Autonomic Nervous System Activation During Social Cognition Tasks in Patients With Schizophrenia and Their Unaffected Relatives

Altered Heart Rate Variability During Rest in Schizophrenia: A State Marker

BACKGROUND

Autonomic nervous system (ANS) imbalance has been reported in a number of psychiatric disorders such as depression, schizophrenia, panic disorder, etc. Autonomic dysfunction in schizophrenia has been associated with the symptoms and manifestation of psychosis. Heart rate variability (HRV) as a tool has been widely used to assess ANS activity and the effect of disease on the sympathovagal balance. Therefore, in the present study, HRV derived from electrocardiogram (ECG) lead II at rest was investigated in order to understand the changes in frequency domain measures in patients with schizophrenia and their first-degree relatives compared to healthy controls.

METHODS

Twenty-five patients with schizophrenia, 24 first-degree relatives of patients, and 24 healthy controls (Diagnostic and Statistical Manual of Mental Disorders (DSM)-5; 18-45 years) were included in the study. HRV of the subjects was measured after five minutes of rest. ECG lead II was recorded for five minutes and HRV was analysed in the frequency domain: low frequency (LF), high frequency (HF), total power, and LF/HF ratio. HRV parameters and heart rate were statistically analysed for group comparisons using general linear model multivariate analysis.

RESULTS

Patients had significantly higher minimum heart rate and lower HF (normalized units (nu)) compared to their first-degree relatives. A trend was observed in HF (nu) with the lowest in patients followed by healthy controls and first-degree relatives and LF/HF ratio was the highest in patients followed by healthy controls and first-degree relatives, although not statistically significant. No significant difference was found between first-degree relatives and healthy controls.

CONCLUSION

The alteration of HRV in schizophrenia could be attributed to reduction in vagal tone and sympathetic dominance, which in turn could serve as state markers of schizophrenia.

Temporal profile of intranasal oxytocin in the human autonomic nervous system at rest: An electrocardiography and pupillometry study

BACKGROUND

Human social behavior is modulated by oxytocin (OT). Intranasal administration of OT (IN-OT) is a noninvasive route shown to elicit changes in the autonomic nervous system (ANS) activity; however, IN-OT's effect on the temporal profile of ANS activity at rest is yet to be described.

AIMS

We aimed to describe the temporal profile of IN-OT at six 10-min time windows from 15- to 100-min post-administration in 20 male participants at rest while continuously recording their pupillary in an eyes-open condition and cardiac activity in eyes-open and eyes-closed conditions.

METHODS

We used a double-blind, placebo-controlled, within-subjects design study where we extracted two proxies of parasympathetic nervous system (PNS) activity: high-frequency heart rate variability (HF-HRV) and pupillary unrest index (PUI); and a proxy of sympathetic nervous system activity: sample entropy of the pupillary unrest.

RESULTS

In the eyes-open condition, we found an effect of IN-OT on the proxies of PNS activity: decreased PUI in the three-time windows post-administration spanning 65-100 min, and as an exploratory finding, an increased HF-HRV in the 80-85 min time window.

CONCLUSIONS

We suggest there is a role of OT in PNS regulation that may be consistent with OT's currently theorized role in the facilitation of alertness and approach behavior.

Associations of common genetic risk variants of the muscarinic acetylcholine receptor M2 with cardiac autonomic dysfunction in patients with schizophrenia

OBJECTIVES

Decreased vagal modulation, which has consistently been observed in schizophrenic patients, might contribute to increased cardiac mortality in schizophrenia. Previously, associations between CHRM2 (Cholinergic Receptor Muscarinic 2) and cardiac autonomic features have been reported. Here, we tested for possible associations between these polymorphisms and heart rate variability in patients with schizophrenia.

METHODS

A total of three single nucleotide polymorphisms (SNPs) in CHRM2 (rs73158705 A>G, rs8191992 T>A and rs2350782 T>C) that achieved significance (p < 5 * 10^-8) in genome-wide association studies for cardiac autonomic features were genotyped in 88 drug-naïve patients, 61 patients receiving antipsychotic medication and 144 healthy controls. Genotypes were analysed for associations with parameters of heart rate variability and complexity, in each diagnostic group.

RESULTS

We observed a significantly altered heart rate variability in unmedicated patients with identified genetic risk status in rs73158705 A>G, rs8191992 T>A and rs2350782 T>C as compared to genotype non-risk status. In patients receiving antipsychotic medication and healthy controls, these associations were not observed.

DISCUSSION

We report novel candidate genetic associations with cardiac autonomic dysfunction in schizophrenia, but larger cohorts are required for replication.

