Peripheral oxytocin is associated with reduced symptom severity in schizophrenia

Evidence of a sex-dependent restrictive epigenome in schizophrenia

When compared to women, men have a higher incidence of schizophrenia, with increases in negative and cognitive symptoms, and an overall poorer disease course. Schizophrenia is conceptualized as a disorder of aberrant gene transcription and regulation. Thus, epigenetics, the study of environmentally induced changes in gene regulation, could advance our understanding of the molecular underpinnings of schizophrenia. Peripheral histone methyltransferase (HMT) mRNA levels have been previously shown to be significantly increased in patients with schizophrenia and correlate with symptomology. In this independent study, peripheral lymphocytes were extracted and clinical symptoms were measured on 74 participants, (40 patients with schizophrenia (19 women, 21 men) and 34 healthy individuals (19 women, 15 men)). HMT (G9α, SETDB1 and GLP) mRNA levels and their resulting histone modification H3K9me2 were measured with RT-PCR and ELISA respectively. Plasma estradiol levels were also measured via ELISA and correlated with HMT mRNA. Clinical symptoms were measured utilizing the Positive and Negative Syndrome Scale (PANSS) and the Heinrichs Carpenter Quality of Life Scale (QLS). The results indicate that men with schizophrenia expressed the highest levels of G9α, SETDB1 mRNA and H3K9me2 protein levels. Additionally, higher levels of symptom presentation and an overall poorer quality of life were correlated with higher HMT mRNA and H3K9me2 protein levels in a sex-dependent pattern. These data support the hypothesis of a sex-dependent restrictive epigenome contributing towards the etiology of schizophrenia. The histone methyltransferases measured here could be potential future therapeutic targets for small molecule pharmacology.

Translational and therapeutic potential of oxytocin as an anti-obesity strategy: Insights from rodents, nonhuman primates and humans

The fact that more than 78 million adults in the US are considered overweight or obese highlights the need to develop new, effective strategies to treat obesity and its associated complications, including type 2 diabetes, kidney disease and cardiovascular disease. While the neurohypophyseal peptide oxytocin (OT) is well recognized for its peripheral effects to stimulate uterine contraction during parturition and milk ejection during lactation, release of OT within the brain is implicated in prosocial behaviors and in the regulation of energy balance. Previous findings indicate that chronic administration of OT decreases food intake and weight gain or elicits weight loss in diet-induced obese (DIO) mice and rats. Furthermore, chronic systemic treatment with OT largely reproduces the effects of central administration to reduce weight gain in DIO and genetically obese rodents at doses that do not appear to result in tolerance. These findings have now been recently extended to more translational models of obesity showing that chronic subcutaneous or intranasal OT treatment is sufficient to elicit body weight loss in DIO nonhuman primates and pre-diabetic obese humans. This review assesses the potential use of OT as a therapeutic strategy for treatment of obesity in rodents, nonhuman primates, and humans, and identifies potential mechanisms that mediate this effect.

The influence of early life sexual abuse on oxytocin concentrations and premenstrual symptomatology in women with a menstrually related mood disorder

Oxytocin (OT), associated with affiliation and social bonding, social salience, and stress/pain regulation, may play a role in the pathophysiology of stress-related disorders, including menstrually-related mood disorders (MRMD's). Adverse impacts of early life sexual abuse (ESA) on adult attachment, affective regulation, and pain sensitivity suggest ESA-related OT dysregulation in MRMD pathophysiology. We investigated the influence of ESA on plasma OT, and the relationship of OT to the clinical phenomenology of MRMD's. Compared to MRMD women without ESA (n=40), those with ESA (n=20) displayed significantly greater OT [5.39pg/mL (SD, 2.4) vs. 4.36pg/mL (SD, 1.1); t (58)=-2.26, p=0.03]. In women with ESA, OT was significantly, inversely correlated with premenstrual psychological and somatic symptoms (r's=-0.45 to -0.64, p's<0.05). The relationship between OT and premenstrual symptomatology was uniformly low and non-significant in women without ESA. In women with ESA, OT may positively modulate MRMD symptomatology.

The many faces of oxytocin: implications for psychiatry

Oxytocin is known as the 'love hormone' due its role in promoting mother-child and pair bonding. More recent research indicates that oxytocin may have broader pro-social effects on behavior and cognition, which points towards oxytocin's potential as an agent to help improve social cognition and functioning in psychiatric disorders such as schizophrenia and autism. However, new research on oxytocin has also uncovered a 'darker side', including oxytocin's possible role in social out-grouping and envy. Instead of a simple view of oxytocin as 'good' or 'bad', a more accurate depiction of oxytocin's role in social processing likely involves the presence of moderating factors. We review moderation effects in oxytocin and their implications for psychiatry. One implication is that, across diagnostic categories, oxytocin administration may have positive effects for patients with social cognitive deficits but negative effects for patients with social cognitive bias. We conclude that future intervention studies should use methods such as signal detection to measure both deficit and bias parameters of social cognition and to evaluate potential individual and contextual moderators both within and between psychiatric diagnoses in order to determine for whom oxytocin treatment may be beneficial and for whom it may actually be harmful.

Plasma oxytocin explains individual differences in neural substrates of social perception

The neuropeptide oxytocin plays a critical role in social cognition and behavior. A number of studies using intranasal administration have demonstrated that oxytocin improves social perception. However, little is known about the relationship between individual differences in endogenous levels of oxytocin and social cognition. In the current study, we assessed the relationship between endogenous oxytocin and brain activity during an animacy perception paradigm. Thirty-seven male participants underwent scanning and provided a blood sample for oxytocin analysis. In line with previous research, perception of animacy was associated with activations in superior temporal sulcus, inferior frontal gyrus, and medial prefrontal cortex (mPFC). Notably, participants’ levels of plasma oxytocin robustly predicted activation in areas critical for social cognitive processes, such that higher oxytocin levels were related to increased activity in dorsal mPFC, ventral mPFC, dorsolateral PFC, superior temporal gyrus, and temporoparietal junction (TPJ), suggesting differential processing of social stimuli. Together these results show that stable variations in endogenous oxytocin levels explain individual differences in social perception.

Plasma oxytocin levels predict social cue recognition in individuals with schizophrenia

Lower endogenous levels of the neuropeptide oxytocin may be an important biological predictor of social cognition impairments in schizophrenia (SZ). Prior studies have demonstrated that lower-level social cognitive processes (e.g., facial affect perception) are significantly associated with reduced plasma oxytocin levels in SZ; however, it is unclear whether higher-level social cognition, which requires inferential processes and knowledge not directly presented in the stimulus, is associated with endogenous oxytocin. The current study explored the association between endogenous oxytocin levels and lower- and higher-level social cognition in 40 individuals diagnosed with SZ and 22 demographically matched healthy controls (CN). All participants received the Social Cue Recognition Test (SCRT), which presents participants with videotaped interpersonal vignettes and subsequent true/false questions related to concrete or abstract aspects of social interactions in the vignettes. Results indicated that SZ had significantly higher plasma oxytocin concentrations than CN. SZ and CN did not differ on SCRT hits, but SZ had more false positives and lower sensitivity scores than CN. Higher plasma oxytocin levels were associated with better sensitivity scores for abstract items in CN and fewer false positives for concrete items in individuals with SZ. Findings indicate that endogenous oxytocin levels predict accurate encoding of lower-level socially relevant information in SZ.

