Depression but not anxiety influences the autonomic control of heart rate after myocardial infarction

Depression and ischemic heart disease

Depression is common in patients with ischemic heart disease, and depressed patients are more likely to develop atherosclerosis and experience major cardiac events compared with the general population. The underlying pathophysiological mechanisms of these two diseases are highly interwoven and include an increased release of stress hormones, dysregulation of the autonomic nervous system, alterations of pathways related to primary and secondary hemostasis, endothelial dysfunction, and higher level of residual inflammation. Furthermore, depression negatively impacts compliance with medication regimens. As such, early recognition and treatment of depression provide the opportunity to improve outcomes of patients with ischemic heart disease. In the present review, we provide a summary of the evidence on the epidemiology, pathophysiology and management of depression in patients with ischemic heart disease.

Chronic mild stress paradigm as a rat model of depression: facts, artifacts, and future perspectives

RATIONALE

The chronic mild stress (CMS) paradigm was first described almost 40 years ago and has become a widely used model in the search for antidepressant drugs for major depression disorder (MDD). It has resulted in the publication of almost 1700 studies in rats alone. Under the original CMS procedure, the expression of an anhedonic response, a key symptom of depression, was seen as an essential feature of both the model and a depressive state. The prolonged exposure of rodents to unpredictable/uncontrollable mild stressors leads to a reduction in the intake of palatable liquids, behavioral despair, locomotor inhibition, anxiety-like changes, and vegetative (somatic) abnormalities. Many of the CMS studies do not report these patterns of behaviors, and they often fail to include consistent molecular, neuroanatomical, and physiological phenotypes of CMS-exposed animals.

OBJECTIVES

To critically review the CMS studies in rats so that conceptual and methodological flaws can be avoided in future studies.

RESULTS

Analysis of the literature supports the validity of the CMS model and its impact on the field. However, further improvements could be achieved by (i) the stratification of animals into 'resilient' and 'susceptible' cohorts within the CMS animals, (ii) the use of more refined protocols in the sucrose test to mitigate physiological and physical artifacts, and (iii) the systematic evaluation of the non-specific effects of CMS and implementation of appropriate adjustments within the behavioral tests.

CONCLUSIONS

We propose methodological revisions and the use of more advanced behavioral tests to refine the rat CMS paradigm, which offers a valuable tool for developing new antidepressant medications.

Autonomic symptoms and associated factors in patients with chronic heart failure

OBJECTIVE

Autonomic disorders are common in chronic illness, and their symptoms may restrict the daily functioning of patients. However, in chronic heart failure, extensive knowledge about autonomic symptoms is still lacking. This study aims to explore self-perceived autonomic symptoms, associated factors, and their relationship with health-related quality of life in chronic heart failure.

METHODS

One hundred and twenty-four patients with documented chronic heart failure (men and women; 50-86 years) and 124 sex and age-matched controls participated in this study. The participants filled validated questionnaires about autonomic symptom profile (COMPASS 31), fatigue (CIS, Checklist for individual strength), anxiety and depression (HADS, Hospital Anxiety and Depression), and health-related quality of life (SF36). Non-parametric statistics were performed to analyse the data.

RESULTS

Total score for autonomic symptoms was higher in chronic heart failure compared to controls [Median: 14.9; IQR: 6.2-25.1 vs. 7.3; 0-18; p < 0.001], especially for orthostatic hypotension [Median: 8; IQR: 0-16 vs. 0; 0-12; p < 0.001], vasomotor [Median: 0; IQR: 0-0 vs. 0; 0-0; p < 0.001] and secretomotor function [Median: 0; IQR: 0-4.2 vs. 0; 0-2.1; p = 0.013]. High scores for autonomic symptoms were moderate correlated with higher scores of fatigue, anxiety and depression (0.343 ≤ rs ≥ 0.420; p < 0.001) and with decreased health-related quality of life (-0.454; p < 0.01).

CONCLUSION

Autonomic symptoms, especially for orthostatic intolerance, vasomotor and secretomotor subdomains, are prevalent and are associated with fatigue complaints and poor health-related quality of life in CHF.

The association between cardiovascular drugs and depression/anxiety in patients with cardiovascular disease: A meta-analysis

This study aimed to investigate the association between cardiovascular drugs and depression/anxiety in patients with cardiovascular disease (CVD). This meta-analysis was registered in PROSPERO (International Prospective Register of Systematic Reviews; CRD42020197839) and conducted in accordance with the MOOSE (Meta-analysis of Observational Studies in Epidemiology) guidelines. The PubMed, EMBASE, Web of Science, China National Knowledge Infrastructure, Wanfang, and VIP databases were systematically searched to identify all available studies on this topic. Random-effects multivariate meta-regression was performed to investigate the sources of study heterogeneity. Review Manager version 5.3 and Stata 12.0 were used for data analyses. This meta-analysis included 54 studies with a total number of 212,640 patients. Overall, in patients with CVD, aspirin (odds ratio [OR]:0.91, 95% confidence interval [CI]:0.86-0.96, P = 0.02) was associated with a lower risk of depression, while calcium channel blockers (CCB) (OR:1.21, 95%CI:1.05-1.38, P = 0.008), diuretics (OR:1.34, 95%CI:1.14-1.58, P = 0.0005), and nitrate esters (OR:1.32, 95%CI:1.08-1.61, P = 0.006) were associated with a higher risk of depression, additionally, statin (OR:0.79, 95%CI:0.71-0.88, P < 0.0001) was associated with a lower risk of anxiety, but diuretics (OR:1.39, 95%CI:1.26-1.52, P < 0.00001) was associated with a higher risk of anxiety. Subgroup analysis presented that, in patients with hypertension, β-blockers were associated with a higher risk of depression (OR:1.45, 95%CI:1.26-1.67, P < 0.00001); in patients with coronary artery disease (CAD), statin (OR:0.77, 95%CI:0.59-0.99, P = 0.04), and aspirin (OR:0.85, 95%CI:0.75-0.97, P = 0.02) were associated with a lower risk of depression, while CCB (OR:1.32, 95%CI:1.15-1.51, P < 0.0001) and diuretics (OR:1.36, 95%CI:1.12-1.64, P = 0.002) were associated with a higher risk of depression, additionally, diuretics was associated with a higher risk of anxiety (OR:1.41, 95%CI:1.28-1.55, P < 0.00001); in patients with heart failure, nitrate esters (OR:1.93, 95%CI:1.19-3.13, P = 0.007), and diuretics (OR:1.58, 95%CI: 1.02-2.43, P = 0.04) were associated with a higher risk of depression. The use of cardiovascular drugs should be considered when evaluating depression or anxiety in patients with CVD to improve the care and treatment of these patients.

Pentoxifylline for treatment of major depression after percutaneous coronary intervention or coronary artery bypass grafting: A randomized, double-blind, placebo-controlled trial

INTRODUCTION

Near one-fifth of patients with coronary artery disease (CAD) develop major depressive disorder (MDD), an independent risk factor of mortality in these patients. We investigated the efficacy of oral pentoxifylline in treating MDD in CAD patients undergoing percutaneous coronary intervention (PCI) or coronary artery bypass grafting (CABG) in a 6-week trial.

METHODS

We only included patients with mild to moderate MDD (having a score between 14 and 17 on the Hamilton depression rating scale (HAM-D)). Sixty-four CAD patients undergoing PCI or CABG aged 40-60 years were randomly assigned to either the pentoxifylline (800 mg daily) or the placebo group. The outcome was assessed with the HAM-D at weeks 2, 4, and 6.

