Daniel Eduardo Vigo

Do not worry, be mindful: effects of induced worry and mindfulness on respiratory variability in a nonanxious population.

Generalized anxiety disorder (GAD) is characterized by chronic worry. Mindfulness-based stress reduction is thought to remediate excessive worry, because it counteracts a permanent defense state of enhanced vigilance to potential threats. The present study aimed to compare respiratory variability (RV) during worry and mindfulness. Following an 8-minute baseline, 37 healthy participants underwent 11-min worry and mindfulness inductions, in randomized order, using auditory scripts. Respiration was measured by chest and abdominal inductance belts. RV was quantified by (1) autocorrelation to assess linear breathing variability and (2) sample entropy to assess nonlinear breathing variability. Compared to baseline and mindfulness, worry showed decreased autocorrelation in all respiratory parameters and compared to mindfulness, worry showed decreased entropy in respiratory rate. These results suggest that, in contrast to mindfulness, worry is characterized by decreased respiratory stability and flexibility, and therefore worry and mindfulness seem to have countering effects on RV and respiratory regulation.

Changing Dynamics: Time-Varying Autoregressive Models Using Generalized Additive Modeling.

In psychology, the use of intensive longitudinal data has steeply increased during the past decade. As a result, studying temporal dependencies in such data with autoregressive modeling is becoming common practice. However, standard autoregressive models are often suboptimal as they assume that parameters are time-invariant. This is problematic if changing dynamics (e.g., changes in the temporal dependency of a process) govern the time series. Often a change in the process, such as emotional well-being during therapy, is the very reason why it is interesting and important to study psychological dynamics. As a result, there is a need for an easily applicable method for studying such nonstationary processes that result from changing dynamics. In this article we present such a tool: the semiparametric TV-AR model. We show with a simulation study and an empirical application that the TV-AR model can approximate nonstationary processes well if there are at least 100 time points available and no unknown abrupt changes in the data. Notably, no prior knowledge of the processes that drive change in the dynamic structure is necessary. We conclude that the TV-AR model has significant potential for studying changing dynamics in psychology.

Sleep habits, alertness, cortisol levels and cardiac autonomic activity in short distance bus drivers: differences between morning and afternoon shifts

Objective: To evaluate sleep, alertness, salivary cortisol levels, and autonomic activity in the afternoon and morning shifts of a sample of short-distance bus drivers. Methods: A sample of 47 bus drivers was evaluated. Data regarding subjects and working characteristics, alertness (psychomotor vigilance task), sleep habits (Pittsburgh Sleep Quality Index, Epworth Sleepiness Scale, Actigraphy), endocrine stress response (salivary cortisol), and autonomic activity (heart-rate variability) were collected. Results: Sleep restriction was highly prevalent. Drivers in the morning shift slept 1 hour less than those in the afternoon shift, showed lower reaction time performance, a flattening of cortisol morning-evening difference, and higher overweight prevalence. Conclusions: The differences found between morning and afternoon shifts point out to the need of the implementation of educational strategies to compensate the sleep loss associated with an early workschedule.

Sleep-wake differences in heart rate variability during a 105-day simulated mission to Mars

INTRODUCTIONnIn prolonged spaceflights the effect of long-term confinement on the autonomic regulation of the heart is difficult to separate from the effect of prolonged exposure to microgravity or other space-related stressors. Our objective was to investigate whether the sleep-wake variations in the autonomic control of the heart are specifically altered by long-term confinement during the 105-d pilot study of the Earth-based Mars500 project.nnnMETHODSnBefore (pre), during (T1: 30, T2: 70, andT3: 100 d), and after (post) confinement, 24-h EKG records were obtained from the six crewmembers that participated in the mission. Sleep and wake periods were determined by fitting a square wave to the data. Autonomic activity was evaluated through time and frequency domain indexes of heart rate variability (HRV) analysis during wake and sleep periods.nnnRESULTSnDuring confinement, wake HRV showed decreased mean heart rate and increased amplitude at all frequency levels, particularly in the very low (pre: 13.3 +/- 0.2; T1: 13.9 +/- 0.3; T2: 13.9 +/- 0.2; T3: 13.9 +/- 0.2; post: 13.2 +/- 0.2) and high (pre: 7.6 +/- 0.4; T1: 8.3 +/- 0.5; T2: 8.2 +/- 0.4; T3: 8.1 +/- 0.4; post: 7.6 +/- 0.3) frequency components (values expressed as mean +/- SE of wavelet power coefficients). Sleep HRV remained constant, while sleep-wake high frequency HRV differences diminished.nnnDISCUSSIONnThe observed autonomic changes during confinement reflect an increase in parasympathetic activity during wake periods. Several factors could account for this observation, including reduced daylight exposure related to the confinement situation.

