Hippocampal volume, memory, and cortisol status in major depressive disorder: effects of treatment

Structural changes in hippocampal subfields in major depressive disorder: a high-field magnetic resonance imaging study

BACKGROUND

Magnetic resonance imaging (MRI) has shown lower hippocampal volume in major depressive disorder (MDD). Preclinical and postmortem studies show that chronic stress and MDD may affect hippocampal subfields differently, but MRI spatial resolution has previously been insufficient to measure subfield volumes.

METHODS

Twenty MDD participants (9 unmedicated and 11 medicated, both > 6 months) and 27 healthy control subjects were studied. We used T2-weighted two-dimensional fast spin echo and T1-weighted three-dimensional magnetization prepared rapid acquisition gradient-echo sequences at 4.7 T to compare hippocampal subfield volumes at .09 μL voxel volume.

RESULTS

Unmedicated MDD participants had a lower dentate gyrus volume than control subjects or medicated MDD participants and a lower cornu ammonis (CA1-3) volume in the hippocampal body subregion than control subjects.

CONCLUSIONS

Hippocampal volumes in unmedicated MDD showed evidence of localization to specific subfields and subregions, findings that appear, on the surface, consistent with preclinical evidence for localized mechanisms of hippocampal neuroplasticity. Strengths include in vivo measurement of entire hippocampal subfields and separation between unmedicated and medicated MDD. Limitations include power to control for multiple comparisons and that MRI landmarks approximate the subfields defined by cellular microstructure.

The neuroprogressive nature of major depressive disorder: pathways to disease evolution and resistance, and therapeutic implications

In some patients with major depressive disorder (MDD), individual illness characteristics appear consistent with those of a neuroprogressive illness. Features of neuroprogression include poorer symptomatic, treatment and functional outcomes in patients with earlier disease onset and increased number and length of depressive episodes. In such patients, longer and more frequent depressive episodes appear to increase vulnerability for further episodes, precipitating an accelerating and progressive illness course leading to functional decline. Evidence from clinical, biochemical and neuroimaging studies appear to support this model and are informing novel therapeutic approaches. This paper reviews current knowledge of the neuroprogressive processes that may occur in MDD, including structural brain consequences and potential molecular mechanisms including the role of neurotransmitter systems, inflammatory, oxidative and nitrosative stress pathways, neurotrophins and regulation of neurogenesis, cortisol and the hypothalamic-pituitary-adrenal axis modulation, mitochondrial dysfunction and epigenetic and dietary influences. Evidence-based novel treatments informed by this knowledge are discussed.

Altered hippocampal formation shape in first-episode depressed patients at 5-year follow-up

It is generally accepted that patients with major depressive disorder have smaller hippocampus size compared to healthy people. However, it is still not known if this situation exists before the onset of the disease or is a result of the toxic mechanism created by the depression itself. The findings of the long-term follow-up studies of first-episode depressed patients might contribute to solve the ongoing problem. In this study, the hippocampus of 18 first-episode patients who were followed-up for 5 years, were compared with those of healthy controls. There were no volumetric differences among groups neither at the baseline nor after 5 years of follow-up. However, shape analyses, using high dimensional mapping methods, revealed regional structural changes in the head and tail of the hippocampal formation in CA1 and subiculum regions in patients at the follow-up. Furthermore, a significant negative correlation was found with the number of days in depression without antidepressant treatment in the CA1 region in the head and tail of the hippocampal formation bilaterally. The findings of this study support the hypothesis that pathophysiological processes of depression induce structural alterations in depressed patients.

Residual memory dysfunction in recurrent major depressive disorder--a longitudinal study from Juntendo University Mood Disorder Project

BACKGROUND

Depression may increase the risk of developing Alzheimer's disease. Large cohort studies have shown that recurrent depression is associated with a risk of developing dementia. Other studies have documented smaller hippocampal volume in patients with recurrent depression. It is speculative that a greater risk of developing dementia may result from a higher number of previous depressive episodes. This study compared patients with recurrent and single-episode depression in the remitted stage, and healthy controls to elucidate the impact of the number of depressive episodes on memory.

METHODS

Logical memory and visual reproduction subtests of the Wechsler Memory Scale-Revised were given to 68 patients with major depressive disorder (MDD) (30 patients with a single episode and residual 38 patients with recurrent multiple episodes) and 57 healthy controls. The patients with MDD received memory assessment at the time of initial remission and at the follow-up period 3 years after remission.

RESULTS

At the time of initial remission, scores of both logical memory and visual reproduction subtests were significantly lower in both patient groups compared with healthy controls. At follow-up, memory dysfunction of the single-episode group disappeared, whereas scores in the recurrent group remained significantly lower than those of the single-episode group and controls.

LIMITATIONS

All patients in the present study were on antidepressant medications.

CONCLUSIONS

Patients with recurrent MDD with multiple depressive episodes showed residual memory dysfunction even after 3 years of remission. Persistence of memory deficits in the recurrent depression may be a risk factor for developing dementia.

Acute and repeated treatment with the 5-HT7 receptor antagonist SB 269970 induces functional desensitization of 5-HT7 receptors in rat hippocampus

BACKGROUND

SB 269970, a 5-HT(7) receptor antagonist may produce a faster antidepressant-like effect in animal models, than do antidepressant drugs, e.g., imipramine. The present work was aimed at examining the effect of single and repeated (14 days) administration of SB 269970 on the 5-HT(7) receptor in the hippocampus.

METHODS

The reactivity of 5-HT(7) receptors was determined using 5-carboxamidotryptamine (5-CT), which increased the bursting frequency of spontaneous epileptiform activity in hippocampal slices. Additionally, the effects of SB 269970 administration on the affinity and density of 5-HT(7) receptors were investigated using [(3)H]-SB 269970 and the influence of SB 269970 and imipramine on mRNA expression levels of Gα(s) and Gα(12) mRNA were studied using RT-qPCR.

RESULTS

Acute and repeated treatment with SB 269970 led to attenuation of the excitatory effects of activation of 5-HT(7) receptors. Neither single nor repeated administration of SB 269970 changed the mean affinity of 5-HT(7) receptors for [(3)H]-SB 269970. Repeated, but not single, administration of SB 269970 decreased the maximum density of [(3)H]-SB 269970 binding sites. While administration of imipramine did not change the expression of mRNAs for Gα(s) and Gα(12) proteins after both single and repeated administration of SB 269970, a reduction in Gα(s) and Gα(12) mRNA expression levels was evident.

CONCLUSIONS

These findings indicate that even single administration of SB269970 induces functional desensitization of the 5-HT(7) receptor system, which precedes changes in the receptor density. This mechanism may be responsible for the rapid antidepressant-like effect of the 5-HT(7) antagonist in animal models.

The Neurobiology of Depression and Anxiety: How Do We Change from Models of Drug Efficacy to Understanding Mood and Anxiety Disorders?

Current treatments for depression and anxiety disorders are only effective in approximately half of the patient population. Effective treatments have negative side-effects including sexual dysfunction, weight gain and gastrointestinal problems. Furthermore, even when patients achieve remission, they often need to increase dosage or change treatment across their lifetime as efficacy weakens. The majority of treatments being used today are based on the monoamine hypothesis of depression, a theory of depression that was based on the effectiveness of drugs discovered by chance to alleviate the symptoms of depression. This chapter provides an overview of the neurobiology of depression and anxiety disorders within the context of drug discovery. The chapter starts with what we currently know about these disorders through the lens of the monoamine hypothesis of depression. We then provide a background into the animal models of depression and anxiety that are being used to understand the underlying biology of these disorders and test new treatments. Work conducted using these animal models has directed human imagining and has provided us with new information about both the molecular and cellular mechanism of depression and anxiety as well as the neural circuitry controlling these disorders. Finally, we will conclude with a discussion of new treatments being developed based on empirical evidence about the neurobiology of depression and anxiety and the need to develop more personalized treatments in the future. It is hoped that these new drugs will be able to provide effective treatment for more people, with fewer negative side-effects.

