Papers by Daniel Quintana
The neuropeptide oxytocin has shown promise as a treatment for symptoms of autism spectrum disord... more The neuropeptide oxytocin has shown promise as a treatment for symptoms of autism spectrum disorders (ASD). However, clinical research progress has been hampered by a poor understanding of oxytocin's dose–response and sub-optimal intranasal delivery methods. We examined two doses of oxytocin delivered using a novel Breath Powered intranasal delivery device designed to improve direct nose-to-brain activity in a double-blind, crossover, randomized, placebo-controlled trial. In a randomized sequence of single-dose sessions, 17 male adults with ASD received 8 international units (IU) oxytocin, 24IU oxytocin or placebo followed by four social-cognitive tasks. We observed an omnibus main effect of treatment on the primary outcome measure of overt emotion salience as measured by emotional ratings of faces (η 2 = 0.18). Compared to placebo, 8IU treatment increased overt emotion salience (P = 0.02, d = 0.63). There was no statistically significant increase after 24IU treatment (P = 0.12, d = 0.4). The effects after 8IU oxytocin were observed despite no significant increase in peripheral blood plasma oxytocin concentrations. We found no significant effects for reading the mind in the eyes task performance or secondary outcome social-cognitive tasks (emotional dot probe and face-morphing). To our knowledge, this is the first trial to assess the dose-dependent effects of a single oxytocin administration in autism, with results indicating that a low dose of oxytocin can significantly modulate overt emotion salience despite minimal systemic exposure.
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There is growing interest in the role of the oxytocin system in social cognition and behavior. Pe... more There is growing interest in the role of the oxytocin system in social cognition and behavior. Peripheral oxytocin concentrations are regularly used to approximate central concentrations in psychiatric research, however, the validity of this approach is unclear. Here we conducted a pre-registered systematic search and meta-analysis of correlations between central and peripheral oxytocin concentrations. A search of databases yielded 17 eligible studies, resulting in a total sample size of 516 participants and subjects. Overall, a positive association between central and peripheral oxytocin concentrations was revealed [r=0.29, 95% CI (0.14, 0.42), p<0.0001]. This association was moderated by experimental context [Qb(4), p=0.003]. While no association was observed under basal conditions (r=0.08, p=.31), significant associations were observed after intranasal oxytocin administration (r=0.66, p<.0001), and after experimentally induced stress (r=0.49, p=0.0011). These results indicate a coordination of central and peripheral oxytocin release after stress and after intranasal administration. Although popular, the approach of using peripheral oxytocin levels to approximate central levels under basal conditions is not supported by the present results.
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There is growing interest in using intranasal oxytocin (OT) to treat social dysfunction in schizo... more There is growing interest in using intranasal oxytocin (OT) to treat social dysfunction in schizophrenia and bipolar disorders (i.e., psychotic disorders). While OT treatment results have been mixed, emerging evidence suggests that OT system dysfunction may also play a role in the aetiology of metabolic syndrome (MetS), which appears in one-third of individuals with psychotic disorders and associated with increased mortality. Here we examine the evidence for a potential role of the OT system in the shared risk for MetS and psychotic disorders, and its prospects for ameliorating MetS. Using several studies to demonstrate the overlapping neurobiological profiles of metabolic risk factors and psychiatric symptoms, we show that OT system dysfunction may be one common mechanism underlying MetS and psychotic disorders. Given the critical need to better understand metabolic dysregulation in these disorders, future OT trials assessing behavioural and cognitive outcomes should additionally include metabolic risk factor parameters.
