Effects of Body Mass Index on Parasympathetic Nervous System Reactivity and Recovery Following Orthostatic Stress.

Vagally mediated heart rate variability (vmHRV), defined as the beat-to-beat fluctuations in a heart series mediated by the vagus nerve, serves as a non-invasive index of parasympathetic nervous system (PNS) activity. Lower resting state vmHRV is associated with greater body mass index (BMI), providing a psychophysiological pathway linking obesity with health and disease. However little research has been conducted to examine how BMI may influence PNS reactivity to orthostatic stress. The present study sought to explore this in a sample of 59 individuals (44 females, mean age = 24.37 years, age range 19-65 years). VmHRV was measured throughout the 5-minute baseline (sitting), orthostatic (standing), and recovery (sitting) conditions. Individuals were stratified into low (BMI < 20), moderate (BMI 20-25), and high (BMI > 25) BMI groups. Results indicate that the high BMI group had a greater decrease in vmHRV from baseline to standing in comparison to the moderate BMI group. Furthermore, the low BMI group showed lower vmHRV during recovery compared to baseline, suggesting that these individuals did not fully recover from the standing position. Taken together, these results extend previous literature showing that those with low and high BMI can show different yet maladaptive patterns of vmHRV in response to orthostatic stress.

Body mass index is related to autonomic nervous system activity as measured by heart rate variability--a replication using short term measurements.

OBJECTIVES: The present analysis is a replication of previous findings presenting first evidence of an association between body mass index (BMI) and autonomic nervous system (ANS) activity as measured by heart rate variability (HRV), in healthy non-obese adults. DESIGN: A total of fifty-nine apparently healthy male (M) and female (F) individuals (M/F = 15/44) were included in the trial. HRV data for analysis was derived from 5 minutes of baseline recordings, while the subject was sitting on a comfortable chair. Subjects' body measures (weight and height) were taken and BMI was obtained according to common calculation (kg/m²). RESULTS: BMI was inversely related to pNN50 and RMSSD components of HRV. Statistically significant differences between stratified groups (BMI<20, BMI 20-25, BMI >25) only occurred for analysis of pNN50 components. The pNN50 components and RMSSD are strongly associated with cardiac vagal influence, and thus represents parasympathetic activity. CONCLUSIONS: The present data supports previous findings, that sympatho-vagal balance is related to BMI in non-obese, healthy individuals, providing evidence for a prominent role of the vagus nerve in the modulation of the energy expenditure of the human organism. Furthermore, this relation can be observed in short term recordings of HRV of 5 minutes in length.

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

BACKGROUND: 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. METHOD: 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. RESULTS: 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. CONCLUSION: 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.

[Current status so far: psychotherapy in transition!]. / Soweit der Stand der Dinge: Psychotherapie im Wandel!

In the context of the current discussion of the volume by Grawe, Donati and Bernauer "Psychotherapie im Wandel; Von der Konfession zur Profession" (1994) the main critical points are reviewed regarding essential-theoretical issues. The crucial points of the resulting criticism refer to the fact that metastudies are historical and culture bound, to etiological validity as well as to ethical-political implications. One main statement designates the investigation by Grawe et al. as a conventional review that bases its conclusions on outcome-studies of psychotherapy that are to be considered outdated. Whether it is possible to decide which therapy is most effective is as doubtful as the necessity to contrast therapeutic orientations by discriminating valuation. The results of Grawe's therapy-outcome-analysis are put into a historical and cultural context. Thereby the findings are put into relation to particular periods and speech areas from which the included studies originate. In this context Grawe's volume appears not to be the Ultima ratio but is fruitful to initiate further research.