A double-blind randomized controlled trial of oxytocin nasal spray and social cognition training for young people with early psychosis

Social-cognitive deficits contribute to poor functional outcomes in early psychosis; however, no effective pharmacological treatments exist for these problems. This study was the first to investigate the efficacy of an extended treatment of oxytocin nasal spray combined with social cognition training (SCT) to improve social cognition, clinical symptoms, and social functioning in early psychosis. In a double-blind, randomized, placebo-controlled, between-subjects trial, 52 individuals (aged 16-35 years) diagnosed with an early psychosis schizophrenia-spectrum illness were recruited. Participants received oxytocin (24 International Units) or placebo nasal spray twice-daily for 6 weeks, combined with group SCT (2 × 1 hour weekly sessions for 6 weeks). An additional dose of oxytocin was administered before each weekly session. Assessments were conducted at baseline, post-treatment, and at 3-month follow-up. Primary outcomes included the Reading the Mind in the Eyes Test, the Scale for the Assessment of Positive and Negative Symptoms, and the Social Functioning Scale. Secondary outcomes included self-report and behavioral assessments of social cognition, symptom severity, and social functioning. Results showed that on all primary and secondary outcomes, there was no benefit of oxytocin nasal spray treatment in comparison to placebo. Exploratory post hoc analysis suggested that increased use of nasal spray was, however, associated with reductions in negative symptoms in the oxytocin condition only. This study represents the first evaluation of oxytocin treatment for early psychosis. Although results suggest no benefit of oxytocin treatment, results also highlight an urgent need to consider nasal spray delivery and dose-related variables for future clinical trials.

Plasma oxytocin levels predict olfactory identification and negative symptoms in individuals with schizophrenia

Basic neuroscience research provides strong evidence for the role of oxytocin in olfactory processes and social affiliation in rodents. Given prior indication of olfactory impairments that are linked to greater severity of asociality in schizophrenia, we examined the association between plasma oxytocin levels and measures of olfaction and social outcome in a sample of outpatients with schizophrenia (n=39) and demographically matched healthy controls (n=21). Participants completed the 40-item University of Pennsylvania Smell Identification Test (UPSIT), and rated each odor for how positive and how negative it made them feel. Results indicated that individuals with schizophrenia had higher plasma oxytocin levels and lower overall accuracy for UPSIT items than controls. Individuals with schizophrenia also reported experiencing more negative emotionality than controls in response to the olfactory stimuli. Lower plasma oxytocin levels were associated with poorer accuracy for pleasant and unpleasant odors and greater severity of asociality in individuals with schizophrenia. These findings suggest that endogenous oxytocin levels may be an important predictor of olfactory identification deficits and negative symptoms in schizophrenia.

Depressive symptoms in the second trimester relate to low oxytocin levels in African-American women: a pilot study

Low-income African-American women report elevated prenatal depressive symptoms more often (42 %) than the national average (20 %). In the USA in 2012, 16.5 % of African-American women experienced a premature birth (less than 36 completed gestational weeks) compared to 10.3 % of white women. In addition, 13 % of African-American women had a low-birth weight infant (less than 2,500 g) compared to 7 % of white women. Variation in the neuropeptide, oxytocin has been implicated in perinatal depression, maternal behavior, regulation of stress responses, and may be associated with this health disparity. The purpose of this investigation was to examine factors associated with prenatal depressive symptoms, including plasma oxytocin levels and birth weight, in a sample of urban African-American women. Pregnant African-American women (N = 57) completed surveys and had blood drawn twice during pregnancy at 15-22 weeks and 25-37 weeks. In addition, birth data were collected from medical records. A large number of participants reported elevated prenatal depressive symptoms at the first (n = 20, 35 %) and the second (n = 19, 33 %) data points. Depressive symptoms were higher in multigravidas (t(51) = -2.374, p = 0.02), women with higher anxiety (r(47) = 0.71, p = 0.001), women who delivered their infants at an earlier gestational age (r(51) = -0.285, p = 0.04), and those without the support of the infant's father (F(4, 48) = 2.676, p = 0.04). Depressive symptoms were also higher in women with low oxytocin levels than in women with high oxytocin levels (F(2, 47) = 3.3, p = 0.05). In addition, women who had low oxytocin tended to have infants with lower birth weights (F(2, 47) = 2.9, p = 0.06). Neither prenatal depressive symptoms nor prenatal oxytocin levels were associated with premature birth. Pregnant multigravida African-American women with increased levels of anxiety and lacking the baby's father's support during the pregnancy are at higher risk for prenatal depressive symptoms. Prenatal depressive symptoms are associated with low oxytocin levels and lower infant birth weights. Further research is needed to understand the mechanisms between prenatal depressive symptoms, oxytocin, and birth weight in order to better understand this health disparity.

Oxytocin, testosterone, and human social cognition

I describe an integrative social-evolutionary model for the adaptive significance of the human oxytocinergic system. The model is based on a role for this hormone in the generation and maintenance of social familiarity and affiliation across five homologous, functionally similar, and sequentially co-opted contexts: mothers with offspring, female and male mates, kin groups, individuals with reciprocity partners, and individuals within cooperating and competing social groups defined by culture. In each situation, oxytocin motivates, mediates and rewards the cognitive and behavioural processes that underlie the formation and dynamics of a more or less stable social group, and promotes a relationship between two or more individuals. Such relationships may be positive (eliciting neurological reward, reducing anxiety and thus indicating fitness-enhancing effects), or negative (increasing anxiety and distress, and thus motivating attempts to alleviate a problematic, fitness-reducing social situation). I also present evidence that testosterone exhibits opposite effects from oxytocin on diverse aspects of cognition and behaviour, most generally by favouring self-oriented, asocial and antisocial behaviours. I apply this model for effects of oxytocin and testosterone to understanding human psychological disorders centrally involving social behaviour. Reduced oxytocin and higher testosterone levels have been associated with under-developed social cognition, especially in autism. By contrast, some combination of oxytocin increased above normal levels, and lower testosterone, has been reported in a notable number of studies of schizophrenia, bipolar disorder and depression, and, in some cases, higher oxytocin involves maladaptively 'hyper-developed' social cognition in these conditions. This pattern of findings suggests that human social cognition and behaviour are structured, in part, by joint and opposing effects of oxytocin and testosterone, and that extremes of such joint effects partially mediate risks and phenotypes of autism and psychotic-affective conditions. These considerations have direct implications for the development of therapies for alleviating disorders of social cognition, and for understanding how such disorders are associated with the evolution of human cognitive-affective architecture.

Social cognition

Social cognition is a major problem underlying deficiencies in interpersonal relationships in several psychiatric populations. And yet there is currently no gold standard for pharmacological treatment of psychiatric illness that directly targets these social cognitive areas. This chapter serves to illustrate some of the most innovative attempts at pharmacological modulation of social cognition in psychiatric illnesses including schizophrenia, borderline personality disorder, autism spectrum disorders, antisocial personality disorder and psychopathy, social anxiety disorder, and posttraumatic stress disorder. Pharmacological modulation includes studies administering oxytocin, ecstasy (MDMA), modafinil, methylphenidate, and D-cycloserine. Furthermore, some background on social cognition research in healthy individuals, which could be helpful in developing future treatments, is provided as well as the potential for each drug as a long-term treatment option.

Neurobiology of Maternal Stress: Role of Social Rank and Central Oxytocin in Hypothalamic-Pituitary Adrenal Axis Modulation

BACKGROUND

Chronic stress may conceivably require plasticity of maternal physiology and behavior to cope with the conflicting primary demands of infant rearing and foraging for food. In addition, social rank may play a pivotal role in mandating divergent homeostatic adaptations in cohesive social groups. We examined cerebrospinal fluid (CSF) oxytocin (OT) levels and hypothalamic-pituitary adrenal (HPA) axis regulation in the context of maternal social stress and assessed the contribution of social rank to dyadic distance as reflective of distraction from normative maternal-infant interaction.

METHODS

Twelve socially housed mother-infant bonnet macaque dyads were studied after variable foraging demand (VFD) exposure compared to 11 unstressed dyads. Dyadic distance was determined by behavioral observation. Social ranking was performed blindly by two observers. Post-VFD maternal plasma cortisol and CSF OT were compared to corresponding measures in non-VFD-exposed mothers.

RESULTS

High-social rank was associated with increased dyadic distance only in VFD-exposed dyads and not in control dyads. In mothers unexposed to VFD, social rank was not related to maternal cortisol levels, whereas VFD-exposed dominant versus subordinate mothers exhibited increased plasma cortisol. Maternal CSF OT directly predicted maternal cortisol only in VFD-exposed mothers. CSF OT was higher in dominant versus subordinate mothers. VFD-exposed mothers with "high" cortisol specifically exhibited CSF OT elevations in comparison to control groups.