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Heart rate variability (HRV) has become an increasingly popular index of cardiac autonomic contro... more Heart rate variability (HRV) has become an increasingly popular index of cardiac autonomic control in the biobehavioral sciences due to its relationship with mental illness and cognitive traits. However, the intraindividual stability of HRV in response to sleep and diurnal disturbances , which are commonly reported in mental illness, and its relationship with executive function are not well understood. Here, in 40 healthy adult males we calculated high frequency HRV—an index of parasympathetic nervous system (PNS) activity—using pulse oximetry during brain imaging, and assessed attentional and executive function performance in a subsequent behavioral test session at three time points: morning, evening, and the following morning. Twenty participants were randomly selected for total sleep deprivation whereas the other 20 participants slept as normal. Sleep deprivation and morning-tonight variation did not influence high frequency HRV at either a group or individual level; however, sleep deprivation abolished the relationship between orienting attention performance and HRV. We conclude that a day of wake and a night of laboratory-induced sleep deprivation do not alter supine high frequency HRV in young healthy male adults.
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Background: Converging evidence demonstrates the important role of the neuropeptide hormone oxyto... more Background: Converging evidence demonstrates the important role of the neuropeptide hormone oxytocin (OT) in human behaviour and cognition. Intranasal OT administration has been shown to improve several aspects of social communication, such as the theory of mind performance and gaze to the eye region, and reduce anxiety and related negative cognitive appraisals. While this early research has demonstrated the potential for intranasal OT to treat psychiatric illnesses characterized by social impairments, the neurobiological mechanisms are not well known. Researchers have used functional magnetic resonance imaging (fMRI) to examine the neural correlates of OT response; however, results have been variable and moderating factors are poorly understood. The aim of this meta-analysis is to synthesize data examining the impact of intranasal OT administration on neural activity. Methods/design: Studies that report fMRI data after intranasal OT administration will be identified. PubMed, Embase, PsycINFO, and Google Scholar databases will be searched as well as the citation lists of retrieved articles. Eligible articles written in English from 2005 onwards will be included in the meta-analysis, and corresponding authors of these papers will be invited to contribute t-maps. Data will be collected from eligible studies for synthesis using Seed-based d Mapping (SDM) or Multi-Level Kernel Density Analysis (MKDA), depending on the number of usable t-maps received. Additionally, publication bias and risk of bias will be assessed. Discussion: This systematic review and meta-analysis will be the first pre-registered synthesis of data to identify the neural correlates of OT nasal spray response. The identification of brain regions underlying OT's observed effects will help guide future research and better identify treatment targets. Systematic review registration: PROSPERO CRD42016038781
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The calculation of heart rate variability (HRV) is a popular tool used to investigate differences... more The calculation of heart rate variability (HRV) is a popular tool used to investigate differences in cardiac autonomic control between population samples. When interpreting effect sizes to quantify the magnitude of group differences, researchers typically use Cohen's guidelines of small (0.2), medium (0.5), and large (0.8) effects. However, these guidelines were originally proposed as a fall back for when the effect size distribution (ESD) was unknown. Despite the availability of effect sizes from hundreds of HRV studies, researchers still largely rely on Cohen's guidelines to interpret effect sizes and to perform power analyses to calculate required sample sizes for future research. This article describes an ESD analysis of 297 HRV effect sizes from between-group/case-control studies, revealing that the 25th, 50th, and 75th effect size percentiles correspond with effect sizes of 0.26, 0.51, and 0.88, respectively. The analyses suggest that Cohen's guidelines may underestimate the magnitude of small and large effect sizes and that HRV studies are generally underpowered. Therefore, to better reflect the observed ESD, effect sizes of 0.25, 0.5, and 0.9 should be interpreted as small, medium, and large effects (after rounding to the closest 0.05). Based on power calculations using the ESD, suggested sample sizes are also provided for planning suitably powered studies that are more likely to replicate. Researchers are encouraged to use the ESD dataset or their own collected datasets in tandem with the provided analysis script to perform custom ESD and power analyses relevant to their specific research area
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Frontiers in psychology, 2014
Major depressive disorder (MDD) is associated with increased heart rate and reductions in its var... more Major depressive disorder (MDD) is associated with increased heart rate and reductions in its variability (heart rate variability, HRV) - markers of future morbidity and mortality - yet prior studies have reported contradictory effects. We hypothesized that increases in heart rate and reductions in HRV would be more robust in melancholia relative to controls, than in patients with non-melancholia. A total of 72 patients with a primary diagnosis of MDD (age M: 36.26, SE: 1.34; 42 females) and 94 controls (age M: 35.69, SE: 1.16; 52 females) were included in this study. Heart rate and measures of its variability (HRV) were calculated from two 2-min electrocardiogram recordings during resting state. Propensity score matching controlled imbalance on potential confounds between patients with melancholia (n = 40) and non-melancholia (n = 32) including age, gender, disorder severity, and comorbid anxiety disorders. MDD patients with melancholia displayed significantly increased heart rate ...