RESULTS

Patients receiving pentoxifylline had greater improvement in HAM-D scores from baseline at each follow-up than patients receiving placebo (p-value = 0.036 at week 2, p-value < 0.001 at week 4, and p-value < 0.001 at week 6). We found a significant effect for treatment, time, and time×treatment interaction in depression improvement (p-value < 0.001). Rate of remission, treatment response, and adverse effects did not differ between the two groups.

DISCUSSION

Our study supports the safety and efficacy of pentoxifylline in treatment of MDD in CAD patients. However, further investigations are required to confirm the generalizability of our results since the results need to be interpreted cautiously because of the imitated range of disease severity for inclusion. This trial was registered with the Iranian Registry of Clinical Trials (www.irct.ir; No. IRCT20090117001556N132).

Screening and Management of Depression in Patients With Cardiovascular Disease: JACC State-of-the-Art Review

Depression is a common problem in patients with cardiovascular disease (CVD) and is associated with increased mortality, excess disability, greater health care expenditures, and reduced quality of life. Depression is present in 1 of 5 patients with coronary artery disease, peripheral artery disease, and heart failure. Depression complicates the optimal management of CVD by worsening cardiovascular risk factors and decreasing adherence to healthy lifestyles and evidence-based medical therapies. As such, standardized screening pathways for depression in patients with CVD offer the potential for early identification and optimal management of depression to improve health outcomes. Unfortunately, the burden of depression in patients with CVD is under-recognized; as a result, screening and management strategies targeting depression have been poorly implemented in patients with CVD. In this review, the authors discuss a practical approach for the screening and management of depression in patients with CVD.

Prevalence of depression in myocardial infarction: A PRISMA-compliant meta-analysis

BACKGROUND

Depression is common in the aftermath of myocardial infarction (MI) and may not only lead to impaired long-term quality of life, but also cause increased mortality among patients with MI. The reported prevalence of depression among patients with MI varied considerably across studies, for which a pooled prevalence was obtained in the only 1 meta-analysis conducted in March 2004. Subsequently, numerous relevant studies have been published, indicating the need for an update on the pooled prevalence. Therefore, this study was aimed at updating the pooled prevalence of depression among patients with MI.

METHODS

A comprehensive literature search in 3 electronic databases, PubMed, Embase, and PsycINFO, was performed in April 2018. The heterogeneity across studies was examined by the Cochran's Q test and quantified by the I statistic. If significant heterogeneity was observed, meta-regression analyses and subgroup analyses were performed to identify the source of heterogeneity. Publication bias was assessed by a funnel plot and verified by the Egger's and Begg's tests.

RESULTS

Nineteen eligible studies conducted in 10 countries were included, which consisted of 12,315 patients with MI, among whom 3818 were identified with depression. High heterogeneity was observed across the eligible studies (I = 98.4%), with the reported prevalence of depression ranging from 9.17% to 65.88%. The pooled prevalence of depression among patients with MI was 28.70% (95% CI: 22.39-35.46%) by a random effects model. Subgroup analyses showed that the pooled prevalence differed significantly by region, tool used to identify depression, study quality, sex, race, anterior MI, and diabetes status (P < .05). Meta-regression analyses did not identify any moderators of heterogeneity, and the heterogeneity was high within most subgroups. Nonetheless, for unmarried subjects, the heterogeneity was low (I = 19.5). The Egger's test and the Begg's test indicated no evidence of publication bias (P > .05).

CONCLUSIONS

Given the high pooled prevalence of depression found in this study and the association between depression and adverse health outcomes among patients with MI, more psychological resources including early assessment and effective treatment of depression should be allocated to patients with MI.

Cardiac and behavioral effects of social isolation and experimental manipulation of autonomic balance

Improved understanding of how depression and social isolation interact to increase cardiac morbidity and mortality will improve public health. This experiment evaluated the effect of pharmacological autonomic blockade on cardiac and behavioral reactivity following social isolation in prairie voles. Experiment 1 validated the dose and time course of pharmacological autonomic antagonism of peripheral β-adrenergic (atenolol) and muscarinic cholinergic receptors (atropine methyl nitrate), and Experiment 2 used a novel protocol to investigate behavioral responses in the tail suspension test during pharmacological autonomic blockade as a function of social isolation (vs. paired control). Prairie voles isolated for 4 weeks (vs. paired) displayed significantly elevated heart rate and reduced heart rate variability. Autonomic receptor antagonism by atenolol led to exaggerated reductions in heart rate and standard deviation of normal-to-normal intervals, and lower amplitude of respiratory sinus arrhythmia in the isolated group (vs. paired). Administration of atropine led to an attenuated increase in heart rate in the isolated group (vs. paired), and similar near-zero levels of respiratory sinus arrhythmia amplitude in both groups. During the tail suspension test, isolated animals (vs. paired) displayed significantly greater immobility. In paired animals, atenolol administration did not influence immobility; atropine administration increased the duration of immobility (vs. vehicle). In isolated animals, atenolol administration increased the duration of immobility; atropine did not influence immobility duration (vs. vehicle). The current study contributes to our understanding of differential effects of social isolation and autonomic imbalance on cardiac and behavioral reactivity.

Oxytocin facilitates adaptive fear and attenuates anxiety responses in animal models and human studies-potential interaction with the corticotropin-releasing factor (CRF) system in the bed nucleus of the stria terminalis (BNST)

Despite its relatively well-understood role as a reproductive and pro-social peptide, oxytocin (OT) tells a more convoluted story in terms of its modulation of fear and anxiety. This nuanced story has been obscured by a great deal of research into the therapeutic applications of exogenous OT, driving more than 400 ongoing clinical trials. Drawing from animal models and human studies, we review the complex evidence concerning OT's role in fear learning and anxiety, clarifying the existing confusion about modulation of fear versus anxiety. We discuss animal models and human studies demonstrating the prevailing role of OT in strengthening fear memory to a discrete signal or cue, which allows accurate and rapid threat detection that facilitates survival. We also review ostensibly contrasting behavioral studies that nonetheless provide compelling evidence of OT attenuating sustained contextual fear and anxiety-like behavior, arguing that these OT effects on the modulation of fear vs. anxiety are not mutually exclusive. To disambiguate how endogenous OT modulates fear and anxiety, an understudied area compared to exogenous OT, we survey behavioral studies utilizing OT receptor (OTR) antagonists. Based on emerging evidence about the role of OTR in rat dorsolateral bed nucleus of stria terminalis (BNST) and elsewhere, we postulate that OT plays a critical role in facilitating accurate discrimination between stimuli representing threat and safety. Supported by human studies, we demonstrate that OT uniquely facilitates adaptive fear but reduces maladaptive anxiety. Last, we explore the limited literature on endogenous OT and its interaction with corticotropin-releasing factor (CRF) with a special emphasis on the dorsolateral BNST, which may hold the key to the neurobiology of phasic fear and sustained anxiety.

Somatic-Affective, But Not Cognitive-Depressive Symptoms are Associated With Reduced Health-Related Quality of Life in Patients With Congestive Heart Failure

BACKGROUND

Depression has been associated with poor health-related quality of life (HRQoL) in patients with congestive heart failure (CHF). However, to date, whether somatic-affective and cognitive-depressive symptoms differently contribute to poor HRQoL and behavioral functional capacity in patients with CHF has yet to be investigated.