Hippocampal N-acetylaspartate and morning cortisol levels in drug-naive, first-episode patients with major depressive disorder: effects of treatment

An excess of glucocorticoids has been associated with hippocampal pathology in major depressive disorder (MDD). However, the relationships between depression, hippocampal structure and function, and cortisol levels are unclear, and the effects of antidepressant treatment on the measures are not well studied. For this study, 26 first-episode, treatment-naive, non-late-life adult depressed patients and 13 healthy controls were enrolled. Subjects underwent proton magnetic resonance spectroscopy ((1)H MRS) to obtain metabolite levels from the bilateral hippocampus. Patients with MDD were treated with serotonergic-noradrenergic reuptake inhibitor duloxetine for 12 weeks. After the 12-week period, all subjects with MDD underwent (1)H MRS again. Morning serum cortisol levels also were measured both before and after antidepressant treatment. Comparison of baseline values indicated that there were no significant differences in any of the metabolite ratios (N-acetyl aspartate/creatine (NAA/Cr) and choline (Cho)/Cr) in the bilateral hippocampus. After treatment, NAA/Cr ratios increased significantly in the right hippocampus compared with pre-treatment values. There was no correlation between morning serum cortisol levels and bilateral hippocampal NAA/Cr or Cho/Cr in patients with MDD. These findings suggest that there are unaltered hippocampal metabolites in the early stage of MDD. Antidepressant treatment may affect hippocampal NAA levels in patients with MDD. In addition, the results do not support cortisol-mediated hippocampal neurotoxicity as the major etiological mechanism.

Brain on stress: how the social environment gets under the skin

Stress is a state of the mind, involving both brain and body as well as their interactions; it differs among individuals and reflects not only major life events but also the conflicts and pressures of daily life that alter physiological systems to produce a chronic stress burden that, in turn, is a factor in the expression of disease. This burden reflects the impact of not only life experiences but also genetic variations and individual health behaviors such as diet, physical activity, sleep, and substance abuse; it also reflects stable epigenetic modifications in development that set lifelong patterns of physiological reactivity and behavior through biological embedding of early environments interacting with cumulative change from experiences over the lifespan. Hormones associated with the chronic stress burden protect the body in the short run and promote adaptation (allostasis), but in the long run, the burden of chronic stress causes changes in the brain and body that can lead to disease (allostatic load and overload). Brain circuits are plastic and remodeled by stress to change the balance between anxiety, mood control, memory, and decision making. Such changes may have adaptive value in particular contexts, but their persistence and lack of reversibility can be maladaptive. However, the capacity of brain plasticity to effects of stressful experiences in adult life has only begun to be explored along with the efficacy of top-down strategies for helping the brain change itself, sometimes aided by pharmaceutical agents and other treatments.

Remodeling of axo-spinous synapses in the pathophysiology and treatment of depression

Dendritic spines provide a compartment for assembly and functional organization of synaptic machinery that plays a fundamental role in neuronal communication and neuroplasticity. Studies in humans as well as in animal models have demonstrated abnormal spine architecture in several psychiatric disorders, including depression and other stress-related illnesses. The negative impact of stress on the density and organization of spines is thought to contribute to the behavioral deficits caused by stress exposure. Moreover, there is now evidence that medication-induced recovery involves changes in synaptic plasticity and dendrite morphology, including increased expression of pre- and postsynaptic plasticity-related proteins, as well as the density and function of axo-spinous synapses. Here we review the evidence from brain imaging and postmortem studies demonstrating that depression is accompanied by structural and functional alterations of cortical and limbic brain regions, including the prefrontal cortex, hippocampus and amygdala. In addition, we present more direct evidence from basic research studies that exposure to stress alters spine morphology, function and plasticity and that antidepressants, particularly new rapid acting agents, reverse these effects. Elucidation of the signaling pathways and molecular mechanisms that control spine synapse assembly and plasticity will contribute to a better understanding of the pathophysiology of depression and development of novel, more effective therapeutic agents.

Hippocampal angiogenesis and progenitor cell proliferation are increased with antidepressant use in major depression

BACKGROUND

Adult neurogenesis is coupled to angiogenesis in neurogenic niches in the dentate gyrus (DG) and increased by antidepressants in rodents. We hypothesized that, in major depressive disorder (MDD), antidepressants increase neural progenitor cells (NPCs) and capillaries in the human DG.

METHODS

Neural progenitor cells and capillaries, detected on hippocampal sections by immunohistochemistry for neural stem cell protein, were quantified by stereology in matched MDDs (untreated, n = 12), MDD treated with selective serotonin reuptake inhibitors (MDD*SSRI, n = 6) or tricyclic antidepressants (MDD*TCA, n = 6), and nonpsychiatric control subjects (n = 12), all confirmed by psychological autopsy.

RESULTS

The MDD*SSRI had a larger capillary area and more NPCs versus MDDs (p = .034 and p = .008, respectively) and control subjects (p = .010 and p = .002, respectively) in the whole DG, more NPCs in the anterior (pes, p = .042) and central (midbody, p = .004) DG, and greater capillary area in the pes (p = .002) and midbody (p = .021). The NPC number and capillary area correlated positively in the whole sample (R2 = .454, p < .001) and in treated subjects (R2 = .749, p = .001). We found no NPCs or antidepressant-related angiogenesis in CA1 and parahippocampal gyrus. The DG volume correlated positively with NPC number (p = .004) and capillary area (p < .001) and differed between groups in whole hippocampus (p = .013) and midbody (p = .036). Age negatively correlated with NPC number (p = .042), capillary area (p = .037), and bifurcations (p = .030). No gender effect was detected.

CONCLUSIONS

Antidepressants increase human hippocampal NPCs and angiogenesis selectively in the anterior and mid DG. These results raise the possibility of a causal relationship between angiogenesis and neurogenesis, as seen in other proliferating tissues, and support their possible role in the mechanism of action of antidepressants.

The ever-changing brain: cellular and molecular mechanisms for the effects of stressful experiences

The adult brain is capable of considerable structural and functional plasticity and the study of hormone actions in brain has contributed to our understanding of this important phenomenon. In particular, stress and stress-related hormones such as glucocorticoids and mineralocorticoids play a key role in the ability of acute and chronic stress to cause reversible remodeling of neuronal connections in the hippocampus, prefrontal cortex, and amygdala. To produce this plasticity, these hormones act by both genomic and non-genomic mechanisms together with ongoing, experience-driven neural activity mediated by excitatory amino acid neurotransmitters, neurotrophic factors such as brain derived neurotrophic factor, extracellular molecules such as neural cell adhesion molecule, neuropeptides such as corticotrophin releasing factor, and endocannabinoids. The result is a dynamic brain architecture that can be modified by experience. Under this view, the role of pharmaceutical agents, such as antidepressants, is to facilitate such plasticity that must also be guided by experiences.

