blockade of cortisol. Satisfaction from smoking was less achieved with DEX than with MET and not modified by impulsivity. Differences between MET and DEX in influencing craving during deprivation and satisfaction from smoking were discussed on the basis of different glucocorticoid receptors. The mineralocorticoid receptor (MR) seems to be the 'turn on switch' and the glucocorticoid receptor (GR) the 'turn off switch' in mediating the rewarding properties of dopamine in drug self-administration.

Anger, and plasma lipid, lipoprotein, and glucose levels in healthy women: the mediating role of physical fitness

The association between anger, lipid profiles, and glucose levels were examined in this study of 103 middle aged, healthy women. A principal component factor analysis of Spielberger's Trait Anger and Anger Expression scales yielded two anger factors: Impulsive Anger-Out and Neurotic Anger. Impulsive anger-out significantly predicted a negative lipid profile (high total serum cholesterol (TSC), low density lipoproteins (LDL), TSC/HDL (high density lipids), and triglyceride levels) and heightened glucose levels, but only in physically unfit women. Neurotic anger did not predict lipid and glucose levels. These findings parallel previous findings regarding the two anger dimensions and CHD, with only impulsive anger-out predicting CHD. Furthermore, our findings indicate that the protective effect of physical fitness, previously documented for men, also occurs in women.

Plasma testosterone and pathological gambling

The authors studied plasma testosterone levels and psychological characteristics of male pathological gamblers. Twenty-nine male pathological gamblers and a group of healthy volunteers matched for age and gender were compared on levels of plasma testosterone and scores on the Eysenck Personality Questionnaire (EPQ) and the Psychopathic Deviance scale of the Minnesota Multiphasic Personality Inventory (MMPI). Plasma testosterone levels were similar in the pathological gambling and comparison group (476.06 ng/100 ml vs. 560.71 ng/100 ml). Patients had higher scores on the Neuroticism subscales of the EPQ (13.83 vs. 10.83) and the Psychopathic Deviance scale of the MMPI (27.03 vs. 21.03), but not on any of the other subscales of the EPQ. Testosterone levels did not correlate with the psychological ratings. Testosterone levels are probably not related to impulsivity in pathological gambling.

Biological markers for suicidal behavior in alcohol dependence

Alcohol-dependent populations have a high lifetime suicide rate (between 7 and 15%, relative risk = 7), and alcoholism is one of the two psychiatric disorders most frequently found in suicidal cases (between 15 and 25%). Biological factors that would detect patients at risk could thus be of value. Carbohydrate-deficient transferrin, monoamine oxidase B, soluble interleukin-2 receptor and cholesterol have been proposed as markers of suicidal risk in alcohol-dependent patients, although nonspecific and with low predictive value. On the other hand, there is large and convergent data stressing the importance of serotonin dysregulation as increasing the risk for aggressive behaviour toward the self, although it is not clear whether serotonin is involved through the altered behavior inhibition system, enhancement of anxiety and depression, or association with specific subtypes of alcohol-dependence, such as early-onset type II alcoholism. Considering the complex but significant impact of alcohol on serotonin metabolism and turnover, it is likely that serotonin mediates a large part of the proneness of ethanol to commit impulsive-aggressive behavior.

Differential abnormalities in plasma 5-HIAA and platelet serotonin concentrations in violent suicide attempters: relationships with impulsivity and depression

