Baseline Autonomic Activity Research Articles

Effects of water ingestion on autonomic activity and gastric motility in patients with celiac disease.

The pathogenesis of celiac disease is associated with an autoimmune process. The disease causes chronic inflammation of the small intestinal mucosa, which may affect the brain-gut axis. The activation of visceral receptors (gastrointestinal mechanoreceptor and osmoreceptor) in response to stomach distension caused by water ingestion has not been studied before. Our results showed reduced responsiveness of the autonomic nervous system to water ingestion in patients with celiac disease, which may lead to disturbances of gastric myoelectrical activity and depends on baseline autonomic activity. Water intake can induce gastric distension and motility response, without changes in gastrointestinal hormones. It can also increase the activity of the autonomic nervous system. On the other hand, inflammation in celiac disease (CeD) can alter visceral perception (increase sensitization), leading to autonomic dysfunction. We aimed to investigate the effect of water ingestion on autonomic activity measured as heart rate variability (HRV) and gastric myoelectrical activity measured by electrogastrography (EGG) in patients with CeD. The study included 53 patients with CeD and 50 healthy controls: mean (SD) age, 43.4 (14.8) years and 44.1 (9.2) years, respectively. Electrocardiography with HRV analysis and simultaneous 4-channel EGG was performed before and after the water load test (WLT) ingestion 500-ml water over 5 minutes. We found that compared with controls, at fasting, patients with CeD showed a reduced percentage of normogastria (P=0.045) and an average percentage of slow wave coupling (P<0.01) with increased dominant power (DP) (P<0.001). Moreover, water ingestion in CeD patients reduced the percentage of gastric arrhythmia (P<0.01) and increased the percentage of normogastria (P<0.01) and DP (P<0.01). Finally, in the CeD group, water ingestion increased HRV indices: low frequency by 116.9% (P<0.001), high frequency by 125.3% (P<0.01), but they did not reach the values of the control group. Patients with CeD showed a smaller increase in parasympathetic autonomic activity after the WLT than controls. Altered autonomic responsiveness may contribute to the disturbances of gastric myoelectrical activity and depends on baseline autonomic activity.

Inverse associations between parasympathetic activity and cognitive flexibility in African Americans: Preliminary findings

Previous research suggests that vagal activity and executive function (EF) are positively associated. However, existing data exploring the relationship between HRV and EF remains limited. Though Blacks may have higher HRV, they remain underrepresented in previous research examining HRV and EF. The current study aimed to determine the relationship between EF and HRV in a sample of 92 Black undergraduates (Mean age = 20.32, SD = 2.28). Participants wore an 6‑lead ambulatory electrocardiographic impedance monitoring system to obtain the root mean square of interbeat interval differences (rMSSD) and Cardiac Sympathetic Index. After baseline autonomic activity assessment, participants completed the Berg Card Sorting Test. Utilizing hierarchical regression analyses, HRV was negatively associated with correct responses (Beta = −0.40, SE = 0.04, p=0.01) and categories experienced (Beta = −0.37, SE = 0.01, p=0.01), and positively associated with total errors (Beta = 0.39, SE =0.04, p=0.01). To further elucidate these findings, participants were assigned to coinhibition (n = 12), parasympathetically dominant (n = 34), sympathetically dominant (n = 35), or coactivation (n = 11) autonomic space subgroups. Participants in the sympathetically dominant subgroup completed more categories (M = 6.86, SD = 2.13) and committed fewer errors (M = 30.63, SD = 11.53) than their parasympathetic counterparts (M = 5.74, SD = 2.44; M = 43.29, SD = 18.83, respectively). This study suggests that a state of sympathetic arousal immediately prior to the administration of an EF task, may aid in better task performance.

Major depressive disorder and generalized anxiety disorder show different autonomic dysregulations revealed by heart-rate variability analysis in first-onset drug-naïve patients without comorbidity.

The aim of the present study was to examine whether depression and anxiety disorder manifest different autonomic dysregulations using heart-rate variability (HRV) and heart rate (HR) measurements. HRV and HR were recorded both at rest and during task execution (random-number generation) in first-onset drug-naïve patients with major depressive disorder (MDD, n = 14) and generalized anxiety disorder (GAD, n = 11) as well as in healthy controls (n = 41). The patients showed no comorbidity of depression and anxiety disorder. GAD patients did not exhibit panic or phobic symptoms at the time of measurement. Following power spectrum analysis of HR trend, the high- (HF) and low-frequency (LF) components, the sum (LF + HF), and the LF/HF ratio were compared among the groups. In the MDD patients, as previously reported, HF was low and the LF/HF ratio was high during the initial-rest condition, and HF was less reactive to the task. In contrast, GAD patients showed significantly high HF, although autonomic reactivity was not impaired. The results indicate that baseline autonomic activity and its reactivity to behavioral changes are different between MDD and GAD in the early stage of illness. High parasympathetic tone in GAD may reflect responses of the parasympathetic system to anxiety. MDD is accompanied by an autonomic shift toward sympathetic activation and a reduced reactivity to task.