CONCLUSION

Pairing of maternal social rank to dyadic distance in VFD presumably reduces maternal contingent responsivity, with ensuing long-term sequelae. VFD-exposure dichotomizes maternal HPA-axis response as a function of social rank with relatively reduced cortisol in subordinates. OT may serve as a homeostatic buffer during maternal stress exposure.

A Role for Oxytocin in the Etiology and Treatment of Schizophrenia

Schizophrenia is a chronic debilitating neuropsychiatric disorder estimated to affect 51 million people worldwide. Several symptom domains characterize schizophrenia, including negative symptoms, such as social withdrawal and anhedonia, cognitive impairments, such as disorganized thinking and impaired memory, and positive symptoms, such as hallucinations and delusions. While schizophrenia is a complex neuropsychiatric disorder with no single "cause," there is evidence that the oxytocin (Oxt) system may be dysregulated in some individuals. Further, treatment with intranasal Oxt reduces some of the heterogeneous symptoms associated with schizophrenia. Since Oxt is known for its modulatory effects on a variety of social and non-social behaviors, it is perhaps not surprising that it may contribute to some aspects of schizophrenia and could also be a useful therapeutic agent. In this review, we highlight what is known about Oxt's contributions to schizophrenia and schizophrenia-related behaviors and discuss its potential as a therapeutic agent.

Oxytocin and vasopressin levels are decreased in the plasma of male schizophrenia patients

OBJECTIVE

Impaired social functioning and autistic symptoms are characteristics of schizophrenia. The social hormones oxytocin (OT) and arginine-vasopressin (AVP) both modulate social interaction and therefore may be involved in the pathogenesis of schizophrenia. We investigated whether men with schizophrenia show altered OT and AVP levels compared with healthy controls (HC) and whether autism symptoms are associated with OT levels.

METHODS

Forty-one men with non-acute schizophrenia and 45 matched HC were enrolled. Schizophrenia was assessed with the Positive and Negative Syndrome Scale (PANSS). Blood samples were collected on 2 days, and plasma OT and AVP levels were measured by ELISA immunoassay.

RESULTS

The schizophrenia patients had significantly lower plasma OT levels than the HC; a similar trend was found for AVP. Plasma OT levels were associated with severe life events, fewer important attached persons, and a higher score on the PANSS negative scale; the most dominant PANSS items were 'preoccupation', 'emotional withdrawal', and 'passive/apathetic social withdrawal'.

CONCLUSION

These findings support an association between the social hormones OT and AVP and schizophrenia. We suggest that OT metabolism may be altered in schizophrenia, but other possible causes for decreased plasma OT levels in schizophrenia patients include decreased OT synthesis, mRNA expression, and translation. Especially the 'autistic' symptoms of schizophrenia seem to be closely linked to an altered metabolism of OT, the 'attachment' hormone.

The role of oxytocin in empathy to the pain of conflictual out-group members among patients with schizophrenia

BACKGROUND

Oxytocin (OT) is associated with our ability to empathize and has been shown to play a major role in mediating social behaviors within the context of intergroup dynamics. Schizophrenia is associated with impaired empathy, and with a dysfunctional oxytocinergic system. The effect of OT on the empathic responses of patients with schizophrenia within the context of intergroup relationships has not been studied. The present study examined the effect of OT on the patients' empathic responses to pain experienced by in-group, conflictual out-group and neutral out-group members.

METHOD

In a double-blind, placebo-controlled, within-subject cross-over design, the responses on the Pain Evaluation Task of 28 male patients with schizophrenia were compared to 27 healthy male controls. All participants received a single intranasal dose of 24 IU OT or placebo, 1 week apart.

RESULTS

OT induced an empathy bias in the healthy controls towards the conflictual out-group members. Although this effect was absent in the patient group, OT seems to heighten an empathic bias in the patient group towards the in-group members when rating non-painful stimuli.

CONCLUSIONS

The study demonstrates that the administration of OT can result in empathic bias towards adversary out-group members in healthy controls but not in patients with schizophrenia. However, the OT-induced bias in both the patients (in the no-pain condition towards the in-group members) and the healthy controls (in the no-pain and pain conditions towards the adversary out-group) suggests that OT enhances the distinction between conflictual in-group and out-group members.

Social approach and avoidance behaviour for negative emotions is modulated by endogenous oxytocin and paranoia in schizophrenia

Patients with schizophrenia suffer from dysfunctional social behaviour. Social approach and avoidance (AA) has been associated with motor responses, as the affective valence and gaze direction of facial stimuli can bias push and pull motor tendencies. The aim of this study was to investigate the role of endogenous oxytocin in social AA behaviour in schizophrenia. Basal plasma oxytocin levels were collected from 28 patients who were then given a joystick-based Approach-Avoidance Task (AAT). Reaction times were recorded and AAT effect scores calculated for responses to happy and angry faces, which either had direct or averted gaze. Individual differences in basal oxytocin had a significant relationship with AAT responses, and patients with higher levels of oxytocin tended to avoid angry faces more. Furthermore, greater avoidance of angry faces was correlated with more severe psychotic (positive and general) symptoms and greater paranoia. This suggests that the endogenous effects of oxytocin may be specific to the interpretation of negative threatening emotions in schizophrenia patients, and also provides evidence that psychotic symptoms and paranoia can impact on social AA behaviour by heightening threat avoidance.

Reduced levels of vasopressin and reduced behavioral modulation of oxytocin in psychotic disorders

Oxytocin (OT) and arginine vasopressin (AVP) exert robust influence on social affiliation and specific cognitive processes in healthy individuals. Abnormalities in these neuroendocrine systems have been observed in psychotic disorders, but their relation to impairments in behavioral domains that these endocrines modulate is not well understood. We compared abnormalities of OT and AVP serum concentrations in probands with schizophrenia (n = 57), schizoaffective disorder (n = 34), and psychotic bipolar disorder (n = 75); their first-degree relatives without a history of psychosis (n = 61, 43, 91, respectively); and healthy controls (n = 66) and examined their association with emotion processing and cognition. AVP levels were lower in schizophrenia (P = .002) and bipolar probands (P = .03) and in relatives of schizophrenia probands (P = .002) compared with controls. OT levels did not differ between groups. Familiality estimates were robust for OT (h(2) = 0.79, P = 3.97e-15) and AVP (h(2) = 0.78, P = 3.93e-11). Higher levels of OT were associated with better emotion recognition (β = 0.40, P < .001) and general neuropsychological function (β = 0.26, P = .04) in healthy controls as expected but not in any proband or relative group. In schizophrenia, higher OT levels were related to greater positive symptom severity. The dissociation of OT levels and behavioral function in all proband and relative groups suggests that risk and illness factors associated with psychotic disorders are not related to reduced OT levels but to a disruption in the ability of physiological levels of OT to modulate social cognition and neuropsychological function. Decreased AVP levels may be a marker of biological vulnerability in schizophrenia because alterations were seen in probands and relatives, and familiality was high.

Learning about oxytocin: pharmacologic and behavioral issues

Despite the accumulating evidence suggesting that the neuropeptide oxytocin (OT) plays a role in neuropsychiatric disorders characterized by social dysfunction, the influence of OT on the nonsocial aspects of learning and memory have been less investigated. To foster research in this area, we review the effects of OT on learning and memory in animal models and humans. In healthy animal models, OT improves memory consolidation and extinction, but only if given at a low dose immediately after the acquisition phase. On the contrary, OT effects in healthy humans have been inconsistent; although, in this case, OT was always given before the acquisition phase and no dose-response curves have ever been drawn up. Interestingly, a specific impairment in the reversal of learning has been found in mice devoid of OT receptors and OT has been demonstrated to enhance fear extinction in rodents. All together, these data suggest that OT plays a role in elementary forms of behavioral flexibility and adaptive responses and support its therapeutic potential in neuropsychiatric disorders characterized by cognitive inflexibility and/or impairment (autism, schizophrenia, Alzheimer's disease, Parkinson disease, stroke, posttraumatic stress disorder). Accordingly, OT has been shown to improve cognitive flexibility in OT receptor-deficient mice, and scattered findings indicate that intranasal OT has positive effects on the memory of patients with schizophrenia or posttraumatic stress disorders. Further studies of the therapeutic potential of OT as an enhancer of learning and memory are warranted.