Melatonin Therapy in Patients with Alzheimer’s Disease

Alzheimer’s disease (AD) is a major health problem and a growing recognition exists that efforts to prevent it must be undertaken by both governmental and non-governmental organizations. In this context, the pineal product, melatonin, has a promising significance because of its chronobiotic/cytoprotective properties potentially useful for a number of aspects of AD. One of the features of advancing age is the gradual decrease in circulating melatonin levels. A limited number of therapeutic trials have indicated that melatonin has a therapeutic value as a neuroprotective drug in the treatment of AD and minimal cognitive impairment (which may evolve to AD). Both in vitro and in vivo, melatonin prevented the neurodegeneration seen in experimental models of AD. For these effects to occur, doses of melatonin about two orders of magnitude higher than those required to affect sleep and circadian rhythmicity are needed. More recently, attention has been focused on the development of potent melatonin analogs with prolonged effects, which were employed in clinical trials in sleep-disturbed or depressed patients in doses considerably higher than those employed for melatonin. In view that the relative potencies of the analogs are higher than that of the natural compound, clinical trials employing melatonin in the range of 50–100 mg/day are urgently needed to assess its therapeutic validity in neurodegenerative disorders such as AD.

Higher autonomic activation predicts better performance in Iowa Gambling Task

ObjectiveTo evaluate the relationship between the autonomic nervous system basal state and performance in decision-making tasks. BackgroundThe link between performance in decision-making tasks and acute changes in autonomic parameters during their execution has been extensively investigated. However, there is lacking evidence regarding the relationship between decision making and basal autonomic state. MethodsResting autonomic nervous system activity in 18 healthy individuals was assessed by means of heart rate variability (HRV) analysis before conducting 3 different decision-making tasks: an ambiguous one, the Iowa Gambling Task; a test that assesses risk-taking behavior, the Game of Dice Task; and a test that assesses reversal learning behavior, the Reversal Learning Task. The tasks were administered in a random manner. ResultsThere was a direct correlation between the Iowa Gambling Task net score and the resting low frequency HRV (r=0.73; P<0.001), which is strongly influenced by sympathetic activity. No correlations were found between HRV and the Game of Dice Task net score or the Reversal Learning Task last error trial. ConclusionsThe results are compatible with the idea that a higher basal activation of autonomic nervous system is beneficial for subsequent decision-making process.

Circadian rhythm of autonomic cardiovascular control during Mars500 simulated mission to Mars.

INTRODUCTIONnThe Mars500 project was conceived to gather knowledge about the psychological and physiological effects of living in an enclosed environment during 520 d as would be required for a real mission to Mars. Our objective was to investigate the circadian profile of heart rate variability (HRV) in the context of the Mars500 study.nnnMETHODSnBefore, during, and after confinement, 24-h EKG records were obtained from the six crewmembers who participated in the mission. Autonomic activity was evaluated through time and frequency domain indexes of HRV analysis. Circadian rhythmicity was assessed both by averaging hourly HRV along wake and sleep scheduled periods and by fitting a 24-h harmonic to the hourly means.nnnRESULTSnDuring confinement, wake HRV showed (mean +/- SE) a progressive increase in mean RR interval (from 778 +/- 24 ms to 916 +/- 42 ms), and in the amplitude (values are wavelet power coefficients) of very low (from 13.3 +/- 0.3 to 14.1 +/- 0.2) and high (from 7.8 +/- 0.4 to 8.3 +/- 0.3) frequency components. During sleep, the relative amplitude of the high frequency component of HRV decreased (from 11.8 +/- 1.6 to 9.4 +/- 1.8 normalized units). Overall, sleep-wake differences of HRV showed a progressive decrease of the relative amplitude of the high frequency component. Also, circadian HRV rhythms were dampened during confinement.nnnDISCUSSIONnData revealed diminished amplitude of the rest-activity pattern of the autonomic nervous system parasympathetic function. Reduced daylight exposure and mood changes could account for this observation.