Depressive symptoms, antidepressant use, and brain volumes on MRI in a population-based cohort of old persons without dementia

We examined whether late-life depression, including depressive symptoms and antidepressant use, was associated with smaller total brain volume, smaller hippocampal volume, and larger white matter hyperintensity (WMH) volume in a large community-based cohort of old persons without dementia. Within the Washington/Hamilton Height-Inwood Columbia Aging Project (WHICAP), a community-based cohort study in northern Manhattan, 630 persons without dementia (mean age 80 years, SD = 5) had volumetric measures of the total brain, hippocampus, and WMH at 1.5 Tesla MRI and data on current depression, defined as a score of 4 or higher on the 10-item Center for Epidemiologic Studies-Depression (CES-D) scale, or use of antidepressants. Multiple linear regression analyses adjusted for age, gender, ethnicity, education, cardiovascular disease history, and MRI parameters showed that subjects with current depression had smaller relative total brain volume (B = -0.86%; 95% CI -1.68 to -0.05%; p < 0.05), smaller relative hippocampal volume (B = -0.07 ml; 95% CI -0.14 to 0.00 ml; p = 0.05), and larger relative WMH volume (natural logtransformed B = 0.19 ml; 95% CI 0.02 to 0.35 ml; p < 0.05). When examined separately, antidepressant use was significantly associated with smaller total brain, smaller hippocampal, and larger WMH volume, while high CES-D scores were not significantly associated with any of the brain measures, although the direction of association was similar as for antidepressant use. With the caveat that analyses were cross-sectional and we had no formal diagnosis of depression, our findings suggest that in this community-based sample of old persons without dementia, late-life depression is associated with more brain atrophy and more white matter lesions, which was mainly driven by antidepressant use.

Does depression impact cognitive impairment in patients with heart failure?

Prevalence studies have noted the cooccurrence of cognitive decline and depression in persons with heart failure. Cognitive impairment is associated with significant mortality and deteriorated quality of life, likely due to impairments in memory and executive function, which impact a patient's ability to understand and comply with prescribed treatment plans. This is especially true in complex diseases such as heart failure. Evidence from literature supports the possibility of a pathophysiological relationship between cognitive impairment, depression, and heart failure. Yet, very few studies have sought to investigate this relationship. This paper reviews current literature on the association between depression and cognitive impairment in persons with heart failure and explores possible mechanisms explaining this complex triad.

Association between subcortical volumes and verbal memory in unmedicated depressed patients and healthy controls

Research has shown poor performance on verbal memory tasks in patients with major depressive disorder relative to healthy controls, as well as structural abnormalities in the subcortical structures that form the limbic-cortical-striatal-pallidal-thalamic circuitry. Few studies, however, have attempted to link the impairments in learning and memory in depression with these structural abnormalities, and of those which have done so, most have included patients medicated with psychotropic agents likely to influence cognitive performance. This study thus examines the relationship between subcortical structural abnormalities and verbal memory using the California Verbal Learning Test (CVLT) in unmedicated depressed patients. A T1 weighted magnetic resonance imaging scan and the CVLT were obtained on 45 subjects with major depressive disorder and 44 healthy controls. Using the FMRIB's Integrated Registration and Segmentation Tool (FIRST) volumes of selected subcortical structures were segmented and correlated with CVLT performance. Depressed participants showed significantly smaller right thalamus and right hippocampus volumes than healthy controls. Depressed participants also showed impaired performance on global verbal learning ability, and appeared to depend upon an inferior memory strategy (serial clustering). Measures of serial clustering were correlated significantly with right hippocampal volumes in depressed participants. Our findings indicate that depressed participants and healthy controls differ in the memory strategies they employ, and that while depressed participants had a smaller hippocampal volume, there was a positive correlation between volume and use of an inferior memory strategy. This suggests that larger hippocampal volume is related to better memory recall in depression, but specifically with regard to utilizing an inferior memory strategy.

Association of amygdala volumes with cortisol secretion in unipolar depressed patients

Major depressive disorder (MDD) is accompanied by morphological changes of brain structures which are of great importance in the neural circuitry mediating depression like the hippocampus and the amygdala. Hyperactivity of the hypothalamic-pituitary-adrenocortical (HPA) system resulting in enhanced glucocorticoid secretion can often be observed during depression and has been thought to play an important role in inducing these morphological changes. We used magnetic resonance imaging to investigate alterations of amygdala and hippocampal volumes in 86 in-patients with unipolar depression and 87 healthy controls, and we then correlated amygdala and hippocampal volumes of 76 in-patients with the area under the curve of cortisol secretion in the dexamethasone/corticotropin releasing hormone (Dex/CRH) test at baseline and during short-term antidepressant therapy. In line with recently published studies both left and right amygdala volumes of patients in a first depressive episode were smaller than those of healthy controls. Patients with recurrent depressive episodes showed a reduction of hippocampal volumes, while amygdala volumes were normal. Larger left and right amygdala volumes correlated with a more pronounced reduction of HPA activity, measured by the cortisol secretion in the combined DEX/CRH test, during antidepressant therapy in patients with recurrent depressive episodes.

Cognitive function in unipolar major depression: a comparison of currently depressed, previously depressed, and never depressed individuals

There is a lack of consensus upon a conclusive cognitive profile characterizing unipolar major depression. Currently depressed (n = 37), recovered previously depressed (n = 81), and never depressed controls (n = 50) underwent assessment of executive functions, working memory, attention, and psychomotor speed. Currently depressed yielded significantly lower test scores than previously and never depressed subjects on a measure of working memory. Both currently depressed and previously depressed scored significantly lower than never depressed subjects on measures of processing speed. Recurrent depressed performed similarly to subjects with a single depressive episode. These findings indicate a mild and limited cognitive impairment during the course of a mild to moderate major depressive disorder among relatively young adults. Impaired processing speed should be considered in further studies as a potential irreversible marker for recurrent depression.

Changes in cortisol secretion during antidepressive treatment and cognitive improvement in patients with major depression: a longitudinal study

OBJECTIVES

We have previously reported that cognitive deficits are cross-sectionally associated with elevated cortisol in depressed patients. Here, we longitudinally examined if changes in cortisol secretion during treatment are associated with improvement of cognition.

METHODS

Cognitive function and salivary cortisol levels were longitudinally examined in 52 patients with major depression before and after 3 weeks of standardized selective serotonin reuptake inhibitor (SSRI) and an add-on treatment modulating the mineralocorticoid receptor and compared to a healthy control group (n=50) matched for age, gender and years of education.

RESULTS

Across add-on treatment groups, SSRI treatment reduced salivary cortisol in patients to levels of healthy controls (time×group interaction p=.05). In patients, reduction of cortisol significantly correlated with improvement in depressive symptoms (r=.52, p<.01), speed of information processing (r=.50, p<.01), and cognitive set-shifting (r=.34, p=.03). Improved depressive symptoms were only associated with improved attention and working memory.

CONCLUSIONS

Improvement of some cognitive domains during SSRI treatment was associated with decreasing cortisol secretion and was only to a lesser extent associated with improved depressive symptoms.

