The Relationship between Heart Rate Variability and Adiposity Differs for Central and Overall Adiposity

While frank obesity is associated with reduced HRV, indicative of poorer autonomic nervous system (ANS) function, the association between body mass index (BMI) and HRV is less clear. We hypothesized that effects of adiposity on ANS are mostly mediated by visceral fat and less by subcutaneous fat; therefore, centrally distributed adipose tissue, that is, waist circumference (WC), should be more strongly associated with HRV than overall adiposity (BMI). To examine this hypothesis, we used data collected in a subset of the Baltimore Longitudinal Study of Aging to compare strength of association between HRV and WC to that of HRV and BMI. Time domain HRV variables SDNN (standard deviation of successive differences in normal-to-normal (N-N) intervals) and RMSSD (root mean square of successive differences in N-N intervals) were calculated from 24-hour Holter recordings in 159 participants (29–96 years). Increasing WC was associated with decreasing SDNN and RMSSD in younger but not older participants (P value for WC-by-age interaction = 0.003). BMI was not associated with either SDNN or RMSSD at any age. In conclusion, central adiposity may contribute to sympathetic and parasympathetic ANS declines early in life

Effects of exercise on the desire to smoke and physiological responses to temporary smoking abstinence: a crossover trial

RATIONALE: Exercise has been shown to attenuate cigarette cravings during temporary smoking abstinence; however, the mechanisms of action are not clearly understood. OBJECTIVES: The objectives of the study were to compare the effects of three exercise intensities on desire to smoke and explore potential neurobiological mediators of desire to smoke. METHODS: Following overnight abstinence, 40 participants (25 males, 18-59 years) completed three 15 min sessions of light-, moderate-, or vigorous-intensity exercise on a cycle ergometer in a randomized crossover design. Ratings of desire to smoke were self-reported pre- and post-exercise and heart rate variability was measured throughout. Saliva and blood were analyzed for cortisol and noradrenaline in a sub-sample. RESULTS: Exercise influenced desire to smoke (F [2, 91] = 7.94, p < 0.01), with reductions greatest immediately after vigorous exercise. There were also significant time x exercise intensity interaction effects for heart rate variability and plasma noradrenaline (F [8, 72] = 2.23, p = 0.03), with a bias in noradrenaline occurring between light and vigorous conditions (adjusted mean difference [SE] = 2850 ng/ml [592], p < 0.01) at 5 min post-exercise. There was no interaction of time x exercise intensity for plasma and salivary cortisol levels. CONCLUSIONS: These findings support the use of vigorous exercise to reduce cigarette cravings, showing potential alterations in a noradrenergic marker

Acute effects of BZP, TFMPP and the combination of BZP and TFMPP in comparison to dexamphetamine on an auditory oddball task using electroencephalography: a single-dose study

Rationale: Piperazine-based designer drugs such as benzylpiperazine (BZP) and trifluoromethylphenylpiperazine (TFMPP) have been marketed and sold as legal alternatives to dexamphetamine and 3,4-methylenedioxymethamphetamine (MDMA) until 2008 in New Zealand. When administered in combination, BZP + TFMPP have been reported to produce drug-drug synergism in rodents by stimulating the release of dopamine and serotonin. Objectives: This study was to evaluate the acute event-related potential effects of BZP, TFMPP or the combination of BZP + TFMPP compared with dexamphetamine in young healthy male adults. Methods: A double-blind, randomised, placebo-controlled study investigated the effects of BZP, TFMPP, the combination of BZP + TFMPP, and dexamphetamine on the event-related potentials during an auditory oddball task. Healthy, right-handed males were given a single oral dose of either BZP (200 mg), TFMPP (60 mg), a combination of BZP + TFMPP (100/30 mg), dexamphetamine (20 mg) or placebo (lactose) and tested both before and 120 min after drug administration. Results: A single dose of either TMFPP (t = -2.29, p = 0.03) or dexamphetamine (t = -2.33, p = 0.02) significantly reduced the P300 amplitude. A similar trend was also found in BZP. In contrast, BZP and TFMPP in combination has no effect. Neither P300 latency nor the mean reaction time was affected by any of the drug treatments. In addition, neither the P100 nor the P200 component was significantly affected following any of the drug treatments. Conclusions: A single oral dose of BZP or TFMPP, but not the combination of BZP/TFMPP, affected auditory sensory-evoked P300 potential in a manner similar to dexamphetamine

Stereotype threat, trait perseveration, and vagal activity: evidence for mechanisms underpinning health disparities in Black Americans

Objective: Black Americans (BAs) are at an elevated risk for morbidity and mortality in comparison to White Americans (WAs). Racial stressors are a common occurrence in American culture and is theorized to contribute to these disparities. When race-focused, stereotype threat (ST) is considered to be a factor that is detrimental to health in BAs; however few studies have directly investigated the impact of a ST manipulation on physiological function. Furthermore, it is proposed that racial stressors such as ST may have prolonged effects when more likely to perseverate (e.g. rumination) over the stressor and thus, those with greater trait perseveration may be more affected by ST. We sought to explore the impact of ST and trait perseveration on changes in vagus nerve activity - an indication of adaptive psychological and physiological well-being - as indexed by vagally mediated heart rate variability (vmHRV). Design: Forty-three (24 females, mean age of 20, standard deviation of 3 years) apparently healthy BA individuals were randomly assigned to one of three experimental conditions in which they received either implicit (subtle), explicit (blatant), or no ST priming (control condition), prior to completing a cognitive task. Resting vmHRV was assessed both at baseline (pre-task) and recovery (post-task). Results: BAs in the explicit ST condition exhibited the greatest decrease in vmHRV in comparison to the control group from pre- to post-task. BAs with moderate to high levels of trait perseveration showed the greatest decrease in vmHRV from pre- to post-task in comparison to those with lower levels of trait perseveration and BAs in the control group. Conclusion: These data suggest that racial ST, especially when explicit and coupled with trait perseveration, can decrease vagal activity, as indexed by decreased vmHRV, which when experienced frequently can have significant consequences for health and longevity in BAs