Mika P. Tarvainen

Cognitive rigidity is mirrored by autonomic inflexibility in daily life perseverative cognition.

Mind wandering (MW) can be persistent and therefore has been included in the repetitive thinking conceptualization. In line with a dimensional view of psychopathology, we hypothesized the existence of a MW-Perseverative Cognition (PC) continuum, where the latter is characterized by a rigid and defensive pattern with attentional, behavioral, affective, and autonomic perseverative manifestations. Ambulatory heart rate (HR) and variability (HRV) of 42 participants were recorded for 24h. Approximately every 30 min during waking, subjects reported their ongoing thoughts and moods using electronic diaries. MW was characterized by less effort to inhibit the thought and less interference with ongoing activities, absence of mood worsening, and higher HRV compared to PC. Worse sleep quality was predicted by higher levels of trait rumination and daily PC. Results suggest that MW and PC represent the functional and pathological ends of a continuum, respectively.

Cognitive, behavioral, and autonomic correlates of mind wandering and perseverative cognition in major depression

Autonomic dysregulation has been hypothesized to play a role in the relationships between psychopathology and cardiovascular risk. An important transdiagnostic factor that has been associated with autonomic dysfunction is perseverative cognition (PC), mainly present in Major Depressive Disorder (MDD) in the form of rumination. As the ability to adaptively let our mind wander without ruminating is critical to mental health, this study aimed to examine the autonomic concomitants of functional vs. dysfunctional intrusive thoughts in MDD. Ambulatory heart rate (HR) and variability (HRV) of 18 MDD subjects and 18 healthy controls were recorded for 24 h. Approximately every 30 min during waking hours subjects reported their ongoing thoughts and moods using electronic diaries. Random regression models were performed. Compared to controls, MDD subjects were more often caught during episodes of PC. In both groups, PC required more effort to be inhibited and interfered more with ongoing activities compared to mind wandering (MW) (ps < 0.0001). This cognitive rigidity was mirrored by autonomic inflexibility, as PC was characterized by lower HRV (p < 0.0001) compared to MW. A worse mood was reported by MDD patients compared to controls, independently of their ongoing cognitive process. Controls, however, showed the highest mood worsening during PC compared to being on task and MW. HRV during rumination correlated with self-reported somatic symptoms on the same day and several dispositional traits. MDD subjects showed lower HRV during sleep, which correlated with hopelessness rumination. Results show that PC is associated with autonomic dysfunctions in both healthy and MDD subjects. Understanding when spontaneous thought is adaptive and when it is not may clarify its role in the etiology of mood disorders, shedding light on the still unexplained association between psychopathology, chronic stress, and risk for health.

A Comparison of nonlinear measures for the detection of cardiac autonomic neuropathy from heart rate variability

In this work we compare three multiscale measures for their ability to discriminate between participants having cardiac autonomic neuropathy (CAN) and aged controls. CAN is a disease that involves nerve damage leading to an abnormal control of heart rate, so one would expect disease progression to manifest in changes to heart rate variability (HRV). We applied multiscale entropy (MSE), multi fractal detrended fluctuation analysis (MFDFA), and Renyi entropy (RE) to recorded datasets of RR intervals. The latter measure provided the best separation (lowest p-value in Mann–Whitney tests) between classes of participants having CAN, early CAN or no CAN (controls). This comparison suggests the efficacy of RE as a measure for diagnosis of CAN and its progression, when compared to the other multiscale measures.

Autonomic nervous system response to L-dopa in patients with advanced Parkinson's disease

Levodopa is the main treatment method for reducing the symptoms of Parkinsons disease. Whereas it reduces the motor symptoms efficiently, its effect on autonomous nervous system is not clear. The information about effect of levodopa on heart rate variability is not coherent between the studies. In this study, ECG of 11 patients with Parkinsons disease was measured during levodopa challenge with pronounced dose of fast release levodopa to ensure the positive drug effect for deep brain stimulation treatment. Heart rate variability analysis was done at three time points, before administration of levodopa, 30 and 60 minutes after administration. After 30 minutes of administration, the HRV parameters show that parasympathetic nervous system activity is decreased and the sympatho-vagal balance is shifted towards sympathetic control. At 60 minutes after administration the parasympathetic nervous system activates slightly and causes a decrease in heart rate.

Complex nonlinear autonomic nervous system modulation link cardiac autonomic neuropathy and peripheral vascular disease

Background Physiological interactions are abundant within, and between, body systems. These interactions may evolve into discrete states during pathophysiological processes resulting from common mechanisms. An association between arterial stenosis, identified by low ankle-brachial pressure index (ABPI) and cardiovascular disease (CVD) as been reported. Whether an association between vascular calcification—characterized by high ABPI and a different pathophysiology—is similarly associated with CVD, has not been established. The current study aims to investigate the association between ABPI, and cardiac rhythm, as an indicator of cardiovascular health and functionality, utilizing heart rate variability (HRV). Methods and Results Two hundred and thirty six patients underwent ABPI assessment. Standard time and frequency domain, and non-linear HRV measures were determined from 5-min electrocardiogram. ABPI data were divided into normal (n = 101), low (n = 67) and high (n = 66) and compared to HRV measures.(DFAα1 and SampEn were significantly different between the low ABPI, high ABPI and control groups (p < 0.05). Conclusion A possible coupling between arterial stenosis and vascular calcification with decreased and increased HRV respectively was observed. Our results suggest a model for interpreting the relationship between vascular pathophysiology and cardiac rhythm. The cardiovascular system may be viewed as a complex system comprising a number of interacting subsystems. These cardiac and vascular subsystems/networks may be coupled and undergo transitions in response to internal or external perturbations. From a clinical perspective, the significantly increased sample entropy compared to the normal ABPI group and the decreased and increased complex correlation properties measured by DFA for the low and high ABPI groups respectively, may be useful indicators that a more holistic treatment approach in line with this more complex clinical picture is required.