Introducing a novel method to assess cumulative steroid concentrations: increased hair cortisol concentrations over 6 months in medicated patients with depression

Depression has been linked to increased cortisol concentrations using point measures taken from urine, blood, or saliva samples. However, with regard to hypercortisolism-induced consequences, long-term cumulative cortisol burden is of relevance. Our objective was to use hair analysis as a new method to assess cortisol exposure over 6 months in depressed patients and healthy controls. We examined 23 depressed patients (8 men and 15 women, mean age: 41.6 years ( ± standard deviation (SD), 13.1 years); mean duration of current depressive episode 9 months ( ± SD, 13 months)) and 64 healthy controls, matched for age and gender. Cortisol concentrations in two 3-cm hair segments from near to the scalp were analyzed, representing cortisol secretion during the 6 months prior to sampling. Compared with healthy individuals, depressed patients had higher hair cortisol concentrations in the first (mean ± SD: 26.7 ± 20.8 vs. 18.7 ± 11.5 pg/mg, p < 0.05) and second hair segment (mean ±  SD: 21.9 ± 23.7 vs. 13.4 ± 9.6 pg/mg, p < 0.05). In conclusion, hair cortisol analysis confirmed enhanced cortisol secretion in depressed patients over a prolonged time period. Because of the retrospective and cumulative nature of cortisol in hair, the assessment of hair cortisol concentration may help in addressing unanswered questions regarding hypothalamic-pituitary-adrenal axis overactivity and associated health consequences in psychiatric disorders.

Treatment-related alteration of cortisol predicts change in neuropsychological function during acute treatment of late-life anxiety disorder

OBJECTIVE

Older adults with anxiety disorders are burdened by impairment in neurocognition, which may be mediated by elevated circulating cortisol levels. In a randomized controlled trial of acute serotonin-reuptake inhibitor treatment for late-life anxiety disorder, we examined whether change in salivary cortisol concentrations during treatment predicted improvements in measures of memory and executive function.

METHODS

We examined 60 adults aged 60 years and older, who took part in a 12-week trial of escitalopram versus placebo for generalized anxiety disorder. All subjects had pre-treatment and post-treatment assessments that included monitoring of peak and total daily cortisol and a comprehensive neuropsychological evaluation.

RESULTS

Salivary cortisol changes during treatment showed significant associations with changes in immediate and delayed memory but no association with executive tasks (measures of working memory and set shifting). Analyses suggested that a decrease in cortisol due to serotonin-reuptake inhibitor treatment was responsible for the memory changes: memory improvement was seen with cortisol reduction among patients receiving escitalopram but not among patients receiving placebo.

CONCLUSION

Serotonin-reuptake inhibitor-induced alteration in circulating cortisol during treatment of generalized anxiety disorder predicted changes in immediate and delayed memory. This finding suggests a novel treatment strategy in late-life anxiety disorders: targeting hypothalamic-pituitary- adrenal axis dysfunction to improve memory.

A lifespan view of anxiety disorders

Neurodevelopmental changes over the lifespan, from childhood through adulthood into old age, have important implications for the onset, presentation, course, and treatment of anxiety disorders. This article presents data on anxiety disorders as they appear in older adults, as compared with earlier in life. In this article, we focus on aging-related changes in the epidemiology, presentation, and treatment of anxiety disorders. Also, this article describes some of the gaps and limitations in our understanding and suggests research directions that may elucidate the mechanisms of anxiety disorder development later in life. Finally we describe optimal management of anxiety disorders across the lifespan, in "eight simple steps" for practitioners.

Reorganization of synaptic inputs to the hypothalamic paraventricular nucleus during chronic psychogenic stress in rats

BACKGROUND

Chronic stress in humans precipitates hyper-reactivity of the hypothalamic-pituitary-adrenocortical (HPA) axis and triggers symptoms associated with certain forms of depression. Reorganization of neuronal networks has been implicated in development of depression, however it remained unknown how chronic exposure to psychogenic challenges affects excitatory and inhibitory inputs to corticotropin-releasing hormone (CRH) neurons in the hypothalamic paraventricular nucleus that govern neuroendocrine stress response.

METHODS

Rats (n = 32) were exposed for 21 days to chronic variable stress and their behavioral (sucrose preference) and hormonal (corticosterone) responses were followed together with electron microscopic stereologic analysis of excitatory and gamma-aminobutyric acid (GABA)-containing, inhibitory synapses on the CRH synthesizing neurons.

RESULTS

Chronic stress in rats resulted in weight loss, anhedonia, and hyperactivity of hypothalamic-pituitary-adrenocortical axis. Following 3 weeks' exposure to variable psychologic stressors the number of synapses has been doubled in the paraventricular nucleus. Asymmetrical excitatory as well as GABAergic inhibitory synaptic contacts were increased on CRH neurons; however, the excitatory/inhibitory input ratio remained constant. In response to chronic stress, we found rearrangement of inhibitory GABA-containing inputs with the increase of contacts on dendrites and decrease at the soma region of CRH neurons.

CONCLUSIONS

Significant remodeling of synaptic contacts was found on CRH neurons in response to chronic stress. This morphologic plasticity might be related to the hyperactivity of the HPA axis and to development of stress-related psychopathologies such as depression.

Role of vascular endothelial growth factor in adult hippocampal neurogenesis: implications for the pathophysiology and treatment of depression

It is now well established that the adult brain has the capacity to generate new neurons throughout life. Although the functional significance of adult neurogenesis still remains to be established, increasing evidence has implicated compromised hippocampal neurogenesis as a possible contributor in the development of major depressive disorder. Antidepressants increase hippocampal neurogenesis and there is evidence in rodent models that the therapeutic efficacy of these agents is attributable, in part, to this neurogenic effect. As such, considerable interest has been directed at identifying molecular signals, including neurotrophic factors and related signaling pathways that are associated with antidepressant action and could operate as key modulators in the regulation of neurogenesis in the adult hippocampus. One interesting candidate is vascular endothelial growth factor (VEGF), which is known to possess strong neurogenic effects. In this review, we will discuss the involvement of VEGF signaling in the etiology and treatment of depression.

Serotonin 1A receptors, depression, and memory in temporal lobe epilepsy

PURPOSE

Memory deficits and depression are common in patients with temporal lobe epilepsy (TLE). Previous positron emission tomography (PET) studies have shown reduced mesial temporal 5HT1A-receptor binding in these patients. We examined the relationships among verbal memory performance, depression, and 5HT1A-receptor binding measured with 18F-trans-4-fluoro-N-2-[4-(2-methoxyphenyl)piperazin-1-yl]ethyl-N-(2-pyridyl) cyclohexane carboxamide (18FCWAY) PET in a cross-sectional study.

METHODS

We studied 40 patients (24 male; mean age 34.5 ± 10.7 years) with TLE. Seizure diagnosis and focus localization were based on ictal video-electroencephalography (EEG) recording. Patients had neuropsychological testing with Wechsler Adult Intelligence Score III (WAIS III) and Wechsler Memory Score III (WMS III) on stable antiepileptic drug (AED) regimens at least 24 h since the last seizure. Beck Depression Inventory (BDI) scores were obtained. We performed interictal PET with 18FCWAY, a fluorinated derivative of WAY 100635, a highly specific 5HT1A ligand, and structural magnetic resonance imaging (MRI) scans to estimate partial volume and plasma free fraction corrected 18FCWAY volume of distribution (V/f1).

KEY FINDINGS

Hippocampal V/f1 was significantly lower in area ipsilateral than contralateral to the epileptic focus (73.7 ± 27.3 vs. 95.4 ± 28.4; p < 0.001). We found a significant relation between both left hippocampal 18FCWAY V/f1 (r = 0.41; p < 0.02) and left hippocampal volume (r = 0.36; p < 0.03) and delayed auditory memory score. On multiple regression, there was a significant effect of the interaction of left hippocampal 18FCWAY V/f1 and left hippocampal volume on delayed auditory memory, but not of either alone. High collinearity was present. In an analysis of variance including the side of the seizure focus, the effect of left hippocampal 18FCWAY V/f1 but not focus laterality retained significance. Mean BDI was 8.3 ± 7.0. There was a significant inverse relation between BDI and 18FCWAY V/f1 ipsilateral to the patient's epileptic focus (r = 0.38 p < 0.02). There was no difference between patients with a right or left temporal focus. There was no relation between BDI and immediate or delayed auditory memory.

