CSF dopamine levels correlate with extraversion in depressed patients

Anxious Personality Traits: Perspectives from Basic Emotions and Neurotransmitters

Objective: Recently, many emotional diseases, such as anxiety and depression, have prevailed, and it is expected that emotional disease will be the leading cause of social and economic burden in 2030. These emotional diseases may be due to certain personality traits, which could be the reasons for the development of mental illness. Personality theories have been constantly developed over the past hundreds of years, and different dimensions of personality traits corresponding to different physiological bases and emotional feelings have been proposed. However, personality may be the least studied area in psychology. Methods: In this paper, we will give a short review on the development of personality theories as well as dimensional emotional theory. Then, we will compare the similarities between the emotional dimension and personality dimension. Furthermore, we will also investigate the neural mechanisms of personality and emotions, focusing on neuromodulators for anxiety-related personality traits, in order to provide a clear relationship between different neurotransmitters and anxiety-related personality traits. Results: The results of our study suggest that the emotional dimension and personality dimension may be somewhat related, for example, the extrovert/introvert dimension of personality might be related to the hedonic dimension, which includes happiness/sadness, and the neurotic dimensions might be related to emotional arousal. In addition, our study found that personality traits are also related to basic emotions, for instance, people who are too self-centered are prone to feeling a mood of disgust or depression, while anger and fear correspond to unstable personality traits. The analysis suggested that the neural substrates of both personality and emotions might be described as follows: extroverted–joy–dopamine (DA); introverted–disgust–5-hydroxytryptamine (5-HT); unstable (neuroticism)–anger/fear–noradrenaline (NE); stable–calmness. Conclusions: The results of this study suggest that there is a correlation between personality traits and emotions, and both depend on monoamine neurotransmitters (dopamine, norepinephrine and serotonin). In addition, personality disorders can be interfered via the regulation of emotions and neurotransmitters. This paper opens up a whole new perspective for future research on personality traits and emotional diseases and has great clinical value and practical significance.

Strong Out-of-Plane Vibrations and Ultrasensitive Detection of Dopamine-like Neurotransmitters

The detection of monoamine neurotransmitters has become a vital research subject due to their high correlations with nervous system diseases, but insufficient detection precisions have obstructed diagnosis of some related diseases. Here, we focus on four monoamine neurotransmitters, dopamine, norepinephrine, epinephrine, and serotonin, to conduct their rapid and ultrasensitive detection. We find that the low-frequency (<200 cm^-1) Raman vibrations of these molecules show some sharp peaks, and their intensities are significantly stronger than those of the high-frequency side. Theoretical calculations identify these peaks to be from strong out-of-plane vibrations of the C-C single bonds at the joint point of the ring-like molecule and its side chain. Using our surface enhanced low-frequency Raman scattering substrates, we show that the detection limit of dopamine as an example can reach 10 nM in artificial cerebrospinal fluid. This work provides a useful way for ultrasensitive and rapid detection of some neurotransmitters.

Where Is Dopamine and how do Immune Cells See it?: Dopamine-Mediated Immune Cell Function in Health and Disease

Dopamine is well recognized as a neurotransmitter in the brain, and regulates critical functions in a variety of peripheral systems. Growing research has also shown that dopamine acts as an important regulator of immune function. Many immune cells express dopamine receptors and other dopamine related proteins, enabling them to actively respond to dopamine and suggesting that dopaminergic immunoregulation is an important part of proper immune function. A detailed understanding of the physiological concentrations of dopamine in specific regions of the human body, particularly in peripheral systems, is critical to the development of hypotheses and experiments examining the effects of physiologically relevant dopamine concentrations on immune cells. Unfortunately, the dopamine concentrations to which these immune cells would be exposed in different anatomical regions are not clear. To address this issue, this comprehensive review details the current information regarding concentrations of dopamine found in both the central nervous system and in many regions of the periphery. In addition, we discuss the immune cells present in each region, and how these could interact with dopamine in each compartment described. Finally, the review briefly addresses how changes in these dopamine concentrations could influence immune cell dysfunction in several disease states including Parkinson's disease, multiple sclerosis, rheumatoid arthritis, inflammatory bowel disease, as well as the collection of pathologies, cognitive and motor symptoms associated with HIV infection in the central nervous system, known as NeuroHIV. These data will improve our understanding of the interactions between the dopaminergic and immune systems during both homeostatic function and in disease, clarify the effects of existing dopaminergic drugs and promote the creation of new therapeutic strategies based on manipulating immune function through dopaminergic signaling. Graphical Abstract.