[Oxytocin: evidence for a therapeutic potential of the social neuromodulator]

Only few substances have achieved such a great prominence in recent years as the hypothalamic neuropeptide oxytocin, which is also widely known as the love hormone. Oxytocin is a potent neuromodulator which can improve social cognitive functions including empathy, trust, cooperation and social learning. However, oxytocin can also promote negative social behavior and increase poor memory and feelings of fear in social situations. Positive data from initial clinical trials give rise to the hope that oxytocin will prove to be a substance which is suitable for targeted treatment of poor social-cognitive behavior in neuropsychiatric diseases. This review article summarizes the most important recent preclinical and clinical human studies and discusses the findings presented with respect to current concepts of personal and contextual influences.

A pilot six-week randomized controlled trial of oxytocin on social cognition and social skills in schizophrenia

The current study explored whether oxytocin can improve social cognition and social skills in individuals with schizophrenia using a six-week, double-blind design. Fourteen participants with schizophrenia were randomized to receive either intranasal oxytocin or a placebo solution and completed a battery of social cognitive, social skills and clinical psychiatric symptom measures. Results showed within group improvements in fear recognition, perspective taking, and a reduction in negative symptoms in the oxytocin group. These preliminary findings indicate oxytocin treatment may help improve certain components of functioning in schizophrenia. Implications for the treatment of social functioning in schizophrenia are discussed.

A meta-analysis and theoretical critique of oxytocin and psychosis: prospects for attachment and compassion in promoting recovery

OBJECTIVES

There is now considerable evidence that affiliative processes are linked to oxytocin (OXT), which is linked to a range of social-cognition competences underpinning interpersonal functioning. There is evidence that OXT circuitry is involved in psychosis and emerging evidence for OXT in treatment. Therefore, this study explored studies investigating OXT and improvements in symptoms and social cognition among individuals diagnosed with psychosis.

METHOD

We conducted a systematic review of randomized controlled trials investigating OXT and psychosis. Specifically we asked, (1) what is the evidence that OXT is associated with improved overall, positive, negative and general symptoms and (2) what is the evidence that OXT is associated with improved social cognition?

RESULTS

There were seven randomized controlled trials that met the inclusion criteria for this review. We conducted an exploratory meta-analysis of data from four of these studies on a total sample size of n = 105. For overall symptoms, using a random-effects model OXT versus placebo was associated with an effect size of d = 0.52 (95% CI = 0.34-0.70; z = 5.66; p < .01). There was evidence of significant heterogeneity (Q = 96.4, p < .001; I(2) = 96.5%). Similar patterns of findings were observed for positive, negative, and general symptoms. We found significant evidence of high risk of bias across all studies. We also identified that one particular study had an undue effect on overall effect size estimates. Finally, evidence regarding OXT was linked to improved social cognition was inconsistent.

CONCLUSIONS

There are significant problems in interpreting the current evidence base for OXT in psychosis. However, OXT may provide a useful biomarker for exploring mechanisms of change occurring in psychological therapies including compassion-focused therapy (CFT), which through its engagement of the attachment system may directly influence OXT.

Negative symptoms of schizophrenia: clinical characteristics, pathophysiological substrates, experimental models and prospects for improved treatment

Schizophrenia is a complex and multifactorial disorder generally diagnosed in young adults at the time of the first psychotic episode of delusions and hallucinations. These positive symptoms can be controlled in most patients by currently-available antipsychotics. Conversely, they are poorly effective against concomitant neurocognitive dysfunction, deficits in social cognition and negative symptoms (NS), which strongly contribute to poor functional outcome. The precise notion of NS has evolved over the past century, with recent studies - underpinned by novel rating methods - suggesting two major sub-domains: "decreased emotional expression", incorporating blunted affect and poverty of speech, and "avolition", which embraces amotivation, asociality and "anhedonia" (inability to anticipate pleasure). Recent studies implicate a dysfunction of frontocortico-temporal networks in the aetiology of NS, together with a disruption of cortico-striatal circuits, though other structures are also involved, like the insular and parietal cortices, amygdala and thalamus. At the cellular level, a disruption of GABAergic-glutamatergic balance, dopaminergic signalling and, possibly, oxytocinergic and cannibinoidergic transmission may be involved. Several agents are currently under clinical investigation for the potentially improved control of NS, including oxytocin itself, N-Methyl-d-Aspartate receptor modulators and minocycline. Further, magnetic-electrical "stimulation" strategies to recruit cortical circuits and "cognitive-behavioural-psychosocial" therapies likewise hold promise. To acquire novel insights into the causes and treatment of NS, experimental study is crucial, and opportunities are emerging for improved genetic, pharmacological and developmental modelling, together with more refined readouts related to deficits in reward, sociality and "expression". The present article comprises an integrative overview of the above issues as a platform for this Special Issue of European Neuropsychopharmacology in which five clinical and five preclinical articles treat individual themes in greater detail. This Volume provides, then, a framework for progress in the understanding - and ultimately control - of the debilitating NS of schizophrenia.

Plasma oxytocin concentrations are lower in depressed vs. healthy control women and are independent of cortisol

The neuropeptide oxytocin (OT) promotes social behavior and attenuates stress responsivity in mammals. Recent clinical evidence suggests OT concentrations may be dysregulated in major depression. This study extends previous research by testing whether: 1) OT concentrations vary systematically in depressive disorders with and without hypercortisolemia, 2) gender differences in OT concentrations are observed in depressed vs. healthy control participants, and 3) OT concentrations are predictive of clinical phenotypes. Plasma OT concentrations of psychotic major depressive (PMD; n = 14: 10 female, 4 male), non-psychotic major depressive (NPMD; n = 17: 12 female, 5 male), and non-depressed, healthy control (n = 19: 11 female, 8 male) participants were assayed at 2000, 2400, 0400, and 0800 h. Plasma cortisol concentrations were quantified at 2300 h, and clinical phenotypes were determined. As expected, PMD participants, compared to NPMD and healthy control participants, showed higher plasma cortisol concentrations. Although both depressed groups showed similar OT concentrations, a significant interaction effect between group and gender was observed. Specifically, depressed females exhibited lower mean OT concentrations than depressed males. Further, depressed vs. healthy control female participants exhibited lower mean OT concentrations, whereas depressed vs. healthy control male participants showed a trend in the opposite direction. OT concentrations were also predictive of desirability, drug dependence, and compulsivity scores as measured by the Million Clinical Multiaxial Inventory-III. All findings were independent of cortisol. These data suggest that OT signaling may provide a mechanism by which to better understand female-biased risk to develop depressive disorders and that plasma OT concentrations may be a useful biomarker of certain clinical phenotypes.

Sex-specific associations between plasma oxytocin levels and schizotypal personality features in healthy individuals

OBJECTIVES

Oxytocin (OT) has been shown to play a crucial role in the biology of social interaction. Sex differences associated with this neuropeptide system have been reported. OT may serves as an indicator of interpersonal stress, especially in women. The aim of this study was to investigate the sex-specific associations between plasma OT levels and schizotypal personality features, especially in interpersonal dimension, in healthy individuals.

METHODS

Ninety six healthy participants, including 41 males and 55 females, were recruited. Fasting blood samples were analyzed by enzyme immunoassay of OT. The Schizotypal Personality Questionnaire (SPQ) was administered. Mann-Whitney U test was used to test the difference between male and female. Spearman's ρ correlation analysis (two-tailed) was carried out to examine the association between OT level and SPQ score.

RESULTS

The results showed that OT level was significantly positively correlated with total score and interpersonal dysfunction dimensional scores of the SPQ only in females.

