Platelet hyperactivity in clinical depression and the beneficial effect of antidepressant drug treatment: how strong is the evidence?

Depression in patients with coronary heart disease

Approximately 20% of patients with coronary heart disease (CHD) have major depression and 20% have minor depression at any given point in the course of their illness. Depression causes significant psychological and social morbidity, and is a risk factor for further cardiac morbidity and mortality. Although there are many possible biological and behavioral mechanisms, the causal pathways through which depression increases the risk for cardiac events and death are not well understood. Despite the morbidity associated with depression, and the devastating impact it has on the quality of life of patients with CHD, it is underdiagnosed and often left untreated. This article describes screening techniques for use in primary care and cardiology settings, and discusses the safety and efficacy of available treatments for depression in patients with CHD.

Vascular factors and depression

OBJECTIVE

This paper examines possible mechanisms that may explain the bi-directional relationship between vascular disease and depression.

DESIGN

A literature review was carried out using Medline from 1996 to 2007, using relevant key words including vascular depression, and supplemented by key references to earlier work.

RESULTS

Several mechanisms were considered including: autonomic dysfunction, platelet activation, hypothalamic pituitary axis activation, endothelial dysfunction, cytokines, omega 3 fatty acids, genetics, homocysteine and effects of treatment.

CONCLUSIONS

The relationship between vascular disease and depression cannot solely be explained by current established risk factors or the effects of treatment for depression. Other mechanisms must apply, and there is some evidence for common genetic factors. Promising future lines of investigation include homocysteine, cytokines and endothelial dysfunction. More longitudinal studies combined with measurements of these biomarkers are needed.

Platelet function in patients with major depression

Depression, ischaemic heart disease and cerebrovascular disease are important causes of morbidity and are among the leading contributors to global health burden. These conditions often occur in the same patient, resulting in considerably greater effect on health than combinations of chronic diseases without depression. The frequent occurrence of these conditions in the same patient raises the possibility of a common genetic predisposition, similar risk factors or a pathophysiological link. Serotoninergic and adrenergic signalling play important roles in causing major depression and also in platelet activation and aggregation, which underlies vascular disease. This review discusses the potential pathophysiological link between major depression and conditions in which platelet activation plays an important role and also provides evidence linking the use of the most commonly used antidepressant drugs (i.e. the selective serotonin re-uptake inhibitors) to increased risk of bleeding.

Effects of depressive and anxious symptoms on norepinephrine and platelet P-selectin responses to acute psychological stress among elderly caregivers

BACKGROUND

Caring for a spouse with Alzheimer's disease is associated with increased psychological distress, impaired immunity, and heightened cardiovascular risk. Hyperreactivity of sympathetic and platelet activation responses to acute psychological stress, or the failure to recover quickly from stressful events, may constitute an important pathway linking stress and negative affect with cardiovascular disease (CVD).

OBJECTIVES

(1) To evaluate associations between negative affect (i.e., depressive and anxious symptoms) with increased norepinephrine and P-selectin responses to an acute psychological stress task. (2) To establish whether these associations are augmented among elderly spousal caregivers (CG) compared to non-caregivers (NC).

METHODS

Depressive (DEP) and anxious (ANX) symptoms from the Brief Symptom Inventory were assessed among 39 CG and 31 NC. Plasma norepinephrine levels (NE) and percent platelet P-selectin (PSEL) expression were assayed at three time-points: rest, immediately following a laboratory speech test (reactivity), and after 14 min of recovery.

RESULTS

Among CG, but not NC, increased symptoms of depression and anxiety were associated with delayed NE recovery (DEP: beta=.460, p=.008; ANX: beta=.361, p=.034), increased PSEL reactivity (DEP: beta=.703, p<.001; ANX: beta=.526, p=.002), and delayed PSEL recovery (DEP: beta=.372, p=.039; ANX: beta=.295, p=.092), while controlling for age, gender, aspirin use, antidepressant use, and preexisting CVD. Bivariate correlations showed delayed NE recovery was also associated with increased PSEL reactivity (r=.416) and delayed PSEL recovery (r=.372; all ps<.05) among CG but not NC.

