Consensus paper of the WFSBP Task Force on Biological Markers: biological markers in depression

Cerebrospinal fluid analysis in affective and schizophrenic spectrum disorders: identification of subgroups with immune responses and blood-CSF barrier dysfunction

Immune and inflammatory mechanisms are detected in a subgroup of treatment resistant hospitalized affective and schizophrenic spectrum disorder patients. We analysed albumin, IgG, IgA, IgM, oligoclonal IgG and specific antibodies in paired cerebrospinal fluid (CSF) and serum samples. Numerical and graphical interpretation of CSF protein data was performed by Reibergrams with a new CSF statistics tool for nonlinear group analysis with reference to a large control group (n=4100). In 41% of the psychiatric patients (n=63) we observed CSF pathologies: 14% displayed intrathecal humoral immune responses, 10% slightly increased CSF cell counts (5-8/microL) and 29% had moderate blood-CSF barrier dysfunctions, in 24% as the only pathological sign with normal IgG, IgA and IgM concentrations in CSF (p=0.9 testing the null hypothesis for intrathecal synthesis with reference to Qmean of the reference group). In the group of affective (n=24) spectrum disorders 20% displayed a systemic immune reaction as detected by oligoclonal IgG. CSF analysis and interdisciplinary clinical approach revealed 6% of psychiatric patients likely to represent a virusspecific, bacterial or autoimmune associated disorder with CNS involvement. Elevated CSF neopterin concentration in 34% of the patients was interpreted as an increased release from astrocytes or from other glia cells. The low level immune response and barrier dysfunctions are discussed on the base of a mild encephalitis pathomechanism in subgroups of psychiatric patients. CSF analysis is shown to be a useful diagnostic tool for differential diagnosis in psychiatric diseases.

Functional change of the auditory cortex related to brain serotonergic neurotransmission in type 1 diabetic adolescents with and without depression

The aim of this study was to determine whether diabetic patients who were depressed present a decrease of brain serotonergic activity compared to diabetic patients without depression or patients with depression but without diabetes. Determination was made with plasma free fraction of L-tryptophan (FFT) and intensity-dependent auditory-evoked potentials (IDAEPs). Thirty-seven adolescents were studied (20 type 1 diabetic subjects: nine with depression, 11 without depression), nine controls and eight subjects with only depression. FFT, glucose, glycated haemoglobin, free fatty acids, albumin and IDAEPs were determined. All diabetic patients showed a significant decrease of FFT. The group diabetic subjects with depression presented a steeper slope of the amplitude-intensity function of N1/P2 component, suggesting a higher reactivity of the auditory cortex in comparison to diabetic subjects without depression, subjects with only depression, and controls. This was associated with lower plasma FFT. Diabetic subjects with depression had a deficiency of metabolic control due to poor treatment adherence. These findings suggest an enhanced deterioration of brain serotonergic neurotransmission in diabetic subjects with depression with abnormal responses of the auditory cortex. The N1/P2 component of IDAEP is proposed as a non-invasive indicator of brain serotonergic tone that differentiates depressed from non-depressed diabetic patients.

Serum brain-derived neurotrophic factor levels as a novel biological marker for the activities of psychiatric symptoms in systemic lupus erythematosus

OBJECTIVES

Neuropsychiatric systemic lupus erythematosus (NPSLE) is a serious but potentially treatable disease. However, biological markers such as IgG index or IL-6 do not always reflect the severity of the psychotic symptoms of NPSLE. We hypothesized that serum BDNF levels may be a biological marker for reflecting the severity of the psychiatric symptoms of NPSLE.

METHODS

The participants enrolled in this study were 28 healthy volunteers and 54 Japanese SLE inpatients at the University Hospital of Occupational and Environmental Health, all of whom fulfilled the criteria for the classification of SLE. SLE patients were divided into the three groups: NPSLE with psychiatric symptoms including an acute confusional state, anxiety disorder, cognitive dysfunction, mood disorder, and psychosis (NP group); NPSLE without psychiatric symptoms (NN group); and SLE without neuropsychiatric symptoms (S group). The serum BDNF levels were measured by ELISA.