Multiscale Renyi Entropy and Cardiac Autonomic Neuropathy

Heart rate variability (HRV) is commonly analysed in respect to time and frequency domain measures as well as nonlinear measures including the fractal dimension using information derived from ECG recordings. Increased risk of adverse cardiac events such as arrhythmia can be detected using heart rate variability analysis. Shannon entropy and the more generalized Renyi entropy provide information on the complexity of the interbeat interval differences associated with heart rate. The latter can be extended to a multiscale distribution akin to fractal analysis. Here we report the spectrum of multiscale Renyi entropy measures. Multiscale Renyi entropy has additional information to add to the common mean and variance measures and should be applied as potential early markers of arrhythmia risk.

Heart rate variability evaluation of Emfit sleep mattress breathing categories in NREM sleep

OBJECTIVE Heart rate variability (HRV) analysis of obstructive sleep apnea patients reveals an increase in sympathetic activity. Sleep disordered breathing (SDB) can be also assessed with sleep mattress sensors, as the Emfit sensor, by dividing the signal into different breathing categories. In addition to normal breathing (NB) and periodic apneas/hypopneas (POB), the sleep mattress unveils a breathing category consisting of sustained partial obstruction (increased respiratory resistance, IRR). The aim of our study was to evaluate HRV during these three breathing categories in NREM sleep. METHODS 53 patients with suspected SDB underwent an overnight polysomnography with an Emfit mattress. The Emfit signal was scored in 3-min epochs according to the established rules. The NB, POB, and IRR epochs were combined to as long NB, POB and IRR periods as possible and HRV was calculated from at least 6-min epochs. RESULTS The meanHR did not differ between the breathing categories. HRV parameters revealed an increase in sympathetic activity during POB. The mean LF/HF ratio was highest during POB (3.0) and lowest during IRR (1.3). During NB it was 1.7 (all p-values ⩽ 0.001). Interestingly sympathetic activity decreased and parasympathetic activity increased during IRR as compared to NB (the mean HF power was 1113.8 ms(2) during IRR and 928.4 ms(2) during NB). CONCLUSIONS The HRV findings during POB resembled HRV results of sleep apnea patients but during sustained prolonged partial obstruction a shift towards parasympathetic activity was achieved. SIGNIFICANCE The findings encourage the use of sleep mattresses in SDB diagnostics. In addition the findings suggest that sustained partial obstruction represents its own SDB entity.

Endurance exercise improves heart rate complexity in the presence of vagal withdrawal in young adults

Sudden cardiac death (SCD) has been reported during and following physical activity. SCD may be due to vagal withdrawal and/or sympathetic dominance associated with the exercise occurring at any time during, immediately following, or up to several days after exercise. Heart rate variability (HRV) describes the influence of the autonomic nervous system on heart rate. We assessed the immediate post-exercise influence of endurance training on HRV in young adults in the morning and also on the same day in the afternoon following the morning exercise session. Linear domain parameter root mean square of successive RR interval differences (RMSSD) showed vagal withdrawal when analysed both immediately after the AM session and also when pre exercise HRV was compared to post exercise HRV during the afternoon (median average change 6.6%). However multiscale Rényi entropy indicated either no change immediately following the exercise for all scaling factors or an increase in HRV complexity of the heart rate. Despite decreased vagal influence, endurance training may be protective for some individuals that retain a higher heart rate complexity as measured by Rényi entropy in the presence of vagal withdrawal.

Is a short re-feeding program effective in reducing adverse cardiac events in eating disorder patients?

Eating Disorder (ED) patients who were admitted to an eating disorders program for a 6-week treatment and were assessed for changes in heart rate variability (HRV). Linear heart rate variability measures (HRV) were determined using Kubios software from 20 minute, Lead 3 ECG recordings following a 5-minute rest period. Eighteen patients and 31 controls were included in the analysis. Results were deemed significant if p<;0.05. No significant differences in HRV parameters were noted for the control group between Pre- and Post-treatment. For the ED group, mean RR interval length decreased significantly compared to the control group (p=0.006). HF peak frequency increased significantly in the ED group (p=0.001). High frequency (HF) peak indicated that the respiratory frequency increased from Pre to Post measurement. RMSSD tended to decrease (p=0.047) in the ED group. Hence at admission to hospital the ED group was more parasympathetic during rest compared to controls, but they became more sympathetic after the intervention and thus approached the HRV measures of the controls suggesting improvement in ANS modulation of the heart.