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Neuropeptides are small molecules that act as messengers between different brain regions. There a... more Neuropeptides are small molecules that act as messengers between different brain regions. There are roughly 100 neuropeptides that are important for various functions, including hunger, memory, and learning. Oxytocin is a neuropeptide that plays a crucial role in childbirth and breastfeeding. More recently, oxytocin has been shown to be essential for our social behaviors. When given to people in the form of a nasal spray, oxytocin can change key aspects of social behavior, such as how easily we can recognize emotions in others. People with autism often have diffculties in understanding and using social information, and scientists have been testing oxytocin nasal spray as a potential treatment. But how does oxytocin nasal spray travel from the nose to the brain, and how does it change how we behave socially?
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Background: Individuals with anxiety disorders display reduced resting-state heart rate variabili... more Background: Individuals with anxiety disorders display reduced resting-state heart rate variability (HRV), although findings have been contradictory and the role of specific symptoms has been less clear. It is possible that HRV reductions may transcend diagnostic categories, consistent with dimensional-trait models of psychopathology. Here we investigated whether anxiety disorders or symptoms of anxiety, stress, worry and depression are more strongly associated with resting-state HRV.
Methods: Resting-state HRV was calculated in participants with clinical anxiety (n = 25) and healthy controls (n = 58). Symptom severity measures of worry, anxiety, stress, and depression were also collected from participants, regardless of diagnosis.
Results: Participants who fulfilled DSM-IV criteria for an anxiety disorder displayed diminished HRV, a difference at trend level significance (p = .1, Hedges' g =-.37, BF 10 = .84). High worriers (Total n = 41; n = 22 diagnosed with an anxiety disorder and n = 19 not meeting criteria for any psychopathology) displayed a robust reduction in resting state HRV relative to low worriers (p = .001, Hedges' g =-.75, BF 10 = 28.16).
Conclusions: The specific symptom of worry – not the diagnosis of an anxiety disorder – was associated with the most robust reductions in HRV, indicating that HRV may provide a transdiagnostic biomarker of worry. These results enhance understanding of the relationship between the cardiac autonomic nervous system and anxiety psychopathology, providing support for dimensional-trait models consistent with the Research Domain Criteria framework.
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The number of publications investigating heart rate variability (HRV) in psychiatry and the behav... more The number of publications investigating heart rate variability (HRV) in psychiatry and the behavioral sciences has increased markedly in the last decade. In addition to the significant debates surrounding ideal methods to collect and interpret measures of HRV, standardized reporting of methodology in this field is lacking. Commonly cited recommendations were designed well before recent calls to improve research communication and reproducibility across disciplines. In an effort to standardize reporting, we propose the Guidelines for Reporting Articles on Psychiatry and Heart rate variability (GRAPH), a checklist with four domains: participant selection, interbeat interval collection, data preparation and HRV calculation. This paper provides an overview of these four domains and why their standardized reporting is necessary to suitably evaluate HRV research in psychiatry and related disciplines. Adherence to these communication guidelines will help expedite the translation of HRV research into a potential psychiatric biomarker by improving interpretation, reproducibility and future meta-analyses.
