Decreased oxytocin plasma levels and oxytocin receptor expression associated with aggressive behavior in aggressive-impulsive disorders

INTRODUCTION

This study aims to enhance the understanding of the association between the phenotypic and endophenotypic characteristics of impulsive-aggressive disorders, through the study of plasma oxytocin (OXT) and oxytocin receptor (OXTR) levels in patients with borderline personality disorder (BPD) and patients with eating disorders (ED), as well as to examine the relationship of OXT system with aggressive behavior in these disorders.

METHODS

68 patients with BPD, 67 patients with ED and 57 healthy control subjects were examined for plasma oxytocin levels and protein expression of OXTR in blood mononuclear cells. Aggressive behavior was assessed using the State-Trait Anger Expression Inventory (STAXI-2). Other self and hetero-aggressive behaviors were also evaluated through interviews.

RESULTS

BPD and ED patients exhibited significantly lower plasma oxytocin levels than control subjects. Furthermore, BPD patients demonstrated significantly reduced expression of OXTR compared to controls. Plasma oxytocin levels negatively correlated with verbal aggression, while OXTR expression was inversely associated with the STAXI trait subscale.

CONCLUSIONS

The findings validate the existence of oxytocin system dysfunction in impulsive-aggressive disorders. They also support the link between low OXT levels in plasma and OXTR expression and the impulsive-aggressive behavior that characterizes these patients in both state and trait situations.

Functional magnetic resonance studies in eating behavior disorders

Eating behavior disorders (EBD) constitute a serious somatic and psychiatric condition that occurs mainly in adolescent and young adult women and is characterized by a persistent desire to be extremely thin, pathologic fear of gaining weight and distortion of body perception. From a neurobiological vantage point, it has been suggested that alterations in some neural systems of these patients may exist, either as a cause or effect of their condition. In recent years various research studies have been conducted with the aim of identifying underlying brain disorders in EBD. The purpose of this article was to review the main findings obtained in neuroimaging studies, including PET, SPECT, magnetic resonance spectroscopy (MRS), focusing mainly on functional magnetic resonance imaging (fMRI). Some alterations and changes in metabolism and blood perfusion that accompany the neuroimaging findings will be reviewed, as well as studies designed to determine whether these alterations persist after recovery from the disease.

[Enhanced suppression of cortisol after dexamethasone in borderline personality disorder. A pilot study]

INTRODUCTION

Some studies have suggested the etiological role of childhood traumatic events in borderline personality disorder (BPD), involving the stress response mechanisms and the activity of hypothalamic-pituitary adrenal (HPA) axis. Recent preliminary results show that BPD, similar to that found in post-traumatic stress disorder (PSD), might have a hypersensitive response to the dexamethasone test.

METHODS

Fourteen BPD patients, diagnosed according to DSM-IV criteria, without a major depressive episode or history of bipolar or psychotic disorder, were compared with 10 patients with other personality disorders (OPD). Plasma cortisol was measured at baseline and following an oral test with 0.25 mg of dexamethasone.

RESULTS

Nine out of 14 (64%) BPD patients were cortisol suppressors in the test versus only 2 out of 10 (20%) patients with other personality disorders (chi square 4.6, degree factors [df] 18, p<0.05). The degree of cortisol suppression was significantly greater for BPD patients (73% ) than for patients with other personality disorder (34 %). Baseline cortisol concentrations, although lower in BPD patients, were not significantly different among groups.

CONCLUSIONS

BPD could be associated with hypersensitivity of feedback mechanisms of the HPA axis similar to PSD, which suggests a possible role for traumatic experiences in the pathogenesis of the disorder.