CONCLUSIONS

Although the causal relationship remains unclear, our findings provide further evidence to support the sexual dimorphic role of OT in interpersonal biology. Moreover, the effect of sex difference also is taken into consideration.

Gene-sex interactions in schizophrenia: focus on dopamine neurotransmission

Schizophrenia is a severe mental disorder, with a highly complex and heterogenous clinical presentation. Our current perspectives posit that the pathogenic mechanisms of this illness lie in complex arrays of gene × environment interactions. Furthermore, several findings indicate that males have a higher susceptibility for schizophrenia, with earlier age of onset and overall poorer clinical prognosis. Based on these premises, several authors have recently begun exploring the possibility that the greater schizophrenia vulnerability in males may reflect specific gene × sex (G×S) interactions. Our knowledge on such G×S interactions in schizophrenia is still rudimentary; nevertheless, the bulk of preclinical evidence suggests that the molecular mechanisms for such interactions are likely contributed by the neurobiological effects of sex steroids on dopamine (DA) neurotransmission. Accordingly, several recent studies suggest a gender-specific association of certain DAergic genes with schizophrenia. These G×S interactions have been particularly documented for catechol-O-methyltransferase (COMT) and monoamine oxidase (MAO), the main enzymes catalyzing DA metabolism. In the present review, we will outline the current evidence on the interactions of DA-related genes and sex-related factors, and discuss the potential molecular substrates that may mediate their cooperative actions in schizophrenia pathogenesis.

Schizophrenia and alcohol dependence: diverse clinical effects of oxytocin and their evolutionary origins

Beginning in 1979 with the first report that central administration of oxytocin stimulates maternal behavior in virgin rats, decades of animal research and more recent human studies have demonstrated that oxytocin has many pro-social effects. These many findings suggest that oxytocin may be an effective treatment for social deficits that are hallmark features of disorders such as autism and schizophrenia. Effects in preclinical animal models also imply that oxytocin may be an efficacious pharmacotherapy in a wide range of psychiatric disorders including psychoses and addictions. To date, 3 small clinical trials found that daily intranasal oxytocin treatment for 2-8 weeks significantly reduced psychotic symptoms in schizophrenia. Two of these trials also found improvement in social cognition or neurocognition, areas in which patients have significant deficiencies that do not respond to conventional antipsychotic treatment and contribute to disability. In another small trial, intranasal oxytocin potently blocked alcohol withdrawal. After reviewing the rationale for these trials, they are described in more detail. Questions are then asked followed by discussions of the large gaps in our knowledge about brain oxytocin systems in humans. The hope is to highlight important directions for future investigations of the role of oxytocin in the pathophysiology of psychotic disorders and addictions and to extend clinical research in these areas. Heretofore unrecognized roles for which oxytocin may have been selected during the evolution of placental mammalian maternal-infant and other social attachments are considered as possible origins of oxytocin antipsychotic and antiaddiction effects.This article is part of a Special Issue entitled Oxytocin and Social Behav.

Oxytocin's role in anxiety: a critical appraisal

A growing literature suggests that the oxytocin (OT) system may play a role in human anxiety states, anxiety-related traits, and moreover, that this system may be a target for the development of novel anxiolytic treatments. However, studies of OT's acute and chronic effects on various aspects of anxiety have produced mixed results. In this forward-looking review, we discuss the myriad phenomena to which the term "anxiety" is applied in the OT literature and the problem this presents developing a coherent picture of OT's role in anxiety. We then survey several different fields of research that support the role of the OT system in human anxiety, including evolutionary perspectives, translational and neuroimaging research, genetic studies, and clinical trials of intranasal OT. As an outgrowth of this data, we propose a "bowtie" model of OT's role at the interface of social attachment and anxiety. We next direct attention to understudied brain regions and neural circuits which may be important to study in OT experiments in humans anxiety disorders. Finally, we conclude by proposing questions and priorities for studying both the clinical potential of OT in anxiety, as well as mechanisms that may underlie this potential. Crucially, these priorities include targeted proof-of-concept clinical trials of IN OT in certain anxiety disorders, including investigations of individual moderators of OT's anxiolytic effects (i.e. sex, genetic factors, and early experience). This article is part of a Special Issue entitled Oxytocin and Social Behav.

May oxytocin be a trait marker for bipolar disorder?

There is evidence to suggest that oxytocin is effective in stabilizing mood in humans. Lower plasma oxytocin levels have been reported in patients with major depression. The objective of this study was to investigate serum oxytocin levels during manic and depressive episodes and in the remission period in patients with bipolar disorder. Twenty-two patients in manic episode, 21 in depressive episode, and 24 in remission at the initial phase, ranging from 18 to 65 years of age, who were diagnosed with BD Type I and 24 healthy individuals were included in this study. Blood samples were collected from subjects in the morning at the beginning of the study. A second blood sampling was obtained from manic and depressive patients after response to treatment. MANCOVA was performed to compare the oxytocin values of the groups. The serum oxytocin levels of patients in manic episode were statistically significantly higher than those of the depressive episode and remission groups and of the healthy subjects. The serum oxytocin levels of patients in the depressive episode group and in the remission group were statistically significantly higher than those of the control group. The serum oxytocin levels of the manic episode and depressive episode patients after response to treatment were statistically significantly higher than those of the control group, and there was no statistically significant difference between the patient groups in serum oxytocin levels. The higher oxytocin levels observed in patient groups, compared to the controls, before and after response to treatment suggest that oxytocin may be a trait marker in BD.

Role of oxytocin signaling in the regulation of body weight

Obesity and its associated metabolic disorders are growing health concerns in the US and worldwide. In the US alone, more than two-thirds of the adult population is classified as either overweight or obese [1], highlighting the need to develop new, effective treatments for these conditions. Whereas the hormone oxytocin is well known for its peripheral effects on uterine contraction during parturition and milk ejection during lactation, release of oxytocin from somatodendrites and axonal terminals within the central nervous system (CNS) is implicated in both the formation of prosocial behaviors and in the control of energy balance. Recent findings demonstrate that chronic administration of oxytocin reduces food intake and body weight in diet-induced obese (DIO) and genetically obese rodents with impaired or defective leptin signaling. Importantly, chronic systemic administration of oxytocin out to 6 weeks recapitulates the effects of central administration on body weight loss in DIO rodents at doses that do not result in the development of tolerance. Furthermore, these effects are coupled with induction of Fos (a marker of neuronal activation) in hindbrain areas (e.g. dorsal vagal complex (DVC)) linked to the control of meal size and forebrain areas (e.g. hypothalamus, amygdala) linked to the regulation of food intake and body weight. This review assesses the potential central and peripheral targets by which oxytocin may inhibit body weight gain, its regulation by anorexigenic and orexigenic signals, and its potential use as a therapy that can circumvent leptin resistance and reverse the behavioral and metabolic abnormalities associated with DIO and genetically obese models.

The role of oxytocin in psychiatric disorders: a review of biological and therapeutic research findings

LEARNING OBJECTIVES

After participating in this educational activity, the physician should be better able to 1. Identify the biological role of oxytocin in forming attachments. 2. Evaluate the relationship between various neuropsychiatric disorders and oxytocin. 3. Identify clinical implications of using oxytocin to treat various neuropsychiatric disorders. Oxytocin is a peptide hormone integral in parturition, milk letdown, and maternal behaviors that has been demonstrated in animal studies to be important in the formation of pair bonds and in social behaviors. This hormone is increasingly recognized as an important regulator of human social behaviors, including social decision making, evaluating and responding to social stimuli, mediating social interactions, and forming social memories. In addition, oxytocin is intricately involved in a broad array of neuropsychiatric functions and may be a common factor important in multiple psychiatric disorders such as autism, schizophrenia, and mood and anxiety disorders. This review article examines the extant literature on the evidence for oxytocin dysfunction in a variety of psychiatric disorders and highlights the need for further research to understand the complex role of the oxytocin system in psychiatric disease and thus pave the way for developing new therapeutic modalities. Articles were selected that involved human participants with various psychiatric disorders and that either compared oxytocin biology to healthy controls or examined the effects of exogenous oxytocin administration.