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It is unclear if and how exogenous oxytocin (OT) reaches the brain to improve social behavior and... more It is unclear if and how exogenous oxytocin (OT) reaches the brain to improve social behavior and cognition and what is the optimal dose for OT response. To better understand the delivery routes of intranasal OT administration to the brain and the dose-response, we compared amygdala response to facial stimuli by means of functional magnetic resonance imaging (fMRI) in four treatment conditions, including two different doses of intranasal OT using a novel Breath Powered device, intravenous (IV) OT, which provided similar concentrations of blood plasma OT, and placebo. We adopted a randomized, double-blind, double-dummy, crossover design, with 16 healthy male adults administering a single-dose of these four treatments. We observed a treatment effect on right amygdala activation during the processing of angry and happy face stimuli, with pairwise comparisons revealing reduced activation after the 8IU low dose intranasal treatment compared to placebo. These data suggest the dampening of amygdala activity in response to emotional stimuli occurs via direct intranasal delivery pathways rather than across the blood-brain barrier via systemically circulating OT.
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Background: Research examining the effects of oxytocin (OT) interventions on psychiatric, social-... more Background: Research examining the effects of oxytocin (OT) interventions on psychiatric, social-behavioral, and social-cognitive outcomes regularly collect peripheral levels of OT as markers of central bioavailability. Such inferences rest on the assumption that central and peripheral levels of OT are directly associated. However, conflicting evidence from coordinated sampling of central and peripheral OT question the validity of this assumption. The purpose of this meta-analysis is to evaluate the correlation between central and peripheral OT, as well as to account for potential heterogeneity in the literature.
Methods/design: Studies that report coordinated sampling of central and peripheral OT in humans and animals will be identified. Research investigating concentrations in both basal states and after exogenous administration will be considered. PubMed and Embase databases will be searched, along with citation lists of retrieved articles. Peer-reviewed studies written in English published from 1971 onwards will be included in the meta-analysis. Data will be extracted from eligible studies for a random-effects meta-analysis. For each study, a summary effect size, heterogeneity, risk of bias, publication bias, and the effect of categorical and continuous moderator variables will be determined.
Discussion: This systematic review and meta-analysis will identify and synthesize evidence to determine if there is an association between central and peripheral OT concentrations. If significant associations are observed, evidence would provide a rationale for future research to use peripheral measures as a proxy for central OT concentrations.
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Aim: Research into Theory of Mind (ToM) in alcohol use disorder (AUD) is sparse and the extant fi... more Aim: Research into Theory of Mind (ToM) in alcohol use disorder (AUD) is sparse and the extant findings contradictory. The objective of this paper was to conduct a meta-analysis to determine whether individuals with AUD show ToM deficits across the available published literature.
Method: A comprehensive literature search was performed with the PsychInfo, PubMed and Web Science databases for studies from 1990 to March 2015, pairing the keywords ‘alcohol’ and ‘theory of mind’. Results were filtered and eight studies met the inclusion criteria and were included in the final meta-analysis.
Results: Results showed that individuals with AUD (n = 187) displayed reduced ToM compared to controls (n = 187). Hedges’ g was −1.62 [(−2.28, −0.96), SE = 0.66, P < 0.01], which is indicative of a large effect size. The percentage of males had a significant impact on the effect size, Q = 7.90, P = 0.005, while IQ and level of education did not.
Conclusions: Results of this study suggest that AUD may be associated with impaired understand- ing of others’ intentions and emotions, which can leave an individual vulnerable to misinterpreting social cues. Clinical care implications of the findings, limitations of the study, and suggestions for future research are discussed.
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Accumulating research demonstrates the potential of intranasal delivery of psychopharmacological ... more Accumulating research demonstrates the potential of intranasal delivery of psychopharmacological agents to treat a range of psychiatric disorders and symptoms. It is believed that intranasal administration offers both direct and indirect pathways to deliver psychopharmacological agents to the central nervous system. This administration route provides a unique opportunity to repurpose both old drugs for new uses and improve currently approved drugs that are indicated for other administration routes. Despite this promise, however, the physiology of intranasal delivery and related assumptions behind the bypassing of the blood brain barrier is seldom considered in detail in clinical trials and translational research. In this review, we describe the current state of the art in intranasal psychopharmacological agent delivery research and current challenges using this administration route, and discuss important aspects of nose-to-brain delivery that may improve the efficacy of these new therapies in future research. We also highlight current gaps in the literature and suggest how research can directly examine the assumptions of nose-to-brain delivery of psychopharmacological agents in humans.