OBJECTIVE

To examine the differential influence of somatic-affective vs cognitive-depressive symptoms on HRQoL and behavioral functional capacity in CHF patients.

METHOD

Overall, 55 patients with CHF completed a psychologic evaluation, including the Minnesota Living with Heart Failure Questionnaire, the Beck Depression Inventory-II, and the Beck Anxiety Inventory for HRQoL, depressive, and anxiety symptoms, respectively. The patients completed the Instrumental Activities of Daily Living Questionnaire and the 6-minute walk test for behavioral functional capacity. Hierarchical regression analyses were used to predict HRQoL and behavioral functional capacity from Beck Depression Inventory-II and Beck Anxiety Inventory scores.

RESULTS

Somatic-affective depressive symptoms were associated with physical (β = 0.37, p = 0.005) and emotional (β = 0.39, p = 0.008) Minnesota Living with Heart Failure Questionnaire subscale scores. Likewise, somatic-affective depressive symptoms predicted Instrumental Activities of Daily Livings Scores (β = 0.43, p = 0.004) and distance ambulated during the 6-minute walk test (β = -0.36, p = 0.029). By contrast, cognitive-depressive symptoms and anxiety were unrelated to HRQoL and behavioral functional capacity (all p > 0.05).

CONCLUSIONS

These findings showed that somatic-affective depressive symptoms, but not cognitive-depressive symptoms and anxiety, are associated with poor HRQoL and behavioral functional capacity independent of age, clinical functional status, and medical comorbidities. This study suggests that patients with CHF with somatic-affective rather than cognitive-depressive symptoms or anxiety may be at greater risk of poor HRQoL and behavioral functional capacity.

Depression and the Link with Cardiovascular Disease

This review provides an outline of the association between major depressive disorder (MDD) and coronary heart disease (CHD). Much is known about the two individual clinical conditions; however, it is not until recently, biological mechanisms have been uncovered that link both MDD and CHD. The activation of stress pathways have been implicated as a neurochemical mechanism that links MDD and CHD. Depression is known to be associated with poorer outcomes of CHD. Psychological factors, such as major depression and stress, are now known as risk factors for developing CHD, which is as important and is independent of classic risk factors, such as hypertension, diabetes mellitus, and cigarette smoking. Both conditions have great socioeconomic importance given that depression and CHD are likely to be two of the three leading causes of global burden of disease. Better understanding of the common causal pathways will help us delineate more appropriate treatments.

Somatic, but not cognitive-affective, symptoms are associated with reduced heart rate variability in individuals with dysphoria

Background: Somatic, but not cognitive–affective, symptoms of depression have been associated with reduced heart rate variability (HRV), and with poor prognosis in cardiovascular patients. However, factors concomitant with cardiovascular diseases may confound the relationship between somatic symptoms of depression and reduced HRV. Therefore, this study examined whether reduced HRV was differentially associated with cognitive–affective and somatic symptoms of depression in medically healthy individuals with and without dysphoria.

Methods: Self-reported cognitive–affective and somatic symptoms as measured with the Beck Depression Inventory-II questionnaire and time and frequency domain parameters of HRV were collected in 62 medically healthy individuals, of whom 25 with and 37 without dysphoria.

Results: Somatic, but not cognitive–affective, symptoms of depression were inversely associated with SD of NN intervals (β = -0.476, p < 0.05), number of interval differences of successive NN intervals greater than 50 ms (NN50; β = -0.498, p < 0.03), and HRV total power (β = -0.494, p < 0.04) in the group with dysphoria, after controlling for sex, anxiety, and lifestyle factors. Cognitive–affective and somatic symptoms were not related to any of the HRV parameters in the group without dysphoria (all ps > 0.24).

Conclusion: By showing that the relationship between somatic depressive symptoms and reduced HRV extends to medically healthy individuals with dysphoria, the present findings suggest that this association is independent of factors concomitant with cardiovascular diseases. The present study also suggests that individuals with somatic rather than cognitive–affective subsets of depressive symptoms may be at greater risk for developing cardiovascular diseases.

The association between diabetes and depression: a very disabling condition

Rates of depression are significantly increased in diabetic patients, and even more in the elderly. About 20-30% of patients with diabetes suffer from clinically relevant depressive disorders, 10% of which being affected by the major depression disorder. Moreover, people with depression seem to be more prone to develop an associated diabetes mellitus, and depression can worsen glycemic control in diabetes, with higher risk to develop complications and adverse outcomes, whereas improving depressive symptoms is generally associated with a better glycemic control. Thus, the coexistence of depression and diabetes has a negative impact on both lifestyle and quality of life, with a reduction of physical activity and an increase in the request for medical care and prescriptions, possibly increasing the healthcare costs and the susceptibility to further diseases. These negative aspects are particularly evident in the elderly, with further decrease in the mobility, worsening of disability, frailty, geriatric syndromes and increased mortality. Healthcare providers should be aware of the possible coexistence of depression and diabetes and of the related consequences, to better manage the patients affected by these two pathological conditions.

Depressive symptoms and autonomic nervous system dysfunction in an elderly population-based study: the PROOF study

BACKGROUND

To assess the relationship between depressive symptoms, evaluated through self-reported history as well as current depressive symptoms, and impaired autonomic nervous system activity, evaluated by long-term heart rate variability and baroreflex sensitivity among elderly community residents, aged 65 years.

METHODS

Subjects from the Proof cohort Study were evaluated for depressive symptoms and self-reported history of depression at inclusion. Autonomic nervous system activity was assessed through 24-h heart rate variability and baroreflex sensitivity. Cross-sectional analyses were performed to study the relationship between the different status of depression and autonomic nervous system activity.

RESULTS

Among the 1011 Proof study participants, 823 subjects were included in the analyses. Current depressive symptoms were present among 67 subjects; history of depression was reported by 228 subjects. Psychoactive drugs were used by 59 subjects. Low frequency (p=0.02), very low frequency (p<0.01) and Low/High frequency ratio (p<0.001) were lower among subjects with depressive symptoms and history of depression, independently of antidepressant treatment. The association remained significant for Low/High frequency ratio after adjustment for gender and physical activity (p=0.004).

CONCLUSION

Current depressive symptoms may be linked to autonomic nervous system lower performances. A possible long-term effect of depressive symptoms at middle-age may influence later-life autonomic nervous system activity. Our results highlight the importance of taking into account the depressive symptoms in the cardiovascular risk, even in the elderly.

The integration of depressive behaviors and cardiac dysfunction during an operational measure of depression: investigating the role of negative social experiences in an animal model

OBJECTIVE

There is a bidirectional association between depression and cardiovascular disease. The neurobiological mechanisms underlying this association may involve an inability to cope with disrupted social bonds. This study investigated in an animal model the integration of depressive behaviors and cardiac dysfunction after a disrupted social bond and during an operational measure of depression, relative to the protective effects of intact social bonds.

METHODS

Depressive behaviors in the forced swim test and continuous electrocardiographic parameters were measured in 14 adult, female socially monogamous prairie voles (rodents), after 4 weeks of social pairing or isolation.