Dopamine transporter binding in social anxiety disorder: the effect of treatment with escitalopram

Social anxiety disorder (SAD) is characterised by fear of social or performance situations where the individual is exposed to unfamiliar people or to possible scrutiny by others. The literature on dopamine ligands and dopamine genotypes in SAD is however inconsistent. In this study we measured the effects of SSRI pharmacotherapy on dopamine transporter (DAT) binding in patients with SAD, also addressing variability in DAT genotype. Adult subjects meeting DSM-IV criteria for generalised SAD were studied before and after 12 weeks of pharmacotherapy with the selective serotonin reuptake inhibitor (SSRI) escitalopram. DAT single photon emission computed tomography (SPECT) using (123)I-FP-CIT was performed at baseline, and repeated at 12 weeks. Striatal DAT binding was analysed for changes following therapy, and for correlations with clinical efficacy, in the whole group as well as for a subgroup with the A10/A10 DAT genotype. The study included 14 subjects (9 male, 5 female) with a mean (SD) age of 41 (±13) years. The subjects' Liebowitz Social Anxiety Scale (LSAS) score was significantly decreased following pharmacotherapy. In the combined group the left caudate and left putamen showed clusters of increased DAT binding after therapy. The left caudate changes were also observed in the subgroup of 9 A10/A10 homozygotes. However no correlation was found between improved symptoms and DAT binding. The changes found in DAT binding in the caudate and putamen may be due to serotonergic activation of dopamine function by SSRI therapy. This is consistent with previous work indicating decreased DAT binding in SAD, and increased DAT binding after SSRI administration.

Dopaminergic modulation of incentive motivation in adolescence: age-related changes in signaling, individual differences, and implications for the development of self-regulation

Behavioral activation that is associated with incentive-reward motivation increases in adolescence relative to childhood and adulthood. This quadratic developmental pattern is generally supported by behavioral and experimental neuroscience findings. It is suggested that a focus on changes in dopamine neurotransmission is informative in understanding the mechanism for this adolescent increase in reward-related behavioral activation and subsequent decline into adulthood. Evidence is presented to indicate that incentive-reward motivation is modulated by mesoaccumbens dopamine, and that it increases in adolescence before declining into adulthood because of normative developmental changes at the molecular level. Potential mechanisms of variation in functional mesoaccumbens dopamine transmission are discussed with a focus on the interplay between tonic and phasic modes of dopamine transmission in modulating both general incentive-motivational biases and the efficacy of reward learning during exposure to novel reward experiences. Interactions between individual difference factors and these age-related trends are discussed.

Mechanisms of impulsivity in bipolar disorder and related illness

Aims – Impulsivity is a multifaceted aspect of behavior that is prominent in psychiatric disorders and has serious behavioral consequences. This paper reviews studies integrating behavioral and physiological mechanisms in impulsivity and their role in severity and course of bipolar and related disorders. Methods – This is a review of work that used questionnaire, human behavioral laboratory, and neurophysiological measurements of impulsivity or related aspects of behavior. Subjects included individuals with bipolar disorder, substance-use disorders, antisocial personality disorder, and healthy controls. Results – Models of impulsivity include rapid-response impulsivity, with inability to reflect or to evaluate a stimulus adequately before responding, and reward-based impulsivity, with inability to delay response for a reward. In normal subjects, rapid-response impulsivity is increased by yohimbine, which increases norepinephrine release. Impulsivity is increased in bipolar disorder, whether measured by questionnaire, by measures of rapid-response impulsivity, or by measures of ability to delay reward. While affective state has differential effects on impulsivity, impulsivity is increased in bipolar disorder regardless of affective state or treatment. Impulsivity, especially rapid-response, is more severe with a highly recurrent course of illness or with comorbid substance-use disorder, and with history of medically severe suicide attempt. In antisocial personality disorder, rapid-response impulsivity is increased, but rewardbased impulsivity is not. In general, impulsivity is increased more in bipolar disorder than in antisocial personality disorder. In combined bipolar disorder and antisocial personality disorder, increased impulsivity is associated with substance-use disorders and suicide attempts. Conclusions – Impulsivity is associated with severe behavioral complications of bipolar disorder, antisocial personality disorder, and substance-use disorders.