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Background: Autonomic nervous system (ANS) dysfunction is a putative underlying mechanism for inc... more Background: Autonomic nervous system (ANS) dysfunction is a putative underlying mechanism for increased cardiovascular disease risk in individuals with psychiatric disorders. Previous studies suggest that this risk may be related to psychotropic medication use. In the present study we systematically reviewed and analyzed published studies of heart rate variability (HRV), measuring ANS output, to determine the effect of psychiatric illness and medication use. Methods: We searched for studies comparing HRV in physically healthy adults with a diagnosed psychiatric disorder to controls and comparing HRV pre- and post-treatment with a psychotropic medication. Results: In total, 140 case–control (mood, anxiety, psychosis, dependent disorders, k = 151) and 30 treatment (antidepressants, antipsychotics; k = 43) studies were included. We found that HRV was reduced in all patient groups compared to controls (Hedges g = –0.583) with a large effect for psychotic disorders (Hedges g = –0.948). Effect sizes remained highly significant for medication-free patients compared to controls across all disorders. Smaller and significant reductions in HRV were observed for specific antidepressants and antipsychotics. Limitations: Study quality significantly moderated effect sizes in case–control analyses, underscoring the importance of assessing methodological quality when interpreting HRV findings. Conclusion: Combined findings confirm substantial reductions in HRV across psychiatric disorders, and these effects remained significant even in medication-free individuals. Reductions in HRV may therefore represent a significant mechanism contributing to elevated cardiovascular risk in individuals with psychiatric disorders. The negative impact of specific medications on HRV suggest increased risk for cardiovascular disease in these groups, highlighting a need for treatment providers to consider modifiable cardiovascular risk factors to attenuate this risk.
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Meta-analysis synthesizes a body of research investigating a common research question. Outcomes f... more Meta-analysis synthesizes a body of research investigating a common research question. Outcomes from meta-analyses provide a more objective and transparent summary of a research area than traditional narrative reviews. Moreover, they are often used to support research grant applications, guide clinical practice and direct health policy. The aim of this article is to provide a practical and nontechnical guide for psychological scientists that outlines the steps involved in planning and performing a meta-analysis of correlational datasets. I provide a supplementary R script to demonstrate each analytical step described in the paper, which is readily adaptable for researchers to use for their analyses. While the worked example is the analysis of a correlational dataset, the general meta-analytic process described in this paper is applicable for all types of effect sizes. I also emphasise the importance of meta-analysis protocols and pre-registration to improve transparency and help avoid unintended duplication. An improved understanding this tool will not only help scientists to conduct their own meta-analyses but also improve their evaluation of published meta-analyses.
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The vagus nerve is a major constituent in the bidirectional relationship between the heart and th... more The vagus nerve is a major constituent in the bidirectional relationship between the heart and the prefrontal cortex. This study investigated the role of the vagus in social cognition using the cold face test (facial cooling) to stimulate the vagus nerve and increase prefrontal inhibitory control. Heart Rate Variability (HRV) was measured to index parasympathetic outflow while social cognition ability was tested using the Reading the Mind in the Eyes Test (RMET). Healthy males (n=25) completed the RMET under two conditions: with and without facial cooling. Results indicated that although facial cooling increased HRV at rest, there was no improvement on the RMET during the facial cooling condition. Interestingly, completing the RMET with facial cooling abolished this increase in HRV, suggesting interference along the vagal reflex arc. These results are consistent with the involvement of a common cortico-subcortical circuit in autonomic and cognitive processes, important for emotion recognition.
