Depressive symptoms and heart rate variability: evidence for a shared genetic substrate in a study of twins

[Psychosomatic aspects of cardiac arrhythmias]

Emotional stress facilitates the occurrence of cardiac arrhythmias including sudden cardiac death. The prevalence of anxiety and depression is increased in cardiac patients as compared to the normal population. The risk of cardiovascular mortality is enhanced in patients suffering from depression. Comorbid anxiety disorders worsen the course of cardiac arrhythmias. Disturbance of neurocardiac regulation with predominance of the sympathetic tone is hypothesized to be causative for this. The emotional reaction to cardiac arrhythmias is differing to a large extent between individuals. Emotional stress may result from coping with treatment of cardiac arrhythmias. Emotional stress and cardiac arrhythmias may influence each other in the sense of a vicious circle. Somatoform cardiac arrhythmias are predominantly of psychogenic origin. Instrumental measures and frequent contacts between physicians and patients may facilitate disease chronification. The present review is dealing with the multifaceted relationships between cardiac arrhythmias and emotional stress. The underlying mechanisms and corresponding treatment modalities are discussed.

Mediterranean dietary pattern is associated with improved cardiac autonomic function among middle-aged men: a twin study

BACKGROUND

Reduced heart rate variability (HRV), a measure of cardiac autonomic dysfunction, is a risk factor for coronary artery disease. Diet can influence HRV, but this association may be confounded by genetic and environmental factors.

METHODS AND RESULTS

We administered the Willett Food Frequency Questionnaire to 276 middle-aged male twins. We derived a score measuring the extent to which an individual's diet conformed to the Mediterranean diet following a published algorithm. The higher the score, the greater the similarity to the Mediterranean diet. All twins underwent 24-hour ambulatory ECG recording. Time and frequency domain measures of HRV were calculated. Mixed-effects regression was used to partition the association into between- and within-twin pair differences. After adjusting for energy intake, other nutritional factors, shared genes, and common environment, a 1-unit higher score was significantly associated with 3.9% to 13% higher time and frequency domain HRV parameters. Further controlling for known cardiovascular risk factors and use of fish oil supplements and medications did not substantially change the estimates.

CONCLUSIONS

The Mediterranean dietary pattern is associated with higher HRV.

Genetic vulnerability and phenotypic expression of depression and risk for ischemic heart disease in the Vietnam era twin study of aging

OBJECTIVE

To determine if depression contributes to incident heart disease after accounting for genetic, behavioral, and medical factors associated with both conditions.

METHODS

We used a prospective twin study with a 12-year follow-up. In 1992, lifetime diagnosis of depression was assessed in 1159 male-male twins and merged with longitudinal health data from the Vietnam Era Twin Registry Study of Aging. Incident heart disease was defined as having myocardial infarction, heart surgery, or angina at 12-year follow-up when twins were 55.4 years (standard deviation, 2.5 years) of age. Risks for heart disease were computed in a logistic regression model that included comparing twins at different levels of phenotypic expression of depression and varying levels of genetic vulnerability at the same time adjusting for pertinent covariates.

RESULTS

After adjusting for sociodemographics, co-occurring psychopathology, smoking, obesity, diabetes, hypertension, and social isolation, twins at high genetic risk and exposed to depression remained at greater risk of developing ischemic heart disease (IHD) (odds ratio, 2.55; 95% confidence interval, 1.44-4.49) compared with those at low genetic risk and without phenotypic expression of depression. Odds ratios suggest that twins at genetic liability but without phenotypic expression were at risk of IHD, but the effect was not statistically significant.

CONCLUSIONS

A history of depression is a risk factor for incident heart disease after adjusting for numerous covariates. Twins with both high genetic vulnerability and phenotypic expression of depression were at greatest risk of IHD. Trends suggest the genetic contribution to IHD that overlaps with depression may partly explain this association, but studies in larger samples are warranted.

Major depression and coronary flow reserve detected by positron emission tomography

BACKGROUND

Major depressive disorder (MDD) is associated with coronary heart disease (CHD), but the mechanisms are unclear. The presence of MDD may increase CHD risk by affecting microvascular circulation. It is also plausible that genetic factors influencing MDD may overlap with those for CHD. We sought to examine the relationship between MDD and coronary flow reserve (CFR), the ratio of maximum flow during stress to flow at rest measured in milliliters per minute per gram of tissue.