Effects of acute beta-adrenergic antagonism on verbal problem solving in autism spectrum disorder and exploration of treatment response markers

ABSTRACTAutism spectrum disorder (ASD) is characterized by impairments in social communication as well as restricted, repetitive behaviors. Evidence suggests that some individuals with ASD have cognitive impairments related to weak central coherence and hyperrestricted processing. Reducing noradrenergic activity may improve aspects of network processing and thus improve cognitive abilities, such as verbal problem solving, in individuals with ASD. The present pilot study explores the effects of acute administration of the beta-adrenergic antagonist propranolol on verbal problem solving in adults and adolescents with ASD. In a within-subject crossover-design, 20 participants with ASD received a single dose of propranolol or placebo on one of two sessions in a double-blinded, counterbalanced manner. Verbal problem solving was assessed via an anagram task. Baseline measurements of autonomic nervous system functioning were obtained, and anxiety was assessed at baseline and following drug administration. Participants solved the anagrams more quickly in the propranolol condition, as compared to the placebo condition, suggesting a potential cognitive benefit of this agent. Additionally, we observed a negative linear relationship between response to propranolol on the anagram task and two measures of baseline autonomic activity, as well as a positive linear relationship between drug response and baseline anxiety. These relationships propose potential markers for treatment response, as propranolol influences both autonomic functioning and anxiety. Further investigation is needed to expand on the present single-dose psychopharmacological challenge and explore the observed effects of propranolol in a serial-dose setting.

Metabotropic glutamate2/3 receptor agonism facilitates autonomic recovery after pharmacological panic challenge in healthy humans.

Group II metabotropic glutamate receptors (mGluR2/3) are suggested to modulate anxiety, arousal, and stress including autonomic control. However, no study has investigated mGluR2/3-related effects on baseline autonomic activity and reactivity to emotional challenge in humans as yet. Using a double-blind, randomized placebo-controlled, cross-over study design, we investigated the influence of a 1-week treatment with the mGluR2/3 agonist LY544344, prodrug of LY354740, on autonomic reactivity to a cholecystokinin tetrapeptide (CCK-4) panic challenge in eight healthy young men. The main outcome measures were time and frequency domain heart rate variability parameters during baseline, CCK-4 challenge, and recovery. There was no evidence for LY544344-mediated effects on baseline and CCK-4 challenge vagal activity, but a significantly lower recovery low frequency (%) and low frequency/high frequency ratio in the LY544344 group, suggesting enhanced autonomic recovery. This pilot study provides first human data indicating that mGluR2/3 agonism is involved in autonomic responsiveness, suggesting an important role of mGluR2/3 in central autonomic regulation.

Sex differences in the relationships between parasympathetic activity and pain modulation

Higher parasympathetic activity is related to lower pain perception in healthy subjects and pain patients. We aimed to examine whether this relationship depends on sex, in healthy subjects. Parasympathetic activity was assessed using time- and frequency-domain heart rate variability indices and deep breathing ratio. Pain perception parameters, consisting of heat pain thresholds and pain ratings of supra-thresholds stimuli, as well as pain modulation parameters of mechanical temporal summation, pain adaptation, offset analgesia and conditioned pain modulation (CPM) response were examined. Forty healthy subjects were examined (20 men). Women demonstrated higher parasympathetic activity compared to men (high frequency power of 0.55±0.2 and 0.40±0.2, respectively, p=0.02) and less pain reduction in the offset analgesia paradigm (−35.4±29.1 and −55.0±31.2, respectively, p=0.046). Separate slopes models analyses revealed sex differences such that a significant negative correlation was observed between higher rMSSD (the root mean square of successive differences) and higher pain adaptation in men (r=−0.649, p=0.003) but not in women (r=0.382, p=0.106). Similarly, a significant negative correlation was found between higher rMSSD and higher efficiency of the CPM response in men (r=−0.510, p=0.026) but not in women (r=0.406, p=0.085). Sex hormones levels, psychological factors or baseline autonomic activity can be possible explanations for these sex differences. Future autonomic interventions destined to change pain modulation should consider sex as an important intervening factor.