RESULTS

After social isolation, animals exhibited (all values are mean ± standard error of the mean; isolated versus paired, respectively) increased heart rate (416 ± 14 versus 370 ± 14 bpm, p < .05) and reduced heart rate variability (3.3 ± 0.2 versus 3.9 ± 0.2 ln(ms(2))). During the forced swim test, isolated animals exhibited greater helpless behavior (immobility = 106 ± 11 versus 63 ± 11 seconds, p < .05), increased heart rate (530 ± 22 versus 447 ± 15 bpm, p < .05), reduced heart rate variability (1.8 ± 0.4 versus 2.7 ± 0.2 ln(ms(2)), p < .05), and increased arrhythmias (arrhythmic burden score = 181 ± 46 versus 28 ± 12, p < .05).

CONCLUSIONS

The display of depressive behaviors during an operational measure of depression is coupled with increased heart rate, reduced heart rate variability, and increased arrhythmias, indicative of dysfunctional behavioral and physiological stress coping abilities as a function of social isolation. In contrast, social pairing with a sibling is behaviorally protective and cardioprotective. The present results can provide insight into a possible social mechanism underlying the association between depression and cardiovascular disease in humans.

Anxiety, depression and autonomic nervous system dysfunction in hypertension

OBJECTIVES

This study examined the relationship between autonomic nervous system dysfunction, anxiety and depression in untreated hypertension.

PATIENTS AND METHODS

86 newly diagnosed hypertensive patients and 98 healthy volunteers were included in the study. The psychological parameters were assessed with Spielberger State-Trait Anxiety Inventory and Beck Depression Inventory by a skilled psychologist. Autonomic parameters were examined during tilt table examination (10min lying position, 10min passive tilt). Heart rate variability (HRV) was calculated by autoregressive methods. Baroreflex sensitivity (BRS) was calculated by non-invasive sequence method from the recorded beat to beat blood pressure values and RR intervals.

RESULTS

Significantly higher state (42.6±9.3 vs. 39.6±10.7 p=0.05) and trait (40.1±8.9 vs. 35.1±8.6, p<0.0001) anxiety scores were found in the hypertension group. There was no statistically significant difference in the depression level. LF-RRI (Low Frequency-RR interval) of HRV in passive tilt (377.3±430.6 vs. 494.1±547, p=0.049) and mean BRS slope (11.4±5.5 vs. 13.2±6.4, p=0.07) in lying position were lower in hypertensives. Trait anxiety score correlates significantly with sympatho/vagal balance (LF/HF-RRI) in passive tilt position (Spearman R=-0.286, p=0.01).

CONCLUSIONS

Anxiety could play a more important role than depression in the development of hypertension. Altered autonomic control of the heart could be one of the pathophysiological links between hypertension and psychological factors.

Prevalence of antidepressant prescription or use in patients with acute coronary syndrome: a systematic review

BACKGROUND AND OBJECTIVES

Depression is common among acute coronary syndrome (ACS) patients and is associated with poor prognosis. Cardiac side effects of older antidepressants were well-known, but newer antidepressants are generally thought of as safe to use in patients with heart disease. The objective was to assess rates of antidepressant use or prescription to patients within a year of an ACS.

METHODS

PubMed, PsycINFO, and CINAHL databases searched through May 29, 2009; manual searching of 33 journals from May 2009 to September 2010. Articles in any language were included if they reported point or period prevalence of antidepressant use or prescription in the 12 months prior or subsequent to an ACS for ≥100 patients. Two investigators independently selected studies for inclusion/exclusion and extracted methodological characteristics and outcomes from included studies (study setting, inclusion/exclusion criteria, sample size, prevalence of antidepressant prescription/use, method of assessing antidepressant prescription/use, time period of assessment).

RESULTS

A total of 24 articles were included. The majority were from North America and Europe, and most utilized chart review or self-report to assess antidepressant use or prescription. Although there was substantial heterogeneity in results, overall, rates of antidepressant use or prescription increased from less than 5% prior to 1995 to 10-15% after 2000. In general, studies from North America reported substantially higher rates than studies from Europe, approximately 5% higher among studies that used chart or self-report data.

CONCLUSIONS

Antidepressant use or prescription has increased considerably, and by 2005 approximately 10% to 15% of ACS patients were prescribed or using one of these drugs.

Pro-inflammatory cytokines and depression in myocardial infarction

Aim. To assess the associations between inflammatory factors and anxiety (A) and depression (D) levels in patients with myocardial infarction (MI). Material and methods. The study included 100 MI patients, hospitalised with a diagnosis of Q-wave MI (mean age 62,0±1,3 years). The methods of psychosocial status assessment included Zung depression scale and SpielbergerKhanin personal and reactive anxiety scales. The inflammatory markers of interest included interleukins (IL) 1-beta, IL-6, IL-8, IL-10, and C-reactive protein (CRP). Results. D and A symptoms in the early post-MI stage were associated with higher risk of cardiovascular events in the following year. Among MI patients with comparable MI severity, D and A symptoms were linked to higher levels of pro-inflammatory cytokines IL-1-beta, IL-8, IL-8, and INF-gamma. Conclusion. In MI patients with D and A symptoms, one of the mechanisms of poor prognosis is an activation of subclinical inflammation.

The Utility of Animal Models in Understanding Links between Psychosocial Processes and Cardiovascular Health

A bidirectional association between mood disorders and cardiovascular disease has been described; however, the neurobiological mechanisms that underlie this link have not been fully elucidated. The purpose of this review is first to describe some of the important behavioral neurobiological processes that are common to both mood and cardiovascular disorders. Second, this review focuses on the value of conducting research with animal models (primarily rodents) to investigate potential behavioral, physiological, and neural processes involved in the association of mood disorders and cardiovascular disease. In combination with findings from human research, the study of mechanisms underlying mood and cardiovascular regulation using animal models will enhance our understanding of the association of depression and cardiovascular disease, and can promote the development of novel interventions for individuals with these comorbid conditions.

The role of the selective serotonin re-uptake inhibitor sertraline in nondepressive patients with chronic ischemic heart failure: a preliminary study

BACKGROUND

Selective serotonin re-uptake inhibitors (SSRIs) have been associated with better psychiatric status, functional capacity, and fewer arrhythmias in depressive patients with heart failure (HF). In this study, we tested the impact of sertraline (an SSRI) on patients with HF, but not clinical depression.

METHODS

We studied 62 clinically stable, nondepressive patients with ischemic HF (New York Heart Association class: I-II), and implantable cardioverter-defibrillator (ICD). Following psychiatric evaluation and quality of life (QoL) assessment, 24-hour electrocardiogram recordings including heart rate variability (HRV) and ICD interrogation were performed every 4 months for 1 year. Ventricular effective refractory period (ERP) at 600-, 500-, and 400-ms cycle length and the inducibility of ventricular tachycardia (VT) were assessed via the ICD. After that, sertraline 50 mg/day was administered for 12 months and the whole evaluation was repeated.

RESULTS

Sertraline was associated with fewer ventricular extrasystoles per 24 hours and a significant change in HRV (increase in mean R-R, 5-minute standard deviation of RR intervals, and root mean-square difference of successive RR intervals, and reduction in ultra and very low frequency). It was also followed by an improvement in patients' QoL. A trend toward a decrease was observed in the number of recalled nonsustained VTs. The episodes of sustained VT were not significantly reduced. Ventricular ERPs and VT inducibility remained unaltered.

CONCLUSION

In clinically stable, nondepressive patients with ischemic HF and ICD, sertraline is associated with reduced ventricular extrasystoles, better QoL, and a possible improvement in some HRV indexes. This suggests that SSRIs may have a favorable clinical impact on these patients, independent of the improvement in depressive symptoms.