Brain serotonergic systems may participate in the regulation of mood, impulsivity and aggressive behavior. Because some monoaminergic mechanisms seem to be similar in the central nervous system and peripheral tissues, we tested whether serotonergic or dopaminergic biochemical parameters in peripheral venous blood are related or not to violent suicide behavior.We simultaneously studied plasma serotonin (5-HT), 5-hydroxyindoleacetic acid (5-HIAA), homovanillic acid (HVA) and platelet 5-HT content in patients within 3 days following a violent suicide attempt and in matched healthy controls. We examined their relationship with depression and impulsivity. Twenty seven drug-free suicide attempters and controls were included. Plasma 5-HIAA and platelet 5-HT concentrations were lower in suicide attempters than in controls. Fifteen patients were classified as impulsive (I), including all patients suffering from personality disorder and alcohol abuse, and 12 as non impulsive (NI), mostly melancholics. MADRS scores were similar in both I and NI suicide attempters. When controlling for age, plasma 5-HIAA was lower in I than in NI suicide attempters or controls; these findings are similar to those we observed recently with CSF 5-HIAA in I and NI violent suicide attempters. Contrarily, platelet 5-HT levels were lower in NI than in I patients or controls. Plasma HVA was not associated with suicide behavior. Plasma 5-HIAA concentration was inversely associated with the degree of impulsivity and platelet 5-HT with the intensity of depression. This study indicates that each peripheral serotonergic index is specifically related to a distinct clinical feature and shows differential alteration according to the impulsivity group. In I and NI drug-free violent suicide attempters an inverse figure between plasma 5-HIAA and platelet 5-HT data was observed indicating a non parallelism between these two peripheral variables. Further prospective studies are needed to investigate whether these peripheral serotonergic parameters may be used as helpful early predictors of violent suicide behavior.

Endogenous plasma testosterone levels and commission errors in women: A preliminary report

A correlation between elevated testosterone and aggressive behavior has been demonstrated in animals and to a lesser degree in humans, primarily in the context of dominance. Some aggression, namely non-premeditated aggression, is characterized by impaired impulse control. Real-world aggressive histories and self-reported impulsivity have correlated with commission errors (failures to withhold responses to nontarget stimuli) in versions of the continuous performance test (CPT). To begin exploring whether testosterone may play a role in aggression due more to a direct relationship with impaired impulse control, we related plasma total testosterone concentrations of 27 psychiatrically healthy women to commission errors in two variants of the CPT - with and without interstimulus distracters. Controlling for age and IQ, testosterone did not relate to rates of correct detections in either task, but correlated positively with commission errors in the distracter CPT variant. In light of the fact previous studies find commission errors on the CPT are associated with impulsivity, the results of this study support a positive relationship between testosterone and impulsivity.

Serum cholesterol, suicidal behavior and impulsivity in cocaine-dependent patients

Relationships between serum cholesterol and suicidal behavior have been reported. As suicidal behavior is common in cocaine dependence, we looked for a relationship with serum cholesterol. To do this, we compared 57 cocaine-dependent patients who had attempted suicide with 111 cocaine-dependent patients who had never attempted suicide for their admission total serum cholesterol levels. We found that there were no significant differences between cocaine-dependent patients who had or had not attempted suicide in their total serum cholesterol levels. Also, there were no significant correlations between total serum cholesterol levels and scores on the Barratt Impulsivity Scale. Thus, admission total serum cholesterol does not appear to be clinically useful in the assessment of suicidal behavior in cocaine-dependent patients.

Serotonin, impulsivity, and alcohol use disorders in the older adolescent: a psychobiological study

BACKGROUND

Alcohol use disorders (AUDs) among adolescents are associated with a high prevalence of conduct disorder (CD), much as type II alcoholism in adults is associated with impulsive-aggressive behavior and antisocial personality traits. Adults with impulsive personality disorders and AUD demonstrate diminished central serotonergic responsiveness to serotonergic agonists. Dysregulation of central serotonergic function may contribute to a vulnerability to impulsive-aggressive behavior, CD, and AUD. We studied older adolescents, both male and female, to examine the relationships between sex, dispositional impulsivity, aggressivity, CD, and responsiveness to serotonergic challenge with d,l fenfluramine (FEN) early in the development of AUD.

METHODS

Thirty-six adolescents between the ages of 16 and 21 years were assessed for DSM-IV AUD and other Axis I disorders by using the Psychoactive Substance Use Disorders section of the Structured Clinical Interview for DSM III-R, the Schedule for Affective Disorders and Schizophrenia for School-Age Children-Present and Lifetime Version, and CD interviews. Impulsivity and aggressivity were assessed by the Barratt Impulsiveness Scale, Lifetime History of Aggression, Buss-Durkee Hostility Inventory, Eysenck Impulsiveness Questionnaire, Youth Self Report, and Multidimensional Personality Questionnaires. FEN was administered as 0.8 mg/kg to a maximum of 60 mg, and blood was sampled at fixed intervals for prolactin, cortisol, fenfluramine, and norfenfluramine levels.