Phospholipase C-β1 and schizophrenia-related behaviors

Abnormal expression patterns of phospholipase C-β1(PLC-β1) in specific brain areas of patients with schizophrenia, and its high genetic linkage to the disorder implicated a pathogenetical involvement of PLC-β1 signaling system. The schizophrenia-related behavioral phenotypes displayed in the mutant mice lacking PLC-β1 (PLC-β1 KO) suggested that PLCβ1-linked signaling pathways may be involved in the neural system whose function is disrupted in the pathogenesis of schizophrenia. In the brain, PLC-β1 is known to be linked to muscarinic acetylcholine receptors, metabotropic glutamatergic, serotonergic, and oxytocinergic systems. The objective of this review is to provide an overview of the current knowledge regarding these schizophrenia-related behaviors and discuss the probable ways in which PLC-β1signalling can be involved in the neural mechanisms for each behavior, which may help suggest future directions for research in this area.

Oxytocin and oxytocin receptor gene polymorphisms and risk for schizophrenia: a case-control study

OBJECTIVES

Dysfunctions of the "social brain" belong to the core features of schizophrenia. The neurohormone oxytocin (OXT), mediated through its specific receptor (OXTR), is involved in the regulation of social behaviour and social cognition. Previous research has suggested a role of OXT system genes in disorders of social reciprocity. Preliminary evidence points to an association of peripheral OXT levels as well as OXT and OXTR gene polymorphisms with psychotic symptoms and treatment response in schizophrenia. This study aims to determine a possible contribution of OXT and OXTR genetic variations to schizophrenia susceptibility.

METHODS

Using n = 406 individuals diagnosed with schizophrenia according to DSM-IV and n = 406 healthy controls matched for age and gender in a case-control design, two single nucleotide polymorphisms (SNPs) within the OXT gene (rs2740204, rs2740210) and four SNPs within the OXTR gene (rs53576, rs237880, rs237885, rs237902) that were previously investigated in other studies were genotyped.

RESULTS

Chi(2)-testing suggested significant associations of OXTR SNPs rs53576(A > G) (P = 0.008) and rs237885(T > G) (P = 0.025) with a diagnosis of schizophrenia. Post-hoc ANCOVA revealed significant associations of OXTR SNPs rs53576 with general psychopathology and rs237902 with negative symptom scores in schizophrenic patients.

CONCLUSIONS

Our findings support hypotheses about an involvement of oxytocinergic gene variants in schizophrenia vulnerability and warrant independent replication.

Characterization of the effects of oxytocin on fear recognition in patients with schizophrenia and in healthy controls

Individuals who suffer from schizophrenia often show a marked deficit in recognition of emotional facial expressions, as part of broader impairment of social cognition. Research has shown that recognition of negative emotions, specifically fear recognition, is particularly impaired among patients with schizophrenia. Recently we reported that intranasal administration of OT (IN OT) increased the ability to correctly recognize fear in a group of healthy men. The aim of the current study was to examine the effects of IN OT administration on fear recognition among patients with schizophrenia. Based on previous research, we also sought to examine a possible selective effect of OT dependent on baseline performance, hypothesizing that IN OT would have a greater enhancement effect on less proficient individuals. It was thus hypothesized that patients will show more improvement in fear recognition following the administration of IN OT as compared to controls. Sixty six participants (31 schizophrenia patients, 35 healthy controls) were enrolled in the current study. All participants received treatment of a single dose of 24 IU IN OT and an equivalent amount of placebo, 1 week apart. The participants' ability to accurately recognize fear and happiness was evaluated using a face morphing task. Overall, as a group, both patients and healthy control participants were more accurate in recognizing fearful facial expressions, but not happy faces, following IN OT administration, as compared to their performance following placebo. IN OT did not differentially affect emotion recognition in patients and healthy controls. Yet, the results indicated a selective effect for IN OT, in which the hormone improves fear recognition only among individuals whose baseline performance was below the median, regardless of their psychiatric status.

Differential correlations between plasma oxytocin and social cognitive capacity and bias in schizophrenia

Social cognitive impairment is related to poor social functioning in schizophrenia. This impairment includes both deficits in emotion perception and theory of mind (ToM), and cognitive biases including attributional bias and jumping to conclusions. Oxytocin (OXT) is a hormone that has been implicated in human social behavior, and that has also been associated with regulation of inflammation. In a cross-sectional study involving 60 patients with schizophrenia and 20 healthy controls, we examined associations between OXT and social cognitive capacity and bias. Secondary analyses examined associations between OXT and inflammation. We found significant correlations between OXT and social cognitive bias in the control group and in patients with delusions, but not in patients without delusions. Social cognitive capacity only correlated significantly with OXT in patients with delusions. A correlation between OXT and inflammation was observed only in patients without delusions. Findings suggest that OXT may be implicated in social cognition both in controls and in patients with delusions, but that this association may be blunted in patients without delusions. Inflammation appears to be related to OXT rather independently of social cognition. Future longitudinal and intervention studies with OXT are needed to clarify causality in the identified associations.

Men perform comparably to women in a perspective taking task after administration of intranasal oxytocin but not after placebo

Oxytocin (OT) is thought to play an important role in human interpersonal information processing and behavior. By inference, OT should facilitate empathic responding, i.e., the ability to feel for others and to take their perspective. In two independent double-blind, placebo-controlled between-subjects studies, we assessed the effect of intranasally administered OT on affective empathy and perspective taking, whilst also examining potential sex differences (e.g., women being more empathic than men). In study 1, we provided 96 participants (48 men) with an empathy scenario and recorded self-reports of empathic reactions to the scenario, while in study 2, a sample of 120 individuals (60 men) performed a computerized implicit perspective taking task. Whilst results from Study 1 showed no influence of OT on affective empathy, we found in Study 2 that OT exerted an effect on perspective taking ability in men. More specifically, men responded faster than women in the placebo group but they responded as slowly as women in the OT group. We conjecture that men in the OT group adopted a social perspective taking strategy, such as did women in both groups, but not men in the placebo group. On the basis of results across both studies, we suggest that self-report measures (such as used in Study 1) might be less sensitive to OT effects than more implicit measures of empathy such as that used in Study 2. If these assumptions are confirmed, one could infer that OT effects on empathic responses are more pronounced in men than women, and that any such effect is best studied using more implicit measures of empathy rather than explicit self-report measures.

Towards a neuroscience of empathy: ontogeny, phylogeny, brain mechanisms, context and psychopathology

Empathy allows individuals to share the affective states of others, predict others' actions, and stimulate prosocial behavior. Whilst the proximate mechanisms of empathy, modulated in part by neuropeptides such as oxytocin, control the ways we interact with our social environment, the ultimate causes seem to have arisen along with the mechanisms involved in mammalian parental care. The conceptual boundaries of empathy, however, have been blurred by definitional inaccuracies of mechanisms that can be regarded as phylogenetic precursors or physiological prerequisites for empathy, including mimicry and emotion contagion. Contextual factors such as early experiences with primary care-givers (attachment), current mood states and other environmental contingencies are capable of modulating empathy. Moreover, evidence suggests that there is also a "dark side" of empathy, namely envy and schadenfreude (gloating) that are elicited by social comparison, competition and ingroup-outgroup distinction. This review aims at clarifying some of the open definitional questions related to empathy, and emphasizing the need for considering contextual factors in the study of empathy in both normal and abnormal psychology.