DISCUSSION

Among chronically stressed caregivers, increased levels of depressive and anxious symptoms are associated with prolonged sympathetic activation and pronounced platelet activation. These changes may represent one pathway linking caregiving stress to cardiovascular risk.

Psychobiology of depression/distress in congestive heart failure

Heart failure affects millions of Americans and new diagnosis rates are expected to almost triple over the next 30 years as our population ages. Affective disorders including clinical depression and anxiety are common in patients with congestive heart failure. Furthermore, the presence of these disorders significantly impacts quality of life, medical outcomes, and healthcare service utilization. In recent years, the literature has attempted to describe potential pathophysiologic mechanisms relating affective disorders and psychosocial stress to heart failure. Several potential mechanisms have been proposed including autonomic nervous system dysfunction, inflammation, cardiac arrhythmias, and altered platelet function. These mechanisms are reviewed in this article. Additional novel mechanisms such as mental stress-induced myocardial ischemia are also discussed.

The platelet of the patients with ischemic cardiopathy and cardiac valve disease showed a reduction of 8OH-DPAT binding sites

Depression is prospectively associated with increased risk of coronary artery disease in individuals initially free of clinical cardiovascular disease probably by an increased platelet activity. The serotonergic receptors mainly implied in depression are 5-HT1A and 5-HT2 receptors. Activation of 5HT2 receptor induces platelet aggregation. Drugs with 5-HT1A receptor agonist and 5-HT2A receptor antagonist effects reduced the receptor-mediated platelet aggregation. There are only indirect data about 5-HT1A receptors presence in platelet membranes, thus our aims were to study the characteristics of the platelet membranes 5-HT1A binding sites of both healthy volunteers and patients with cardiac valve disease and ischemic cardiopathy. The bound of the 5-HT1A selective agonist 3H-8OH-DPAT to the platelet membranes 5-HT1A binding sites of patients with cardiac valve disease and ischemic cardiopathy were compared with a control group of healthy voluntaries using radioligand binding methods. The patients with cardiovascular disease showed a reduction (-50.40%) (p<0.01) of the 3H-8OH-DPAT bound to the platelet membranes 5-HT1A receptors (1.652+/-0.79 fmol/mg protein) with respect to the control group (3.331+/-0.16 fmol/mg protein). 3H-8OH-DPAT binding to human platelet membranes is saturable, of high affinity, and seems selective for 5-HT1A receptors, and similar to that described in animal brain and in other human cells. Patients with ischemic cardiopathy and cardiac valve disease showed a reduction of the 8OH-DPAT bound to the platelet membranes. Taken together, these findings suggest that the 8OH-DPAT bound to the human platelet membranes is modulated by modifications produced by cardiovascular disease conditions.

Baseline level of platelet-leukocyte aggregates, platelet CD63 expression, and soluble P-selectin concentration in patients with posttraumatic stress disorder: a pilot study

Platelets may have an important role in the development of cardiovascular disease (CVD) as a result of chronic stress. We conducted a pilot study to evaluate the effect of posttraumatic stress disorder (PTSD) on baseline platelet activation. Platelet-leukocyte aggregates (PLA) and CD63 expression were measured by flow cytometry, and soluble (s)P-selectin concentration was determined in sera of 20 Croatian male combat veterans with PTSD and 20 healthy civilians. Groups were matched in sex, age, body mass index (BMI) and traditional CVD risk factors. Our data showed no differences in measured parameters. Other platelet activation markers should be determined and a larger sample size used in future studies.

Acute depressed mood as a trigger of acute coronary syndromes

BACKGROUND

Some cases of acute coronary syndrome (ACS) may be triggered by emotional states such as anger, but it is not known if acute depressed mood can act as a trigger.

METHODS

295 men and women with a verified ACS were studied. Depressed mood in the two hours before ACS symptom onset was compared with the same period 24 hours earlier (pair-matched analysis), and with usual levels of depressed mood, using case-crossover methods.