24-hour autonomic dysfunction and depressive behaviors in an animal model of social isolation: implications for the study of depression and cardiovascular disease

OBJECTIVE

To investigate the hypothesis that long-term social isolation in an animal model would produce depression-relevant behaviors and disruptions in the 24-hour autonomic and activity parameters, and to further demonstrate the utility and validity of an animal model for the study of social environment, behavior, and autonomic function. Converging evidence from both experimental and epidemiological studies indicates that there is a bidirectional association between depression and cardiovascular disease; however, the precise neurobiological mechanisms underlying this relationship are not well understood. Disruptions in the social environment may influence this relationship.

METHODS

Depression-relevant behaviors and ambulatory electrocardiographic and activity data were measured in 12 adult, socially monogamous prairie voles (rodents) during a period of chronic social isolation or social pairing (control conditions).

RESULTS

Prairie voles exposed to 4 weeks of social isolation versus control conditions (social pairing) exhibited anhedonia, increased 24-hour heart rate, reduced 24-hour heart rate variability, and predictable correlations between the behavioral measure (anhedonia) and the autonomic measures.

CONCLUSIONS

Social isolation is associated with depressive behaviors, 24-hour autonomic dysfunction, and predictable interrelationships between these variables in prairie voles but does not seem to be associated with rhythmicity changes in activity level or autonomic function. These findings have implications for understanding the role of the social environment in mediating the association of mood and cardiovascular disorders in humans.

Effect of omega-3 fatty acids on heart rate variability in depressed patients with coronary heart disease

OBJECTIVE

To determine whether omega-3 fatty acid (FA) increases the natural log of very low frequency (lnVLF) power, an index of heart rate variability (HRV), and reduces 24-hour heart rate (HR) in depressed patients with coronary heart disease (CHD). Low intake of omega-3 FAs is associated with depression and with low HRV, and all three are associated with an increased risk of death in patients with CHD.

METHODS

Thirty-six depressed patients with CHD randomized to receive 50 mg of sertraline and 2 g of omega-3/day, and 36 randomized to sertraline and a placebo, had 24-hour HRV measured at baseline and after 10 weeks of treatment.

RESULTS

There was a significant treatment × time interaction for covariate adjusted lnVLF (p = .009), for mean 24-hour HR (p = .03), and for 1-minute resting HR (p = .02). The interaction was not significant for three other measures of HRV. LnVLF did not change over time in the omega-3 arm but decreased in the placebo arm (p = .002), suggesting that omega-3 may have prevented or slowed deterioration in cardiac autonomic function.

CONCLUSIONS

The effects of omega-3 FAs on lnVLF and HR, although modest, were detected after only 10 weeks of treatment with 2 g per day of omega-3. Whether a longer course of treatment or a higher dose of omega-3 would further decrease HR, improve other indices of HRV, or reduce mortality in depressed CHD patients should be investigated.

Depression and the cardiovascular system: increasing evidence of a link and therapeutic implications

This review explores the epidemiological evidence for the relationship between depression and cardiovascular disease from a mechanistic standpoint. It is important to examine the biological, behavioral and social mechanisms to improve outcomes for depressed cardiac patients. A number of plausible biobehavioral mechanisms linking depression and cardiovascular disease have been identified. Tricyclic antidepressants have various effects on the cardiovascular system, while selective serotonin reuptake inhibitors are not associated with adverse cardiac effects and should, therefore, be the preferred choice for the treatment of most patients with comorbid depression and cardiovascular disease.

Oxytocin protects against negative behavioral and autonomic consequences of long-term social isolation

Positive social interactions and social support may protect against various forms of mental and physical illness, although the mechanisms for these effects are not well identified. The socially monogamous prairie vole, which--like humans--forms social bonds and displays high levels of parasympathetic activity, has provided a useful model for investigating neurobiological systems that mediate the consequences of sociality. In the present study, adult female prairie voles were exposed to social isolation or continued pairing with a female sibling (control conditions) for 4 weeks. During weeks 3 and 4 of this period, animals were administered oxytocin (20 microg/50 microl, s.c.) or saline vehicle (50 microl, s.c.) daily for a total of 14 days. In Experiment 1, autonomic parameters were recorded during and following isolation or pairing. Isolation (vs. pairing) significantly increased basal heart rate (HR) and reduced HR variability and vagal regulation of the heart; these changes in isolated animals were prevented with oxytocin administration. In Experiment 2, behaviors relevant to depression [sucrose intake and swimming in the forced swim test (FST)] were measured as a function of isolation. Isolation reduced sucrose intake and increased immobility in the FST; these behaviors also were prevented by oxytocin. Administration of oxytocin did not significantly alter cardiac, autonomic or behavioral responses of paired animals. These findings support the hypothesis that oxytocinergic mechanisms can protect against behavioral and cardiac dysfunction in response to chronic social stressors, and can provide insight into social influences on behavior and autonomic function in humans.

Cardiovascular abnormalities in patients with major depressive disorder: autonomic mechanisms and implications for treatment

This article provides a detailed review of the association of major depression with coronary heart disease (CHD), examines the biological variables underpinning the linkage and discusses the clinical implications for treatment. When considering the co-morbidity between major depressive disorder (MDD) and CHD it is important to differentiate between (i) the prevalence and impact of MDD in those with existing CHD and (ii) MDD as a risk factor for the development of CHD. Whether the same biological mechanisms are at play in these two instances remains unknown. Depression is common in patients with CHD. Importantly, depression in these patients increases mortality. There is also consistent evidence that MDD is a risk factor for the development of CHD. The relative risk of developing CHD is proportional to the severity of depression and is independent of smoking, obesity, hypercholesterolaemia, diabetes mellitus and hypertension. There is a clear need to identify the underlying neurochemical mechanisms responsible for MDD and their linkage to the heart and vascular system. Of particular interest are activation of stress pathways, including both the sympathetic nervous system and hypothalamic-pituitary-adrenal axis, and inflammatory-mediated atherogenesis. Elevated sympathetic activity, reduced heart rate variability and increased plasma cortisol levels have been documented in patients with MDD. In addition to direct effects on the heart and vasculature, activation of stress pathways may also be associated with increased release of inflammatory cytokines such as interleukin-6 and tumour necrosis factor-alpha. Elevated levels of C-reactive protein are commonly observed in patients with MDD. The majority of investigations examining treatment of depression following myocardial infarction have focused on safety and efficacy; there is little evidence to indicate that treating depression in these patients improves survival. Given that strategies for preventive therapy remain incompletely formulated, future research should focus on generating a better understanding of the neurobiology of MDD and heart disease as a basis for rational and effective therapy.

Depression and heart rate variability in patients with coronary heart disease

Depression is common in patients with coronary heart disease (CHD) and is a risk factor for cardiac morbidity and mortality in these patients. Depression is associated with autonomic nervous system dysfunction, which may at least partially explain this increased risk. Low heart rate variability (HRV), which reflects excessive sympathetic and/or inadequate parasympathetic modulation of heart rate, is a strong predictor of mortality in patients with CHD. Most studies-both in patients with stable CHD and in patients with a recent acute coronary event-have found HRV to be lower in depressed patients than in their nondepressed counterparts. This manuscript provides an overview of this literature and concludes that HRV may account for a substantial part of the risk associated with depression in CHD.