RESULTS

Eighteen adolescents (12 male, 6 female) with AUD scored significantly higher on all measures of impulsivity and aggressivity compared with 18 healthy controls (12 male, 6 female). There were no significant differences between groups in peak prolactin or cortisol responses (minus baseline), or area-under-the-curve determinations (AUC); however, 9 subjects with AUD and comorbid CD had significantly elevated cortisol AUC levels compared with subjects with AUD and no CD or with normal controls. In the total sample, cortisol AUC was associated positively with measures of aggression.

CONCLUSIONS

Adolescents with early-onset AUD are characterized by impulsivity and aggressivity compared with healthy peers but do not demonstrate the diminished prolactin or cortisol responses to FEN characteristic of adult alcoholics with impulsive-aggression.

Differences in whole blood serotonin levels based on a typology of parasuicide

Suicidal behavior has to be considered as a multifactorial phenomenon, which can be analyzed in a classifying-phenomenological manner. We have examined the relation of parasuicide typology to whole blood concentrations of serotonin, HVA, and tryptophan in 58 patients classified into 4 groups of parasuicide typology compared to 22 nonsuicidal depressed patients and 20 healthy subjects. Suicidal patients classified as impetuous, desperate and ambivalent types had significantly reduced whole blood 5-HT levels in comparison with the appealing type as well as nonsuicidal subjects. No differences were detected in the HVA content, but whole blood tryptophan concentrations were significantly reduced in impetuous suicidal patients and depressed patients compared to healthy subjects. This study provides evidence for reduced whole blood serotonin content based on different types of parasuicide.

Upregulation of the platelet Serotonin2A receptor and low blood serotonin in suicidal psychiatric patients

Suicidality has been found to be associated with low pre- and postsynaptic serotonin functioning. The purpose of this study was to examine whether in acutely suicidal psychiatric inpatients, the blood serotonin concentration was related to the underlying psychiatric disorder and whether it was associated with changes in the affinity (dissociation constant, KD) or in the maximal binding capacity (Bmax) of the platelet serotonin2A receptor. We therefore determined the blood serotonin concentrations and the platelet serotonin2A receptor activities of 45 suicidal psychiatric patients and 20 healthy subjects. We found that the blood serotonin concentrations were significantly lower in suicidal patients compared to healthy subjects. In all diagnostic categories (affective disorder, schizophrenia and adjustment disorder) we noted a significantly higher maximal binding capacity of the platelet serotonin2A receptor. These findings support the notion that a reduction in the availability of serotonin and an upregulation of the serotonin2A receptors in psychiatric patients are associated with a loss of control over suicidal impulses.

Behavioral disinhibition induced by tryptophan depletion in nonalcoholic young men with multigenerational family histories of paternal alcoholism

OBJECTIVE

A deficit in serotonergic neurotransmission has been linked to impulsive behavior, as well as to disorders characterized by disinhibition. The present study tested the hypothesis that young men at high risk for alcoholism demonstrate greater behavioral disinhibition after acute dietary depletion of tryptophan, the amino acid precursor of serotonin.

METHOD

A double-blind, placebo-comparison, between-subjects study design was used. Nonalcoholic young men with a multigenerational paternal family history of alcoholism (N = 13) or with no family history of alcoholism (N = 15) in two previous generations were administered mixtures of tryptophan-deficient amino acid to achieve plasma tryptophan depletion. Comparison subjects with a multigenerational paternal family history of alcoholism (N = 1) and comparison subjects with no family history of alcoholism (N = 18) were given a balanced mixture. Five hours after this, all were tested on a modified Taylor task and a go/ no-go task measuring aggressive response and disinhibition, respectively.

