Contingent Negative Variation in the Evaluation of Neurocognitive Disorders Due to Possible Alzheimer's Disease.

The usefulness of Contingent Negative Variation (CNV) potential as a biomarker of neurocognitive disorders due to possible Alzheimer's disease, is based on its possible physiological correlates. However, its application in the diagnostic evaluation of these disorders is still incipient. The aim of this study is to characterize the patterns of cognitive processing of information in the domain of nonspecific global attention, by recording potential CNV in a group of patients with neurocognitive disorders due to possible Alzheimer's disease. An experimental study of cases and controls was carried out. The sample included 39 patients classified according to DSM-5 with a neurocognitive disorder subtype possibly due Alzheimer's disease, and a Control Group of 53 subjects with normal cognitive functions. CNV potential was registered using standard protocol. The analysis of variance obtained significant differences in mean values and confidence intervals of total CNV amplitude between the three study groups. The late CNV segment amplitudes makes it possible to discriminate between the level of mild and major dysfunction in the group of patients. The CNV total amplitudes of potential allows for effective discrimination between normal cognitive functioning and neurocognitive disorders due to possible Alzheimer's disease.

The Relationship between Paresthesia and the Presence of Cardiac Dysautonomia in Patients with Post-COVID-19 Syndrome: A Preliminary Observational Study.

INTRODUCTION: Post-Coronavirus disease 2019 (Post-COVID-19) syndrome has neurological symptoms related to the dysfunction of the autonomous nerve system. However, a pathogenic relationship between post-COVID-19 syndrome and dysautonomia still remains to be demonstrated. Establishing a pathogenic relationship between paresthesia and the presence of cardiac dysautonomia in patients with post-COVID-19 syndrome is the objective of this study. PARTICIPANTS AND METHODS: This observational study was carried out in the neurophysiology service wing of the Juan Bruno Zayas Hospital, Santiago de Cuba, in Cuba. The patients were recruited through a post-COVID-19 clinic at the same hospital. A variability study of cardiac frequency and a test of autonomic cardiovascular reflexes was carried out, which is composed of deep breathing, orthostatism, and the Valsalva maneuver. RESULTS: The variability parameters of the cardiac frequency, the expiration-inspiration ratio between deep breaths, and the Valsalva Index showed no statistically significant differences between healthy participants and those with post-COVID-19 syndrome. During the Valsalva maneuver, there was a greater cardiac frequency response in participants with post-COVID-19 syndrome than in healthy subjects. The difference in supine and standing blood pressure was significantly minor in patients with post-COVID-19 syndrome. The logarithm of high frequency (log HF) increased significantly in patients with paresthesia when compared to patients without paresthesia. CONCLUSIONS: In the autonomic function tests, no signs of dysautonomia were found in patients with post-COVID-19 syndrome. The presence of paresthesias is associated with differences in cardiac vagal activity, which may suggest that damage to peripheral sensory nerve fibers could be associated with an affectation to autonomic fibres.

Autonomic and Vascular Responses during Reactive Hyperemia in Healthy Individuals and Patients with Sickle Cell Anemia.

Background and Objectives: To compare autonomic and vascular responses during reactive hyperemia (RH) between healthy individuals and patients with sickle cell anemia (SCA). Materials and Methods: Eighteen healthy subjects and 24 SCA patients were subjected to arterial occlusion for 3 min at the lower right limb level. The pulse rate variability (PRV) and pulse wave amplitude were measured through photoplethysmography using the Angiodin® PD 3000 device, which was placed on the first finger of the lower right limb 2 min before (Basal) and 2 min after the occlusion. Pulse peak intervals were analyzed using time-frequency (wavelet transform) methods for high-frequency (HF: 0.15-0.4) and low-frequency (LF: 0.04-0.15) bands, and the LF/HF ratio was calculated. Results: The pulse wave amplitude was higher in healthy subjects compared to SCA patients, at both baseline and post-occlusion (p < 0.05). Time-frequency analysis showed that the LF/HF peak in response to the post-occlusion RH test was reached earlier in healthy subjects compared to SCA patients. Conclusions: Vasodilatory function, as measured by PPG, was lower in SCA patients compared to healthy subjects. Moreover, a cardiovascular autonomic imbalance was present in SCA patients with high sympathetic and low parasympathetic activity in the basal state and a poor response of the sympathetic nervous system to RH. Early cardiovascular sympathetic activation (10 s) and vasodilatory function in response to RH were impaired in SCA patients.

Discriminant Model for Insulin Resistance in Type 2 Diabetic Patients.