RESULTS

Serum BDNF levels were significantly increased in the NP group (mean +/- SE = 37.0 +/- 5.46 ng/ml) compared with those in the other three groups (NN group; mean +/- SE = 9.1 +/- 2.44 ng/ml, P < 0.0001, S group; mean +/- SE = 10.4 +/- 2.51 ng/ml, P < 0.0001, healthy control; mean +/- SE = 11.44 +/- 0.69, P < 0.0001). Subsequently, serum BDNF levels were decreased in parallel with the improvement of psychiatric symptoms in the NP group.

CONCLUSION

These results suggest that serum BDNF is a biological marker for the severity of psychiatric symptoms in NPSLE patients.

Serum adiponectin and resistin levels in major depressive disorder

OBJECTIVE

To examine the role of the adipose-tissue-derived low-grade inflammation markers adiponectin and resistin in major depressive disorder (MDD) in a population-based sample.

METHOD

Serum levels of adiponectin and resistin were measured from 70 DSM-IV MDD subjects and 70 healthy controls. Depression severity was assessed with the 29-item Hamilton Depression Rating Scale.

RESULTS

The MDD group had lowered serum adiponectin levels. Regression modelling with adjustments for age, gender, overweight, several socioeconomic and lifestyle factors, coronary heart disease and metabolic syndrome showed that each 5.0 microg/ml decrease in serum adiponectin increased the likelihood of MDD by approximately 20% (P = 0.01). The resistin levels correlated with atypical (P = 0.02), but not with typical depressive symptoms (P = 0.12).

CONCLUSION

Our findings suggest that the lowered adiponectin levels in MDD are depression-specific and not explained by conventional low adiponectin-related factors such as such as coronary heart disease and metabolic disorders.

Major depression: an illness with objective physical signs

Major depression is an illness with objective physical signs occurring with some consistency. These signs are retardation of movements and diminished gestures and expressions. The patient may appear tired, self-concerned, bored, and inattentive and display a loss of interest in the surroundings. Anxiety is a conspicuous and an integral element of affective state and may be expressed by severe restlessness and agitation. Muscle tension, wringing of hands, weeping and moaning, repeating over and over in a monotonous and stereotyped way phrases expressive of misery are all important clinical signs of major depression. Similarly tachycardia, dry tongue/mouth, sweaty palms and/or bodily extremities, cold clammy skin, pallor, pupillary dilatation, tremor, and the fluctuations in blood pressure with wide pulse pressure are all important and give away the underlying distress. These signs have formed an integral part of both the Hamilton Depression Rating Scale and the Montgomery-Asberg Depression Rating Scale as they have a positive correlation with the diagnosis and the severity of illness. Current practice of operational criteria does not help exclude patients with subjective perception of distress and also fails to make room for aetiopathogenesis. The DSM-IV does not include these physical signs as an integral part of the clinical picture of depression, consequently leaving the diagnosis of MDE to subjective criteria and perceptions. This could also explain a large placebo response in recent randomised controlled clinical trials.

Depression and immunity: a role for T cells?

Much attention has been paid to the potential role of the immune system in the pathophysiology of major depression in humans. While activation of innate immune responses currently dominates the research landscape, early studies in depressed patients demonstrating impairment in acquired immune responses, in particular T cell responses, may warrant further consideration. Intriguing data suggest that activated T cells may play an important neuroprotective role in the context of both stress and inflammation. For example, generation of autoreactive T cells through immunization with central nervous system (CNS) specific antigens has been shown to reverse stress-induced decreases in hippocampal neurogenesis as well as depressive-like behavior in rodents. In addition, trafficking of T cells to the brain following stress, in part related to glucocorticoids, has been found to reduce stress-induced anxiety-like behavior. Data indicate that T regulatory cells may also play a role in depression through downregulation of chronic inflammatory responses. Based on the notion that T cells may subserve neuroprotective and anti-inflammatory functions during stress and inflammation, impaired T cell function may directly contribute to the development of depression. Indeed, increased sensitivity to apoptosis as well as reduced responsiveness to glucocorticoids, may not only decrease the availability of T cells in depressed patients, but also may reduce their capacity to traffic to the brain in response to relevant neuroendocrine or immune stimuli. Further elucidation of T cell pathology may lead to new insights into immune system contributions to depression. Moreover, enhancement of T cell function may represent an alternative strategy to treat depression.