RESULTS

Plasma tryptophan levels were reduced by 89% in both groups. Tryptophan depletion had no effect on aggressive response. In contrast, tryptophan-depleted individuals with a family history of alcoholism made more commission errors (responses to stimuli associated with punishment or loss of reward) than did tryptophan-depleted individuals with no family history of alcoholism and those receiving the balanced (comparison) mixture of amino acid in either group.

CONCLUSIONS

Low serotonin levels may be implicated in the high disinhibition or impulsivity observed in some individuals with a genetic vulnerability to alcohol abuse or dependence.

Serum cholesterol, suicidal tendencies, impulsivity, aggression, and depression in adolescent psychiatric inpatients

BACKGROUND

This study was undertaken to examine the relationship between serum cholesterol levels and suicidal behaviors in adolescent psychiatric inpatients. Any association between serum cholesterol and measures of suicidal behavior, impulsivity, aggression, anxiety, and depression was also examined.

METHODS

Consecutive admissions (n = 152) to an adolescent psychiatric inpatient unit were assessed using measures of suicidal behavior, violence, impulsivity, and depression. Serum cholesterol was compared between those admitted for reasons of suicidal tendencies and those for other reasons. Correlation between serum cholesterol and measures of suicidal behavior, violence, impulsivity, and depression were examined.

RESULTS

Serum cholesterol levels were significantly higher in adolescent patients who were currently suicidal than in nonsuicidal adolescents. Within the suicidal group, but not in the total inpatient group, serum cholesterol correlated negatively with the degree of suicidal behavior. No correlation between serum cholesterol levels and depression, violence, and impulsivity were detected. No significant differences were found in serum cholesterol levels between diagnoses or between suicidal and nonsuicidal patients within each diagnostic group.

CONCLUSIONS

The association between cholesterol and suicidal tendencies remains complex and may depend on several variables within the population studied. Its usefulness as a biologic risk factor in clinical samples remains to be determined.

CSF 5-HIAA levels are lower in impulsive as compared to nonimpulsive violent suicide attempters and control subjects

BACKGROUND

We studied CSF 5-HIAA and HVA concentrations in violent suicide attempters and examined their relationship with depression, anxiety, and impulsivity.

METHODS

CSF 5-HIAA and HVA concentrations were determined very shortly after hospital admission and compared to those of a matched control population. Clinical evaluation was performed concomitantly; the level impulsivity was evaluated by the Impulsivity Rating Scale (IRS).

RESULTS

Twenty-three patients and 23 control subjects were included. According to the IRS, 14 patients were classified as impulsive, including all patients suffering from personality disorders, and 9 as nonimpulsive, with a main DSM-IIIR diagnosis of melancholia. CSF 5-HIAA concentrations in the suicide group were significantly lower than in control subjects. This difference was entirely due to the impulsive suicide attempters. There was an inverse correlation between the IRS score and CSF 5-HIAA (r = -.47, p = .02) and only a trend for HVA (r = -.41, p = .078) levels in the suicide group.

CONCLUSIONS

This study of a group of violent suicide attempters distinguished a subgroup of patients diagnosed with personality disorder with high impulsivity scores and a subgroup of patients with the main diagnosis of severe depression. CSF 5-HIAA was significantly lower in impulsive violent attempters than in nonimpulsive violent attempters, therefore desintangling violence from impulsivity and linking this biologic abnormality to impulsivity.

Serum cholesterol and impulsivity in personality disorders

Decreased serum cholesterol has been associated with impulsive aggressive behaviors. This study was designed to explore the relationship between serum cholesterol levels and measures of impulsive aggression in personality disordered patients. Forty-two personality disordered patients (14 borderline personality disorder, 28 other personality disorders) were included. Fasting serum cholesterol was measured by standard enzymatic assay. An ANOVA was performed with factors of gender and diagnosis, looking at two-way interactions between the factors and serum cholesterol. Patients with borderline personality disorder were found to have significantly lower serum cholesterol than non-borderline personality disorders. A significant interaction effect was also seen between gender and diagnosis with the male patients having lower cholesterol levels. This study suggests there may be a relationship between borderline personality disorder and low serum cholesterol.