RESULTS

46 (18.2%) patients experienced depressed mood in the two hours before ACS onset. The odds of ACS following depressed mood were 2.50 (95% confidence intervals 1.05 to 6.56) in the pair-matched analysis, while the relative risk of ACS onset following depressed mood was 4.33 (95% confidence intervals 3.39 to 6.11) compared with usual levels of depressed mood. Depressed mood preceding ACS onset was more common in lower income patients (p = .032), and was associated with recent life stress, but was not related to psychiatric status.

CONCLUSIONS

Acute depressed mood may elicit biological responses that contribute to ACS, including vascular endothelial dysfunction, inflammatory cytokine release and platelet activation. Acute depressed mood may trigger potentially life-threatening cardiac events.

Coronary heart disease and depression: a review of recent mechanistic research

OBJECTIVE

Both behavioural and physiological factors have been proposed as mechanisms that may explain the negative effect of depression on coronary heart disease (CHD). Our aim is to review some of the most important findings since our prior review.

METHOD

We searched MEDLINE, PsycINFO, and other sources for recent studies of candidate mechanisms, with an emphasis on publications since 2002.

RESULTS

Physiological pathways have received far greater attention than behavioural ones in the emerging literature. Recent studies have identified shared genetic determinants, inflammation, blood clotting, and vascular mechanisms as plausible explanatory mechanisms.

CONCLUSIONS

Future research should focus on relations between behavioural and physiological mechanisms and on the effects of pharmacologic and psychotherapeutic treatments for depression on candidate mechanisms.

Platelets, coronary heart disease, and stress

Coronary heart disease is the leading cause of death in Western society, and its development is associated with chronic stress and other psychosocial factors. Atherosclerosis, the disorder underlying this disease, is an inflammatory process in which leukocytes interact with structurally intact but dysfunctional endothelium of the arteries. Platelets play a key role in this process by binding to leukocytes and promoting their recruitment to the endothelium. Platelet-leukocyte interactions also stimulate the release of pro-inflammatory and pro-thrombotic factors which promote atherosclerosis. Elevated circulating levels of platelet-leukocyte aggregates have been reported in cardiac patients and in individuals of low socioeconomic status, a factor associated with chronic psychological stress. Increased platelet activation has also been observed in individuals prone to depression or hostility, and in people subject to high levels of work stress. Acute psychological stress increases circulating platelet-leukocyte aggregates in healthy individuals and this effect is prolonged in cardiac patients. Platelet activation may be a mechanism linking psychosocial stress with increased coronary risk, and may also play a role in the emotional triggering of acute coronary syndromes in patients with advanced coronary disease.

Poor Sleep Is Associated with Higher Plasma Proinflammatory Cytokine Interleukin-6 and Procoagulant Marker Fibrin D-Dimer in Older Caregivers of People with Alzheimer's Disease

OBJECTIVES

To determine whether objective measures of sleep correlate with plasma levels of the proinflammatory cytokine interleukin (IL)-6 and the procoagulant marker fibrin D-dimer in caregivers of patients with dementia.

DESIGN

Cross-sectional study.

SETTING

Subjects' homes.

PARTICIPANTS

Sixty-four community-dwelling spousal caregivers (69% women, mean age+/-standard deviation 72+/-9) and 36 sex-matched noncaregiving controls.

MEASUREMENTS

All participants underwent in-home full-night polysomnography. Demographic and lifestyle factors, depression, diseases, and medication that could affect inflammation, coagulation, and sleep were controlled for in analyses regressing sleep variables and caregiver status and their interaction on plasma levels of IL-6 and D-dimer.