Heart rate variability and experimentally induced pain in healthy adults: A systematic review

Reactivity of the autonomic nervous system to experimental pain stimuli has been extensively studied using measures of heart rate and blood pressure. Heart rate variability (HRV) attempts to tease out the relative contributions of sympathetic and parasympathetic activity in the autonomic control of the heart and may therefore be more appropriate to investigate autonomic response to short-term nociceptive stimulation in detail. The current evidence on HRV and experimentally induced pain has not yet been synthesized within a systematic review. English articles indexed in PubMed, EMBASE, Psyndex, PsycINFO, CINAHL and the Cochrane Library were reviewed for eligibility under pre-specified inclusion criteria. Studies were included when they reported empirical work on autonomic response (specifically, HRV) to experimentally induced pain in healthy adults. The method of pain induction, the methodological features of HRV analysis (time domain and frequency domain measures), as well as pain and HRV-related findings were derived from the studies. The search revealed a total of 20 publications eligible for inclusion. Key results demonstrate an increase in sympathetic-baroreflex activity and a decrease in vagal-parasympathetic activity as reflected by changes in frequency domain measures of HRV. HRV has several advantages compared to other measures of autonomic reactivity in studies investigating physiological response to nociceptive stimulation. Future studies should focus on comparisons between different methods of pain induction, interindividual variability in pain sensitivity by baseline autonomic activity, and the implications of both on the use of HRV within routine clinical evaluations.

Breathing exercises with vagal biofeedback may benefit patients with functional dyspepsia

Objective. Many patients with functional dyspepsia (FD) have postprandial symptoms, impaired gastric accommodation and low vagal tone. The aim of this study was to improve vagal tone, and thereby also drinking capacity, intragastric volume and quality of life, using breathing exercises with vagal biofeedback. Material and methods. Forty FD patients were randomized to either a biofeedback group or a control group. The patients received similar information and care. Patients in the biofeedback group were trained in breathing exercises, 6 breaths/min, 5 min each day for 4 weeks, using specially designed software for vagal biofeedback. Effect variables included maximal drinking capacity using a drink test (Toro® clear meat soup 100 ml/min), intragastric volume at maximal drinking capacity, respiratory sinus arrhythmia (RSA), skin conductance (SC) and dyspepsia-related quality of life scores. Results. Drinking capacity and quality of life improved significantly more in the biofeedback group than in the control group (p=0.02 and p=0.01) without any significant change in baseline autonomic activity (RSA and SC) or intragastric volume. After the treatment period, RSA during breathing exercises was significantly correlated to drinking capacity (r=0.6, p=0.008). Conclusions. Breathing exercises with vagal biofeedback increased drinking capacity and improved quality of life in FD patients, but did not improve baseline vagal tone.

Clinical Neurophysiology: Motor/Sensory Physiology

Clinical Neurophysiology: Motor/Sensory Physiology

Early-onset schizophrenia as a progressive-deteriorating developmental disorder: evidence from child psychiatry.

The developmental perspective as reflected by investigations of childhood and early-onset schizophrenia has become a major research area during recent years and contributed much to the understanding of schizophrenia at all ages. This paper reviews clinical features, neurobiological and neuropsychological findings in childhood and adolescent onset schizophrenia including some results of studies of the author on age at onset, premorbid symptoms, treatment and course. Childhood-onset schizophrenia is a rare disorder with a prevalence of one child in 10,000 before the age of 12 and a remarkable increase around puberty and early adolescence. Developmental events and precursors of schizophrenia cover a wide range of dysfunctions and disturbances including elevated rates of soft neurological signs and birth complications, slow habituation and high baseline autonomic activity, high rate of developmental disorders of speech and/or language and overall and specific cognitive deficits. Brain morphological studies and intelligence testing as well as investigations of the course provide evidence of deterioration. Therefore, early-onset schizophrenia can be understood as a progressive-deteriorating developmental disorder.

Ambulatory monitoring of panic patients during regular activity: A preliminary report

Ten patients with panic disorder and 10 matched control subjects were compared as to their blood pressure and heart rate during regular daily activity. Physiological responses were monitored by ambulatory recorder, and subjective reports of mood were collected. Data were analyzed controlling for activity and stress level of the subjects. Diastolic blood pressure emerged as a possible discriminatory factor between the groups. A trend for higher heart rate occurred in the panic group. In behavioral terms, panic patients tended to avoid anxiety-provoking situations, resulting in anxiety ratings comparable to those of the control group. Thus, recorded physiological differences between the groups may reflect heightened baseline autonomic activity in panic patients.