The intricate brain-heart connection: The relationship between heart rate variability and cognitive functioning

Neuroscience. 2024 Dec 5:S0306-4522(24)00705-X. doi: 10.1016/j.neuroscience.2024.12.004. Online ahead of print.

ABSTRACT

In the last years, there has been a growing interest in the brain-heart connection. A core aspect of this connection appears to be the autonomic nervous system, particularly through the vagus nerve. Accordingly, vagally mediated heart rate variability (vmHRV) is currently considered as an index of top-down control processes involved in cognition and emotion regulation. Recent evidence indicates that higher vmHRV is associated with enhanced cognitive performance across multiple domains, such as executive functions, memory, attention, and language skills. From this premises, this study examined the relationship between cardiac vagal tone, as indicated by heart rate variability (vmHRV), and cognitive functions. A sample of 143 healthy young adults completed a comprehensive neuropsychological battery. The results revealed a strong correlation between resting vmHRV and cognitive functions, particularly in executive processes. Participants with higher resting vagal tone showed superior cognitive performance in tasks requiring cognitive control, motor and cognitive inhibition, cognitive flexibility, and working memory in comparison to those with lower resting vagal tone. Furthermore, vagal-mediated heart rate variability was also found to be associated with memory, attention, and executive performance. The current research provides new insights into the interactions between cognitive and autonomic systems, further supporting evidence for body-brain interactions.

PMID:39645073 | DOI:10.1016/j.neuroscience.2024.12.004

Changes in Response Inhibition, Visual Anticipation and Verbal Fluency During Vagus Nerve Stimulation Therapy in Patients With Drug-Resistant Epilepsy

Brain Behav. 2024 Dec;14(12):e70176. doi: 10.1002/brb3.70176.

ABSTRACT

BACKGROUND: The effect of vagus nerve stimulation (VNS) on cognitive domain of attention and executive functions (AEFs) has not been extensively researched. This study was set up to investigate performance variability on cognitive tests assessing AEFs in drug-resistant epilepsy (DRE) patients receiving VNS therapy during a follow-up of up to 5 years.

METHODS: Thirty-three DRE patients were assessed with the interference, maze, and written verbal fluency tests as a part of EpiTrack screening before and after VNS implantation through repeated follow-ups according to the clinical VNS protocol. A linear mixed-effects model was used to analyse changes in test scores.

RESULTS: Maze performance improved significantly by an average of 0.20 s per month (95% confidence interval (CI): -0.365 to -0.041; p = 0.014). Interference performance improved by an average of 0.05 s per month (p = 0.207) and number of words increased by an average of 0.03 words per month (p = 0.079) on the verbal fluency test. On the maze test, patients with psychiatric comorbidities improved the most (0.52 s/month, p = 0.001), while on the interference test, patients with frontal lobe epilepsy (FLE), those taking 1-2 antiseizure medications (ASMs) and patients with focal to bilateral tonic-clonic seizures improved the most (0.14 s/month, p = 0.005; 0.14 s/month, p = 0.033 and 0.16 s/month, p = 0.087, respectively). For verbal fluency, no clinically meaningful improvement was noted in any of the groups.

CONCLUSION: During the follow-up, maze performance markedly improved, while performance on the interference and verbal fluency tasks remained relatively stable at the group level. Accordingly, visual anticipation and planning improved during VNS therapy whereas response inhibition was unchanged at the group level despite significant enhancements in patients with FLE and those taking 1-2 ASM. Furthermore, the presence of psychiatric comorbidities correlated with even greater improvement on maze performance.

PMID:39643448 | DOI:10.1002/brb3.70176

A Body-Temperature-Triggered In Situ Softening Peripheral Nerve Electrode for Chronic Robust Neuromodulation

Adv Sci (Weinh). 2024 Dec 6:e2412361. doi: 10.1002/advs.202412361. Online ahead of print.