Stress, depression and cardiovascular dysregulation: a review of neurobiological mechanisms and the integration of research from preclinical disease models

Bidirectional associations between mood disorders and cardiovascular diseases are extensively documented. However, the precise physiological and biochemical mechanisms that underlie such relationships are not well understood. This review focuses on the neurobiological processes and mediators that are common to both mood and cardiovascular disorders. The discussion places an emphasis on the role of exogenous stressors in addition to: (a) neuroendocrine and neurohumoral changes involving dysfunction of the hypothalamic-pituitary-adrenal axis and the activation of the renin-angiotensin-aldosterone system, (b) immune alterations including activation of pro-inflammatory cytokines, (c) autonomic and cardiovascular dysregulation including increased sympathetic drive, withdrawal of parasympathetic tone, cardiac rate and rhythm disturbances, and altered baroreceptor reflex function, (d) central neurotransmitter system dysfunction involving the dopamine, norepinephrine and serotonin systems, and (e) behavioral changes including fatigue and physical inactivity. The review also discusses experimental investigations using preclinical disease models to elucidate the neurobiological mechanisms underlying the link between mood disorders and cardiovascular disease. These include: (a) the chronic mild stress model of depression, (b) a model of congestive heart failure, (c) a model of cardiovascular deconditioning, (d) pharmacological manipulations of body fluid and sodium balance, and (e) pharmacological manipulations of the central serotonergic system. In combination with an extensive human research literature, the investigation of mechanisms underlying mood and cardiovascular regulation using animal models will enhance understanding the association between depression and cardiovascular disease. This will ultimately promote the development of better treatments and interventions for individuals with co-morbid psychological and somatic pathologies.

Mechanisms underlying altered mood and cardiovascular dysfunction: the value of neurobiological and behavioral research with animal models

A bidirectional association between mood disorders and cardiovascular diseases has been described in humans, yet the precise neurobiological mechanisms that underlie this association are not fully understood. This article is focused on neurobiological processes and mediators in mood and cardiovascular disorders, with an emphasis on common mechanisms including stressor reactivity, neuroendocrine and neurohumoral changes, immune alterations, autonomic and cardiovascular dysregulation, and central neurotransmitter and neuropeptide dysfunction. A discussion of the utility of experimental investigations with rodent models, including those in rats and prairie voles (Microtus ochrogaster), is presented. Specific studies using these models are reviewed, focusing on the analysis of behavioral, physiological and neural mechanisms underlying depressive disorders and cardiovascular disease. Considered in combination with studies using human samples, the investigation of mechanisms underlying depressive behaviors and cardiovascular regulation using animal models will enhance our understanding of the association of depression and cardiovascular disease, and will promote the development of improved interventions for individuals with these detrimental disorders.

Hindlimb unloading elicits anhedonia and sympathovagal imbalance

The hindlimb-unloaded (HU) rat model elicits cardiovascular deconditioning and simulates the physiological adaptations to microgravity or prolonged bed rest in humans. Although psychological deficits have been documented following bed rest and spaceflight in humans, few studies have explored the psychological effects of cardiovascular deconditioning in animal models. Given the bidirectional link established between cardiac autonomic imbalance and psychological depression in both humans and in animal models, we hypothesized that hindlimb unloading would elicit an alteration in sympathovagal tone and behavioral indexes of psychological depression. Male, Sprague-Dawley rats confined to 14 days of HU displayed anhedonia (a core feature of human depression) compared with casted control (CC) animals evidenced by reduced sucrose preference (CC: 81 +/- 2.9% baseline vs. HU: 58 +/- 4.5% baseline) and reduced (rightward shift) operant responding for rewarding electrical brain stimulation (CC: 4.4 +/- 0.3 muA vs. 7.3 +/- 1.0 muA). Cardiac autonomic blockade revealed elevated sympathetic [CC: -54 +/- 14.1 change in (Delta) beats/min vs. HU: -118 +/- 7.6 Delta beats/min] and reduced parasympathetic (CC: 45 +/- 11.8 Delta beats/min vs. HU: 8 +/- 7.3 Delta beats/min) cardiac tone in HU rats. Heart rate variability was reduced (CC: 10 +/- 1.4 ms vs. HU: 7 +/- 0.7 ms), and spectral analysis of blood pressure indicated loss of total, low-, and high-frequency power, consistent with attenuated baroreflex function. These data indicate that cardiovascular deconditioning results in sympathovagal imbalance and behavioral signs consistent with psychological depression. These findings further elucidate the pathophysiological link between cardiovascular diseases and affective disorders.

Sertraline treatment for depression associated with acute coronary syndromes: a cost analysis from the viewpoint of the Italian Healthcare System

BACKGROUND AND AIMS

Depressive disorders (DD) are independent risk factors for rehospitalization after acute coronary syndromes (ACS) and, hence, for increased healthcare costs. A placebo-controlled safety trial of 24 weeks of treatment with sertraline after ACS (Sertraline Anti-Depressant Heart Attack Randomized Trial, SADHART) suggested that active treatment was associated with reduced rehospitalization due to coronary and non-coronary events. With the SADHART database, a cost analysis was carried out to determine the economic consequences of treating DD after ACS in the perspective of the Italian Healthcare System.

METHODS

Clinical information on medical events and rehospitalizations recorded over the study period was drawn from the original SADHART database, which did not contain information necessary for estimating indirect costs. Analysis was therefore limited to direct medical costs due to rehospitalizations, emergency room visits and hospital procedures, and the average Italian Diagnosis-Related Group (DRG) tariffs were applied.

RESULTS

With the exclusion of the cost of sertraline treatment, the average direct cost per patient over the study period was 3,418+/-8,290 euro in the active treatment group and 4,409+/-9,439 euro in the placebo group (p=0.3). After including the cost of 24 weeks of sertraline treatment, the average cost in sertraline-treated patients was only modestly increased, to 3,524+/-8,290 euro.

CONCLUSIONS

Treatment of major DD in patients with recent ACS can improve patient care without additional costs, and possibly with some savings, to the healthcare system.

Persistent alterations in heart rate variability, baroreflex sensitivity, and anxiety-like behaviors during development of heart failure in the rat

Depressed heart rate variability and mood are associated with increased mortality in patients with congestive heart failure (CHF). Here autonomic indexes were assessed 3 and 7 wk after left coronary artery ligation in telemetered rats, after which anxiety-like behaviors were assessed in an elevated plus maze. Low frequency (LF) and high frequency (HF) heart rate variability were reduced in CHF rats 3 wk after infarction (LF, 1.60 +/- 0.52 vs. 6.97 +/- 0.79 ms(2); and HF, 1.53 +/- 0.39 vs. 6.20 +/- 1.01 ms(2); P < 0.01). The number of sequences of interbeat intervals that correlated with arterial pressure was decreased in CHF rats at 3 and 7 wk (week 3, 26.60 +/- 10.85 vs. 59.75 +/- 11.4 sequences, P < 0.05; and week 7, 20.80 +/- 8.97 vs. 65.38 +/- 5.89 sequences, P < 0.01). Sequence gain was attenuated in CHF rats by 7 wk (1.34 +/- 0.06 vs. 2.70 +/- 0.29 ms/mmHg, P < 0.01). Coherence between interbeat interval and mean arterial blood pressure variability in the LF domain was reduced in CHF rats at 3 (0.12 +/- 0.03 vs. 0.26 +/- 0.05 k(2), P < 0.05) and 7 (0.16 +/- 0.02 vs. 0.31 +/- 0.05 k(2), P < 0.05) wk. CHF rats invariably entered the open arm of the elevated plus maze first and spent more time in the open arms (36.0 +/- 15% vs. 4.6 +/- 1.9%, P < 0.05). CHF rats also showed a tendency to jump head first off the apparatus, whereas controls did not. Together the data indicate that severe autonomic dysfunction is accompanied by escape-seeking behaviors in rats with verified CHF.