Correlations between plasma-neuropeptides and temperament dimensions differ between suicidal patients and healthy controls

BACKGROUND

Decreased plasma levels of plasma-neuropeptide Y (NPY) and plasma-corticotropin releasing hormone (CRH), and increased levels of plasma delta-sleep inducing peptide (DSIP) in suicide attempters with mood disorders have previously been observed. This study was performed in order to further understand the clinical relevance of these findings.

METHODS

Examination of correlates between temperament dimensions (Karolinska Scales of Personality (KSP), the Eysenck Personality Questionnaire together with the IVE- impulsiveness scale (EPQI), and the Marke-Nyman Temperament (MNT)) and NPY, CRH and DSIP and serum-cortisol in the dexamethasone suppression test (DST) in 38 suicidal patients and matched controls.

RESULTS

NPY correlated significantly and positively with psychasthenia, irritability, and stability and significantly and negatively with validity in patients, but significantly and negatively with muscular tension, psychasthenia, verbal aggression and irritability in controls. DSIP correlated significantly and positively with impulsiveness (EPQI) in controls. CRH correlated negatively with lie in controls. Cortisol correlated significantly and positively with validity, extraversion and verbal aggression and significantly and negatively with inhibition of aggression in controls.

CONCLUSION

NPY may be related to stress tolerance. DSIP seems to be associated with impulsivity/antisocial traits.

LIMITATIONS

Non-suicidal patients were not included in the examination.

CLINICAL RELEVANCE

The state of depression or stress seems to influence the correlations studied.

Fluoxetine and impulsive aggressive behavior in personality-disordered subjects

BACKGROUND

Evidence of an inverse relationship between central serotonergic (serotonin [5-hydroxytryptamine]) system function and impulsive aggressive behavior has been accumulating for more than 2 decades. If so, pharmacological enhancement of serotonin activity should be expected to reduce impulsive aggressive behavior in subjects in whom this behavior is prominent.

METHODS

A double-blind, placebo-controlled trial of the selective serotonin-uptake inhibitor fluoxetine hydrochloride was conducted in 40 nonmajor-depressed, nonbipolar or schizophrenic, DSM-III-R personality-disordered individuals with current histories of impulsive aggressive behavior and irritability. Measures included the Overt Aggression Scale-Modified for Outpatients, Clinical Global Impression Rating of Improvement, and several secondary measures of aggression, depression, and anxiety.

RESULTS

Fluoxetine, but not placebo, treatment resulted in a sustained reduction in scores on the Irritability and Aggression subscales of the Overt Aggression Scale-Modified for Outpatients that was first apparent during months 2 and 3 of treatment, respectively. Fluoxetine was superior to placebo in the proportion of "responders" on the Clinical Global Impression Rating of Improvement: first at the end of month 1, and then finally demonstrating a sustained drug-placebo difference from the end of month 2 through the end of month 3 of treatment. These results were not influenced by secondary measures of depression, anxiety, or alcohol use.

CONCLUSION

Fluoxetine treatment has an antiaggressive effect on impulsive aggressive individuals with DSM-III-R personality disorder.

Borderline personality, impulsiveness, and platelet monoamine measures in bulimia nervosa and recurrent suicidal behavior

This study examined the relationship between borderline and impulsive personality traits on the one hand, and monoamine function on the other in 15 women with bulimia nervosa and 15 women with recurrent suicidal behavior. Platelet serotonin (5-HT) and platelet monoamine oxidase (MAO) activity were used as peripheral measures of monoaminergic function. All suicide attempters were diagnosed as having a borderline personality disorder, whereas this diagnosis was less frequent in bulimics. Bulimics with borderline comorbidity resembled recurrent suicide attempters with borderline personality disorder more closely in both psychological (anger, impulsive behavior) and biochemical characteristics (platelet 5-HT) than bulimics without borderline personality disorder. Platelet 5-HT was higher in patients with borderline personality than in normal female controls and was positively correlated with the disposition to experience anger. Impulsive personality traits were consistently negatively correlated with platelet MAO activity. Our findings support the subdivision of bulimics according to the presence of borderline or "multi-impulsive" personality disorder.