[Correlation of depression with stroke. Pathophysiological mechanisms]

Stroke is the third leading cause of death, just after heart disease and cancer. Its incidence will probably increase dramatically in the coming decades. For prevention it is urgently necessary to gain fundamental knowledge about the risk factors and pathophysiological mechanisms. It is now widely accepted that depression and stroke are correlated with each other. There is little knowledge, however, about the links that might connect both diseases. This review discusses different mechanisms that lead to an increased stroke risk and can be influenced by depression as well thus possibly linking depression and stroke.

Rationale and design of the participant, investigator, observer, and data-analyst-blinded randomized AGENDA trial on associations between gene-polymorphisms, endophenotypes for depression and antidepressive intervention: the effect of escitalopram versus placebo on the combined dexamethasone-corticotrophine releasing hormone test and other potential endophenotypes in healthy first-degree relatives of persons with depression

BACKGROUND

Endophenotypes are heritable markers, which are more prevalent in patients and their healthy relatives than in the general population. Recent studies point at disturbed regulation of the hypothalamic-pituitary-adrenocortical axis as a possible endophenotype for depression. We hypothesize that potential endophenotypes for depression may be affected by selective serotonin re-uptake inhibitor antidepressants in healthy first-degree relatives of depressed patients. The primary outcome measure is the change in plasma cortisol in the dexamethasone-corticotrophin releasing hormone test from baseline to the end of intervention.

METHODS

The AGENDA trial is designed as a participant, investigator, observer, and data-analyst-blinded randomized trial. Participants are 80 healthy first-degree relatives of patients with depression. Participants are randomized to escitalopram 10 mg per day versus placebo for four weeks. Randomization is stratified by gender and age. The primary outcome measure is the change in plasma cortisol in the dexamethasone-corticotrophin releasing hormone test at entry before intervention to after four weeks of intervention. With the inclusion of 80 participants, a 60% power is obtained to detect a clinically relevant difference in the primary outcome between the intervention and the placebo group. Secondary outcome measures are changes from baseline to four weeks in scores of: 1) cognition and 2) neuroticism. Tertiary outcomes measures are changes from baseline to four weeks in scores of: 1) depression and anxiety symptoms; 2) subjective evaluations of depressive symptoms, perceived stress, quality of life, aggression, sleep, and pain; and 3) salivary cortisol at eight different timepoints during an ordinary day. Assessments are undertaken by assessors blinded to the randomization group.

The longitudinal effects of depression on physical activity

OBJECTIVES

It has been posited that depression and sedentary lifestyle have bidirectional relationships. Although the role of baseline physical activity as a risk factor for emerging depression has been recently reviewed, there has been no systematic review of the literature to assess the reverse relationship. We reviewed the results of longitudinal studies in the world's literature that have studied the effect of baseline depression on ensuing levels of physical activity.

MEASURES

MEDLINE, PsycINFO, CINHAL Plus, Health Source: Nursing Academic Edition and Cochrane databases were searched from 1959 to 2008 with a focus on depression, sedentary lifestyle and exercise. Published longitudinal studies in English and more than 100 patients were included.

RESULTS

Eleven studies met our inclusion criteria, eight of which reported that baseline depression was significantly associated with subsequent sedentary lifestyle or poor adherence to the physical exercise regimens recommended by physicians after a coronary event. However, the studies used different depression scales and physical activity outcome measures, and varied a great deal in the range of potential confounders they controlled for. In addition, there were only three studies that were specifically designed to assess the role of baseline depression on the subsequent level of physical activity.