SIGNIFICANCE

Our study suggests that reduced left hippocampal 5HT1A-receptor binding may play a role in memory impairment in patients with TLE.

Magnetic resonance imaging studies in unipolar depression: systematic review and meta-regression analyses

Previous meta-analyses of structural MRI studies have shown diffuse cortical and sub-cortical abnormalities in unipolar depression. However, the presence of duplicate publications, recruitment of particular age groups and the selection of specific regions of interest means that there is uncertainty about the balance of current research. Moreover, the lack of systematic exploration of highly significant heterogeneity has prevented the generalisability of finding. A systematic review and random-effects meta-analysis was carried out to estimate effect sizes. Possible publication bias, and the impact of various study design characteristics on the magnitude of the observed effect size were systematically explored. The aim of this study was 1) to include structural MRI studies systematically comparing unipolar depression with bipolar disorder and healthy volunteers; 2) to consider all available structures of interest without specific age limits, avoiding data duplication, and 3) to explore the influence of factors contributing to the measured effect sizes systematically with meta-regression analyses. Unipolar depression was characterised by reduced brain volume in areas involved in emotional processing, including the frontal cortex, orbitofrontal cortex, cingulate cortex, hippocampus and striatum. There was also evidence of pituitary enlargement and an excess of white matter hyperintensity volume in unipolar depression. Factors which influenced the magnitude of the observed effect sizes were differences in methods, clinical variables, pharmacological interventions and sample age.

State dependent posterior hippocampal volume increases in patients with major depressive disorder

BACKGROUND

The hippocampal formation has been implicated in etiology and therapy response in major depressive disorder (MDD). However, prospective longitudinal studies investigating volumes in hippocampal subregions and their association with clinical findings are still lacking.

METHODS

Global and regional hippocampal volumes and neuropsychological performance were assessed longitudinally in 15 young patients with unipolar early onset MDD who responded to therapy and 13 matched healthy control subjects.

RESULTS

Although volumes at baseline did not differ between groups, patients with MDD showed significant posterior hippocampal volume increases during the treatment course (mean observation period 161.4 ± 58.6 days). Posterior hippocampal volume increases were seen in every single patient. The detected posterior hippocampal volume increases were significantly correlated with the number of solved problems in a planning task at baseline.

LIMITATIONS

The study is limited by the small sample size. Moreover, future studies should include patients who do not respond to antidepressant treatment.

CONCLUSION

Patients with MDD showed selective increases in posterior hippocampal volumes which were not correlated to the degree of functional restitution. However, posterior hippocampal volume increases might constitute a surrogate parameter of neuroplasticity taking place during antidepressant therapy which might be predicted by executive functioning at baseline.

Milk-based phospholipids increase morning cortisol availability and improve memory in chronically stressed men

Phospholipids (PLs) have been shown to dampen the activity and reactivity of the hypothalamic-pituitary-adrenal axis (HPAA). To further investigate stress protective effects of PL, 75 chronically stressed men aged 30 to 51 years were enrolled in a randomized and placebo-controlled trial. The subjects received a bovine milk drink with either 0.5% PL, 1% PL, or a placebo for 42 days to test the hypothesis that supplementation with specific phospholipids would normalize the cortisol response of the HPAA. For determining HPAA activity, the cortisol awakening response was studied before and after treatment. In addition, participants were exposed to an acute stressor, the Trier Social Stress Test, to assess treatment effects on stress reactivity and stress-related memory impairment. After receiving PL-enriched milk, both PL groups showed a delayed decline from peak levels in morning salivary cortisol, suggesting a prolonged availability of free cortisol. Treatment with 0.5% PL additionally resulted in a stronger increase of cortisol after awakening, whereas no such differences could be observed in the 1% PL group and the placebo group, respectively. The acute stress response did not significantly differ among placebo and PL groups. An exploratory data analysis further revealed that elderly participants receiving the higher PL dosage had a significant better memory performance after the Trier Social Stress Test as compared with elderly participants from the placebo and low-PL dosage group; no such difference was observed at baseline. Our results suggest that PL may increase the availability of cortisol in chronically stressed men and may attenuate stress-induced memory impairments. Results of the present study are discussed within the context of previous research and current state of knowledge.

Biological outcome measurements for behavioral interventions in multiple sclerosis

Behavioral interventions including exercise, stress management, patient education, psychotherapy and multidisciplinary neurorehabilitation in general are receiving increasing recognition in multiple sclerosis (MS) clinical practice and research. Most scientific evaluations of these approaches have focused on psychosocial outcome measures such as quality of life, fatigue or depression. However, it is becoming increasingly clear that neuropsychiatric symptoms of MS are at least partially mediated by biological processes such as inflammation, neuroendocrine dysfunction or regional brain damage. Thus, successful treatment of these symptoms with behavioral approaches could potentially also affect the underlying biology. Rigidly designed scientific studies are needed to explore the potential of such interventions to affect MS pathology and biological pathways linked to psychological and neuropsychiatric symptoms of MS. Such studies need to carefully select outcome measures on the behavioral level that are likely to be influenced by the specific intervention strategy and should include biomarkers with evidence for an association with the outcome parameter in question. In this overview, we illustrate how biological and psychological outcome parameters can be combined to evaluate behavioral interventions. We focus on two areas of interest as potential targets for behavioral interventions: depression and fatigue.

The hippocampus, neurotrophic factors and depression: possible implications for the pharmacotherapy of depression

Depression is a prevalent, highly debilitating mental disorder affecting up to 15% of the population at least once in their lifetime, with huge costs for society. Neurobiological mechanisms of depression are still not well known, although there is consensus about interplay between genetic and environmental factors. Antidepressant medications are frequently used in depression, but at least 50% of patients are poor responders, even to more recently discovered medications. Furthermore, clinical response only occurs following weeks to months of treatment and only chronic treatment is effective, suggesting that actions beyond the rapidly occurring effect of enhancing monoaminergic systems, such as adaptation of these systems, are responsible for the effects of antidepressants. Recent studies indicate that an impairment of synaptic plasticity (neurogenesis, axon branching, dendritogenesis and synaptogenesis) in specific areas of the CNS, particularly the hippocampus, may be a core factor in the pathophysiology of depression. The abnormal neural plasticity may be related to alterations in the levels of neurotrophic factors, namely brain-derived neurotrophic factor (BDNF), which play a central role in plasticity. As BDNF is repressed by stress, epigenetic regulation of the BDNF gene may play an important role in depression. The hippocampus is smaller in depressed patients, although it is unclear whether smaller size is a consequence of depression or a pre-existing, vulnerability marker for depression. Environmental stressors triggering activation of the hypothalamic-pituitary-adrenal axis cause the brain to be exposed to corticosteroids, affecting neurobehavioural functions with a strong downregulation of hippocampal neurogenesis, and are a major risk factor for depression. Antidepressant treatment increases BDNF levels, stimulates neurogenesis and reverses the inhibitory effects of stress, but this effect is evident only after 3-4 weeks of administration, the time course for maturation of new neurons. The ablation of hippocampal neurogenesis blocks the behavioural effects of antidepressants in animal models. The above findings suggest new possible targets for the pharmacotherapy of depression such as neurotrophic factors, their receptors and related intracellular signalling cascades; agents counteracting the effects of stress on hippocampal neurogenesis (including antagonists of corticosteroids, inflammatory cytokines and their receptors); and agents facilitating the activation of gene expression and increasing the transcription of neurotrophins in the brain.

