Effects of a cognitive stress challenge on myocardial perfusion and plasma cortisol in coronary heart disease patients with depression

A Pilot Study of Neurobiological Mechanisms of Stress and Cardiovascular Risk

Objective

Coronary heart disease is a leading cause of death and disability. Although psychological stress has been identified as an important potential contributor, mechanisms by which stress increases risk of heart disease and mortality are not fully understood. The purpose of this study was to assess mechanisms by which stress acts through the brain and heart to confer increased CHD risk.

Methods

Coronary Heart Disease patients (N=10) underwent cardiac imaging with [Tc-99m] sestamibi single photon emission tomography at rest and during a public speaking mental stress task. Patients returned for a second day and underwent positron emission tomography imaging of the brain, heart, bone marrow, aorta (indicating inflammation) and subcutaneous adipose tissue, after injection of [18F]2-fluoro-2-deoxyglucose for assessment of glucose uptake followed mental stress. Patients with (N=4) and without (N=6) mental stress-induced myocardial ischemia were compared for glucose uptake in brain, heart, adipose tissue and aorta with mental stress.

Results

Patients with mental stress-induced ischemia showed a pattern of increased uptake in the heart, medial prefrontal cortex, and adipose tissue with stress. In the heart disease group as a whole, activity increase with stress in the medial prefrontal brain and amygdala correlated with stress-induced increases in spleen (r=0.69, p=0.038; and r=0.69, p=0.04 respectfully). Stress-induced frontal lobe increased uptake correlated with stress-induced aorta uptake (r=0.71, p=0.016). Activity in insula and medial prefrontal cortex was correlated with post-stress activity in bone marrow and adipose tissue. Activity in other brain areas not implicated in stress did not show similar correlations. Increases in medial prefrontal activity with stress correlated with increased cardiac glucose uptake with stress, suggestive of myocardial ischemia (r=0.85, p=0.004).

Conclusions

These findings suggest a link between brain response to stress in key areas mediating emotion and peripheral organs involved in inflammation and hematopoietic activity, as well as myocardial ischemia, in Coronary Heart Disease patients.

Transcutaneous Cervical Vagal Nerve Stimulation in Patients with Posttraumatic Stress Disorder (PTSD): A Pilot Study of Effects on PTSD Symptoms and Interleukin-6 Response to Stress

BACKGROUND

Posttraumatic stress disorder (PTSD) is a highly disabling condition associated with alterations in multiple neurobiological systems, including increases in inflammatory and sympathetic function, responsible for maintenance of symptoms. Treatment options including medications and psychotherapies have limitations. We previously showed that transcutaneous Vagus Nerve Stimulation (tcVNS) blocks inflammatory (interleukin (IL)-6) responses to stress in PTSD. The purpose of this study was to assess the effects of tcVNS on PTSD symptoms and inflammatory responses to stress.

METHODS

Twenty patients with PTSD were randomized to double blind active tcVNS (N=9) or sham (N=11) stimulation in conjunction with exposure to personalized traumatic scripts immediately followed by active or sham tcVNS and measurement of IL-6 and other biomarkers of inflammation. Patients then self administered active or sham tcVNS twice daily for three months. PTSD symptoms were measured with the PTSD Checklist (PCL) and the Clinician Administered PTSD Scale (CAPS), clinical improvement with the Clinical Global Index (CGI) and anxiety with the Hamilton Anxiety Scale (Ham-A) at baseline and one-month intervals followed by a repeat of measurement of biomarkers with traumatic scripts. After three months patients self treated with twice daily open label active tcVNS for another three months followed by assessment with the CGI.

RESULTS

Traumatic scripts increased IL-6 in PTSD patients, an effect that was blocked by tcVNS (p<.05). Active tcVNS treatment for three months resulted in a 31% greater reduction in PTSD symptoms compared to sham treatment as measured by the PCL (p=0.013) as well as hyperarousal symptoms and somatic anxiety measured with the Ham-A p<0.05). IL-6 increased from baseline in sham but not tcVNS. Open label tcVNS resulted in improvements measured with the CGI compared to the sham treatment period p<0.05).

CONCLUSIONS

These preliminary results suggest that tcVNS reduces inflammatory responses to stress, which may in part underlie beneficial effects on PTSD symptoms.