CONCLUSIONS

Baseline depression may be a significant risk factor for development of sedentary lifestyle or decreased level of physical exercise. Future studies should examine mechanisms by which depression may lead to decline in activity.

Does the dexamethasone suppression test reliably discriminate between psychotic and nonpsychotic major depression?: an exploratory analysis of potential confounds

Previous research has shown that psychotic major depression (PMD) is often associated with higher rates of nonsuppression on the dexamethasone suppression test (DST) compared with nonpsychotic major depression (NMD), suggesting the potential importance of cortisol hypersecretion in the psychotic subtype of the disorder. However, these patient groups also are known to differ from one another on a variety of other clinical variables, and there are numerous factors independent of diagnostic status known to affect the DST. Thus, we investigated possible confounds that could help account for the apparent DST abnormalities in PMD sometimes reported in past research. Hospitalized patients with PMD (n = 11) and NMD (n = 58) were compared on the DST and other clinical variables. As expected, PMD patients showed significantly higher rates of DST nonsuppression (55% vs. 24%; p = 0.04). However, PMD patients also had significantly higher levels of anxiety severity (p = 0.01). The higher rates of nonsuppression in the PMD group were attenuated when these patients were compared with a subsample of NMD patients matched on anxiety severity (55% vs. 55%). Implications for future research on biological markers of PMD are discussed.

Immunological and histochemical analyses of cerebrospinal fluid and peripheral blood from patients with neurological and psychiatric disorders

Epidemiological, clinical and post mortem studies indicate that inflammatory and immune reactions are involved in the pathomechanisms of affective and schizophrenic spectrum disorders. However, in psychiatric patients, only sporadic investigation on immunochemistry has been performed and information about immunofunction derived by investigation of immunocompetent cells in the CSF is not available to date. Here we present an interdisciplinary work of neurologists, psychiatrists and hemato-immunologists focusing on the immunology of psychiatric and neurological disorders. In a first study including 63 patients with therapy resistant affective and schizophrenic spectrum disorders we applied conventional, validated neurological CSF investigation such as analysis of albumin, IgG, IgA, IgM, oligoclonal IgG and specific antibodies, cell count and interpreted the data by Reibergrams. In a second study, we applied the highly sensitive and specific multicolour flowcytometry of paired samples of CSF and peripheral blood cells to characterize the immunostatus of psychiatric and neurological patients. We demonstrate that flowcytometry technology constitutes an appropriate method to investigate subsets of lymphocytes even with low CSF cell numbers, and therefore as a promising diagnostic tool for routine purposes in the differential diagnosis of psychiatric diseases. Furthermore, knowledge of the frequencies of T cell subsets such as the T regulatory cell type might open new avenues to models of psychiatric and neurological diseases as well as diagnostic and monitoring implications.

Inflammation and its discontents: the role of cytokines in the pathophysiology of major depression

Recognition that inflammation may represent a common mechanism of disease has been extended to include neuropsychiatric disorders including major depression. Patients with major depression have been found to exhibit increased peripheral blood inflammatory biomarkers, including inflammatory cytokines, which have been shown to access the brain and interact with virtually every pathophysiologic domain known to be involved in depression, including neurotransmitter metabolism, neuroendocrine function, and neural plasticity. Indeed, activation of inflammatory pathways within the brain is believed to contribute to a confluence of decreased neurotrophic support and altered glutamate release/reuptake, as well as oxidative stress, leading to excitotoxicity and loss of glial elements, consistent with neuropathologic findings that characterize depressive disorders. Further instantiating the link between inflammation and depression are data demonstrating that psychosocial stress, a well-known precipitant of mood disorders, is capable of stimulating inflammatory signaling molecules, including nuclear factor kappa B, in part, through activation of sympathetic nervous system outflow pathways. Interestingly, depressed patients with increased inflammatory biomarkers have been found to be more likely to exhibit treatment resistance, and in several studies, antidepressant therapy has been associated with decreased inflammatory responses. Finally, preliminary data from patients with inflammatory disorders, as well as medically healthy depressed patients, suggest that inhibiting proinflammatory cytokines or their signaling pathways may improve depressed mood and increase treatment response to conventional antidepressant medication. Translational implications of these findings include the unique opportunity to identify relevant patient populations, apply immune-targeted therapies, and monitor therapeutic efficacy at the level of the immune system in addition to behavior.