Introduction: Patients with type 2 diabetes mellitus tend to have insulin resistance, a condition that is evaluated using expensive methods that are not easily accessible in routine clinical practice. Objective: To determine the anthropometric, clinical, and metabolic parameters that allow for the discrimination of type 2 diabetic patients who have insulin resistance from those who do not. Methods: A cross-sectional analytical observational study was carried out in 92 type 2 diabetic patients. A discriminant analysis was applied using the SPSS statistical package to establish the characteristics that differentiate type 2 diabetic patients with insulin resistance from those without it. Results: Most of the variables analyzed in this study have a statistically significant association with the HOMA-IR. However, only HDL-c, LDL-c, glycemia, BMI, and tobacco exposure time allow for the discrimination of type 2 diabetic patients who have insulin resistance from those who do not, considering the interaction between them. According to the absolute value of the structure matrix, the variable that contributes most to the discriminant model is HDL-c (-0.69). Conclusions: The association between HDL-c, LDL-c, glycemia, BMI, and tobacco exposure time allows for the discrimination of type 2 diabetic patients who have insulin resistance from those who do not. This constitutes a simple model that can be used in routine clinical practice.

Reactive Hyperemia and Cardiovascular Autonomic Neuropathy in Type 2 Diabetic Patients: A Systematic Review of Randomized and Nonrandomized Clinical Trials.

Objective: This work aimed to determine the relationship between the autonomic nervous system and reactive hyperemia (RH) in type 2 diabetes patients with and without cardiovascular autonomic neuropathy (CAN). Methodology: A systematic review of randomized and nonrandomized clinical studies characterizing reactive hyperemia and autonomic activity in type 2 diabetes patients with and without CAN was performed. Results: Five articles showed differences in RH between healthy subjects and diabetic patients with and/or without neuropathy, while one study did not show such differences between healthy subjects and diabetic patients, but patients with diabetic ulcers had lower RH index values compared to healthy controls. Another study found no significant difference in blood flow after a muscle strain that induced reactive hyperemia between normal subjects and non-smoking diabetic patients. Four studies measured reactive hyperemia using peripheral arterial tonometry (PAT); only two found a significantly lower endothelial-function-derived measure of PAT in diabetic patients than in those without CAN. Four studies measured reactive hyperemia using flow-mediated dilation (FMD), but no significant differences were reported between diabetic patients with and without CAN. Two studies measured RH using laser Doppler techniques; one of them found significant differences in the blood flow of calf skin after stretching between diabetic non-smokers and smokers. The diabetic smokers had neurogenic activity at baseline that was significantly lower than that of the normal subjects. The greatest evidence revealed that the differences in RH between diabetic patients with and without CAN may depend on both the method used to measure hyperemia and that applied for the ANS examination as well as the type of autonomic deficit present in the patients. Conclusions: In diabetic patients, there is a deterioration in the vasodilator response to the reactive hyperemia maneuver compared to healthy subjects, which depends in part on endothelial and autonomic dysfunction. Blood flow alterations in diabetic patients during RH are mainly mediated by sympathetic dysfunction. The greatest evidence suggests a relationship between ANS and RH; however, there are no significant differences in RH between diabetic patients with and without CAN, as measured using FMD. When the flow of the microvascular territory is measured, the differences between diabetics with and without CAN become evident. Therefore, RH measured using PAT may reflect diabetic neuropathic changes with greater sensitivity compared to FMD.

Early cardiovascular sympathetic reflex activation is independent of occlusion time during reactive hyperemia / La activación temprana del reflejo simpático cardiovascular es independiente del tiempo de oclusión durante la hiperemia reactiva / A ativação precoce do reflexo simpático cardiovascular é independente do tempo de oclusão durante a hiperemia reativa

Purpose: The aim of the present study was to investigate the role of occlusion time in dynamic changes of autonomic activation during reactive hyperemia. Methods: Healthy subjects (n = 30) in the age range of 18­25 years participated in this study. Vascular reactivity was assessed by measuring the dynamic changes in finger pulse volume amplitude (PVA) and  pulse transit time relative to the RR intervals in the test (occluded arm) and control arm (contralateral non-occluded arm) during 1, 3 and 5 minute of occlusion using two separate Photoplethysmographic sensors. Heart Rate Variability was computed from a simultaneously acquired ECG signal to monitor the dynamic changes in cardiac autonomic nervous activity. Time-varying analysis of all signals were shown every 1 second in average response graphs. Results: Time-varying analysis of vascular and autonomic response during reactive hyperemia demonstrated the presence of a characteristic response pattern with an increase in the Sympathetic index and a decrease in Parasympathetic index at 8 to 10 seconds, an increase in heart rate at 20 seconds and a progressive increase in PVA during the first 60 seconds after occlusion regardless of the time spent in the procedure. Moreover, a decrease in pulse transits time relative to RR intervals,  followed by an increase regardless of the occlusion time was evidenced.  Conclusions: Early cardiovascular sympathetic activation is independent of occlusion time during reactive hyperemia, which suggests this is a vascular autonomic reflex response involved in the generation of the physiological phenomenon of reactive hyperemia.