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Objective: Despite current diagnostic systems distinguishing schizophrenia (SZ) and bipolar disor... more Objective: Despite current diagnostic systems distinguishing schizophrenia (SZ) and bipolar disorder (BD) as separate diseases, emerging evidence suggests they share a number of clinical and epidemiological features, such as increased cardiovascular disease (CVD) risk. It is not well understood if poor cardiac autonomic nervous system regulation, which can be indexed non-invasively by the calculation of heart rate variability (HRV), contributes to these common CVD risk factors in both diseases.
Method: We calculated HRV in 47 patients with SZ, 33 patients with BD, and 212 healthy controls. Measures of symptom severity were also collected from the patient groups.
Results: HRV was significantly reduced in both these disorders in comparison to the healthy participants, however, there were no HRV differences between disorders. Importantly, these reductions were independent of the medication, age, or BMI effects. There was also preliminary evidence that patients with reduced HRV had increased overall and negative psychosis symptom severity regardless of SZ or BD diagnosis.
Conclusion: We suggest that HRV may provide a possible biomarker of CVD risk and symptom severity in severe mental illness. Thus, our results highlight the importance of cardiometabolic screening across schizophrenia and bipolar spectrum disorders.
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Papers by Daniel Quintana
Methods: Resting-state HRV was calculated in participants with clinical anxiety (n = 25) and healthy controls (n = 58). Symptom severity measures of worry, anxiety, stress, and depression were also collected from participants, regardless of diagnosis.
Results: Participants who fulfilled DSM-IV criteria for an anxiety disorder displayed diminished HRV, a difference at trend level significance (p = .1, Hedges' g =-.37, BF 10 = .84). High worriers (Total n = 41; n = 22 diagnosed with an anxiety disorder and n = 19 not meeting criteria for any psychopathology) displayed a robust reduction in resting state HRV relative to low worriers (p = .001, Hedges' g =-.75, BF 10 = 28.16).
Conclusions: The specific symptom of worry – not the diagnosis of an anxiety disorder – was associated with the most robust reductions in HRV, indicating that HRV may provide a transdiagnostic biomarker of worry. These results enhance understanding of the relationship between the cardiac autonomic nervous system and anxiety psychopathology, providing support for dimensional-trait models consistent with the Research Domain Criteria framework.
Methods/design: Studies that report coordinated sampling of central and peripheral OT in humans and animals will be identified. Research investigating concentrations in both basal states and after exogenous administration will be considered. PubMed and Embase databases will be searched, along with citation lists of retrieved articles. Peer-reviewed studies written in English published from 1971 onwards will be included in the meta-analysis. Data will be extracted from eligible studies for a random-effects meta-analysis. For each study, a summary effect size, heterogeneity, risk of bias, publication bias, and the effect of categorical and continuous moderator variables will be determined.
Discussion: This systematic review and meta-analysis will identify and synthesize evidence to determine if there is an association between central and peripheral OT concentrations. If significant associations are observed, evidence would provide a rationale for future research to use peripheral measures as a proxy for central OT concentrations.
Method: A comprehensive literature search was performed with the PsychInfo, PubMed and Web Science databases for studies from 1990 to March 2015, pairing the keywords ‘alcohol’ and ‘theory of mind’. Results were filtered and eight studies met the inclusion criteria and were included in the final meta-analysis.
Results: Results showed that individuals with AUD (n = 187) displayed reduced ToM compared to controls (n = 187). Hedges’ g was −1.62 [(−2.28, −0.96), SE = 0.66, P < 0.01], which is indicative of a large effect size. The percentage of males had a significant impact on the effect size, Q = 7.90, P = 0.005, while IQ and level of education did not.
Conclusions: Results of this study suggest that AUD may be associated with impaired understand- ing of others’ intentions and emotions, which can leave an individual vulnerable to misinterpreting social cues. Clinical care implications of the findings, limitations of the study, and suggestions for future research are discussed.
Method: We calculated HRV in 47 patients with SZ, 33 patients with BD, and 212 healthy controls. Measures of symptom severity were also collected from the patient groups.
