MAOIs: impact on social behavior

Neurocomputational mechanisms underpinning aberrant social learning in young adults with low self-esteem

Low self-esteem is a risk factor for a range of psychiatric disorders. From a cognitive perspective a negative self-image can be maintained through aberrant learning about self-worth derived from social feedback. We previously showed that neural teaching signals that represent the difference between expected and actual social feedback (i.e., social prediction errors) drive fluctuations in self-worth. Here, we used model-based functional magnetic resonance imaging (fMRI) to characterize learning from social prediction errors in 61 participants drawn from a population-based sample (n = 2402) who were recruited on the basis of being in the bottom or top 10% of self-esteem scores. Participants performed a social evaluation task during fMRI scanning, which entailed predicting whether other people liked them as well as the repeated provision of reported feelings of self-worth. Computational modeling results showed that low self-esteem participants had persistent expectations that others would dislike them, and a reduced propensity to update these expectations in response to social prediction errors. Low self-esteem subjects also displayed an enhanced volatility in reported feelings of self-worth, and this was linked to an increased tendency for social prediction errors to determine momentary self-worth. Canonical correlation analysis revealed that individual differences in self-esteem related to several interconnected psychiatric symptoms organized around a single dimension of interpersonal vulnerability. Such interpersonal vulnerability was associated with an attenuated social value signal in ventromedial prefrontal cortex when making predictions about being liked, and enhanced dorsal prefrontal cortex activity upon receipt of social feedback. We suggest these computational signatures of low self-esteem and their associated neural underpinnings might represent vulnerability for development of psychiatric disorder.

Platelet vesicular monoamine transporter density in untreated patients diagnosed with social phobia

The vesicular monoamine transporter (VMAT2) is important in the storage and release of monoamines. Platelet VMAT2 was characterized using high-affinity [(3)H]dihydrotetrabenazine ([(3)H]TBZOH) binding in untreated social phobia (SP) patients (n=20) compared with sex- and age-matched healthy controls (n=15). No significant differences in VMAT2 density (B(max)) and affinity constants (K(d)) were observed.

The neurobiology of social anxiety disorder: the relevance of fear and anxiety

OBJECTIVE

Social anxiety disorder (SAD) is a ubiquitous anxiety disorder. Despite being the third most common psychiatric disorder, little is known about the interaction between genetic predisposition and environmental factors in the development of SAD. The available literature on SAD has been compared with data on the genetics and environmental impact on the phenotypic expression of fear and anxiety, and its implicated neurobiology, in order to explore the neurobiology of SAD as understood through the neurochemical dysregulation expressed in fear and anxiety.

METHOD

A systematic review of the literature was employed for the years from 1966 to 2001.

RESULTS

SAD does indeed have much overlap with fear and anxiety. This is best demonstrated by the interactions of the noradrenergic and serotonergic systems with each other and the hypothalamic-pituitary-adrenal axis.

CONCLUSION

SAD may well be understood as one potential outcome for predisposed individuals who are exposed to the proverbial 'second hit', or environmental insult, in childhood. Behavioral inhibition may be an early expression of this predisposition, with natural progression to SAD occurring via a disruption of neurochemical homeostasis. Through animal and human data it has become evident that fear and anxiety have shared, as well as distinct, neurochemical and neuroanatomical pathways. These similarities are expressed as symptoms and objective signs that are common to many individuals with social anxiety disorder.

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.

A preliminary study of dopamine-mediated prolactin inhibition in generalised social phobia

The biology of social phobia has been little studied, but a possible role for dopamine has been implicated in this disorder. The aim of this study was to examine central dopaminergic function in patients with generalised social phobia using the prolactin response to quinagolide, a dopamine D2 receptor agonist, and to compare responses with those of normal controls. The study included 14 patients with moderate or severe generalised social phobia and 14 healthy age- and gender-matched comparison subjects. Quinagolide (0.5 mg) was administered orally and prolactin responses were measured over 4 h. There was no significant difference between prolactin responses in patients and healthy controls, nor was there a correlation between prolactin response and age, sex, or severity of illness. This would suggest that tuberoinfundibular dopamine D2 receptor sensitivity is normal in this disorder.

Social anxiety disorder

In 1990s, it was found that GSAD is more common, more disabling, and more chronic than previously realized. For the first time, there are good data about a range of effective treatment options that can offer these patients substantial relief and protection from their disability.

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.

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.

Reversible and irreversible monoamine oxidase inhibitors in other psychiatric disorders

In addition to being effective in depressive disorders, monoamine oxidase inhibitors (MAOIs) have been shown to be effective in controlled studies of patient with panic disorder with agoraphobia, social phobia, atypical depression or mixed anxiety and depression, bulimia, posttraumatic stress disorder (PTSD) and borderline personality disorder. Uncontrolled case reports have noted MAOI efficacy in obsessive-compulsive disorder (OCD), trichotillomania, dysmorphophobia and avoidant personality disorder. Reversible inhibitors of MAO-A (RIMAs) appear safer than the classical irreversible MAOIs since they have less potential to increase blood pressure. They have not been studied as yet, however, in most of the conditions responsive to MAOIs. If RIMAs are found effective in these disorders, they would probably achieve wider use than MAOIs because they are safer and tend to cause fewer side effects.

Symptoms of interpersonal sensitivity in depression

Six self-rated items of interpersonal sensitivity (IPS) were examined in 174 depressed outpatients. These items were "feeling critical of others," "your feelings being easily hurt," "feeling others do not understand you or are unsympathetic," "feeling others are unfriendly," "feeling inferior to others," "feeling shy or uneasy with the opposite sex." The population was grouped into tertiles based on their pretreatment IPS score. High levels of IPS were associated with earlier onset and greater chronicity of depression, higher Hamilton Rating Scale for Depression (HRSD) score, more severe depressed mood, guilt, suicidality, impaired work and interest, retardation, depersonalization, paranoia, and cognitive symptoms of depression. More frequent atypical features were found, e.g., overeating/weight gain, self-pity, phobic avoidance, and panic attacks. Response to a monoamine oxidase (MAO) inhibitor drug increased at higher levels of IPS, while the response to a placebo decreased.