Memory dysfunction in panic disorder: an investigation of the role of chronic benzodiazepine use

BACKGROUND

Studies of the neurocognitive effects of long-term benzodiazepine use have been confounded by the presence of neurocognitive deficits characterizing the clinical conditions for which these medications are taken. Similarly, studies of the neurocognitive effects of anxiety disorders have been confounded by the inclusion of chronically benzodiazepine-medicated patients. This study was designed to tease apart the potentially confounding effects of long-term benzodiazepine use and panic disorder (PD) on memory and visuoconstructive abilities.

METHODS

Twenty chronically benzodiazepine-medicated and 20 benzodiazepine-free patients with PD with agoraphobia were compared with a group of 20 normal control participants, group-matched for age, education, and gender on a battery of neuropsychological tests assessing short-term, episodic long-term, and semantic memory, as well as visuoconstructive abilities.

RESULTS

Results indicated that benzodiazepine-free panic patients were relatively impaired in nonverbal short-term and nonverbal episodic long-term memory and visuoconstructive abilities, whereas verbal short-term and verbal episodic memory and semantic memory were preserved. Only limited evidence was found for more pronounced impairments in chronically benzodiazepine-medicated PD patients.

CONCLUSIONS

This study provides evidence that patients with PD are characterized by relative impairments in nonverbal memory and visuoconstructive abilities, independent of benzodiazepine use. Nonetheless, we found evidence that chronic treatment with benzodiazepines is associated with intensification of select relative impairments in this realm. Documentation of these deficits raises questions about the broader etiology of neurocognitive impairment in PD as well as its impact on daily functioning.

No effect of 5HTTLPR or BDNF Val66Met polymorphism on hippocampal morphology in major depression

Neuroimaging research implicates the hippocampus in the aetiology of major depressive disorder (MDD). Imaging genetics studies have investigated the influence of the serotonin transporter-linked polymorphic region (5HTTLPR) and brain-derived neurotrophic factor (BDNF) Val66Met polymorphism on the hippocampus in healthy individuals and patients with depression (MDD). However, conflicting results have led to inconclusive evidence about the effect of 5HTTLPR or BDNF on hippocampal volume (HCV). We hypothesized that analysis methods based on three-dimensional (3D) hippocampal shape mapping could offer improved sensitivity to clarify these effects. Magnetic resonance imaging data were collected in parallel samples of 111 healthy individuals and 84 MDD patients. Manual hippocampal segmentation was conducted and the resulting data used to investigate the influence of 5HTTLPR and BDNF Val66Met genotypes on HCV and 3D shape within each sample. Hippocampal volume normalized by intracranial volume (ICV) showed no significant difference between 5HTTLPR S allele carriers and L/L homozygotes or between BDNF Met allele carriers and Val/Val homozygotes in the group of healthy individuals. Moreover, there was no significant difference in normalized HCV between 5HTTLPR diallelic and triallelic classifications or between the BDNF Val66Met genotypes in MDD patients, although there was a relationship between BDNF Val66Met and ICV. Shape analysis detected dispersed between-group differences, but these effects did not survive multiple testing correction. In this study, there was no evidence of a genetic effect for 5HTTLPR or BDNF Val66Met on hippocampal morphology in either healthy individuals or MDD patients despite the relatively large sample sizes and sensitive methodology.

Differences between effects of psychological versus pharmacological treatments on functional and morphological brain alterations in anxiety disorders and major depressive disorder: a systematic review

The most prevalent mental disorders, anxiety and mood disorders, are associated with both functional and morphological brain changes that commonly involve the 'fear network' including the (medial) prefrontal cortex, hippocampus and amygdala. Patients suffering from anxiety disorders and major depressive disorder often show excessive amygdala and reduced prefrontal cortex functioning. It is, however, still unclear whether these brain abnormalities disappear or diminish following effective treatment. This review aims to compare the effects of psychotherapy and pharmacotherapy on functional and morphological brain measures in these disorders. Sixty-three studies were included, 30 investigating psychotherapy effects and 33 investigating pharmacotherapy effects. Despite methodological differences, results suggest a functional normalization of the 'fear network'. Pharmacotherapy particularly decreases over-activity of limbic structures (bottom-up effect) while psychotherapy tends to increase activity and recruitment of frontal areas (top-down effect), especially the anterior cingulate cortex. Additionally, pharmacotherapy, but not psychotherapy, has been associated with morphological changes, depending on the disorder. These findings suggest that both types of treatments normalize (functional) brain abnormalities each in specific ways.

Structural neuroimaging studies in major depressive disorder. Meta-analysis and comparison with bipolar disorder

CONTEXT

Although differences in clinical characteristics exist between major depressive disorder (MDD) and bipolar disorder (BD), consistent structural brain abnormalities that distinguish the disorders have not been identified.

OBJECTIVES

To investigate structural brain changes in MDD using meta-analysis of primary studies; assess the effects of medication, demographic, and clinical variables; and compare the findings with those of a meta-analysis of studies on BD.

DATA SOURCES

The MEDLINE, EMBASE, and PsycINFO databases were searched for studies from January 1, 1980, to February 2, 2010.

STUDY SELECTION

Two hundred twenty-five studies that used magnetic resonance imaging or x-ray computed tomography to compare brain structure in patients with MDD with that of controls were included in an online database, and 143 that measured common brain structures were selected for meta-analysis.

DATA EXTRACTION

Twenty-five variables, including demographic and clinical data, were extracted from each study, when available. For the meta-analysis, mean structure size and standard deviation were extracted for continuous variables, and the proportion of patients and controls with an abnormality in brain structure was extracted for categorical variables.

DATA SYNTHESIS

Compared with the structure of a healthy brain, MDD was associated with lateral ventricle enlargement; larger cerebrospinal fluid volume; and smaller volumes of the basal ganglia, thalamus, hippocampus, frontal lobe, orbitofrontal cortex, and gyrus rectus. Patients during depressive episodes had significantly smaller hippocampal volume than patients during remission. Compared with BD patients, those with MDD had reduced rates of deep white matter hyperintensities, increased corpus callosum cross-sectional area, and smaller hippocampus and basal ganglia. Both disorders were associated with increased lateral ventricle volume and increased rates of subcortical gray matter hyperintensities compared with healthy controls.

CONCLUSIONS

The meta-analyses revealed structural brain abnormalities in MDD that are distinct from those observed in BD. These findings may aid investigators attempting to discriminate mood disorders using structural magnetic resonance imaging data.

Demonstration of decreased gray matter concentration in the midbrain encompassing the dorsal raphe nucleus and the limbic subcortical regions in major depressive disorder: an optimized voxel-based morphometry study

BACKGROUND

Previous neuroimaging studies in patients with major depressive disorder (MDD) have reported changes in several brain areas, such as the medial and dorsolateral orbital cortex, amygdala, hippocampus, and basal ganglia. However, the results of these studies are inconsistent, and relatively few studies have been conducted using voxel-based morphometry (VBM) to detect gray matter concentration (GMC) abnormalities in patients with MDD.