METHODS

We examined 289 male middle-aged twins, including 106 twins (53 twin pairs) discordant for a lifetime history of MDD and 183 control twins (unrelated to any twins in the experimental group) without MDD. To calculate CFR, we used positron emission tomography with nitrogen 13 ((13)N) ammonia to evaluate myocardial blood flow at rest and after adenosine stress. A standard perfusion defect score was also used to assess myocardial ischemia.

RESULTS

There was no difference in myocardial ischemia between twins with and without MDD. Among the dizygotic twin pairs discordant for MDD, the CFR was 14% lower in the twins with MDD than in their brothers without MDD (2.36 vs 2.74) (P = .03). This association was not present in the monozygotic discordant pairs who were genetically matched (2.86 vs 2.64) (P = .19). The zygosity-MDD interaction after adjustment was significant (P = .006). The CFR in the dizygotic twins with MDD was also lower than in the control twins.

CONCLUSIONS

Our results provide evidence for a shared genetic pathway between MDD and microvascular dysfunction. Common pathophysiologic processes may link MDD and early atherosclerosis.

Recent insights on central processing and psychological processes in functional gastrointestinal disorders

There is increasing evidence for a key role of psychological processes and their central nervous system substrates in functional gastrointestinal disorders, although the exact nature of the relationship remains only partially understood. However, progress in this key area of psychosomatic medicine is rapidly being made. In this review article, we will give an overview of recent advances in understanding the complex mechanisms by which psychological processes and functional gastrointestinal disorder symptoms reciprocally influence each other. Various lines of evidence from different branches of biomedical and psychological science will be discussed, particularly epidemiology, patho- and psychophysiology and functional brain imaging, focusing on the most recent and novel findings. We will conclude this paper with a paragraph on new insights into treatment.

Preadolescents' somatic and cognitive-affective depressive symptoms are differentially related to cardiac autonomic function and cortisol: the TRAILS study

OBJECTIVE

To examine in a nonclinical sample of preadolescents the possibility that somatic and cognitive-affective depressive symptoms are differentially related with the autonomic nervous system (ANS) and the hypothalamic-pituitary-adrenal (HPA) axis. Depression is a well-known risk factor for cardiovascular disease and mortality. Dysregulation of the ANS and the HPA axis have been proposed as underlying mechanisms. Several studies suggest that only a subset of the depression symptoms account for associations with cardiovascular prognosis.

METHODS

Self-reported somatic and cognitive-affective depressive symptoms were examined in relationship to heart rate variability (HRV), spontaneous baroreflex sensitivity (BRS), and the cortisol awakening response (CAR) in 2049 preadolescents (mean age = 11.1 years; 50.7% = girls) from the Tracking Adolescents' Individual Lives Survey (TRAILS).

RESULTS

Physiological measurements were not associated with the overall measure of depressive symptoms. Somatic depressive symptoms were negatively related to HRV and BRS, and positively to the CAR; cognitive-affective depressive symptoms were positively related to HRV and BRS, and negatively to the CAR. Associations with the CAR pertained to boys only.

CONCLUSIONS

Somatic and cognitive-affective depressive symptoms differ in their association with both cardiac autonomic and HPA axis function in preadolescents. Particularly, somatic depression symptoms may mark cardiac risk.

Association between symptoms of depression and anxiety with heart rate variability in patients with implantable cardioverter defibrillators

OBJECTIVE

This study investigated whether depression and anxiety symptoms are associated with measures of autonomic nervous system dysfunction in patients with implantable cardioverter defibrillators who are at high risk of cardiac rhythm disturbances. Depression and anxiety are associated with autonomic nervous system dysfunction, which may promote the risk of malignant cardiac arrhythmias.

METHODS

Patients with an implantable cardioverter defibrillator (ICD) underwent ambulatory electrocardiographic (ECG) monitoring (n = 44, mean age = 62.1 +/- 9.3 years). Depression was assessed using the Beck Depression Inventory and anxiety was evaluated using the Taylor Manifest Anxiety Scale. Heart rate variability was assessed using time (RMSSD, pNN50, and SDNN) and frequency domain measures derived from 24-hour R-R intervals. Multivariate models were adjusted for age, sex, hypertension, diabetes, and smoking status.

RESULTS

Defibrillator patients with elevated depression symptoms (n = 12) had significantly lower RMSSD (15.25 +/- 1.66 ms versus 24.97 +/- 2.44 ms, p = .002) and pNN50 (1.83 +/- 0.77 versus 5.61 +/- 1.04, p = .006) than defibrillator patients with low depression symptoms (n = 32). These associations remained significant after multivariate adjustment for covariates. ICD patients with high anxiety levels (n = 10) displayed lower RMSSD (p = .013), which became marginally significant when adjusting for covariates (p = .069).