The influence of interest in tasks on the autonomic nervous system

Although prior studies have indicated the relationships among decreased parasympathetic activity, schizophrenia, and depression, the physiological effects of psychiatric occupational therapy tasks have not been adequately explored. Therefore, it is necessary to quantitatively examine the physiological changes in the autonomic nervous system when performing such tasks to devise more individualized therapies. Accordingly, we examined the influence of task interest and its relationship with psychological characteristics. The participants included in this study were 22 healthy individuals. They completed the State-Trait Anxiety Inventory, the Center for Epidemiologic Studies Depression Scale, and the Social Phobia Scale. Participants selected the most and least interesting bookmarks from a set of 19 different color options, and indicated their degree of interest on a visual analog scale. An electrocardiogram was used during each task to record participants' cardiac sympathetic index (CSI) and cardiac vagal index (CVI) as they performed two tasks (interesting and uninteresting). The correlations between the degree of interest and CSI/CVI, and between the scores of the questionnaires and CSI/CVI were examined. There was a negative correlation between the degree of interest and CSI during the uninteresting task. Task interest may have contributed to suppressing sympathetic dominance and reducing mental and physiological loads, even if the tasks differed only color-wise. Physiological effects emerged from participants’ degree of task interest. Further identification of objective and therapeutic mechanisms may lead to wider applications of activities in different areas.

The Heart in the Mind: A Systematic Review and Meta-Analysis of the Association Between Theory of Mind and Cardiac Vagal Tone

Theory of mind (ToM) is the human ability to infer the mental states of others in order to understand their behaviors and plan own actions. In the past decades, accumulating evidence has shown that heart rate variability (HRV), an index of parasympathetic control of the heart, is linked to behavioral regulation, social competence, and social cognition abilities, all implicated-to some extent-in ToM. This study aims to systematically review and meta-analyze the available studies, investigating the relation between ToM and HRV in typically developing people. Six studies were eligible for the meta-analysis, yielding a significant association between HRV and ToM of a small-to-medium effect size (g = 0.44). This result was not influenced by publication bias. Due to the small number of studies eligible for the meta-analysis, it was not possible to test for the effect of categorical moderators. The moderating role of sex and quality of the studies was examined by meta-regression analysis. Moderation analysis did not yield any significant effect; however, at a descriptive level, studies yielding the largest effect size were characterized by the use of high frequency-HRV assessment at rest and the Reading the Mind in the Eyes Test to evaluate ToM abilities. The results preliminarily suggest that tonic HRV might be used as an indicator of the ability to understand the content of mind of others.

Autonomic nervous system dysfunction in schizophrenia: impact on cognitive and metabolic health

Schizophrenia (SCZ) is a psychiatric disorder characterized by a wide range of positive, negative and cognitive symptoms, along with an increased risk of metabolic syndrome and cardiovascular disease that contribute to a 15-20-year reduced life expectancy. Autonomic dysfunction, in the form of increased sympathetic activity and decreased parasympathetic activity, is postulated to be implicated in SCZ and its treatment. The aim of this narrative review is to view SCZ through an autonomic lens and synthesize the evidence relating autonomic dysfunction to different domains of SCZ. Using various methods of assessing autonomic activity, autonomic dysfunction was found to be associated with multiple aspects of SCZ pathophysiology, including symptom severity, cognitive impairment, and the development of cardiometabolic comorbidities, such as metabolic syndrome and high BMI. The strongest association of low heart rate variability was noted among patients on antipsychotic treatment with high-affinity muscarinic antagonism (i.e., clozapine, olanzapine and quetiapine). The review will also suggest ways in which studying autonomic dysfunction can help reduce morbidity and mortality associated with SCZ and its treatment.

A common variation in HCN1 is associated with heart rate variability in schizophrenia

BACKGROUND

There is growing evidence for a shared genetic basis between schizophrenia risk and cardiovascular disease. Reduced efferent vagal activity, indexed by reduced heart rate variability (HRV), has been consistently described in patients with schizophrenia and may potentially contribute to the increased cardiovascular risk in these patients. In this study, we tested the hypothesis whether the established schizophrenia risk variant HCN1 rs16902086 (A > G) is associated with reduced HRV.

METHODS

We analyzed the risk status of HCN1 rs16902086 (AG/GG vs. AA genotype) in 83 unmedicated patients with schizophrenia and 96 healthy controls and investigated genotype-related impacts on various HRV parameters.

RESULTS

We observed significantly increased resting heart rates and a marked decrease of vagal modulation in our patient cohort. Strikingly, HCN1 rs16902086 (A > G) was associated with reduced HRV parameters in patients only. A trend towards more pronounced HRV deviations was observed in homozygous (GG) compared to heterozygous patients (AG).

