Katherine A. Sauder

Sleep misperception and chronic insomnia in the general population: role of objective sleep duration and psychological profiles.

Objective: To examine the role of objective sleep duration, a novel marker in phenotyping insomnia, and psychological profiles on sleep misperception in a large, general population sample. Sleep misperception is considered by some investigators a common characteristic of chronic insomnia, whereas others propose it as a separate diagnosis. The frequency and the determinants of sleep misperception in general population samples are unknown. Methods: A total of 142 insomniacs and 724 controls selected from a general random sample of 1,741 individuals (aged ≥20 years) underwent a polysomnographic evaluation, completed the Minnesota Multiphasic Personality Inventory-2, and were split into two groups based on their objective sleep duration: “normal sleep duration” (≥6 hours) and “short sleep duration” (<6 hours). Results: The discrepancy between subjective and objective sleep duration was determined by two independent factors. Short sleepers reported more sleep than they objectively had, and insomniacs reported less sleep than controls with similar objective sleep duration. The additive effect of these two factors resulted in underestimation only in insomniacs with normal sleep duration. Insomniacs with normal sleep duration showed a Minnesota Multiphasic Personality Inventory-2 profile of high depression and anxiety and low ego strength, whereas insomniacs with short sleep duration showed a profile of a medical disorder. Conclusions: Underestimation of sleep duration is prevalent among insomniacs with objective normal sleep duration. Anxious-ruminative traits and poor resources for coping with stress seem to mediate the underestimation of sleep duration. These data further support the validity and clinical utility of objective sleep measures in phenotyping insomnia. BMI = body mass index; DSM-IV = Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition; MANCOVA = multivariate analysis of covariance; MMPI-2 = Minnesota Multiphasic Personality Inventory-2; PLMS = periodic limb movements; SDB = sleep disordered breathing.

Sleep-Disordered Breathing in Obese Children Is Associated with Prevalent Excessive Daytime Sleepiness, Inflammation, and Metabolic Abnormalities

BACKGROUND In obese adults, sleep apnea is associated with excessive daytime sleepiness (EDS) and cardiometabolic risk factors. In children, on the other hand, sleep-disordered breathing (SDB) is primarily associated with anatomic abnormalities and neurocognitive impairment, whereas studies on potential concurrent metabolic aberrations and EDS have been limited and inconsistent. In this study, we examined the joint effect of SDB and obesity in EDS as well as proinflammatory and metabolic markers. METHODS One hundred fifty children, aged 5-17 yr, were consecutively recruited from our sleep disorders clinic and a subset of the Penn State Childrens Cohort. Every child had a thorough history and physical examination, 9-h polysomnographic study, and a single blood draw for the assessment of IL-6, TNFalpha, soluble IL-6 receptor, TNF receptor-1, hypersensitive C-reactive protein, leptin, and adiponectin. In addition, parents completed a subjective questionnaire to assess EDS. Analysis of covariance was performed on four groups that were separated by SDB severity and body mass index. RESULTS EDS frequency increased progressively and significantly in the four groups. There was a significant linear trend in plasma IL-6, TNF receptor-1, hypersensitive C-reactive protein, and leptin concentrations, with lowest levels observed in lean controls and highest in overweight/obese with moderate SDB. Adiponectin followed the opposite pattern. CONCLUSIONS This study suggests that in a clinical sample of obese children, SDB is associated with EDS, elevation of proinflammatory cytokines, increased leptin, and decreased adiponectin. All these changes point to an inflammatory/insulin resistance state, suggesting that SDB in obese children share many similarities with SDB in obese adults.

Effects of pistachios on the lipid/lipoprotein profile, glycemic control, inflammation, and endothelial function in type 2 diabetes: A randomized trial.