Impulsive aggression in personality disorder correlates with tritiated paroxetine binding in the platelet

BACKGROUND

To examine the relationship between binding parameters of the platelet central serotonergic (5-HT) transporter and measures of aggression and impulsivity in adult human subjects.

METHODS

Maximal number of platelet tritiated paroxetine binding sites (Bmax) and dissociation constant (Kd) values were measured in patients with personality disorder (n = 24) and healthy volunteers (n = 12). Measures of aggression and impulsivity included the total score and aggression subscale of the Life History of Aggression, the Motor Aggression factor and the assault subscale of the Buss-Durkee Hostility Inventory, and the total score and motor impulsivity subscale of the Barratt Impulsiveness Scale.

RESULTS

The Bmax, but not Kd, values of platelet tritiated paroxetine binding was inversely correlated with the Life History of Aggression total score and aggression score and with the Buss-Durkee Hostility Inventory assault score in patients with personality disorder but not in healthy volunteer subjects. This relationship was independent of influences of factors related to depression, global function, or history of alcoholism or drug abuse.

CONCLUSIONS

Reduced numbers of platelet 5-HT transporter sites may covary with life history of aggressive behavior in patients with personality disorder. This may represent another abnormality in 5-HT function in individuals with personality disorder and aggressive behavior.

High levels of free testosterone in women with bulimia nervosa

Women with normal-weight bulimia nervosa (n = 11) displayed significantly higher serum levels of free testosterone than age-matched controls (6.0 +/- 0.7 vs 3.9 +/- 0.8 pmol/l; P = 0.03). The possible importance of androgens, in women, for the pathophysiology of conditions characterized by an impairment in impulse control is being discussed.

Is prolactin related to activity and emotional reactivity in rats?

Recent studies have shown different relationships between hormones and personality in humans, including a relationship between prolactin levels and impulsivity. The aim of the present work was to study the relationships between basal levels of prolactin and some measures of activity and emotional reactivity in rats. One of the most consistent results showed a negative correlation between basal prolactin levels and activity. This finding is in line with the serotonergic theories of impulsive behavior and with the effects of dopamine upon activity.

Tryptophanemia and tyrosinemia in adolescents with impulsive behavior

Tryptophan (TRP) and tyrosine (TYR), respectively the circulating precursors of the central serotonergic (5-HT) and catecholamine systems, were measured in eight adolescents with impulsive behavior regardless of the exact type of disorder. The 6 week study period included weekly blood sampling and clinical evaluation. The ratios of TRP and TYR to large neutral amino acids (LNAA), which indicate the availability for the synthesis of neurotransmitters, were calculated. Comparison of results with eight hospitalized controls of the same age (12.5 to 18 years) revealed lower total TRP levels in four adolescent patients, a lower TRP/LNAA ratio in three adolescents, and a lower free TRP concentration in six adolescents with discretely enhanced albuminemia. A slight increase in TYR and the TYR/LNAA ratio was noted in nearly all of the adolescent patients. Despite the heterogeneity of individual biological results, the impulsive behavior subjects in this study seemed to present abnormalities in neurotransmitter precursors.

Neurobiology of impulsivity and the impulse control disorders

Clinical impulsivity has been characterized in both dimensional and categorical terms. Whereas DSM-III-R classifies personality disorders characterized by impulsivity and impulse control disorders as discrete entities, impulsive symptoms and traits can also be conceived in terms of an underlying behavioral dimension. The authors review research on impulsivity and the impulse control disorders from a biological perspective. In particular, they critically review evidence that the serotonin neurotransmitter system mediates symptoms and traits of impulsive personality disorders and the impulse control disorders.