CONCLUSION

We present first evidence for a genetic risk factor that is associated with decreased vagal modulation in unmedicated patients with schizophrenia. Moreover, our findings suggest that HCN1 might be involved in reduced vagal modulation and possibly in increased cardiac mortality in schizophrenia patients. Thus, our data indicate that reduced vagal modulation might be an endophenotype of schizophrenia.

Incongruent Expression of Brain-Derived Neurotrophic Factor and Cortisol in Schizophrenia: Results from a Randomized Controlled Trial of Laughter Intervention

OBJECTIVE

Schizophrenia has been associated with dysfunction of the hypothalamic-pituitary-adrenal axis. Furthermore, alterations in neurotrophic factors might contribute to the pathogenesis of schizophrenia. We aimed to evaluate the effects of a simulated laughter intervention on the levels of cortisol and BDNF and to determine whether the effects associated with simulated laughter could be sustained after discontinuation of the intervention.

METHODS

In this randomized controlled study, patients with schizophrenia according to DSM-IV clinical criteria were randomly assigned to receive either 8-week-long simulated laughter intervention (n=32) or treatment-as-usual group (control group, n=27). The serum levels of BDNF and cortisol were measured at baseline, week 8, and four weeks after discontinuation (week 12) of the intervention program.

RESULTS

After an 8-week simulated laughter intervention, the laughter group had significantly higher levels of BDNF; however, four weeks after discontinuation of the intervention, the levels of BDNF significantly dropped. Interestingly, the levels of cortisol did not change significantly at week 8, but they were significantly elevated at week 12. The levels of BDNF and cortisol in the control group did not change significantly between week 0 and week 8.

CONCLUSION

These findings suggest that the simulated laughter intervention has an early effect on neurogenesis with a significant delayed effect on stress regulation in subjects with schizophrenia.

Early Signs of Schizophrenia and Autonomic Nervous System Dysregulation: A Literature Review

OBJECTIVE

Recent research suggests that early signs of schizophrenia can be detected several years before its onset. Evidence suggests that the identification of at-risk individuals before the psychotic onset can significantly improve the course of the disorder. However, instruments employed for the detection of prodromal symptoms are far from being accurate in the prediction of a future transition to psychosis. The aim of the present review is to summarize literature on the early signs of schizophrenia and to identify physiological markers that may aid the identification of the disorder before psychotic transition.

METHOD

This critical review includes studies published between 1979 and 2018 that were indexed in major databases with the following keywords: schizophrenia, prodromal phase, basic symptoms, autonomic nervous system, heart rate variability.

RESULTS

The examination of the relevant literature showed that, despite recent progress in the identification of at-risk states, the currently employed instruments do not allow an effective prediction of a future psychotic onset. Also, evidence suggests a significant association between alterations in the autonomic nervous system (ANS) functioning and psychotic disorders. However, literature on the association between ANS functioning and at-risk states for psychosis is still scarce. The addition of physiological risk indicators may represent a step forward in the detection of at-risk individuals.

CONCLUSIONS

Overall, the present literature review highlights that a future schizophrenic onset cannot be strongly predicted with current available measures. Given the established correlation between schizophrenia and autonomic dysregulation, an investigation of the ANS functioning in individuals who are at increased risk of developing schizophrenia may be particularly useful to improve the quality of the assessment, to identify at an early stage the dysregulated physiological patterns that have been linked with schizophrenia, and therefore to develop tailored interventions. Accordingly, it is crucial that future research investigates the presence of autonomic deficits in individuals at risk for psychosis.

Modeling physiological responses induced by an emotion recognition task using latent class mixed models

Correctly recognizing emotions is an essential skill to manage interpersonal relationships in everyday life. Facial expression represents the most powerful mean to convey important information on emotional and cognitive states during interactions with others. In this paper, we analyze physiological responses triggered by an emotion recognition test, which requires the processing of facial cues. In particular, we evaluate the modulation of several Heart Rate Variability indices, collected during the Reading the Mind in the Eyes Test, accounting for test difficulty (derived from a Rasch analysis), test performances, demographic and psychological characteristics of the participants. The main idea is that emotion recognition is associated with the Autonomic Nervous System and, as a consequence, with the Heart Rate Variability. The principal goal of our study was to explore the complexity of the collected measures and their possible interactions by applying a class of flexible models, i.e., the latent class mixed models. Actually, this modelling strategy allows for the identification of clusters of subjects characterized by similar longitudinal trajectories. Both univariate and multivariate latent class mixed models were used. In fact, while the interpretation of the Heart Rate Variability indices is very difficult when considered individually, a joint evaluation provides a better description of the Autonomic Nervous System state.