Developmental changes in dopamine neurotransmission in adolescence: behavioral implications and issues in assessment

Adolescence is characterized by increased risk-taking, novelty-seeking, and locomotor activity, all of which suggest a heightened appetitive drive. The neurotransmitter dopamine is typically associated with behavioral activation and heightened forms of appetitive behavior in mammalian species, and this pattern of activation has been described in terms of a neurobehavioral system that underlies incentive-motivated behavior. Adolescence may be a time of elevated activity within this system. This review provides a summary of changes within cortical and subcortical dopaminergic systems that may account for changes in cognition and affect that characterize adolescent behavior. Because there is a dearth of information regarding neurochemical changes in human adolescents, models for assessing links between neurochemical activity and behavior in human adolescents will be described using molecular genetic techniques. Furthermore, we will suggest how these techniques can be combined with other methods such as pharmacology to measure the impact of dopamine activity on behavior and how this relation changes through the lifespan.

Dopamine transporters, D2 receptors, and dopamine release in generalized social anxiety disorder

BACKGROUND

Dopamine D2 receptor and dopamine transporter (DAT) availability in the striatum (STR) have each been reported abnormal in generalized social anxiety disorder (GSAD) in studies using single photon emission computerized tomography (SPECT). D2 receptors and DAT have not previously been studied within the same GSAD subjects, however, and prior GSAD studies have not assessed dopamine release or subdivided the STR into functional subregions.

METHODS

Unmedicated adults with GSAD (N=17) and matched healthy comparison (HC) subjects (N=13) participated in this study. Of these, 15 GSAD and 13 HC subjects completed baseline assessment of D2 receptor availability using positron emission tomography (PET) with the radiotracer [11C]raclopride. Twelve GSAD and 13 HC subjects completed a repeat scan after intravenous administration of d-amphetamine to study dopamine release. Twelve of the GSAD subjects and 10 of the HC subjects also completed SPECT with the radiotracer [123I] methyl 3beta-(4-iodophenyl) tropane-2beta-carboxylate ([123I]beta-CIT) to assess DAT availability.

RESULTS

GSAD and HC groups did not differ significantly in striatal DAT availability, the overall striatal or striatal subregion D2 receptor availability at baseline, or change in D(2) receptor availability after d-amphetamine. Receptor availability and change after d-amphetamine were not significantly associated with severity of social anxiety or trait detachment.

CONCLUSIONS

These findings do not replicate previous findings of altered striatal DAT and D2 receptor availability in GSAD subjects assessed with SPECT. The differences from results of prior studies may be due to differences in imaging methods or characteristics of samples.

Striatal dopamine D(2) receptor availability in OCD with and without comorbid social anxiety disorder: preliminary findings

Dopamine D(2) receptor availability in the striatum has been reported to be low in generalized social anxiety disorder (GSAD) and obsessive-compulsive disorder (OCD), but it has not been studied in persons with comorbid OCD and GSAD (OCD+GSAD). D(2) receptor availability was assessed in 7 subjects with OCD+GSAD, 8 with OCD, and 7 matched healthy comparison (HC) subjects, all unmedicated adults. D(2) receptor availability was assessed with single-photon emission computerized tomography (SPECT) to measure binding potential (BP) of the D(2) receptor radiotracer [(123)I] iodobenzamide ([(123)I]IBZM). Mean striatal [(123)I]IBZM BP was significantly lower in the OCD+GSAD group (72.58 mL/g, SD=18.17) than in the HC group (118.41 mL/g, SD=45.40; P=.025). Mean BP in the OCD group (93.08 mL/g, SD=36.90) did not differ significantly from the HC group (P=.247). Trait detachment, as measured by the Detachment subscale of the Karolinska Scales of Personality, was negatively correlated with D(2) availability across all subjects (r(s)= -.55, P=.013). Comorbid GSAD and OCD may be associated with decreased availability of D(2) receptors in the striatum, consistent with prior findings in GSAD. Prior findings of decreased D(2) receptor availability in noncomorbid OCD were not confirmed. Decreased D(2) receptor availability was also associated with trait detachment, supporting prior findings in samples of healthy subjects.