OBJECTIVE The health benefits of regular nut consumption have been well-documented; however, effects on cardiovascular risk in diabetes are emerging. This study examined the effects of daily pistachio consumption on the lipid/lipoprotein profile, glycemic control, markers of inflammation, and endothelial function in adults with type 2 diabetes. MATERIALS/METHODS We enrolled 30 adults (40-74 years) with well-controlled type 2 diabetes (mean glycated hemoglobin 6.2%) in a randomized, crossover, controlled feeding study. After a 2-week run-in period, participants consumed nutritionally-adequate diets with pistachios (contributing 20% of total energy) or without pistachios for 4 weeks each, separated by a 2-week washout. We assessed fasting lipids/lipoproteins, glycemic measures (while fasted and during a 75 g oral glucose tolerance test), inflammatory markers, and endothelial function after each diet period. RESULTS Total cholesterol and the ratio of total to HDL cholesterol were significantly lower (p<0.05) following the pistachio diet (4.00 mmol/L and 4.06 mmol/L, respectively) compared to the control diet (4.15 mmol/L and 4.37 mmol/L, respectively). Triglycerides were significantly lower (p=0.003) following the pistachio diet (1.56 mmol/L) compared to the control diet (1.84 mmol/L). There were no treatment differences in fasting glucose and insulin, but fructosamine was significantly lower (p=0.03) following the pistachio diet (228.5 μmol/l) compared to the control diet (233.5 μmol/l). Inflammatory markers and endothelial function were unchanged. CONCLUSION Daily pistachio consumption can improve some cardiometabolic risk factors in adults with well-controlled type 2 diabetes. Our findings support recommendations that individuals with diabetes follow healthy dietary patterns that include nuts.

Acute effects of pistachio consumption on glucose and insulin, satiety hormones and endothelial function in the metabolic syndrome

Background/Objective:Nut consumption has been found to decrease risk of coronary heart disease and diabetes and to promote healthy body weights possibly related to their favorable macronutrient profile. We therefore assessed the effect of pistachios on postprandial glucose and insulin levels, gut hormones related to satiety and endothelial function.Subjects/Methods:In this randomized crossover study, 20 subjects with metabolic syndrome consumed five study meals over 5–10 weeks. The meals differed in fat type and quantity, but were matched according to available carbohydrates (CHOs). Three meals had 50 g available CHO: white bread (WB50g), white bread, butter and cheese (WB+B+Ch) and white bread and pistachios (WB+P). Two meals had 12 g available CHO: white bread (WB12g) and pistachios (P).Results:Within each group of available CHO meals, postprandial glucose levels were the highest following the white bread-only meals, and glucose response was significantly attenuated when butter and cheese or pistachios were consumed (P<0.05). Postprandial insulin levels were highest after the WB+B+Ch meal (P<0.05), but did not differ between the white bread-only and pistachio meals. Both endothelial function (reactive hyperemia index) and arterial stiffness (augmentation index) significantly increased after the white bread-only meals compared with the WB+B+Ch meal (all P<0.05). Insulin secretagogue levels were higher when butter and cheese or pistachios were consumed than when white bread only was consumed (P<0.05).Conclusions:Compared with white bread, pistachio consumption reduced postprandial glycemia, increased glucagon-like-peptide levels and may have insulin-sparing properties. These effects could be beneficial for individuals with diabetes and metabolic syndrome.

Effect of meal content on heart rate variability and cardiovascular reactivity to mental stress.

Little is known about transient effects of foods and nutrients on reactivity to mental stress. In a randomized crossover study of healthy adults (n=20), we measured heart rate variability (respiratory sinus arrhythmia), blood pressure, and other hemodynamic variables after three test meals varying in type and amount of fat. Measurements were collected at rest and during speech and cold pressor tasks. There were significant postmeal changes in resting diastolic blood pressure (-4%), cardiac output (+18%), total peripheral resistance (-17%), and interleukin-6 (-27%). Heart rate variability and hemodynamic reactivity to stress was not affected by meal content. We recommend that future studies control for time since last meal and continue to examine effects of meal content on heart rate variability.