Growth hormone responses to intravenous clonidine challenge correlate with behavioral irritability in psychiatric patients and healthy volunteers

To explore the relationship between central noradrenergic receptor responsivity and indices of impulsive aggression, growth hormone responses to infusions with the alpha 2-adrenergic receptor agonist clonidine (GH[CLON]) and responses on the Buss-Durkee Hostility Inventory (BDHI) were examined in healthy male volunteers and male patients with major affective or personality disorder. GH[CLON] values were found to correlate significantly with the BDHI "Irritability" subscale in all subjects, but especially in healthy volunteer and personality disorder patients. GH[CLON] values did not correlate with the BDHI "Assault" subscale. These results suggest a role for central alpha 2-adrenergic receptor responsivity in the personality trait characterized by behavioral irritability, but not overt assaultiveness, in humans.

Serum cholesterol and aggressive behavior in psychiatrically hospitalized children

The relationship between serum cholesterol and a number of measures of impulsiveness and aggression was examined in 38 prepubertal, psychiatrically hospitalized children. Although care was taken to use reports and direct observations of both variables within 2 weeks of admission and 8 weeks later, no consistent relationship was found. The reasons for these findings are discussed.

Platelet imipramine binding in children and adolescents with impulsive behavior

The serotonergic system has been implicated in the regulation of impulsive aggressive behavior either toward oneself or others. Imipramine binding sites were measured in the platelets of 23 impulsive aggressive children. Subjects ratings of total behavior, externalizing behavior, hostility, and aggression, as measured by the Child Behavior Checklist, were inversely correlated with the platelet imipramine binding. These findings are consistent with previous studies that suggest that decreased serotonergic activity is associated with impulsive aggressive behavior.

Psychobiological concomitants of history of suicide attempts among violent offenders and impulsive fire setters

Psychobiological data on 58 violent offenders and impulsive fire setters were analyzed for associations with history of suicide attempts. Subjects with a history of suicide attempts serious enough to require an admission to a medical facility had significantly lower mean cerebrospinal fluid 5-hydroxyindoleacetic acid and 3-methoxy-4-hydroxyphenylglycol concentrations than subjects who had not made such attempts. A linear discriminant function analysis based on psychobiological and behavioral variables correctly classified 79% of the subjects according to the suicide attempt history positive and negative outcomes.

Relationship of psychobiological variables to recidivism in violent offenders and impulsive fire setters. A follow-up study

Fifty-eight violent offenders and impulsive fire setters were followed up for an average of 3 years after release from prison. Recidivists who committed a new violent offense or arson had significantly lower cerebrospinal fluid 5-hydroxyindoleacetic acid and homovanillic acid concentrations and blood glucose nadirs after oral glucose challenge than did nonrecidivists. A discriminant analysis, based on the blood glucose nadir and cerebrospinal fluid 5-hydroxyindoleacetic acid concentration, correctly classified 84.2% of the subjects.

Impulsivity, aggression, and neuroendocrine responses to serotonergic stimulation in substance abusers

Alterations in the activity of central serotonergic systems have been implicated in impulsive and aggressive behavior. We examined the neuroendocrine and psychological responses of 24 substance users with differing levels of aggressiveness and impulsivity to the oral administration of an indirect serotonin agonist fenfluramine (60 mg) or placebo given in a double-blind crossover design. All subjects were volunteers on a closed research ward and were abstinent from drugs for a minimum of 5 days. Baseline plasma prolactin (PRL) levels were greater in the groups with higher levels of self-reported aggressiveness and impulsivity. When adjusted for the baseline, PRL and cortisol responses 180 min after fenfluramine administration were significantly elevated in subjects with higher levels of aggressiveness and impulsivity. Peak cortisol levels were correlated with impulsivity. PRL and cortisol responses to fenfluramine were more strongly correlated with impulsivity than aggressiveness. Also, the more impulsive subjects reported a decrease in subjective states of depression, hostility and anxiety after drug treatment. These data further support the hypothesis of altered serotonergic activity in aggressive and impulsive behaviors.