The social anxiety spectrum

Social anxiety disorder is well suited to the spectrum concept because it has trait-like qualities of early onset, chronicity, and no empirically derived threshold that demarcates normal from clinically significant trait social anxiety. Social anxiety disorder has been shown to respond to relatively specific pharmacologic and cognitive-behavioral therapies, which makes identification of other conditions that may lie on the social anxiety disorder spectrum important because of possible treatment implications. Biologic markers associated with social anxiety disorder also may be shared by similar but nonidentical traits, such as behavioral inhibition and detachment. Clarification of the trait spectrums associated with specific biologic systems offers an opportunity for improving the understanding of the origin of these conditions. Strong evidence exists that at least some forms of shyness, avoidant personality disorder, and selective mutism lie on a social anxiety disorder spectrum. For several other disorders that share a prominent focus on social comparison, significant subgroups of patients seem to have features of social anxiety disorder. These disorders include major depression (especially the atypical subtype), body dysmorphic disorder, and eating disorders. Several other disorders marked by social dysfunction or inhibition, including substance use disorders (especially alcoholism), paranoid disorder, bipolar disorder, autism, and Asperger's disorder, also may show some overlap with social anxiety disorder features (e.g., social anxiety as a cause or complication of substance abuse, social avoidance in paranoid disorder, social disinhibiton in bipolar disorder, and social communication deficits in autism and Asperger's disorder). Social anxiety disorder also is associated with other anxiety disorders in general and other phobias in particular. In respect to traits, a growing body of evidence links behavioral inhibition to the unfamiliar to a social anxiety disorder spectrum with some specificity. Biologic measures of dopamine system hypoactivity have been linked to social anxiety disorder, trait detachment, and general deficits in reward and incentive function. It remains to be clarified, however, whether this brain system function is best characterized by a social anxiety disorder spectrum or some variant that incorporates social reward deficits or social avoidance behavior. Social anxiety disorder, shyness, and behavioral inhibition all seem to have a genetic component, but more research is needed to attempt to identify a more specifically heritable temperament associated with these conditions. Finally, the emergent concept of a social anxiety spectrum needs maturation. Although the notion of a single social anxiety disorder spectrum currently has some clinical use, the authors believe that exclusive focus on the notion of a single continuum with two extremes--from social disinhibition in mania to the most severe form of social anxiety, avoidant personality disorder--is premature and limiting in respect to etiologic research. An alternative approach is to conceptualize multiple, probably overlapping spectra in this area of social psychopathology. Individual dimensions might be based on various core phenomenologic, cognitive, or biologic characteristics. A bottom-up biologic approach holds promise for identifying spectra with a common etiology that might respond to specific treatments. Taking a pluralistic view of the concept of spectrum at this stage may help accelerate our understanding of social anxiety and related disorders.

The neurobiology of social phobia: from pharmacotherapy to brain imaging

Social phobia is a common psychiatric disorder that is often associated with significant psychiatric comorbidity and disability. There is currently considerable evidence for the efficacy of pharmacotherapy, especially the selective serotonin reuptake inhibitors, in the treatment of this disorder. In addition, researchers have recently begun to explore the underlying neurobiology of social phobia with results that will likely have important implications for future treatments. This article provides a review of the results to date of controlled medication trials. A review of chemical and neuroendocrine challenges, neurotransmitter functioning, and neuroimaging studies in social phobia is provided, followed by a discussion of the implications of these findings for future treatment and research.