Objetivo: El objetivo del presente estudio fue investigar el papel del tiempo de oclusión en los cambios dinámicos de la activación autónoma durante la hiperemia reactiva.Métodos: Participaron en este estudio sujetos sanos (n = 30) en el rango de edad de 18 a 25 años. La reactividad vascular se evaluó midiendo los cambios dinámicos en la amplitud del volumen del pulso del dedo (PVA) y el tiempo de tránsito del pulso en relación con los intervalos RR en la prueba (brazo ocluido) y el brazo de control (brazo contralateral no ocluido) durante 1, 3 y 5 minutos. de oclusión utilizando dos sensores fotopletismográficos separados. La variabilidad de la frecuencia cardíaca se calculó a partir de una señal de ECG adquirida simultáneamente para controlar los cambios dinámicos en la actividad nerviosa autónoma cardíaca. El análisis variable en el tiempo de todas las señales se mostró cada segundo en gráficos de respuesta promedio.Resultados: El análisis variable en el tiempo de la respuesta vascular y autonómica durante la hiperemia reactiva demostró la presencia de un patrón de respuesta característico con un aumento en el índice simpático y una disminución en el índice parasimpático a los 8 a 10 segundos, un aumento en la frecuencia cardíaca a los 20 segundos y un aumento progresivo de PVA durante los primeros 60 segundos después de la oclusión independientemente del tiempo transcurrido en el procedimiento. Además, se evidenció una disminución en el tiempo de tránsitos del pulso en relación con los intervalos RR, seguido de un aumento independientemente del tiempo de oclusión.Conclusiones: La activación simpática cardiovascular temprana es independiente del tiempo de oclusión durante la hiperemia reactiva, lo que sugiere que se trata de una respuesta refleja autonómica vascular involucrada en la generación del fenómeno fisiológico de hiperemia reactiva.

Objetivo: O objetivo do presente estudo foi investigar o papel do tempo de oclusão nas mudanças dinâmicas da ativação autonômica durante a hiperemia reativa.Métodos: Participaram deste estudo indivíduos saudáveis ​​(n = 30) na faixa etária de 18 a 25 anos. A reatividade vascular foi avaliada medindo as mudanças dinâmicas na amplitude do volume do pulso do dedo (PVA) e tempo de trânsito do pulso em relação aos intervalos RR no teste (braço ocluído) e braço controle (braço não ocluído contralateral) durante 1, 3 e 5 minutos de oclusão usando dois sensores fotopletismográficos separados. A variabilidade da frequência cardíaca foi calculada a partir de um sinal de ECG adquirido simultaneamente para monitorar as mudanças dinâmicas na atividade nervosa autonômica cardíaca. A análise variável no tempo de todos os sinais foi mostrada a cada 1 segundo em gráficos de resposta média.Resultados: A análise variável no tempo da resposta vascular e autonômica durante a hiperemia reativa demonstrou a presença de um padrão de resposta característico com um aumento no índice simpático e uma diminuição no índice parassimpático em 8 a 10 segundos, um aumento na frequência cardíaca em 20 segundos e aumento progressivo do PVA durante os primeiros 60 segundos após a oclusão, independentemente do tempo despendido no procedimento. Além disso, foi evidenciada uma diminuição no tempo de trânsito de pulso em relação aos intervalos RR, seguida de um aumento independente do tempo de oclusão.Conclusões: A ativação simpática cardiovascular precoce independe do tempo de oclusão durante a hiperemia reativa, o que sugere que se trata de uma resposta reflexa autonômica vascular envolvida na geração do fenômeno fisiológico de hiperemia reativa.

Dynamics of cardiac autonomic regulation during isometric sustained weight test in hypertensive patients

Background: The Sustained Weight Test (SWT) is an isometric exercise test that has great practical value for carrying out massive studies on hypertension, however, is insufficient knowledge of the dynamics of cardiac autonomic regulation during this test. The aim of this study was to determine variations in the dynamics of cardiac autonomic regulation and in hemodynamic response during SWT in hypertensive subjects. Methods: A quasi-experimental study was conducted on 15 hypertensive patients of both sexes, paired with 30 normotensive individuals, measuring arterial blood pressure, entropy sample and the Heart Rate Variability (HRV) in time-frequency with the Continuous Wavelet Transform Morlet-type (CWT  morlet) through the electrocardiographic signal of the polygraph AD Instruments in the functional states of Rest and SWT. Results: A significant increase in heart rate and blood pressure was found, as well as a decrease in sample entropy in the functional states of normotensive and hypertensive patients. In hypertensive patients, an early response pattern increased with multiple fluctuations during SWT in the time-frequency analysis of HRV with the CWT morlet. Conclusions: SWT produces an increase in blood pressure, which is more frequent and evident in hypertensive subjects. Cardiac autonomic regulation during SWT increases the sympathetic and decreases the parasympathetic components, manifesting itself in hypertensive patients with a pattern of imbalance in the regulation of both sympathetic and parasympathetic response.