Brain-heart connections in stress and cardiovascular disease: Implications for the cardiac patient

The influence of psychological stress on the physiology of the cardiovascular system, and on the etiology and outcomes of cardiovascular disease (CVD) has been the object of intense investigation. As a whole, current knowledge points to a "brain-heart axis" that is especially important in individuals with pre-existing CVD. The use of acute psychological stress provocation in the laboratory has been useful to clarify the effects of psychological stress on cardiovascular physiology, immune function, vascular reactivity, myocardial ischemia, neurobiology and cardiovascular outcomes. An emerging paradigm is that dynamic perturbations of physiological and molecular pathways during stress or negative emotions are important in influencing cardiovascular outcomes, and that some patient subgroups, such as women, patients with an early-onset myocardial infarction, and patients with adverse psychosocial exposures, may be at especially high risk for these effects. This review summarizes recent knowledge on mind-body connections in CVD among cardiac patients and highlights important pathways of risk which could become the object of future intervention efforts. As a whole, this research suggests that an integrated study of mind and body is necessary to fully understand the determinants and consequences of CVD.

Transcutaneous vagal nerve stimulation blocks stress-induced activation of Interleukin-6 and interferon-γ in posttraumatic stress disorder: A double-blind, randomized, sham-controlled trial

Posttraumatic stress disorder (PTSD) is a highly disabling condition associated with alterations in multiple neurobiological systems, including increases in inflammatory function. Vagus nerve stimulation (VNS) decreases inflammation, however few studies have examined the effects of non-invasive VNS on physiology in human subjects, and no studies in patients with PTSD. The purpose of this study was to assess the effects of transcutaneous cervical VNS (tcVNS) on inflammatory responses to stress. Thirty subjects with a history of exposure to traumatic stress with (N ​= ​10) and without (N ​= ​20) PTSD underwent exposure to stressful tasks immediately followed by active or sham tcVNS and measurement of multiple biomarkers of inflammation (interleukin-(IL)-6, IL-2, IL-1β, Tumor Necrosis Factor alpha (TNFα) and Interferon gamma (IFNγ) over multiple time points. Stressful tasks included exposure to personalized scripts of traumatic events on day 1, and public speech and mental arithmetic (Mental Stress) tasks on days 2 and 3. Traumatic scripts were associated with a pattern of subjective anger measured with Visual Analogue Scales and increased IL-6 and IFNγ in PTSD patients that was blocked by tcVNS (p ​< ​.05). Traumatic stress had minimal effects on these biomarkers in non-PTSD subjects and there was no difference between tcVNS or sham. No significant differences were seen between groups in IL-2, IL-1β, or TNFα. These results demonstrate that tcVNS blocks behavioral and inflammatory responses to stress reminders in PTSD.

Confederates in the Attic: Posttraumatic Stress Disorder, Cardiovascular Disease, and the Return of Soldier's Heart

Da Costa originally described Soldier's Heart in the 19th Century as a syndrome that occurred on the battlefield in soldiers of the American Civil War. Soldier's Heart involved symptoms similar to modern day posttraumatic stress disorder (PTSD) as well as exaggerated cardiovascular reactivity felt to be related to an abnormality of the heart. Interventions were appropriately focused on the cardiovascular system. With the advent of modern psychoanalysis, psychiatric symptoms became divorced from the body and were relegated to the unconscious. Later, the physiology of PTSD and other psychiatric disorders was conceived as solely residing in the brain. More recently, advances in psychosomatic medicine led to the recognition of mind-body relationships and the involvement of multiple physiological systems in the etiology of disorders, including stress, depression PTSD, and cardiovascular disease, has moved to the fore, and has renewed interest in the validity of the original model of the Soldier's Heart syndrome.

Quantifying acute physiological biomarkers of transcutaneous cervical vagal nerve stimulation in the context of psychological stress

BACKGROUND

Stress is associated with activation of the sympathetic nervous system, and can lead to lasting alterations in autonomic function and in extreme cases symptoms of posttraumatic stress disorder (PTSD). Vagal nerve stimulation (VNS) is a potentially useful tool as a modulator of autonomic nervous system function, however currently available implantable devices are limited by cost and inconvenience.

OBJECTIVE

The purpose of this study was to assess the effects of transcutaneous cervical VNS (tcVNS) on autonomic responses to stress.

METHODS

Using a double-blind approach, we investigated the effects of active or sham tcVNS on peripheral cardiovascular and autonomic responses to stress using wearable sensing devices in 24 healthy human participants with a history of exposure to psychological trauma. Participants were exposed to acute stressors over a three-day period, including personalized scripts of traumatic events, public speech, and mental arithmetic tasks.