Influence of personality on behavioral response to cholecystokinin-tetrapeptide in patients with panic disorder

The relationship between personality, as measured by selected clinical scales of the Minnesota Multiphasic Personality Inventory (MMPI) (Hypochondriasis, Depression, Hysteria, Psychasthenia, Social Introversion, and Anxiety) and the Anxiety Sensitivity Index (ASI), and behavioral response to the panicogenic agent cholecystokinin-tetrapeptide (CCK-4) was examined in 29 patients with panic disorder with or without agoraphobia. Significant correlations were found between the MMPI Social Introversion scale and somatic, cognitive, and affective response to CCK-4. Both the MMPI Anxiety scale and the ASI correlated significantly with cognitive response to CCK-4, but not with somatic or affective response. None of the other selected MMPI clinical scales correlated with response to CCK-4. Multiple regression analyses identified the MMPI Social Introversion scale as the best predictor of all three indices of panic-anxiety induced by CCK-4. The results suggest that the relationship between neurotic introversion and sensitivity to CCK requires closer scrutiny.

Recent developments in the psychopharmacology of social phobia

The past 2 decades have witnessed an upsurge in the interest in anxiety disorders. Much research effort has been dedicated to panic disorder and obsessive-compulsive disorder. However, it is only very recently that we have begun to understand some of the basic principles about the psychopharmacology of social phobia. Drug classes thus far studied include beta-blockers, nonselective and irreversible monoamine oxidase inhibitors (MAOIs), and benzodiazepines. Beta blockers appear to be of use in specific social phobias, such as public speaking, whereas they are of little use in generalized social phobia. There is considerable evidence suggesting that MAOIs are effective in reducing both social anxiety as well as social avoidance in generalized social phobia. A disadvantage of the conventional irreversible MAOIs is their risk for hypertensive crises when combined with dietary tyramine. Thus far only a small number of studies with selective MAO-A inhibitors, such as moclobemide and brofaromine, have been conducted in social phobia, and the results indicate that both compounds are effective. Drugs exerting selective and specific actions on certain components of, for example, the serotonergic system, can now be studied, and it is hoped that the role of 5-hydroxytryptamine) and other neuronal systems in social phobia can be elucidated. In order to gain more information about selective serotonergic drugs, the first double-blind placebo-controlled study with fluvoxamine was recently published. Preliminary results indicate a reduction in social anxiety after a prolonged treatment period. Finally, the role of peptides in the treatment of social phobia is critically reviewed. The MSH/ACTH analog Org 2766 was investigated in patients suffering from social phobia.(ABSTRACT TRUNCATED AT 250 WORDS)

Recent advances in the psychopharmacology of social phobia

1. The last two decades have witnessed an upsurge in the interest in anxiety disorders. Much research effort has been dedicated to panic disorder and obsessive compulsive disorder. However, it is only very recently that we have begun to understand some of the basic principles about the psychopharmacology of social phobia. 2. Drug classes sofar studied include beta-blockers, nonselective and irreversible MAO-inhibitors (MAOI's) and benzodiazepines. 3. Beta blockers appear to be of use in specific social phobias, like public speaking. There is considerable evidence suggesting that MAOI's are effective in reducing both social anxiety as well as social avoidance. A disadvantage of the conventional irreversible MAOI's is their risk for hypertensive crises when combined with dietary tyramine. So far only a small number of studies with selective MAOI-A inhibitors such as moclobemide and brofaromine have been conducted in social phobia, and the results indicate that both compounds are effective. 4. Drugs exerting selective and specific actions on certain compounds of e.g. the serotonergic system can now be studied and it is hoped that the role of 5-HT and other neuronal systems in social phobia can be elucidated. 5. In order to gain more information about selective serotonergic drugs the first double blind placebo controlled study with fluvoxamine in social phobia is here reported. Preliminary results indicate a reduction of social anxiety. 6. Finally the role of peptides in the treatment of social phobia is critically reviewed. The MSH/ACTH analog Org 2766 was investigated in patients suffering from social phobia. No anxiolytic effects of this peptide could be observed.