Improving social perception in schizophrenia: the role of oxytocin

Previous research has shown that patients with schizophrenia are impaired in a wide range of social cognitive abilities, including emotion recognition, empathy for others, and mental perspective-taking. Recent studies suggest that a dysfunction of the oxytocinergic system contributes to the social impairment in schizophrenia. Accordingly, the present study sought to examine whether patients with schizophrenia would improve in a social perception task after taking a single dose of oxytocin, as compared to a placebo. Thirty-five patients diagnosed with schizophrenia were compared with 46 psychologically healthy matched controls on their recognition of kinship and intimacy, using the Interpersonal Perception Task. All participants received a single intranasal dose of 24 IU oxytocin or placebo, one week apart. Overall, the participants were more accurate in judging intimacy and kinship following the administration of oxytocin, as opposed to a placebo. However, when comparing patients with controls, only the recognition of kinship improved significantly in the patient group, whereas no such effect was observed in the control group or in the recognition of intimacy in either group. This is one of the first studies to demonstrate that social perception in schizophrenia can be improved by the administration of oxytocin and that patients show a greater treatment effect than controls.

Sniffing around oxytocin: review and meta-analyses of trials in healthy and clinical groups with implications for pharmacotherapy

The popularity of oxytocin (OT) has grown exponentially during the past decade, and so has the number of OT trials in healthy and clinical groups. We take stock of the evidence from these studies to explore potentials and limitations of pharmacotherapeutic applications. In healthy participants, intranasally administered OT leads to better emotion recognition and more trust in conspecifics, but the effects appear to be moderated by context (perceived threat of the 'out-group'), personality and childhood experiences. In individuals with untoward childhood experiences, positive behavioral or neurobiological effects seem lowered or absent. In 19 clinical trials, covering autism, social anxiety, postnatal depression, obsessive-compulsive problems, schizophrenia, borderline personality disorder and post-traumatic stress, the effects of OT administration were tested, with doses ranging from 15 IU to more than 7000 IU. The combined effect size was d=0.32 (N=304; 95% confidence interval (CI): 0.18-0.47; P<0.01). However, of all disorders, only studies on autism spectrum disorder showed a significant combined effect size (d=0.57; N=68; 95% CI: 0.15-0.99; P<0.01). We hypothesize that for some of the other disorders, etiological factors rooted in negative childhood experiences may also have a role in the diminished effectiveness of treatment with OT.

Peripheral vasopressin but not oxytocin relates to severity of acute psychosis in women with acutely-ill untreated first-episode psychosis

BACKGROUND

In women with chronic schizophrenia, higher levels of peripheral oxytocin have been associated with lower levels of positive but not negative symptoms. Sex-specific associations between endogenous levels of oxytocin (OT) and arginine vasopressin (AVP) with clinical symptoms and cognition in untreated early course patients have not been examined.

METHOD

Clinical ratings and neuropsychological testing were performed in thirty-eight acutely ill, unmedicated first-episode schizophrenia patients (14 women, 24 men). Serum hormone assays were obtained in patients and thirty-eight demographically similar healthy controls.

RESULTS

Patients demonstrated increased AVP levels compared to controls (p = 0.01). Higher AVP levels were associated with greater positive symptoms (r = 0.58, p = 0.03) and worse verbal learning (r = -0.63, p = 0.02) in female, but not male, patients. OT levels did not statistically differ between patients and controls, and were unrelated to clinical symptoms or cognition in patients.

CONCLUSION

Results suggest an association of endogenous AVP with increased positive symptom severity and worse cognition in untreated female, but not male, schizophrenia patients. Findings support the role of neuroendocrine alterations in acute psychosis and the importance of examining sex-specific neuroendocrine alterations early in the course of schizophrenia.

Nocturnal oxytocin secretion is lower in amenorrheic athletes than nonathletes and associated with bone microarchitecture and finite element analysis parameters

OBJECTIVE

Preclinical data indicate that oxytocin, a hormone produced in the hypothalamus and secreted into the peripheral circulation, is anabolic to bone. Oxytocin knockout mice have severe osteoporosis, and administration of oxytocin improves bone microarchitecture in these mice. Data suggest that exercise may modify oxytocin secretion, but this has not been studied in athletes in relation to bone. We therefore investigated oxytocin secretion and its association with bone microarchitecture and strength in young female athletes.

DESIGN

Cross-sectional study of 45 females, 14-21 years (15 amenorrheic athletes (AA), 15 eumenorrheic athletes (EA), and 15 nonathletes (NA)), of comparable bone age and BMI.

METHODS

We used high-resolution peripheral quantitative CT to assess bone microarchitecture and finite element analysis to estimate bone strength at the weight-bearing distal tibia and non-weight-bearing ultradistal radius. Serum samples were obtained every 60  min, 2300-0700  h, and pooled for an integrated measure of nocturnal oxytocin secretion. Midnight and 0700  h samples were used to assess diurnal variation of oxytocin.

RESULTS

Nocturnal oxytocin levels were lower in AA and EA than in NA. After controlling for estradiol, the difference in nocturnal oxytocin between AA and NA remained significant. Midnight and 0700  h oxytocin levels did not differ between groups. At the tibia and radius, AA had impaired microarchitecture compared with NA. In AA, nocturnal oxytocin correlated strongly with trabecular and cortical microarchitecture, particularly at the non-weight-bearing radius. In regression models that include known predictors of microarchitecture in AA, oxytocin accounted for a substantial portion of the variability in microarchitectural and strength parameters.

CONCLUSIONS

Nocturnal oxytocin secretion is low in AA compared with NA and associated with site-dependent microarchitectural parameters. Oxytocin may contribute to hypoestrogenemic bone loss in AA.

Alternative pharmacologic targets for the treatment of schizophrenia: results from phase I and II trials

PURPOSE OF REVIEW

The current article provides a brief review of the clinical efficacy and safety outcomes from selected phase I and II clinical trials of compounds in development acting on targets beyond the dopamine D2 receptor in patients with schizophrenia.

RECENT FINDINGS

A number of experimental pharmacological targets have been studied in clinical trials. Among those, glutamatergic and nicotinergic pathways have received most attention. Glycine transporter 1 inhibitors used adjunctively with antipsychotics suggest efficacy for negative symptoms of schizophrenia. Adjunctive alpha7 nicotinic acetylcholine receptor agonists and minocycline may improve negative symptoms and cognitive deficits. Adjunctive oxytocin may benefit psychotic symptoms and social cognitive deficits. Adjunctive erythropoietin may improve cognitive function.

SUMMARY

Experimental therapeutic research for schizophrenia is rapidly expanding and a number of compounds with novel mechanisms of action are demonstrating encouraging evidence for efficacy across a range of symptoms. However, much work still needs to be conducted before these new agents can be considered for routine clinical treatment. In particular, further assessment of efficacy and longer term safety and tolerability monitoring are required.

Sex, receptors, and attachment: a review of individual factors influencing response to oxytocin

As discussed in the larger review in this special issue (MacDonald and Feifel), intranasal oxytocin (OT) is demonstrating a growing potential as a therapeutic agent in psychiatry. Importantly, research suggests that a variety of individual factors may influence a person's response to OT. In this mini-review, I provide a review of three: (1) sex and hormonal status; (2) genetic variation in aspects of the OT system (i.e., OT receptors); and (3) attachment history. Each of these factors will be important to monitor as we strive to develop a richer understanding of OT's role in human development, brain-based disease, and the potential for individualized, OT-targeted treatments.

The role of estrogen in the treatment of men with schizophrenia

Schizophrenia is a debilitating and pervasive mental illness with devastating effects on many aspects of psychological, cognitive and social wellbeing. Epidemiological and life-cycle data point to significant differences in the incidence and course of schizophrenia between men and women, suggesting that estrogen plays a "protective" role . Adjunctive estrogen therapy has been shown to be effective in enhancing the treatment of schizophrenia in women. In men, consideration of estrogen therapy has been impacted by concerns of feminisation, however, clinical trials using estrogen to treat prostate cancer, bone density loss and even aggression in men with dementia or traumatic brain injury, show estrogen to be a safe and effective therapy. Findings do, however, suggest that further exploration of a therapeutic role for adjunctive estradiol treatment in men with schizophrenia is warranted. The development of the new estrogen compounds - Selective Estrogen Receptor Modulators (SERMs) which do not cause feminisation - opens up the possibility of using a different type of estrogen for a longer period of time at higher doses. Estrogen could therefore prove to be an important component in the treatment of psychotic symptoms in men with schizophrenia. This review explains the scientific rationale behind the estrogen hypothesis and how it can be clinically utilised to address concerns unique to the care of men with schizophrenia.