RESULTS

tcVNS relative to sham applied immediately after traumatic stress resulted in a decrease in sympathetic function and modulated parasympathetic/sympathetic autonomic tone as measured by increased pre-ejection period (PEP) of the heart (a marker of cardiac sympathetic function) of 4.2 ms (95% CI 1.6-6.8 ms, p < 0.01), decreased peripheral sympathetic function as measured by increased photoplethysmogram (PPG) amplitude (decreased vasoconstriction) by 47.9% (1.4-94.5%, p < 0.05), a 9% decrease in respiratory rate (-14.3 to -3.7%, p < 0.01). Similar effects were seen when tcVNS was applied after other stressors and in the absence of a stressor.

CONCLUSION

Wearable sensing modalities are feasible to use in experiments in human participants, and tcVNS modulates cardiovascular and peripheral autonomic responses to stress.

Brain Correlates of Mental Stress-Induced Myocardial Ischemia

OBJECTIVE

Coronary artery disease (CAD) is a major cause of morbidity and mortality, and despite important advances in our understanding of this disorder, the underlying mechanisms remain under investigation. Recently, increased attention has been placed on the role of behavioral factors such as emotional stress on CAD risk. Brain areas involved in memory and the stress response, including medial prefrontal cortex, insula, and parietal cortex, also have outputs to the peripheral cardiovascular system. The purpose of this study was to assess the effects of mental stress on brain and cardiac function in patients with CAD.

METHODS

CAD patients (N = 170) underwent cardiac imaging with [Tc-99m] sestamibi single-photon emission tomography at rest and during a public speaking mental stress task. On another day, they underwent imaging of the brain with [O-15] water positron emission tomography (PET) during mental stress (arithmetic and public speaking) and control conditions.

RESULTS

Patients with mental stress-induced myocardial ischemia showed increased activation with stress in anterior cingulate, inferior frontal gyrus, and parietal cortex (p < .005). This was seen with both arithmetic stress and public speaking stress. Arithmetic stress was additionally associated with left insula activation, and public speaking with right pre/postcentral gyrus and middle temporal gyrus activation (p < .005).

CONCLUSIONS

These findings suggest that mental stress-induced myocardial ischemia is associated with activation in brain areas involved in the stress response and autonomic regulation of the cardiovascular system. Altered brain reactivity to stress could possibly represent a mechanism through which stress leads to increased risk of CAD-related morbidity and mortality.

Brain mechanisms of stress and depression in coronary artery disease

INTRODUCTION

Major depression is associated with an increased risk for and mortality from coronary artery disease (CAD), however the mechanisms by which this occurs are not clear. Depression, which is linked to stress, is associated with changes in brain areas involved in memory and the stress response, and it is likely that these regions play an important role in this increased risk. This study assessed the effects of stress on brain and cardiac function in patients with CAD with and without depression.

METHODS

CAD patients with (N = 17) and without (N = 21) major depression based on the Structured Clinical Interview for DSM-IV (DSM-IV) and/or a Hamilton Depression Scale score of nine or greater underwent imaging of the brain with high resolution positron emission tomography (HR-PET) and [O-15] water and imaging of the heart with single photon emission tomography (SPECT) and [Tc-99 m] sestamibi during mental stress (mental arithmetic) and control conditions.

RESULTS

Patients with CAD and major depression showed increased parietal cortex activation and a relative failure of medial prefrontal/anterior cingulate activation during mental stress compared to CAD patients without depression. Depressed CAD patients with stress-induced myocardial ischemia, however, when compared to depressed CAD patients without showed increased activation in rostral portions of the anterior cingulate.

CONCLUSIONS

These findings are consistent with a role for brain areas implicated in stress and depression in the mechanism of increased risk for CAD morbidity and mortality in CAD patients with the diagnosis of major depression.

Childhood heart problems, adulthood emotional stability, and sex associated with self-report heart conditions in adulthood

The present study investigated biomedical, social, and psychological factors associated with self-reported heart conditions in adulthood in a British cohort. In total, 5697 (50.7% males) participants with data on parental socioeconomic status, childhood cognitive ability, childhood heart problems, educational qualifications, current occupational levels, adulthood personality traits, and the prevalence of self-reported heart conditions in adulthood were included in the study. The prevalence of self-reported heart conditions measured at age 54 years was the outcome variable. Hierarchical logistic regression analysis showed that childhood heart problems identified by physicians (OR = 3.47:1.74-6.92, p < 0.001) and trait emotional stability (OR = 0.83:0.75-0.93, p < 0.001) were the significant and independent predictors of self-reported heart conditions in adulthood. There were also significant sex effects on the prevalence of the outcome variable (OR = 0.53:0.42-0.63, p < 0.001). Both a biomedical and a psychological factor were significantly associated with self-reported heart conditions in adulthood.