CONCLUSIONS

Depression and anxiety in defibrillator patients are associated with autonomic nervous system dysfunction indices of reduced parasympathetic control. Autonomic nervous system dysfunction may partially explain the association between depression and anxiety with life-threatening cardiac outcomes in vulnerable patients.

Stressful life events and depressive symptoms in young adolescents: Modulation by respiratory sinus arrhythmia? The TRAILS study

BACKGROUND

Respiratory sinus arrhythmia (RSA) has been proposed as a physiological marker of emotion-regulation capacity, and shown to be cross-sectionally associated with depression. Little is known about the role of RSA as a predictor of (subclinical) depressive symptoms over time and as a modifier of the depressogenic effect of stressful life events (SLEs).

METHODS

In a longitudinal population-based study with data collected in 1653 adolescents twice (at age 11 and 13.5 years, respectively), RSA was assessed in supine position at the first assessment wave. Depressive symptoms were assessed at both waves and SLEs experienced between the two waves at the last wave.

RESULTS

Low levels of RSA were not associated with concurrent or future depressive symptoms, and did not enhance the depressogenic effects of SLEs.

CONCLUSIONS

In a normal population of young adolescents, a low level of RSA does not identify adolescents at risk for depressive symptoms when confronted with SLEs. In post hoc analyses, among those reporting high exposure to stressful life events, higher RSA tended to predict less self-reported anxiety and more self-reported somatic symptoms as compared to those with lower RSA.

A twin study of metabolic syndrome and autonomic tone

INTRODUCTION

One possible mechanism of higher cardiovascular mortality associated with the metabolic syndrome (MetS) may be through abnormal modulation in autonomic tone.

METHODS AND RESULTS

We examined the association between the MetS and autonomic tone as measured by heart rate variability (HRV) among 288 twins from the Twins Heart Study (THS). Of the 288 participants, 151 (52%) had the MetS. The MetS was associated with decreased HRV across all frequency ranges, and each additional MetS risk factor was associated with lower HRV. After adjustment for several potential confounders, very-low frequency (P < 0.001), low frequency (P < 0.001), and total power (P = 0.02) spectra of HRV remained significantly lower in twins with a progressively higher number of MetS components (18-50% decrease comparing twins with 5 risk factors to those with no risk factors). Among 87 twin pairs who were discordant for the number of MetS components, a one-unit increment in MetS components was associated with an 8% smaller very-low frequency (p = 0.03) and a 15% smaller low frequency spectrum (P = 0.002) comparing each twin with his brother.

CONCLUSION

MetS was associated with lower HRV in a well-characterized sample of middle-aged male twins. This association persisted even after controlling for genetic and shared environmental factors accounted for by comparison within twin pairs. Abnormalities of autonomic tone, as evidenced by lower HRV, may be partly responsible for the higher rate of atrial fibrillation, coronary heart disease, cardiac death, and overall mortality seen in patients with the MetS.

Decreased heart rate variability is associated with higher levels of inflammation in middle-aged men

BACKGROUND

Many traditional risk factors for coronary artery disease (CAD) are associated with altered autonomic function. Inflammation may provide a link between risk factors, autonomic dysfunction, and CAD. We examined the association between heart rate variability (HRV), a measure of autonomic function, and inflammation, measured by C-reactive protein (CRP) and interleukin-6 (IL-6).

METHODS

We examined 264 middle-aged male twins free of symptomatic CAD. All underwent ambulatory electrocardiogram monitoring and 24-hour ultra low, very low, low, and high-frequency power were calculated using power spectral analysis. C-reactive protein and IL-6 were measured, and risk factors including age, smoking, hypertension, lipids, diabetes, body mass index (BMI), depression, and physical activity were assessed.

RESULTS

Physical activity, BMI, high-density lipoprotein cholesterol, smoking, depression, and hypertension were directly associated with CRP and IL-6 and inversely associated with one or more HRV variables. There was a graded inverse relationship between all HRV parameters (except high frequency) and CRP and IL-6. After adjustment for age, BMI, activity, high-density lipoprotein, smoking, hypertension, depression, and diabetes, ultra low frequency and very low frequency remained significant predictors of CRP (P < .01).

CONCLUSIONS

C-reactive protein is associated with decreased HRV, even after controlling for traditional CAD risk factors. Autonomic dysregulation leading to inflammation may represent one pathway through which traditional risk factors promote development of CAD.