Magnetic resonance imaging in social phobia

Recent studies have implicated dopamine and the basal ganglia circuits in the pathophysiology of social phobia. Twenty-two patients who met DSM-III-R criteria for social phobia and 22 age- and sex-matched control subjects underwent magnetic resonance imaging (MRI). MRI was performed with a 1.5 Tesla General Electric Signa System. No statistically significant difference was demonstrated between social phobia patients and normal control subjects in respect to total cerebral, caudate, putamen, and thalamic volumes. Although this study failed to demonstrate any specific cerebral structure abnormalities in patients with social phobia, it did reveal an age-related reduction in putamen volumes in patients with social phobia that was greater than that seen in controls. This age-related reduction in putamen volumes in patients with social phobia was not correlated with the severity of their illness.

Social phobia: biological aspects and pharmacotherapy

1. Social phobia is one of the anxiety disorders that until recently, had not been thoroughly investigated. 2. Social phobia is a relatively common anxiety disorder that appears to have a genetic basis. 3. There are certain physiological aspects of social phobia that separate it from the other anxiety disorders. 4. Support for a dopaminergic abnormality related to social phobia is supported by investigation studies and pharmacotherapy. 5. There are a number of studies reporting success in the treatment of social phobia with medications.

The biology of personality

Historically, models of personality have generally postulated, or assumed, a link with biology. This century has witnessed a major revision of these ideas with both behavioural and psychoanalytic theorists emphasising life experiences as being largely responsible for behaviour as adults. Challenges to this assumption of the overwhelming importance of life experiences are reviewed. An extensive body of data now exists suggesting that biology contributes significantly to individual variability. This biological contribution occurs at a relatively low level in the central nervous system, best defined as temperament. Further research has suffered from the lack of a cohesive psychobiological model. Cloninger's tridimensional theory of personality is presented as a model which attempts to bridge the gap between theoretical temperamental traits, neurotransmitter function and clinical psychiatry. It is to be hoped that new theoretical models will be formulated which will focus on the importance of temperamental variables in psychiatric disorders.

The relationship of social phobia subtypes and avoidant personality disorder

The diagnoses of social phobia (SP) and avoidant personality disorder (APD) have evolved from different historical sources, but their criteria appear to converge in DSM-III-R. Fifty anxiety disorder clinic patients with DSM-III-R SP were evaluated for presence of DSM-III-R APD. APD was present in 89% of those with the generalized subtype of SP (GSP) and 21% of those with the discrete subtype of SP (DSP). The findings are discussed in conjunction with other recent reports showing substantial overlap between GSP and APD.

Effect of forced unilateral nostril breathing on blink rates: relevance to hemispheric lateralization of dopamine

The involuntary blink rate is a clinical monitor of dopaminergic activity. Since there is disagreement in the literature on the relative neurochemical hemispheric asymmetry or laterality of dopamine, we studied the effects of differential forced unilateral nostril breathing on blink rate. This technique has been demonstrated to induce selective contralateral hemispheric stimulation as measured by relative increases in the EEG amplitude as well as alternating lateralization of plasma catecholamines. We used the artifact of the two-channel electro-oculogram to measure the endogenous eyeblink in an N = 1 design with 11 reversals of left vs. right hemisphere activation. There was a significant increase in blink rate (p less than .01) with right hemisphere activation, and this suggests that dopamine may be lateralized to the right cerebral hemisphere.

Tonic arousal and activity: relationships to personality and personality disorder traits in panic patients

Personality theorists have long predicted a relationship between personality traits and autonomic activation. In this study, 48 patients with panic disorder underwent personality assessment by questionnaire (Eysenck Personality Inventory: 48 patients) and by interview (Personality Disorders Examination: 35 patients). Ambulatory heart rate and activity were measured by the Vitalog method and were used as measures of activation and autonomic arousal. There was a significant positive correlation between histrionic traits and activity level and a significant negative correlation between sociability and heart rate. The findings are consistent with previous studies showing a negative relationship between sensation-seeking personality traits and cerebrospinal fluid levels of norepinephrine and a positive relationship between extroversion and cerebrospinal fluid levels of dopamine.