METHODS

We examined 47 MDD patients and 51 healthy controls to investigate structural abnormalities using a 1.5 T magnetic resonance imaging system, which was normalized to a customized T1 template and segmented with optimized VBM. Analysis of covariance with age and gender as covariates was adopted for the VBM statistics; the level of statistical significance was set at P<0.05 for the corrected false discovery rate.

RESULTS

Decreased GMC was found in MDD patients in the bilateral amygdalae, hippocampi, fusiform gyri, lingual gyri, insular gyri, middle-superior temporal gyri, thalami, cingulate gyri, the central lobule of the cerebellum, and the midbrain encompassing the dorsal raphe nuclei (DRN).

LIMITATIONS

Half of our study subjects were taking antidepressants. This may have been a potential confounding factor if any of the medications affected cortical volume.

CONCLUSIONS

The results suggest that the GMC of several regions associated with emotion regulation was lower in MDD patients. In particular, we found decreased GMC in the DRN. These findings may provide a better understanding of the anatomical properties of the neural mechanisms underlying the etiology of MDD.

Antidepressant use and salivary cortisol in depressive and anxiety disorders

Antidepressants are an effective treatment for depressive and anxiety disorders. Those disorders are frequently accompanied by heightened cortisol levels. Antidepressants may affect hypothalamic-pituitary-adrenal axis functioning, the alteration of which could be partially responsible for treatment efficacy. The association between antidepressants and cortisol was investigated in 1526 subjects of the Netherlands Study of Depression and Anxiety who were grouped into 'serotonin reuptake inhibitor (SSRI) users' (n=309), 'tricyclic antidepressant (TCA) users' (n=49), 'other antidepressant users' (n=100), and 'non-users' (n=1068). All subjects had a current or past diagnosis of anxiety and/or depression. Subjects provided 7 saliva samples from which 3 cortisol indicators were calculated: cortisol awakening response (CAR), evening cortisol, and cortisol suppression after ingestion of 0.5mg dexamethasone. As compared to non-users, TCA users had a flattened CAR (effect size: Cohen's d=0.34); SSRI users had higher evening cortisol levels (d=0.04); and SSRI users showed decreased cortisol suppression after dexamethasone ingestion (d=0.03). These findings suggest that antidepressant subtypes are associated with distinct alterations of the HPA axis. TCA users, who showed a flattened CAR, displayed the strongest alterations of salivary cortisol.

The effects of antidepressants on human brain as detected by imaging studies. Focus on major depression

Recent brain imaging studies have shed light on understanding the pathogenesis of mood disorders. Evidence of structural, chemical, and functional brain changes, particularly in prefrontal cortex, cingulate, and amygdala, has been revealed in major depressive disorder (MDD). Furthermore, imaging techniques have been applied to monitor the effects of antidepressants (ADs) both in the brains of healthy volunteers and MDD patients. Although with some discrepancies due to the differences in study designs and patient samples, imaging findings have shown that ADs, particularly those having effects on the serotonergic system, modulate the volumes, functions and biochemistry of brain structures, i.e. dorsolateral prefrontal cortex, anterior cingulate and amygdala, which have been demonstrated abnormal in MDD by earlier imaging studies. This paper reviews imaging studies conducted in MDD patients and healthy controls treated with different ADs.

Depression, hypothalamic pituitary adrenal axis, and hippocampal and entorhinal cortex volumes--the SMART Medea study

BACKGROUND

Structural brain changes have often been found in major depressive disorder (MDD), and it is thought that hypothalamic-pituitary-adrenal (HPA) axis hyperactivity may explain this relation. We investigated the association of MDD and history of depression with hippocampal and entorhinal cortex volumes and whether HPA axis activity explained this association.

METHODS

In 636 participants with a history of atherosclerotic disease (mean age 62 ± 9 years, 81% male) from the second Manifestation of ARTerial disease-Memory depression and aging (SMART-Medea) study, a 12-month diagnosis of MDD and history of depression were assessed. Age of first depressive episode was classified into early-onset depression (< 50 years) and late-onset depression (≥ 50 years). HPA axis regulation was assessed by four morning saliva samples, two evening samples, and one awakening sample after .5 mg dexamethasone. Hippocampus and entorhinal cortex volume were manually outlined on three-dimensional T1-weighted magnetic resonance images.

RESULTS

General linear models adjusted for demographics, vascular risk, antidepressant use, and white matter lesions showed that ever having had MDD was associated with smaller hippocampal volumes but not with entorhinal cortex volumes. Remitted MDD was related to smaller entorhinal cortex volumes (p < .05). Participants with early-onset depression had smaller hippocampal volumes than those who were never depressed (p < .05), whereas participants with late-onset depression had smaller entorhinal cortex volumes (p < .05). HPA axis activity did not explain these differences.

CONCLUSIONS

We found differential associations of age of onset of depression on hippocampal and entorhinal cortex volumes, which could not be explained by alterations in HPA axis regulation.

Identifying a cognitive impairment subgroup in adults with mood disorders

BACKGROUND

We hypothesized that only a minority of patients with mood disorders have measurable cognitive impairment, and this minority drives the small-to-medium effect sizes detected in group studies. Removal of this minority from group statistical analyses will illustrate that the majority appear to have broadly normal cognitive functioning.

METHODS

Participants were adults between the ages of 20 and 54, including 659 healthy control subjects, 84 unmedicated outpatients diagnosed with depression, 59 outpatients diagnosed with depression who were on medications at the time of the evaluation, and 43 outpatients with bipolar disorder. All completed the CNS Vital Signs computerized cognitive screening battery.

RESULTS

The prevalence rates of low cognitive test scores were calculated for the healthy control subjects and the patients with mood disorders. Having two scores at or below the 5th percentile occurred in 31.2% of the patients and only 8.2% of the control subjects [χ(2)(1)=66.67, p<.0001; Odds Ratio=5.1, 95% CI=3.4-7.7]. For the control subjects, this low false positive rate for cognitive impairment was maintained across age groups, sexes, and education levels. A larger proportion of patients with bipolar disorder (41.9%) than patients with depression (27.1-28.6%) met this criterion for cognitive impairment.

CONCLUSIONS

This study suggests that cognitive impairment associated with mood disorders is limited to a minority of patients with the majority being broadly cognitively normal. Future research should determine if this identified subgroup has neuroanatomical, neurophysiological, or neuroendocrine abnormalities. Cognitive screening tools of this type might be useful in selecting participants for studies.

A transdisciplinary perspective of chronic stress in relation to psychopathology throughout life span development

The allostatic load (AL) model represents an interdisciplinary approach to comprehensively conceptualize and quantify chronic stress in relation to pathologies throughout the life cycle. This article first reviews the AL model, followed by interactions among early adversity, genetics, environmental toxins, as well as distinctions among sex, gender, and sex hormones as integral antecedents of AL. We next explore perspectives on severe mental illness, dementia, and caregiving as unique human models of AL that merit future investigations in the field of developmental psychopathology. A complimenting transdisciplinary perspective is applied throughout, whereby we argue that the AL model goes beyond traditional stress–disease theories toward the advancement of person-centered research and practice that promote not only physical health but also mental health.