Evaluation of baroreceptor reflex function in the chronic mild stress rodent model of depression

OBJECTIVE

There is a bidirectional relationship between mood disorders (e.g., depression) and altered cardiovascular regulation (e.g., heart disease); however, the precise causal and/or common mechanisms underlying this association are unclear. In previous studies, we have noted indications of altered sympathetic drive to the heart in rats that exhibit anhedonia, an operational sign of depression induced by subjecting the animals to a series of mild and unpredictable stressors (chronic mild stress (CMS) rodent model of depression). The purpose of the present study was to more fully characterize baroreceptor reflex function in rats with experimentally induced depression.

METHODS

Male, Sprague-Dawley rats were exposed to either 4 weeks of mild, unpredictable stressors (CMS group) or standard housing conditions (control group). Depression-like behavior, resting hemodynamic and cardiac parameters, and baroreceptor reflex function were investigated in all animals after the CMS period.

RESULTS

CMS produced anhedonia, evidenced by reduced sucrose intake and sucrose preference, as well as elevated resting heart rate (HR), slightly elevated blood pressure, and reduced HR variability. These animals also exhibited significantly attenuated sympathoexcitatory responses to hypotension, and an elevation of basal sympathetic nerve activity.

CONCLUSIONS

These findings suggest that CMS is associated with altered sympathoexcitatory responses after baroreceptor unloading and provide further insights into potential common mechanisms underlying the association of depression and altered cardiovascular control.

Trait negative affect: toward an integrated model of understanding psychological risk for impairment in cardiac autonomic function

OBJECTIVE

To assess depression, anxiety, and anger as well as the variance that these emotions share (conceptualized as negative affect) in relationship to high-frequency heart rate variability (HF-HRV), a specific indicator of parasympathetic cardiac autonomic function related to premature cardiovascular morbidity and mortality. Although individual trait negative emotions have been studied in relation to risk for coronary heart disease (CHD) as well as biological mechanisms leading to CHD end points (e.g., autonomic nervous system [ANS] dysfunction), the degree to which a general tendency to experience negative emotions may account for these relations is not known.

METHODS

The sample included 653 community volunteers (51.0% female; 15.8% Black) aged 30 to 54 years (mean +/- standard deviation = 43.8 +/- 7.1 years). Latent constructs of depression, anxiety, and anger were each measured by three scales from well-validated self-report questionnaires. Resting HF-HRV was derived from 5-minute segments of continuous electrocadiographs recorded during both unpaced and paced respiration conditions.

RESULTS

Structural equation models (SEM) of the individual trait emotions showed depression and anxiety related inversely to HF-HRV and anger unrelated to HF-HRV. SEM also showed negative affect related inversely to HF-HRV. All associations were present after covariate adjustment for traditional cardiovascular risk factors, including age, sex, race, education, body mass index, smoking status, and blood pressure.

CONCLUSIONS

Negative affect as a common pathway between depression, anxiety, and anger and impairments in cardiac autonomic function was supported, suggesting negative affect may be the unifying and potentially toxic element linking individual trait negative emotions to ANS dysregulation.

Depression and anxiety as predictors of heart rate variability after myocardial infarction

BACKGROUND

Reduced heart rate variability (HRV) is a prognostic factor for cardiac mortality. Both depression and anxiety have been associated with increased risk for mortality in cardiac patients. Low HRV may act as an intermediary in this association. The present study examined to what extent depression and anxiety differently predict 24-h HRV indices recorded post-myocardial infarction (MI).

METHOD

Ninety-three patients were recruited during hospitalization for MI and assessed on self-reported symptoms of depression and anxiety. Two months post-MI, patients were assessed on clinical diagnoses of lifetime depressive and anxiety disorder. Adequate 24-h ambulatory electrocardiography data were obtained from 82 patients on average 78 days post-MI.

RESULTS

In unadjusted analyses, lifetime diagnoses of major depressive disorder was predictive of lower SDNN [standard deviation of all normal-to-normal (NN) intervals; beta=-0.26, p=0.022] and SDANN (standard deviation of all 5-min mean NN intervals; beta=0.25, p=0.023), and lifetime anxiety disorder of lower RMSSD (root mean square of successive differences; beta=-0.23, p=0.039). Depression and anxiety symptoms did not significantly predict HRV. After adjustment for age, sex, cardiac history and multi-vessel disease, lifetime depressive disorder was no longer predictive of HRV. Lifetime anxiety disorder predicted reduced high-frequency spectral power (beta=-0.22, p=0.039) and RMSSD (beta=-0.25, p=0.019), even after additional adjustment of anxiety symptoms.

CONCLUSIONS

Clinical anxiety, but not depression, negatively influenced parasympathetic modulation of heart rate in post-MI patients. These findings elucidate the physiological mechanisms underlying anxiety as a risk factor for adverse outcomes, but also raise questions about the potential role of HRV as an intermediary between depression and post-MI prognosis.

Associations of psychosocial factors with heart rate and its short-term variability: multi-ethnic study of atherosclerosis

OBJECTIVE

To examine the association of psychosocial factors with heart rate (HR) and its variability across multiple ethnic groups and by gender. Increased HR and reduced HR variability are markers of increased cardiovascular risk.

METHODS

Between 2000 and 2002, 6814 men and women (2624 Whites, 1895 African-Americans, 1492 Hispanics, and 803 Chinese) aged 45 to 84 years took part in the first examination of the Multi-Ethnic Study of Atherosclerosis. Associations of psychosocial variables with mean values of HR and its short-term variability were tested, using multivariate regression models.

RESULTS

In age, gender, race/ethnicity, and risk factor-adjusted analyses, a depressive symptom score was positively associated with HR and inversely associated with HR variability (standard deviation of normal-to-normal (N-N) interbeat intervals (SDNN) and the root mean square of successive differences in N-N intervals (RMSSD)). The adjusted mean differences per 1-SD (8 points) increment of depression score for HR, RMSSD, and SDNN were 0.5 (95% confidence interval (CI), 0.2-0.7), -0.8 (95% CI, -1.5 to -0.2), and -0.7 (95% CI, -1.1 to -0.2). The social support score was inversely associated with HR, but nonsignificantly associated with RMSSD and SDNN. There was no association of trait anger or trait anxiety with HR, RMSSD, or SDNN. Associations were generally consistent in men and women.

CONCLUSIONS

These findings generally support the hypothesis that depression may be associated with increased HR and reduced HR variability, which increase the risk of cardiovascular diseases.

Social isolation disrupts autonomic regulation of the heart and influences negative affective behaviors

BACKGROUND

There is a documented association between affective disorders (e.g., depression and anxiety) and cardiovascular disease in humans. Chronic social stressors may play a mechanistic role in the development of behavioral and cardiac dysregulation. The current study investigated behavioral, cardiac, and autonomic responses to a chronic social stressor in prairie voles, a rodent species that displays social behaviors similar to humans.