Intranasal oxytocin as an adjunct to risperidone in patients with schizophrenia : an 8-week, randomized, double-blind, placebo-controlled study

BACKGROUND

Impairment of oxytocinergic function and/or oxytocin receptor genetic abnormalities has been demonstrated in patients with schizophrenia. Oxytocin reverses emotional recognition deficit and might restore sense of trust in patients with schizophrenia. Some short-term studies have shown efficacy and tolerability of oxytocin in patients with schizophrenia. However, there is a lack of evidence on the efficacy and tolerability of oxytocin in patients with schizophrenia beyond 3 weeks.

OBJECTIVE

The objective of this study was to assess the efficacy and tolerability of oxytocin intranasal spray (given as an adjuvant to risperidone) in patients with schizophrenia.

STUDY DESIGN

This was an 8-week, randomized, double-blind, placebo-controlled study.

STUDY SETTING

Inpatients of two large referral psychiatric hospitals in Iran were recruited for the study.

PATIENTS

Forty patients (male and female gender) aged 18-50 years with a diagnosis of schizophrenia (DSM-IV-TR) who were on a stable dose of risperidone for a minimum of 1 month and who were chronically partially responsive to antipsychotic monotherapy were included in the study.

INTERVENTIONS

The patients were randomly assigned to oxytocin intranasal spray (Syntocinon(®); Novartis, Basel, Switzerland) or placebo intranasal spray containing normal saline (ACER, Tehran, Iran) for 8 weeks. Oxytocin spray was administered as 20 IU (five sprays) twice a day for the first week followed by 40 IU (ten sprays) twice a day for the following 7 weeks. Placebo spray was administered at the same dose as the oxytocin spray. In addition, participants were on a stable dose of risperidone (5 or 6 mg/day).

OUTCOMES

The patients were assessed using Positive and Negative Syndrome Scale (PANSS) at baseline and at weeks 0, 2, 4, 6 and 8. Primary outcomes were the differences in the PANSS scores between the two groups at the end of the trial. Adverse effects were recorded using a checklist and the Extrapyramidal Symptom Rating Scale (ESRS) at baseline and at weeks 1, 2, 4, 6 and 8.

RESULTS

All patients had at least one post-baseline measurement and 37 patients (19 in the oxytocin and 18 in the placebo group) completed the study. Repeated measure analysis of variance showed significant effect for time X treatment interaction on the PANSS total [F(2.291,87.065) = 22.124, p < 0.001], positive [F(1.285,48.825) = 11.655, p = 0.001], negative [F(2.754,104.649) = 11.818, p < 0.001] and general psychopathology [F(1.627,61.839) = 4.022, p = 0.03] subscale scores. By week 8, patients in the oxytocin group showed significantly greater improvement on the positive (Cohen's d = 1.2, 20 % vs. 4 % reduction in score, p < 0.001), negative (Cohen's d = 1.4, 7 % vs. 2 % reduction in score, p < 0.001) and general psychopathology (Cohen's d = 0.8, 8 % vs. 2 % reduction in score, p = 0.021) subscales and total (Cohen's d = 1.9, 11 % vs. 2 % reduction in score, p < 0.001) PANSS scores than the placebo group. Adverse effects including the sodium concentration change were similar between the two groups.

CONCLUSION

Oxytocin as an adjunct to risperidone tolerably and efficaciously improves positive symptoms of schizophrenia. In addition, effects on negative and total psychopathology scores were statistically significant, but likely to be clinically insignificant. The interesting findings from the present pilot study need further replication in a larger population of patients.

Emotion recognition impairment is present early and is stable throughout the course of schizophrenia

Individuals with schizophrenia experience problems in the perception of emotion throughout the course of the disorder. Few studies have addressed the progression of the deficit over time. The present investigation explores face emotion recognition (FER) performance throughout the course of schizophrenia. The aim of the study was to test the hypotheses that: 1) FER impairment was present in ultra high-risk (putatively prodromal) individuals, and that 2) impairment was stable across the course of the illness. Forty-three individuals with a putative prodromal syndrome, 50 patients with first episode of schizophrenia, 44 patients with multi-episode schizophrenia and 86 unaffected healthy control subjects were assessed to examine emotion recognition ability. ANCOVA analysis adjusted for possible confounder factors and subsequent planned contrasts with healthy controls was undertaken. The results revealed deficits in recognition of sadness and disgust in prodromal individuals, and of all negative emotions in both first-episode and multi-episode patients. Furthermore, there were no significant differences between clinical groups. Within the framework of the neurodevelopmental model of schizophrenia, our results suggest the presence of emotional recognition impairment before the onset of full-blown psychosis. Moreover, the deficit remains stable over the course of illness, fitting the pattern of a vulnerability indicator in contrast to an indicator of chronicity or severity.

Hormonal imprinting in the central nervous system: causes and consequences

The notion of the perinatal „hormonal imprinting” has been published at first in 1980 and since that time it spred expansively. The imprintig develops at the first encounter between the developing receptor and the target hormone – possibly by the alteration of the methylation pattern of DNA – and it is transmitted to the progeny generations of the cell. This is needed for the complete development of the receptor’s binding capacity. However, molecules similar to the target hormone (hormone-analogues, drugs, chemicals, environmental pollutants) can also bind to the developing receptor, causing faulty imprinting with life-long consequences. This can promote pathological conditions. Later it was cleared that in other critical periods such as puberty, imprinting also can be provoked, even in any age in differentiating cells. The central nervous system (brain) also can be mistakenly imprinted, which durably influences the dopaminergic, serotonergic and noradrenergic system and this can be manifested – in animal experiments – in alterations of the sexual and social behavior. In our modern age the faulty hormonal imprintig is inavoidable because of the mass of medicaments, chemicals, the presence of hormone-like materials (e.g. soya phytosteroids) in the food, and environmental pollutants. The author especially emphasizes the danger of oxytocin, as a perinatal imprinter, as it is used very broadly and can basically influence the emotional and social spheres and the appearance of certain diseases such as auitism, schizophrenia and parkinsonism. The danger of perinatal imprinters is growing, considering their effects on the human evolution. Orv. Hetil., 2013, 154, 128–135.

Association between oxytocin receptor gene polymorphisms and self-rated 'empathic concern' in schizophrenia

The nonapeptide oxytocin (OXT) and its receptor (OXTR) have been implicated in social cognition, empathy, emotion and stress regulation in humans. Previous studies reported associations between OXT and OXTR genetic polymorphisms and risk for disorders characterized by impaired socio-emotional functioning, such as schizophrenia and autism. Here we investigate the influence of two single nucleotide polymorphisms (SNPs) within the OXTR gene on a measure of socio-emotional functioning in schizophrenic patients. OXTR SNPs that were previously investigated in other studies were genotyped in 145 patients diagnosed with schizophrenia according to DSM-IV and 145 healthy controls matched for age and gender. The Interpersonal Reactivity Index (IRI) was used to assess cognitive ('perspective taking'), affective ('empathic concern') and self-related ('personal distress') dimensions of empathy. No group differences in genotype frequencies were observed. MANCOVA revealed a significant main (F [1,282] = 10.464; p<0.01) and interaction effect (genotype by diagnosis: F [1,282] = 4.329; p<0.05) of OXTR SNP rs2254298(A>GG) with 'empathic concern'. Within the schizophrenia group, linear regression analysis determined OXTR rs2254298 genotype, PANSS negative and general symptom score, and age of disease onset as being significantly associated with 'empathic concern'. OXTR rs2254298 significantly impacted PANSS general psychopathology scores. No associations were found for OXTR rs53576, IRI 'perspective taking' or 'personal distress' ratings. Our preliminary findings support hypotheses about an involvement of OXTR rs2254298 in emotional empathy in schizophrenic and healthy individuals, warranting independent replication.