Blood platelet uptake of serotonin in episodic aggression

Blood platelet uptake of 3H-serotonin (5HT uptake), a potential marker of serotonergic function, was determined in male outpatients with episodic aggression (n = 15) and in age- and sex-matched nonaggressive controls (n = 15). Correlations with rating scales of "impulsivity" (Barratt Impulsivity Scale, 10th revision) and "anger" (Spielberger Anger Expression Scale) were performed. Mean 5HT uptake was 18% lower in patients with episodic aggression. A significant negative correlation between % difference in platelet 5HT uptake and impulsivity score was observed, but the correlation between 5HT uptake and anger was not significant. These results support the hypothesis of disturbed serotonergic function in aggression and suggest that the primary relationship is in the "control" of aggression. The blood platelet may be useful in identifying impulsive subtypes.

Plasma phospholipid essential fatty acids and prostaglandins in alcoholic, habitually violent, and impulsive offenders

Plasma phospholipid essential fatty acids and some of their main metabolites, prostaglandins, were measured among habitually violent and impulsive male offenders, who all had alcohol abuse problems, and nonviolent control persons. Linoleic acid (18:2n-6), the precursor of the n-6 fatty acids, was below normal in intermittent explosive disorder, but the dihomogammalinolenic acid (DGLA) (20:3n-6) and some subsequent n-6 acids were at the same time elevated among all offenders. Also, a monounsaturate, oleic acid (18:1n-9) was elevated. The high DGLA correlated with low cholesterol level in intermittent explosive disorder. The arachidonic acid metabolites PGE2 and TxB2 were elevated in violent antisocial personality. The PGE1/DGLA ratio was low in intermittent explosive disorder. The number of registered violent crimes and violent suicidal attempts correlated with high phospholipid DGLA values. The possibility that the high phospholipid DGLA is connected with low free DGLA pool, and therefore low PGE1 formation, among these offenders is discussed.

Plasma insulin, tryptophan and serotonin levels during the glucose tolerance test among habitually violent and impulsive offenders

Insulin activity in plasma and the concentrations of tryptophan and serotonin were measured during the glucose tolerance test (GTT) in habitually violent and impulsive male offenders and in psychiatric personnel as controls. Insulin was enhanced in the intermittent explosive disorder; at the same time the concentration of plasma tryptophan and the ratio of tryptophan to large neutral amino acids were on a high level and tryptophan even increased in many cases during GTT. Serotonin values did not differ. Many offenders with enhanced insulin secretion displayed abnormal neuroglycopenic symptoms during GTT.

Personality correlates of platelet monoamine oxidase (MAO) activity in female and male subjects

Associations between platelet monoamine oxidase (MAO) activity and scale scores from the Eysenck Personality Questionnaire, the Impulsiveness-Venturesomeness-Empathy inventory and the Karolinska Scales of Personality were studied in 32 female and 29 male students (age range 17-19 years). There were significant negative correlations between MAO activity and extraversion-related scales for male subjects; in the female group the correlations were also negative but nonsignificant. When comparing subgroups with low, intermediate, and high platelet MAO activity subjects, consistent trends were observed in the direction of higher scores in the impulsivity scales, the sensation seeking-related Monotony avoidance scale, and the Indirect Aggression scale for both female and male low MAO activity groups.

Twelve blood markers and measures of temperament

This project tested the association of 12 blood marker systems with the Eysenck Extraversion-Introversion/Neuroticism forms and the Buss-Plomin Temperament forms. The sample was about 400 males and 470 females who were given medical examinations during the Tecumseh Community Health Study (Michigan). ANOVA and Scheffe tests were used to test for significant differences; personality traits were adjusted for age. The Lewis red blood cell phenotypes were significantly associated with Anger and Impulsivity for males and Sensation-seeking (a subscale of Impulsivity) for females. It is suggested that these temperament factors merit further exploration.

The effect of lithium on luteinizing hormone and testosterone in man

Serum luteinizing hormone and testosterone were determined weekly during the course of a comparison of the effects of lithium versus placebo on impulsive aggressive behavior in 16-24 year-old male prisoners. The duration of drug treatment for each individual was up to 3 months. A significant reduction of serious agressive behavioral incidents occurred in the third month on lithium and was accompanied by a significant rise in serum luteinizing hormone, with no change in serum testosterone.