Test–retest reliability of peripheral arterial tonometry in the metabolic syndrome

Endothelial dysfunction is an important contributor to atherosclerosis and cardiovascular disease. However, routine assessment via angiography or flow-mediated dilation is difficult due to technical limitations. Peripheral arterial tonometry (PAT) is a promising alternative method for non-invasive assessment of endothelial dysfunction. This study assessed the test–retest reliability of PAT in adults with the metabolic syndrome (n = 20) and provides sample size and power estimates for study design. Participants completed five PAT tests each separated by 1 week. The PAT-derived reactive hyperaemia index (RHI) showed robust repeatability (intra-class correlation = 0.74). A parallel-arm study powered at 0.90 would require 22 participants to detect an absolute change in RHI of 0.40 units (equal to ~25% change in this sample), whereas a crossover study would require 12 participants. In conclusion, we have demonstrated that PAT can be used to assess endothelial dysfunction in adults with the metabolic syndrome as reliably as in healthy samples.

Endothelial function, arterial stiffness and adherence to the 2010 Dietary Guidelines for Americans: a cross-sectional analysis

Endothelial dysfunction and arterial stiffness are early predictors of CVD. Intervention studies have suggested that diet is related to vascular health, but most prior studies have tested individual foods or nutrients and relied on small samples of younger adults. The purpose of the present study was to examine the relationships between adherence to the 2010 Dietary Guidelines for Americans and vascular health in a large cross-sectional analysis. In 5887 adults in the Framingham Heart Study Offspring and Third Generation cohorts, diet quality was quantified with the 2010 Dietary Guidelines Adherence Index (DGAI-2010). Endothelial function was assessed via brachial artery ultrasound and arterial stiffness via arterial tonometry. In age-, sex- and cohort-adjusted analyses, a higher DGAI-2010 score (greater adherence) was modestly associated with a lower resting flow velocity, hyperaemic response, mean arterial pressure, carotid-femoral pulse wave velocity (PWV), and augmentation index, but not associated with resting arterial diameter or flow-mediated dilation (FMD). In multivariable models adjusting for cardiovascular risk factors, only the association of a higher DGAI-2010 score with a lower baseline flow velocity and augmentation index persisted (β = - 0·002, P= 0·003 and β = - 0·05 ± 0·02, P< 0·001, respectively). Age-stratified multivariate-adjusted analyses suggested that the relationship of higher DGAI-2010 scores with lower mean arterial pressure, PWV and augmentation index was more pronounced among adults younger than 50 years. Better adherence to the 2010 Dietary Guidelines for Americans, particularly in younger adults, is associated with a lower peripheral blood flow velocity and arterial wave reflection, but not FMD. The present results suggest a link between adherence to the Dietary Guidelines and favourable vascular health.

Pistachio Nut Consumption Modifies Systemic Hemodynamics, Increases Heart Rate Variability, and Reduces Ambulatory Blood Pressure in Well‐Controlled Type 2 Diabetes: a Randomized Trial

Background Managing cardiovascular risk factors is important for reducing vascular complications in type 2 diabetes, even in individuals who have achieved glycemic control. Nut consumption is associated with reduced cardiovascular risk; however, there is mixed evidence about the effect of nuts on blood pressure (BP), and limited research on the underlying hemodynamics. This study assessed the effect of pistachio consumption on BP, systemic hemodynamics, and heart rate variability in adults with well‐controlled type 2 diabetes. Methods and Results We enrolled 30 adults (40 to 74 years) with type 2 diabetes in a randomized, crossover, controlled feeding study. After a 2‐week run‐in period, participants consumed a low‐fat control diet (27% fat) containing low‐fat/high‐carbohydrate snacks and a moderate‐fat diet (33% fat) containing pistachios (20% of total energy) for 4 weeks each, separated by a 2‐week washout. Following each diet period, we assessed BP, systemic hemodynamics, and heart rate variability at rest and during acute mental stress, and, in a subset of participants (n=21), 24‐hour ambulatory BP. BP at rest and during stress did not differ between treatments. The pistachio diet significantly reduced total peripheral resistance (−3.7±2.9%, P=0.004), increased cardiac output (3.1±2.3%, P=0.002), and improved some measures of heart rate variability (all P<0.05). Systolic ambulatory BP was significantly reduced by 3.5±2.2 mm Hg (P=0.046) following the pistachio diet, with the greatest reduction observed during sleep (−5.7±2.6 mm Hg, P=0.052). Conclusions A moderate‐fat diet containing pistachios modestly improves some cardiovascular risk factors in adults with well‐controlled type 2 diabetes. Clinical Trial Registration URL: www.clinicaltrials.gov. Unique identifier: NCT00956735.