RESULTS

Caregivers had higher levels of D-dimer (781+/-591 vs 463+/-214 ng/mL, P=.001) and IL-6 (1.42+/-1.52 vs 0.99+/-0.86 pg/mL, P<.06) and lower levels of total sleep time (369+/-70 vs 393+/-51 minutes, P=.049) and sleep efficiency (77+/-11 vs 82+/-9%, P=.04) than controls. After controlling for age and body mass index, longer wake time after sleep onset (change in coefficient of determination (DeltaR2)=0.039, P=.04) and the interaction between caregiver status and higher apnea-hypopnea index (DeltaR2=0.054, P=.01) were predictors of IL-6. Controlling for age, caregiver status independently predicted D-dimer levels (DeltaR2=0.047, P=.01). Controlling for age and caregiver status, lower sleep efficiency (DeltaR2=0.032, P=.03) and the interaction between caregiver status and more Stage 2 sleep (DeltaR2=0.037, P=.02) independently predicted plasma D-dimer levels.

CONCLUSION

Poor sleep was associated with higher plasma IL-6 and D-dimer levels. These effects were most pronounced in caregivers of subjects with Alzheimer's disease. The findings suggest a mechanism that may explain how disturbed sleep might be associated downstream with cardiovascular risk, particularly in older people under chronic stress.

Opposite effect of negative and positive affect on stress procoagulant reactivity

Exaggerated procoagulant responses to acute mental stress may contribute to coronary thrombosis, and continuing low-grade systemic coagulation activation may link negative affect with the development of coronary artery disease. We investigated whether negative and positive affect and perceived social support would moderate stress procoagulant reactivity. Psychological functioning, exhaustion, negative affectivity, depression, anxiety, worrying, vigor, and social support were assessed in 27 apparently healthy men (mean age 47 +/- 8 years) who underwent the 13-min Trier Social Stress Test combining preparation, speech, and mental arithmetic. Plasma levels of von Willebrand factor antigen (VWF:Ag), fibrinogen, factor VII clotting activity (FVII:C), FVIII:C, FXII:C, and D-dimer were measured immediately before and after stress. Acute stress elicited significant increases in hemodynamic, cortisol, and coagulant activity (p values < 0.05). VWF:Ag reactivity showed inverse relationships with exhaustion (r = -0.63, p < 0.001), negative affectivity (r = -0.53, p = 0.005), and worrying (r = -0.53, p = 0.005). Exhaustion and negative affectivity emerged as independent predictors of VWF:Ag reactivity explaining 54% of its variance. Fibrinogen reactivity showed inverse relationships with negative affectivity (r = -0.59, p = 0.002) and anxiety (r = -0.54, p = 0.005); negative affectivity emerged as an independent predictor of fibrinogen reactivity explaining 35% of its variance. Psychological functioning and FVII:C reactivity were also correlated (r = -0.52, p = 0.006). Whereas FVIII:C reactivity correlated positively with vigorous mood (r = 0.48, p = 0.012), positive associations between social support and procoagulant reactivity did not reach significance. Negative affect was associated with attenuated procoagulant reactivity to stress and the opposite was observed for positive affect. Negative affect is not likely to enhance the acute procoagulant stress response in healthy men.

Reflections on relevance: Psychotherapy and Psychosomatics in 2004

Relevance of an article is a highly desirable yet hardly predictable quality at the time of its publication. Article relevance is frequently measured by the impact factor of the journal where the article is published. Furthermore, impact factor, citation index and citation analysis are used as a measure of research progress and scientific wealth of a nation. The wisdom and significance of this approach to relevance is debatable and thus discussed here. In 2004, Psychotherapy and Psychosomatics published a variety of articles which, in the author's view, are clinically relevant. Several selected clinically relevant issues reviewed in this article include: the conceptualization of fibromyalgia as a stress disorder; the psychosocial impact and psychosocial interventions in cancer; the impact of alexithymia on patient care; the possible relationship between depression and nutrition (namely intake of folate and pyridoxal phosphate); the significance of hypercoagulability in panic-like anxiety; the questionable value of single isomer drugs, and the relevance and adequacy of clinimetrics versus psychometrics in clinical research. The reviewed issues seem to be relevant to clinical practice, research or both, but also to our critical thinking, and the critical review of the developments in psychiatry and psychology.