Cognitive dysfunction in depression: neurocircuitry and new therapeutic strategies

Major depressive disorder (MDD) is a disabling medical condition associated with significant morbidity, mortality and public health costs. However, neurocircuitry abnormalities underlying depression remain incompletely understood and consequently current treatment options are unfortunately limited in efficacy. Recent research has begun to focus specifically on cognitive aspects of depression and potential neurobiological correlates. Two fundamental types of cognitive dysfunction observed in MDD are cognitive biases, which include distorted information processing or attentional allocation toward negative stimuli, and cognitive deficits, which include impairments in attention, short-term memory and executive functioning. In this article, we present a selective review of current research findings in these domains and examine neuroimaging research that is beginning to characterize the neurocircuitry underlying these biases and deficits. We propose that deficient cognitive functioning, attention biases and the sustained negative affect characteristic of MDD can be understood as arising in part from dysfunctional prefrontal-subcortical circuitry and related disturbances in the cognitive control of emotion. Finally, we highlight potential new pharmacological and non-pharmacological therapeutic strategies for MDD based on an evolving mechanistic understanding of the disorder.

Stress, glucocorticoids and glutamate release: effects of antidepressant drugs

Stressful life events impact on memory, cognition and emotional responses, and are known to precipitate mood/anxiety disorders. It is increasingly recognized that stress and its neurochemical and endocrine mediators induce changes in glutamate synapses and circuitry, and this in turn modify mental states. Half a century after the monoamine hypothesis, it is widely accepted that maladaptive changes in excitatory/inhibitory circuitry have a primary role in the pathophysiology of mood/anxiety disorders. The neuroplasticity hypothesis posits that volumetric changes consistently found in limbic and cortical areas of depressed subjects are in good part due to remodeling of neuronal dendritic arbors and loss of synaptic spines. A considerable body of work, carried out with in vivo microdialysis as well as alternative methodologies, has shown that both stress and corticosterone treatment induce enhancement of activity-dependent glutamate release. Accordingly, results from preclinical studies suggest that stress- and glucocorticoid-induced enhancement of glutamate release and transmission plays a main role in the induction of maladaptive cellular effects, in turn responsible for dendritic remodeling. Additional recent work has showed that drugs employed for therapy of mood/anxiety disorders (antidepressants) prevent the enhancement of glutamate release induced by stress. Understanding the action of traditional drugs on glutamate transmission could be of great help in developing drugs that may work directly at this level.

Major depressive disorder, generalised anxiety disorder, and their comorbidity: associations with cortisol in the Vietnam Experience Study

OBJECTIVES

The aim of these analyses was to examine the association of cortisol, dehydroepiandrosterone sulphate (DHEAS), and the cortisol:DHEAS ratio with the diagnoses of major depressive disorder (MDD), generalised anxiety disorder (GAD), and their comorbidity.

DESIGN

This was a cross-sectional study.

METHODS

Participants were 4256 Vietnam era US army veterans. From military service files, telephone interviews, and a medical examination, occupational, socio-demographic, and health data were collected. One-year prevalence of MDD and GAD was determined through a diagnostic interview schedule based on the DSM-IV criteria. Contemporary morning fasted cortisol and DHEAS concentrations were determined. Analyses of covariance were run, first with adjustment for age and then additionally adjusting for a range of candidate confounders.

RESULTS

In fully adjusted analyses, there was evidence of lower basal cortisol levels in individuals with MDD and co-morbid MDD and GAD than those with GAD alone or no diagnosis.

CONCLUSION

This suggests that MDD and its comorbidity can also be characterised by low as well as high cortisol levels. A profitable line of future research might be to examine cortisol and DHEAS levels in more representative samples including older participants and women with and without MDD, GAD, and other psychiatric diagnoses.

Major depressive disorder skews the recognition of emotional prosody

OBJECTIVE

Major depressive disorder (MDD) is associated with abnormalities in the recognition of emotional stimuli. MDD patients ascribe more negative emotion but also less positive emotion to facial expressions, suggesting blunted responsiveness to positive emotional stimuli. To ascertain whether these emotional biases are modality-specific, we examined the effects of MDD on the recognition of emotions from voices using a paradigm designed to capture subtle effects of biases.

METHODS

Twenty-one MDD patients and 21 healthy controls (HC) underwent clinical and neuropsychological assessments, followed by a paradigm featuring pseudowords spoken by actors in five types of emotional prosody, rated on continuous scales.

RESULTS

Overall, MDD patients performed more poorly than HC, displaying significantly impaired recognition of fear, happiness and sadness. Compared with HC, they rated fear significantly more highly when listening to anger stimuli. They also displayed a bias toward surprise, rating it far higher when they heard sad or fearful utterances. Furthermore, for happiness stimuli, MDD patients gave higher ratings for negative emotions (fear and sadness). A multiple regression model on recognition of emotional prosody in MDD patients showed that the best fit was achieved using the executive functioning (categorical fluency, number of errors in the MCST, and TMT B-A) and the total score of the Montgomery-Asberg Depression Rating Scale.

CONCLUSIONS

Impaired recognition of emotions would appear not to be specific to the visual modality but to be present also when emotions are expressed vocally, this impairment being related to depression severity and dysexecutive syndrome. MDD seems to skew the recognition of emotional prosody toward negative emotional stimuli and the blunting of positive emotion appears not to be restricted to the visual modality.

Fluoxetine reverses the memory impairment and reduction in proliferation and survival of hippocampal cells caused by methotrexate chemotherapy

RATIONALE

Adjuvant cancer chemotherapy can cause long-lasting, cognitive deficits. It is postulated that these impairments are due to these drugs targeting neural precursors within the adult hippocampus, the loss of which has been associated with memory impairment.

OBJECTIVES

The present study investigates the effects of the chemotherapy, methotrexate (MTX) on spatial working memory and the proliferation and survival of the neural precursors involved in hippocampal neurogenesis, and the possible neuroprotective properties of the antidepressant fluoxetine.

METHODS

Male Lister hooded rats were administered MTX (75 mg/kg, two i.v. doses a week apart) followed by leucovorin rescue (i.p. 18 h after MTX at 6 mg/kg and at 26, 42 and 50 h at 3 mg/kg) and/or fluoxetine (10 mg/kg/day in drinking water for 40 days). Memory was tested using the novel location recognition (NLR) test. Using markers, cell proliferation (Ki67) and survival (bromodeoxyuridine/BrdU), in the dentate gyrus were quantified.

RESULTS

MTX-treated rats showed a cognitive deficit in the NLR task compared with the vehicle and fluoxetine-treated groups. Cognitive ability was restored in the group receiving both MTX and fluoxetine. MTX reduced both the number of proliferating cells in the SGZ and their survival. This was prevented by the co-administration of fluoxetine, which alone increased cell numbers.

CONCLUSIONS

These results demonstrate that MTX induces an impairment in spatial working memory and has a negative long-term effect on hippocampal neurogenesis, which is counteracted by the co-administration of fluoxetine. If translatable to patients, this finding has the potential to prevent the chemotherapy-induced cognitive deficits experienced by many cancer survivors.

Neuropsychologische Aspekte der Depression

Zusammenfassung. Patienten mit Depressionen klagen häufig über Symptome und Störungen nicht nur auf der emotionalen, sondern auch auf der kognitiven Ebene. In dieser Übersichtsarbeit werden schwerpunktmäßig neuropsychologische Befunde zu kognitiven Funktionen bei unipolaren Depressionen zusammengefasst. Die kognitive Theorie der Depression postulierte eine Beeinflussung kognitiver Vorgänge durch emotionale Verzerrungen, die eine wichtige Rolle bei Vulnerabilität, Entstehung, Aufrechterhaltung und Rezidiven depressiver Episoden spielen. Befunde zu dieser Interaktion von kognitiven und emotionalen Prozessen werden dargestellt, außerdem wird auf die Bedeutung dieser Aspekte für die Emotionsregulation und für die Therapie der Depression eingegangen.