The brain 5-HT4 receptor binding is down-regulated in the Flinders Sensitive Line depression model and in response to paroxetine administration

The 5-hydroxytryptamine (5-HT(4)) receptor may be implicated in depression and is a new potential target for antidepressant treatment. We have investigated the brain 5-HT(4) receptor [(3)H]SB207145 binding in the Flinders Sensitive Line rat depression model by quantitative receptor autoradiography, and related this to 5-HT transporter (S)-[N-methyl-(3)H]citalopram binding. We also determined the regulation of 5-HT(4) receptor binding by 1, 14, and 21 days of paroxetine administration and subchronic 5-HT depletion, and compared this with changes in 5-HT(2A) receptor [(3)H]MDL100907 binding. In the Flinders Sensitive Line, the 5-HT(4) receptor and 5-HT transporter binding were decreased in the dorsal and ventral hippocampus, and the changes in binding were directly correlated within the dorsal hippocampus. Chronic but not acute paroxetine administration caused a 16-47% down-regulation of 5-HT(4) receptor binding in all regions evaluated including the basal ganglia and hippocampus, while 5-HT depletion increased the 5-HT(4) receptor binding in the dorsal hippocampus, hypothalamus, and lateral globus pallidus. In comparison, the 5-HT(2A) receptor binding was decreased in the frontal and cingulate cortices after chronic paroxetine administration, and markedly reduced in several regions after 5-HT depletion. Thus, the 5-HT(4) receptor binding was decreased in the Flinders Sensitive Line depression model and in response to chronic paroxetine administration.

Effects of fluoxetine and venlafaxine on serum brain derived neurotrophic factor levels in depressed patients

BACKGROUND

Several studies demonstrated that depressed patients had low serum BDNF levels which correlated with the severity of their depression, and antidepressant treatment increases levels of serum BDNF in depressed patients. It was speculated that agents acting on both noradrenergic and serotonergic transporters might have a greater influence on BDNF levels. The aim of our study was to determine effects of venlafaxine vs. fluoxetine on serum BDNF levels in depressive patients.

METHODS

Forty-three patients diagnosed as major depressive disorder according to DSM-IV are included in the study. Forty-three patients were randomized to take fluoxetine (22 cases) or venlafaxine (21 cases). Serum levels of BDNF were measured by ELISA at baseline and 6 weeks after the start of treatment.

RESULTS

Baseline levels of BDNF were not significantly different between the patient group and the controls. But male patients and the male controls showed statistical differences with respect to baseline BDNF levels. BDNF levels of the patient group did not change with treatment. Yet, the increase of BDNF levels was close to statistically significant in the fluoxetine group, whereas not significant in the venlafaxine group. There were no significant differences in baseline and 6th week BDNF levels between the responders and the non-responders.

CONCLUSION

Further studies controlling for a wide variety of confounding variables are needed, which may help to reach a clear conclusion about the potential of BDNF as a biomarker for depression or as a predictor of antidepressant efficacy.

Norman Cousins Lecture. Mechanisms of cytokine-induced behavioral changes: psychoneuroimmunology at the translational interface