Effects of Omega-3 Fatty Acid Supplementation on Heart Rate Variability at Rest and During Acute Stress in Adults With Moderate Hypertriglyceridemia

Objective This study examined the dose-dependent effects of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) supplementation on heart rate variability (HRV) at rest and during standard laboratory stress tasks. We also investigated whether EPA + DHA supplementation was associated with changes in mood state. Methods This placebo-controlled, double-blind, randomized, three-period crossover trial (8-week treatment, 6-week washout) compared two doses of EPA + DHA supplementation (0.85 and 3.4 g/d) in 26 adults with elevated triglycerides. After each treatment period, HRV was assessed during an acute stress protocol that included a resting baseline, standard laboratory stress tasks (speech task and cold pressor), and recovery periods. In addition, mood state was assessed. Results Root mean square of successive differences in interbeat interval and total power increased 9.9% and 20.6%, respectively, after the high dose relative to placebo (Tukey p = .016 and .012, respectively). The low dose was not significantly different from the high dose or placebo dose. There was a trend for a treatment effect on high-frequency HRV (p = .058), with 21.0% greater power observed after the high dose compared with placebo (Tukey p = .052). Mood did not differ between treatments, and there was no association between mood state and HRV. Conclusions In healthy adults with elevated triglycerides, supplementation of 3.4 g/d EPA + DHA resulted in greater HRV, whereas 0.85 g/d EPA + DHA had no effect. These results indicate that EPA + DHA supplementation may improve autonomic tone in adults at increased risk for cardiovascular disease within 8 weeks. Trial Registration NCT00504309(ClinicalTrials.gov).

Noninvasive assessment of hemodynamics: a comparative analysis of fingertip pulse contour analysis and impedance cardiography.

ObjectiveSystemic hemodynamic assessment is useful for characterizing the underlying physiology of hypertension, selecting individualized treatment approaches, and understanding the underlying mechanisms of action of interventions. Invasive methods are not suitable for routine clinic or research use, and noninvasive methods such as impedance cardiography have technical and practical limitations. Fingertip pulse contour analysis using the Nexfin device is a novel alternative to noninvasive assessment of blood pressure and hemodynamics. Although both impedance cardiography and the Nexfin have been validated against invasive methods, the extent to which they are correlated with each other is unknown. This study is a comparative analysis of data simultaneously obtained by impedance cardiography and using the Nexfin device. MethodsAs part of a larger clinical trial, 13 adults with type 2 diabetes completed cardiovascular reactivity testing on three occasions: at study baseline and after two 4-week dietary treatment periods. Blood pressure, hemodynamics, and heart rate variability were assessed at rest and during acute mental stress. ResultsBlood pressure, heart rate, and heart rate variability data were significantly correlated between the two devices, but hemodynamic data (stroke volume, cardiac output, total peripheral resistance) were not significantly correlated. Both techniques detected treatment-related changes in blood pressure and total peripheral resistance, but significantly differed in the magnitude and/or direction of treatment effects. ConclusionWe conclude that Nexfin is not an appropriate alternative to impedance cardiography for measurement of underlying hemodynamics in psychophysiological research, but may be useful for beat-to-beat monitoring of blood pressure and heart rate variability.