Aberrant parasympathetic reactivity to acute psychosocial stress in male patients with schizophrenia spectrum disorders

Autonomic dysfunction represents a core domain of the pathophysiology of schizophrenia spectrum disorders (SCZ), with aberrant physiologic arousal underlying maladaptive social and cognitive behaviors. Antagonistic parasympathetic and sympathetic systems support autonomic flexibility to appropriately regulate arousal and respond to environmental challenges, which can be modeled using physiologic measures. SCZ patients consistently show heightened basal stress, however, their parasympathetic reactivity to an acute psychosocial stressor is poorly understood. Heart period (HP-arousal), respiratory sinus arrhythmia (RSA-parasympathetic vagal activity), and their relationship were measured in SCZ patients (n = 19) and healthy controls (n = 20) at baseline and during psychosocial stress exposure. Parasympathetic vagal control of arousal, reflected in RSA-HP coupling, was assessed for the first time in SCZ. Patients demonstrated blunted physiologic reactivity (less change in heart period and respiratory sinus arrhythmia), a unique increase in respiratory sinus arrhythmia relative to baseline during recovery, and elevated arousal was associated with poor cognitive performance and greater positive symptoms. Arousal regulation was tightly controlled by parasympathetic activity in controls only, indicated by a strong association between changes in heart period and respiratory sinus arrhythmia. Results are the first to demonstrate maladaptive, inefficient parasympathetic arousal regulation (RSA-HP decoupling) in reaction to psychosocial stress in SCZ, representing an autonomic profile incompatible with appropriate social and emotional functioning.

The beat of social cognition: Exploring the role of heart rate variability as marker of mentalizing abilities

There is a long-standing debate on the influence of physiological signals on social behavior. Recent studies suggested that heart rate variability (HRV) may be a marker of social cognitive processes. However, this evidence is preliminary and limited to laboratory studies. In this study, 25 participants were assessed with a social cognition battery and asked to wear a wearable device measuring HRV for 6 consecutive days. The results showed that reduced HRV correlated with higher hostility attribution bias. However, no relationship was found between HRV and other social cognitive measures including facial emotion recognition, theory of mind or emotional intelligence. These results suggest that HRV may be linked to specific social cognitive processes requiring online emotional processing, in particular those related to social threat. These findings are discussed in the context of the neurovisceral integration model.

Autonomic nervous system dysfunction in psychiatric disorders and the impact of psychotropic medications: a systematic review and meta-analysis

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.

Resting vagal activity in schizophrenia: meta-analysis of heart rate variability as a potential endophenotype

BACKGROUND

Cardiac vagal tone, indexed by heart rate variability (HRV), is a proxy for the functional integrity of feedback mechanisms integrating central and peripheral physiology.

AIMS

To quantify differences in HRV in individuals with schizophrenia compared with healthy controls.

METHOD

Databases were systematically searched for studies eligible for inclusion. Random effect meta-analyses of standardised mean differences were calculated for vagal activity indicated by high-frequency HRV and the root mean square of successive R-R interval differences (RMSSD).

RESULTS

Thirty-four studies were included. Significant main effects were found for high-frequency HRV (P = 0.0008; Hedges' g = -0.98, 95% CI -1.56 to -0.41, k = 29) and RMSSD (P<0.0001; g = -0.91, 95% CI -1.19 to -0.62, k = 24), indicating lower vagal activity in individuals with schizophrenia than in healthy controls. Considerable heterogeneity was evident but effects were robust in subsequent sensitivity analyses.

CONCLUSIONS

Given the association between low HRV, threat processing, emotion regulation and executive functioning, reduced vagal tone may be an endophenotype for the development of psychotic symptoms.

Heart rate variability and vagal tone in schizophrenia: A review

Recent heart rate variability (HRV) research has identified diminished levels of parasympathetic activity among schizophrenia patients. Over two dozen empirically-based studies have been published on this topic; primarily over the last decade. However, no theoretical review appears to have been published on this work. Further, only one empirical study has evaluated HRV research findings in the context of documented hypothalamic-pituitary-adrenal axis hyperactivity in schizophrenia. HRV research indicates that no abnormalities exist in the initial sympathetic stress response of schizophrenia patients. However, evidence has consistently demonstrated that patients exhibit a diminished capacity to recover from a stress response as a result of deficits in parasympathetic activity. Moreover, this diminished parasympathetic nervous system (PNS) response, also known as decreased vagal tone, has been found to relate to increased symptom severity. Although these findings may cause speculation that the observed vagal tone disruption merely results from anxiety produced by the presence of positive symptomology, additional studies have identified similar parasympathetic dysfunction among nonpsychotic relatives of individuals with schizophrenia. We posit that the resulting sympathovagal imbalance leads to an overall sympathetic dominance despite the fact that sympathetic nervous system activity is not abnormally elevated among patients. Implications are discussed within the context of the diathesis-stress/vulnerability-stress model, including the potential for identifying a mechanism of action by which environmental stressors may contribute to triggering first-episode psychosis.