METHODS

Female prairie voles were exposed to 4 weeks of social isolation (n = 8) or pairing (control conditions; n = 7). Electrocardiographic parameters were recorded continuously during isolation, and behavioral tests were conducted during and following this period.

RESULTS

Isolation induced a significant increase in resting heart rate, reduction in heart rate variability (standard deviation of normal-to-normal intervals and amplitude of respiratory sinus arrhythmia), and exaggerated cardiac responses during an acute resident-intruder paradigm. Isolation led also to both depression-like and anxiety-like behaviors in validated operational tests. These changes in response to social isolation showed predictable interrelations and were mediated by a disruption of autonomic balance including both sympathetic and parasympathetic (vagal) mechanisms.

CONCLUSIONS

These findings indicate that social isolation induces behavioral, cardiac, and autonomic alterations related to those seen after other stressors and which are relevant to cardiovascular disease and affective disorders. This model may provide insight into the mechanisms that underlie these co-occurring conditions.

Specific serotonin reuptake inhibition in major depressive disorder adversely affects novel markers of cardiac risk

There exists a growing body of evidence linking depression with cardiovascular events, although the mechanisms responsible remain unknown. We investigated the role of the autonomic nervous system and inflammation in the link between coronary heart disease and major depressive disorder (MDD), and examined the cardiac risk modification following pharmacological treatment of depression. We measured cardiac baroreflex function, heart rate variability, pulse pressure and high sensitivity C-reactive protein (hsCRP), all of which have an impact on cardiac risk, pre- and post-treatment in 25 patients with MDD, with no history of coronary heart disease, and in 15 healthy subjects. Treatment consisted of selective serotonin reuptake inhibitors for approximately 12 weeks. No significant differences were observed between untreated MDD patients and healthy subjects in blood pressure, heart rate, baroreflex sensitivity or heart rate variability. Pulse pressure and hsCRP, however, were significantly elevated in patients with MDD prior to treatment (p=0.023 and p=0.025, respectively). Moreover, while pharmacotherapy was effective in alleviating depression, surprisingly, each of cardiac baroreflex function, heart rate variability, pulse pressure and hsCRP was modified (p<0.05) in a manner likely to increase cardiac risk. In conclusion, this study demonstrated higher pulse pressure and hsCRP plasma levels in patients with MDD, which might contribute to increased cardiac risk. Following treatment vagal activity was reduced, as indicated by reductions in baroreflex sensitivity and heart rate variability, accompanied by increases in pulse pressure and plasma hsCRP levels. Mechanisms potentially responsible for generating cardiac risk in patients treated with selective serotonin reuptake inhibitors may need to be therapeutically targeted to reduce the incidence of coronary heart disease in this population.

Caffeine challenge test in panic disorder and depression with panic attacks

Our aim was to observe if patients with panic disorder (PD) and patients with major depression with panic attacks (MDP) (Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition criteria) respond in a similar way to the induction of panic attacks by an oral caffeine challenge test. We randomly selected 29 patients with PD, 27 with MDP, 25 with major depression without panic attacks (MD), and 28 healthy volunteers. The patients had no psychotropic drug for at least a 4-week period. In a randomized double-blind experiment performed in 2 occasions 7 days apart, 480 mg caffeine and a caffeine-free (placebo) solution were administered in a coffee form and anxiety scales were applied before and after each test. A total of 58.6% (n = 17) of patients with PD, 44.4% (n = 12) of patients with MDP, 12.0% (n = 3) of patients with MD, and 7.1% (n= 2) of control subjects had a panic attack after the 480-mg caffeine challenge test (chi(2)(3) = 16.22, P = .001). The patients with PD and MDP were more sensitive to caffeine than were patients with MD and healthy volunteers. No panic attack was observed after the caffeine-free solution intake. The patients with MD had a lower heart rate response to the test than all the other groups (2-way analysis of variance, group by time interaction with Greenhouse-Geisser correction: F(3,762) = 2.85, P = .026). Our data suggest that there is an association between panic attacks, no matter if associated with PD or MDP, and hyperreactivity to an oral caffeine challenge test.

Baroreflex mechanisms in major depression

BACKGROUND

Recent studies have shown that depressive disorder is associated with impaired baroreceptor or baroreflex sensitivity, which is proposed to be a predisposing factor for sudden death in patients with manifest cardiac disease. These studies have not evaluated the afferent and efferent components of the cardiac baroreflex loop or other baroreflex mechanisms that regulate target processes (cardiac metabolism and blood pressure variability) related to the impairment. The objective of this study was to gain more insight into autonomic functioning in depressive disorder to more fully examine the potential basis for increased cardiac mortality.

METHODS

The subjects were 28 women and men with unipolar major depression who were taking antidepressant medications and who were in partial remission and free of cardiovascular or other serious disease, and 28 healthy control subjects matched for sex, age, and ethnicity. The two samples were compared for negative affective dispositions (anger expression, hostility, defensiveness, anxiety), spontaneous (closed-loop) baroreflex activity, heart rate, heart rate variability, systolic blood pressure, and heart rate-systolic blood pressure double product under resting conditions.

RESULTS

Depressed patients showed a general disposition to anger suppression coupled with higher hostility and anxiety, and lower defensiveness. The patients showed higher general sympathetic activity (high levels of blood pressure, low-frequency heart rate variability) and lower parasympathetic-related activity (high heart rate and reduced high frequency heart rate variability) with affected cardiac metabolism estimated by the double product. Depressed patients had lower baroreflex sensitivity related to a higher gain of the afferent component of the baroreflex without respective gain adjustment of its efferent component (reflex gain 'de-afferentation'). It was coupled with a compensatory higher number of effective baroreflex reactions (reflex gating 're-afferentation'). Antidepressant agents and depressed mood had additional independent effects on baroreflex sensitivity through the efferent component of the cardiac baroreflex loop.

CONCLUSIONS

The data indicate that different baroreflex components and mechanisms may be impaired in patients with depression and may contribute to their increased cardiac risk.

Linear and nonlinear methods for analyses of cardiovascular variability in bipolar disorders

OBJECTIVES

Heart rate variability (HRV), blood pressure variability (BPV), and the assessment of baroreflex sensitivity are widely accepted methods for analyzing and characterizing cardiovascular regulation and for an enhanced risk evaluation in different diseases. As a result of the complexity of the investigated regulatory systems, univariate analyses do not often provide a convenient description of pathological changes in the cardiovascular regulation. Therefore, the application of a multivariate approach is preferable.

METHODS

We present principal methods of time-domain, frequency-domain, and nonlinear analyses of HRV, BPV as well as methods for coupling and interaction analyses.

RESULTS

Changes in autonomic nervous system (ANS) tone are known to accompany various mental disorders. Depressive patients frequently complain of symptoms of ANS dysfunction, such as dry mouth, diarrhea, and insomnia. These clinical observations propose the assumption of altered autonomic dysfunction in these patients. In contrast to these clinical assumptions, inconsistent results have been found in studies of HRV in depressive patients. This work therefore covers a brief review of the literature in respect to bipolar disorder and the rationale to study autonomic changes in such a psychiatric disease.

CONCLUSIONS

Prospective studies of cardiovascular changes in mania and depression are needed to evaluate a psychopathological state in connection with cardiovascular changes and cardiac morbidity and mortality. These studies should consider BPV, coupling and interaction analyses, the application of nonlinear methods, and a multivariate approach in addition to the traditional analysis of HRV.