Work in our laboratory has focused on the mechanisms by which cytokines can influence the brain and behavior in humans and non-human primates. Using administration of interferon (IFN)-alpha as a tool to unravel these mechanisms, we have expanded upon findings from the basic science literature implicating cytokine-induced changes in monoamine metabolism as a primary pathway to depression. More specifically, a role for serotonin metabolism has been supported by the clinical efficacy of serotonin reuptake inhibitors in blocking the development of IFN-alpha-induced depression, and the capacity of IFN-alpha to activate metabolic enzymes (indolamine 2,3 dioxygenase) and cytokine signaling pathways (p38 mitogen activated protein kinase) that can influence the synthesis and reuptake of serotonin. Our data also support a role for dopamine depletion as reflected by IFN-alpha-induced changes in behavior (psychomotor slowing and fatigue) and regional brain activity, which implicate the involvement of the basal ganglia, as well as the association of IFN-alpha-induced depressive-like behavior in rhesus monkeys with decreased cerebrospinal fluid concentrations of the dopamine metabolite, homovanillic acid. Neuroimaging data in IFN-alpha-treated patients also suggest that activation of neural circuits (dorsal anterior cingulate cortex) associated with anxiety and alarm may contribute to cytokine-induced behavioral changes. Taken together, these effects of cytokines on the brain and behavior appear to subserve competing evolutionary survival priorities that promote reduced activity to allow healing, and hypervigilance to protect against future attack. Depending on the relative balance between these behavioral accoutrements of an activated innate immune response, clinical presentations may be distinct and warrant individualized therapeutic approaches.

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.

Brain-derived neurotrophic factor: the neurotrophin hypothesis of psychopathology

While monoaminergic hypotheses of psychopathology remain popular, there has been growing interest in the role of neurotrophins in neuropsychiatric disorders. Basic laboratory work has documented the importance of neurotrophins in neuronal survival and synaptic plasticity, and a range of clinical studies has provided analogous evidence of their role in neuropathology. Work on gene variants in brain-derived neurotrophic factor, and associated changes in structural and function brain imaging, have further contributed to our understanding of this area. Much remains to be done to delineate fully the relevant mechanisms by which brain-derived neurotrophic factor and other neurotrophins contribute to psychopathology, and to develop targeted therapeutic interventions. Nevertheless, the neurotrophin hypothesis has already given impetus to a range of valuable research.

Individualized preventive psychiatry: syndrome and vulnerability diagnostics

The development of prevention and treatment strategies of psychiatric disorders will depend on a more profound knowledge of the complex relationships between gene-environment interactions, particularly the interplay of vulnerability and resilience factors within a person's biography. In this article, the advantages and limitations of the current psychiatric classification systems will be discussed. New directions for a future multiaxial system including biological, psychological, social, life span, gender and cultural factors based on the DSM-V- and ICD-11-research agenda are going to be outlined. Psychiatry without psychopathology is impossible. However, in the future, psychopathology will be closer linked to the biological and psychological nature of the disease process and more function-based. Future diagnostic classification manuals should include dimensional and categorical aspects as well as vulnerability and resilience diagnostic elements. There is a need for a personalized integrative diagnosis and care.

Imaging and imagining: current positions on the epistemic priority of theoretical concepts and data in psychiatric neuroimaging

PURPOSE OF REVIEW

To give an overview of recent developments in neuroimaging in psychiatry and on the current discussion about the relationship between theoretical concepts and data from neuroimaging studies.

RECENT FINDINGS

In psychiatric neuroimaging, broad concepts such as the self, well being, insight, empathy and volition form an integral part of the questions to be answered and cannot be avoided. Although, currently, the intradisciplinary discussion in neuroscience is mainly focused at the methodological and neurobiological level, psychological and philosophical theories are also needed for the interpretation of results. This raises questions regarding the epistemic priority of neuroimaging data and theories.

SUMMARY

In the current paper, we present the hypothesis that there is an interdependence of neuroimaging data and theoretical concepts. An approach to 'correlational neuroscience' with an awareness of this issue may help in avoiding misunderstandings and oversimplifications as well as building an interdisciplinary theoretical framework that is able to integrate findings from life sciences, mind sciences and humanities.

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.

Depressive Störungen

Das Spektrum depressiver Erkrankungen macht den Hauptteil affektiver Störungen aus und gehört mit einer Inzidenz von ca. 8–20% zu den häufigsten psychischen Erkrankungen. Depressionen werden nach wie vor zu selten einer adäquaten Therapie (Antidepressiva, störungsspezifische Psychotherapie wie z. B. kognitive Verhaltenstherapie) zugeführt.