Cardiac Autonomic Dysfunction in Patients with Schizophrenia and Their Healthy Relatives - A Small Review

The majority of excess mortality among people with schizophrenia seems to be caused by cardiovascular complications, and in particular, coronary heart disease. In addition, the prevalence of heart failure and arrhythmias is increased in this population. Reduced efferent vagal activity, which has been consistently described in these patients and their healthy first-degree relatives, might be one important mechanism contributing to their increased cardiac mortality. A decrease in heart rate variability and complexity was often shown in unmedicated patients when compared to healthy controls. In addition, faster breathing rates, accompanied by shallow breathing, seem to influence autonomic cardiac functioning in acute unmedicated patients substantially. Moreover, low-physical fitness is a further and independent cardiac risk factor present in this patient population. Interestingly, new studies describe chronotropic incompetence during physical exercise as an important additional risk factor in patients with schizophrenia. Some studies report a correlation of the autonomic imbalance with the degree of positive symptoms (i.e., delusions) and some with the duration of disease. The main body of psychiatric research is focused on mental aspects of the disease, thereby neglecting obvious physical health needs of these patients. Here, a joint effort is needed to design interventional strategies in everyday clinical settings to improve physical health and quality of life.

Prenatal maternal immune disruption and sex-dependent risk for psychoses

BACKGROUND

Previous studies suggest that abnormalities in maternal immune activity during pregnancy alter the offspring's brain development and are associated with increased risk for schizophrenia (SCZ) dependent on sex.

METHOD

Using a nested case-control design and prospectively collected prenatal maternal sera from which interleukin (IL)-1β, IL-8, IL-6, tumor necrosis factor (TNF)-α and IL-10 were assayed, we investigated sex-dependent associations between these cytokines and 88 psychotic cases [SCZ = 44; affective psychoses (AP) = 44] and 100 healthy controls from a pregnancy cohort followed for > 40 years. Analyses included sex-stratified non-parametric tests adjusted for multiple comparisons to screen cytokines associated with SCZ risk, followed by deviant subgroup analyses using generalized estimating equation (GEE) models.

RESULTS

There were higher prenatal IL-6 levels among male SCZ than male controls, and lower TNF-α levels among female SCZ than female controls. The results were supported by deviant subgroup analyses with significantly more SCZ males with high IL-6 levels (>highest quartile) compared with controls [odd ratio (OR)75 = 3.33, 95% confidence interval (CI) 1.13-9.82], and greater prevalence of low TNF-α levels (<lowest quartile) among SCZ females compared with their controls (OR25 = 6.30, 95% CI 1.20-33.04) and SCZ males. Higher levels of IL-6 were only found among SCZ compared with AP cases. Lower TNF-α levels (non-significant) also characterized female AP cases versus controls, although the prevalence of the lowest levels was higher in SCZ than AP females (70% v. 40%), with no effect in SCZ or AP males.

CONCLUSIONS

The results underscore the importance of immunologic processes affecting fetal brain development and differential risk for psychoses depending on psychosis subtype and offspring sex.

Social cognition and functional outcome in schizophrenia: The moderating role of cardiac vagal tone

Individuals with schizophrenia face significant challenges in daily functioning, and although social cognition predicts how well patients respond to these challenges, associated physiological mechanisms remain unspecified. The present study draws from polyvagal theory and tested the hypothesis that respiratory sinus arrhythmia (RSA), an established indicator of the capacity to self-regulate and adapt to environmental demands, combines with social cognition to predict functional outcome. Using data from 41 schizophrenia patients and 36 healthy comparison subjects, we replicated group differences in RSA and social cognition and also demonstrated that RSA and social cognition interact to predict how effectively patients manage work and independent living activities. Specifically, RSA did not enhance functional outcomes when social cognition was already strong, but higher levels of RSA enabled effective role functioning when social-cognitive performance was impaired. Jointly, RSA and social cognition accounted for 40% of the variance in outcome success, compared with 21% when evaluating social cognition alone. As polyvagal theory suggests, physiological flexibility and self-regulatory capacity may compensate for poorer social-cognitive skills among schizophrenia patients.