Results: HRV was significantly reduced in both these disorders in comparison to the healthy participants, however, there were no HRV differences between disorders. Importantly, these reductions were independent of the medication, age, or BMI effects. There was also preliminary evidence that patients with reduced HRV had increased overall and negative psychosis symptom severity regardless of SZ or BD diagnosis.
Conclusion: We suggest that HRV may provide a possible biomarker of CVD risk and symptom severity in severe mental illness. Thus, our results highlight the importance of cardiometabolic screening across schizophrenia and bipolar spectrum disorders.
Methods: Resting-state HRV was calculated in participants with clinical anxiety (n = 25) and healthy controls (n = 58). Symptom severity measures of worry, anxiety, stress, and depression were also collected from participants, regardless of diagnosis.
Results: Participants who fulfilled DSM-IV criteria for an anxiety disorder displayed diminished HRV, a difference at trend level significance (p = .1, Hedges' g =-.37, BF 10 = .84). High worriers (Total n = 41; n = 22 diagnosed with an anxiety disorder and n = 19 not meeting criteria for any psychopathology) displayed a robust reduction in resting state HRV relative to low worriers (p = .001, Hedges' g =-.75, BF 10 = 28.16).
Conclusions: The specific symptom of worry – not the diagnosis of an anxiety disorder – was associated with the most robust reductions in HRV, indicating that HRV may provide a transdiagnostic biomarker of worry. These results enhance understanding of the relationship between the cardiac autonomic nervous system and anxiety psychopathology, providing support for dimensional-trait models consistent with the Research Domain Criteria framework.
Methods/design: Studies that report coordinated sampling of central and peripheral OT in humans and animals will be identified. Research investigating concentrations in both basal states and after exogenous administration will be considered. PubMed and Embase databases will be searched, along with citation lists of retrieved articles. Peer-reviewed studies written in English published from 1971 onwards will be included in the meta-analysis. Data will be extracted from eligible studies for a random-effects meta-analysis. For each study, a summary effect size, heterogeneity, risk of bias, publication bias, and the effect of categorical and continuous moderator variables will be determined.
Discussion: This systematic review and meta-analysis will identify and synthesize evidence to determine if there is an association between central and peripheral OT concentrations. If significant associations are observed, evidence would provide a rationale for future research to use peripheral measures as a proxy for central OT concentrations.
Method: A comprehensive literature search was performed with the PsychInfo, PubMed and Web Science databases for studies from 1990 to March 2015, pairing the keywords ‘alcohol’ and ‘theory of mind’. Results were filtered and eight studies met the inclusion criteria and were included in the final meta-analysis.
Results: Results showed that individuals with AUD (n = 187) displayed reduced ToM compared to controls (n = 187). Hedges’ g was −1.62 [(−2.28, −0.96), SE = 0.66, P < 0.01], which is indicative of a large effect size. The percentage of males had a significant impact on the effect size, Q = 7.90, P = 0.005, while IQ and level of education did not.
Conclusions: Results of this study suggest that AUD may be associated with impaired understand- ing of others’ intentions and emotions, which can leave an individual vulnerable to misinterpreting social cues. Clinical care implications of the findings, limitations of the study, and suggestions for future research are discussed.
Method: We calculated HRV in 47 patients with SZ, 33 patients with BD, and 212 healthy controls. Measures of symptom severity were also collected from the patient groups.
Results: HRV was significantly reduced in both these disorders in comparison to the healthy participants, however, there were no HRV differences between disorders. Importantly, these reductions were independent of the medication, age, or BMI effects. There was also preliminary evidence that patients with reduced HRV had increased overall and negative psychosis symptom severity regardless of SZ or BD diagnosis.
Conclusion: We suggest that HRV may provide a possible biomarker of CVD risk and symptom severity in severe mental illness. Thus, our results highlight the importance of cardiometabolic screening across schizophrenia and bipolar spectrum disorders.