Agomelatine: Its Role in the Management of Major Depressive Disorder

Circadian rhythm abnormalities, as shown by sleep/wake cycle disturbances, constitute one the most prevalent signs of depressive illness; advances or delays in the circadian phase are documented in patients with major depressive disorder (MDD), bipolar disorder, and seasonal affective disorder (SAD). The disturbances in the amplitude and phase of rhythm in melatonin secretion that occur in patients with depression resemble those seen in chronobiological disorders, thus suggesting a link between disturbed melatonin secretion and depressed mood. Based on this, agomelatine, the first MT1/MT2 melatonergic agonist displaying also 5-HT2C serotonergic antagonism, has been introduced as an antidepressant. Agomelatine has been shown to be effective in several animal models of depression and anxiety and it has beneficial effects in patients with MDD, bipolar disorder, or SAD. Among agomelatines characteristics are a rapid onset of action and a pronounced effectiveness for correcting circadian rhythm abnormalities and improving the sleep/wake cycle. Agomelatine also improves the 3 functional dimensions of depression—emotional, cognitive, and social—thus aiding in the full recovery of patients to a normal life.

Cardiovascular autonomic adaptation to long-term confinement during a 105-day simulated Mars mission

INTRODUCTIONnLong-term confinement and microgravity may entail alteration in the regulation of the cardiovascular system. A 105-d pilot study of a Mars mission simulation was conducted to test the cardiovascular response to slow-paced breathing and mental stress.nnnMETHODSnFinger blood pressure and beat-to-beat heart rate were monitored in six male volunteers taking part in a 105-d Mars mission simulation. Data were collected before, during (Days 35-38, 70-72, and 100), and after confinement. Recordings were performed in the sitting position during 5-min spontaneous breathing, 3-min 12 cycle/min breathing, 3-min 6 cycle/min breathing, and 5-min mental task performance.nnnRESULTSnWe found significant U-shaped changes across the confinement period in systolic arterial pressure (SAP), diastolic arterial pressure (DAP), and mean arterial pressure (MAP). In the first month of confinement, mental task performance significantly lowered SAP by 34.23 mmHg and MAP by 19.89 mmHg compared to spontaneous breathing, whereas these changes were reversed during other periods. Furthermore, no differences in arterial pressure and heart rate were found between spontaneous, 12 cycle/min, and 6 cycle/min breathing.nnnCONCLUSIONSnOur findings are in line with and extend previous findings on the alteration of blood pressure regulation due to long-term confinement.

Hours of service regulations for professional drivers in continental Latin America

Objectives: To describe the hours of service provisions in continental Latin America. Design: Information on regulations of service hours was extracted from either the national transportation authorities or ministries of transportation (or the equivalent institution) from each country. Setting: Seventeen sovereign countries in continental Latin America (Argentina, Bolivia, Brazil, Chile, Colombia, Costa Rica, Ecuador, El Salvador, Guatemala, Honduras, Mexico, Nicaragua, Panama, Paraguay, Peru, Uruguay, Venezuela). Participants: N/A Intervention (if any): N/A Measurement: Data on (a) limit on work hours, (b) mandatory daily time off (or rest), (c) overall schedule (mandatory weekly time off), and (d) daily breaks were extracted and summarized. Results: Of the 17 countries surveyed, 9 countries have provisions limiting the daily amount of hours of service for professional drivers. Ten have provisions for mandatory daily rest, but only 5 have explicit provisions limiting the number of continuous working days, with mandatory uninterrupted time off >35 hours. Eight countries have provisions for mandatory breaks that limit the hours of continuous driving (ranging from 3 to 5:30 hours). Conclusion: Regulations that govern a population with 6 million injuries and over 100,000 deaths per year due to motor vehicle accidents leave important gaps. A minority, 6, of the countries regulated all 3 aspects; daily hours, breaks, and time off, and 3 regulate none of these. The regulations are less precise and restrictive than those in high‐income countries, despite the doubled road injury mortality, and likely expose professional drivers and other road users to an increased risk of fatigue‐related accidents.