ABSTRACT

Implantable peripheral nerve electrodes are crucial for monitoring health and alleviating symptoms of chronic diseases. Advanced compliant electrodes have been developed because of their biomechanical compatibility. However, these mechanically tissue-like electrodes suffer from unmanageable operating forces, leading to high risks of nerve injury and fragile electrode-tissue interfaces. Here, a peripheral nerve electrode is developed that simultaneously fulfills the criteria of body temperature softening and tissue-like modulus (less than 0.8 MPa at 37 °C) after implantation. The central core is altered from the tri-arm crosslinker to the star-branched monomer to kill two birds (close the translation temperature to 37 °C and decrease the modulus after implantation) with one stone. Furthermore, the decreased interfacial impedance (325.1 ± 46.9 Ω at 1 kHz) and increased charge storage capacity (111.2 ± 5.8 mC cm-2) are achieved by an in situ electrografted conductive polymer on the strain-insensitive conductive network of Au nanotubes. The electrodes are readily wrapped around nerves and applied for long-term stimulation in vivo with minimal inflammation. Neuromodulation experiments demonstrate their potential clinical utility, including vagus nerve stimulation in rats to suppress seizures and alleviation of cardiac remodeling in a canine model of myocardial infarction.

PMID:39639850 | DOI:10.1002/advs.202412361

Safety and effectiveness of transcutaneous auricular vagus nerve stimulation on patients with depersonalization-derealization disorder: study protocol for a randomized controlled trial

Trials. 2024 Dec 5;25(1):812. doi: 10.1186/s13063-024-08658-w.

ABSTRACT

BACKGROUND: Depersonalization-derealization disorder (DPD) is a complex psychiatric condition marked by profound and often relentless feelings of detachment from one’s self and surroundings. Transcranial electrical stimulation (taVNS) holds promise as a potential therapeutic approach for DPD. This study aims to investigate the safety and efficacy of taVNS in treating DPD.

METHODS: DPD patients were recruited as research subjects and randomly allocated to the experimental and control groups, with the former receiving active-taVNS treatment and the latter receiving sham stimulation treatment for 6 weeks. The efficacy of taVNS in treating DPD was evaluated by comparing scores for DPD symptoms, depression and anxiety symptoms, cognitive function, and social function before and after treatment between the two groups. The safety of taVNS in treating DPD was assessed by comparing general safety assessment results between the two groups of DPD patients.

DISCUSSION: This study will assess taVNS as a potential treatment for DPD, evaluating its safety, efficacy, and impact on patient outcomes and societal burden.

TRIAL REGISTRATION: Chinese Clinical Trial Registry, ChiCTR2300078183, Registered on 30 November, 2023, https://www.chictr.org.cn/showproj.html?proj=206119.

PMID:39639403 | DOI:10.1186/s13063-024-08658-w

Comparison of vagus nerve cross-sectional area between brain-first and body-first Parkinson’s disease

NPJ Parkinsons Dis. 2024 Dec 5;10(1):231. doi: 10.1038/s41531-024-00844-6.

ABSTRACT

The vagus nerve (VN) is the main neural pathway linking the gut and brain in Parkinson’s disease (PD). In this study, we utilized high-resolution ultrasound to measure the VN cross-sectional area (CSA) in 96 healthy controls (HCs) and 75 PD patients. The PD group was further categorized into three subgroups: PD-preRBD, PD-postRBD, and PD-nonRBD. PD-preRBD was the body-first subtype, and PD-postRBD and PD-nonRBD were the brain-first subtype. The PD group had a significantly lower VN CSA than HCs. Subgroup analysis revealed that the PD-preRBD group tended to exhibit a smaller VN CSA than both the PD-postRBD and PD-nonRBD groups. The VN CSA, specifically the right VN, was significantly correlated with the body-first subtype and some components of PD-related assessment scales. Overall, these findings provide evidence of VN atrophy in PD, especially in body-first PD, suggesting that VN ultrasound could serve as an adjunctive diagnostic tool.

PMID:39639003 | PMC:PMC11621687 | DOI:10.1038/s41531-024-00844-6

Transcutaneous auricular vagus nerve stimulation attenuates stroke-heart syndrome: The role of parasympathetic activity

Exp Neurol. 2024 Dec 3:115094. doi: 10.1016/j.expneurol.2024.115094. Online ahead of print.