Respuesta autonómica cardiovascular al estrés mental inducido por la prueba de cálculo aritmético / Autonomic cardiovascular response to mental stress induced by the arithmetic computation test

Introducción: El estrés mental agudo, así como los estados de ansiedad inducidos para influenciar la reactividad psicofisiológica en jóvenes sanos, aportan cambios en los patrones nerviosos que pueden ser medidos mediante la variabilidad de la frecuencia cardiaca. Objetivo: Determinar las diferencias en los parámetros lineales del balance autonómico cardiovascular en individuos jóvenes en estado basal y durante la prueba de cálculo aritmético. Métodos: Se realizó un estudio cuasi-experimental, sin grupo control de tipo antes y después, en el Laboratorio de Ciencias Básicas Biomédicas de la Universidad de Ciencias Médicas de Santiago de Cuba. Población y muestra de 10 sujetos. Se registró el trazado electrocardiográfico (5 min) durante el reposo y luego durante la prueba de cálculo aritmético. Resultados: Existieron diferencias significativas entre ambos estados en las variables frecuencia cardiaca (p = 0,005); mínima (p = 0,007); máxima (p = 0,005); intervalo RR (p = 0,005); stress index (p = 0,028); índice simpático (p = 0,005); bajas frecuencias (p = 0,005); relación LF/HF (p = 0,005); RMSSD (p = 0,007); NN50 (p = 0,008); pNN50 (p = 0,005); índice parasimpático (p = 0,005) y altas frecuencias (p = 0,005). El estrés mental provocó una disminución parasimpática y un predominio simpático uniforme en todos los sujetos participantes en el estudio. Conclusiones: Durante el estrés mental inducido por la prueba de cálculo aritmético la dinámica lineal de la respuesta autonómica cardiovascular experimenta un aumento en la actividad simpática y una disminución del tono parasimpático, traduciendo una respuesta adaptativa en la regulación de la función cardiovascular por el sistema nervioso autónomo(AU)

Introduction: Acute mental stress and states of anxiety induced to influence psychophysiological reactivity in healthy young people, result in changes in nervous patterns which may be measured in terms of heart rate variability. Objective: Determine the differences in linear parameters for autonomic cardiovascular balance in young individuals at baseline and during the arithmetic computation test. Methods: A non-observational quasi-experimental before-after study without a control group was conducted at the Basic Biomedical Sciences Laboratory of the University of Medical Sciences of Santiago de Cuba. The study population and sample was 10 subjects. The electrocardiographic tracing (5 min) was recorded at rest and then during the arithmetic computation test. Results: Significant differences were found between the two states as to the variables heart rate (p = 0.005), minimum (p = 0.007), maximum (p = 0.005), RR interval (p = 0.005), stress index (p = 0.028), sympathetic index (p = 0.005), low frequencies (p = 0.005), LF/HF ratio (p = 0.005), RMSSD (p = 0.007), NN50 (p = 0.008), pNN50 (p = 0.005), parasympathetic index (p = 0.005) and high frequencies (p = 0.005). Mental stress caused a parasympathetic reduction and uniform sympathetic predominance in all the subjects participating in the study. Conclusions: During the mental stress induced by the arithmetic computation test, the linear dynamic of the autonomic cardiovascular response experiences an increase in sympathetic activity and a reduction in parasympathetic tone, displaying an adaptive response in cardiovascular function regulation by the autonomous nervous system(AU)

Cardiac vagal imbalance to the isometric sustained weight test in adolescents with emotional eating behavior.

PURPOSE: To assess the relationship between emotional eating behavior and heart rate variability in Spanish adolescents during an isometric exercise test. METHODS: Participants included 52 adolescents aged between 13 and 18 years old. Heart rate was continuously recorded at rest (2 minutes) and during the sustained weight test (2 minutes). Linear and nonlinear methods of heart rate variability were assessed and related to the emotional eating behavior divided in two clusters. RESULTS: Statistically significant differences were observed in linear and non-linear parameters of heart rate variability comparing rest and sustained weight test. An increase in the value of emotional eating in overweight adolescents was founded. During the sustained weight test, there were differences between the two emotional eating clusters regarding the variables peak high frequency power, normalized low frequency power, normalized high frequency power, low frequency/high frequency ratio, and sample entropy. A positive correlation between the emotional eating behavior and the peak high frequency power was observed, though the prediction capacity of the high frequency waves is low it is observed that there is a good fit to the regression line. CONCLUSION: Results of this study shows that there was a relationship between vagal tone and emotional eating behavior in adolescents during an isometric exercise, with excessive parasympathetic predominance and sympathetic withdrawal during a physical effort.