ABSTRACT

Stroke induces cardiac dysfunction, which increases poststroke mortality and morbidity. An imbalance in the autonomic nervous system resulting from brain injury may serve as the underlying mechanism. The present study investigated whether transcutaneous auricular vagus nerve stimulation (taVNS) attenuates poststroke cardiac dysfunction by activating the parasympathetic nervous system. Adult male mice were subjected to transient middle cerebral artery occlusion (MCAO) and reperfusion surgery. The mice in the treatment group received repeated taVNS starting 60 min after the onset of cerebral ischemia. To assess whether the effects of taVNS were associated with parasympathetic activity, the MCAO mice in the atropine group received intraperitoneal injections of atropine to inhibit parasympathetic activity prior to taVNS. taVNS significantly increased the left ventricular ejection fraction (EF), attenuated myocardial apoptosis, reduced myocardial hypertrophy, and reduced fibrosis following stroke. The beneficial effects of taVNS on cardiac dysfunction were abolished by atropine administration. Heart rate variability (HRV) analysis and western blot analysis revealed that taVNS increased parasympathetic activity but decreased sympathetic dominance in mice with MCAO. Furthermore, the cardioprotective effects of taVNS were associated with muscarinic acetylcholine receptor activation, PI3K-Akt pathway modulation, and eNOS regulation in the heart. Therefore, taVNS alleviates cardiac dysfunction after stroke and is associated with activation of the parasympathetic nervous system.

PMID:39637965 | DOI:10.1016/j.expneurol.2024.115094

First-aid knowledge and practices towards patients with epileptic seizures among the dental students in Saudi Arabia – A cross-sectional study

J Family Med Prim Care. 2024 Oct;13(10):4217-4224. doi: 10.4103/jfmpc.jfmpc_153_24. Epub 2024 Oct 18.

ABSTRACT

BACKGROUND: Dental care of patients with epilepsy and seizures must be performed by dentists who are familiar with these disorders. Improper training and incapability to manage medical emergencies, including epileptic seizures, may cause thoughtful consequences and legal actions. Therefore, dental students must have a proper knowledge of the disease and its consequences. They should have the ability to provide first-aid measures helping a patient experiencing an epileptic seizure in their clinics. This study aims to evaluate the first-aid knowledge and practices towards patients with epileptic seizures among the dental students in Saudi Arabia.

METHODS: A cross-sectional study was conducted targeting dental students in Saudi Arabia from 15 September 2022 to 15 December 2022 using convenience sampling. An online questionnaire was sent to the students via social media platforms for data collection. The data analysis was conducted using the Statistical Package for the Social Sciences (SPSS) version 16.0.

RESULTS: Of the 499 dental students included, 154 (30.86%) students had ever seen an epileptic patient in the clinics. About 16% of students did not know about performing cardiopulmonary resuscitation (CPR) on patients. The majority (66.5%) would call the ambulance after the patient’s seizure stops. About 82% of students prefer to call an ambulance if the patients face difficulty breathing or waking up after the seizure. More than 60% of students were taking precautions before treating an epilepsy patient. About 58.5% of the students were using local anaesthesia for an epilepsy patient. Nearly 41.9% do not have the confidence to treat an epilepsy patient. About 28.0% would swipe the vagus nerve stimulation (VNS) magnet over the left side of the chest. Of 154 students, who had ever seen epileptic patients, the majority (68.8%) refused to treat patients if they observe noncompliance with medication and follow-up among the patients who had any recent illness or seizures (16.2%).

CONCLUSION: The undergraduate dental students had an intermediate knowledge regarding epilepsy and epileptic seizure first aid. However, some students lacked the confidence to deal with the epileptic cases in their clinics. Educational campaigns on epilepsy and first-aid courses targeting dental students are highly recommended.

PMID:39629417 | PMC:PMC11610869 | DOI:10.4103/jfmpc.jfmpc_153_24

Update on Research and Treatment of Chronic Kidney Disease

No Shinkei Geka. 2024 Nov;52(6):1206-1214. doi: 10.11477/mf.1436205037.

ABSTRACT

The kidney and brain share strain vessels, which are short and small arterioles that branch out of larger arteries. These vessels are vulnerable to risk factors such as atherosclerosis, old age, hypertension, diabetes, dyslipidemia, and smoking. The nervous system and the kidneys interact to maintain homeostasis. Many chronic kidney disease(CKD)-specific and nonspecific factors contribute to structural and functional cerebral changes in patients with CKD. In contrast, vagus nerve stimulation has been reported to alleviate inflammatory diseases, including kidney disease. Several new drugs have recently become available for the treatment of CKD: sodium-glucose co-transporter-2 inhibitors for CKD; finerenone, a mineralocorticoid receptor antagonist for CKD with type 2 diabetes; and a hypoxia-inducible factor prolyl-hydroxylase inhibitor for anemia in patients with CKD.

PMID:39622326 | DOI:10.11477/mf.1436205037