Effects of glucocorticoids on declarative memory function in major depression

Efficacy and acceptability of anti-inflammatory agents in major depressive disorder: a systematic review and meta-analysis

Background

Anti-inflammatory agents have emerged as a potential new therapy for major depressive disorder (MDD). In this meta-analysis, our aim was to evaluate the antidepressant effect of anti-inflammatory agents and compare their efficacy.

Methods

We conducted a comprehensive search across multiple databases, including PubMed, Embase, Web of Science, Cochrane Review, Cochrane Trial, and ClinicalTrials.gov, to identify eligible randomized clinical trials. The primary outcome measures of our meta-analysis were efficacy and acceptability, while the secondary outcome measures focused on remission rate and dropout rate due to adverse events. We used odds ratio (OR) and 95% confidence interval (95% CI) to present our results.

Results

A total of 48 studies were included in our analysis. In terms of efficacy, anti-inflammatory agents demonstrated a significant antidepressant effect compared to placebo (OR = 2.04, 95% CI: 1.41-2.97, p = 0.0002). Subgroup analyses revealed that anti-inflammatory agents also exhibited significant antidepressant effects in the adjunctive therapy subgroup (OR = 2.17, 95% CI: 1.39-3.37, p = 0.0006) and in MDD patients without treatment-resistant depression subgroup (OR = 2.33, 95% CI: 1.53-3.54, p < 0.0001). Based on the surface under the cumulative ranking curve (SUCRA) value of network meta-analysis, nonsteroidal anti-inflammatory drugs (NSAIDs) (SUCRA value = 81.6) demonstrated the highest acceptability among the included anti-inflammatory agents.

Conclusion

In summary, our meta-analysis demonstrates that anti-inflammatory agents have significant antidepressant effects and are well-accepted. Furthermore, adjunctive therapy with anti-inflammatory agents proved effective in treating MDD. Among the evaluated anti-inflammatory agents, NSAIDs exhibited the highest acceptability, although its efficacy is comparable to placebo.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=422004), identifier CRD42023422004.

Effects of Cortisol Administration on Resting-State Functional Connectivity in Women with Depression

Previous resting-state functional connectivity (rsFC) research has identified several brain networks impacted by depression and cortisol, including default mode (DMN), frontoparietal (FPN), and salience networks (SN). In the present study, we examined the effects of cortisol administration on rsFC of these networks in individuals varying in depression history and severity. We collected resting-state fMRI scans and self-reported depression symptom severity for 74 women with and without a history of depression after cortisol and placebo administration using a double-blind, crossover design. We conducted seed-based rsFC analyses for DMN, FPN, and SN seeds to examine rsFC changes after cortisol vs. placebo administration in relation to depression history group and severity. Results revealed a main effect of depression group, with lower left amygdala (SN)-middle temporal gyrus connectivity in women with a history of depression. Cortisol administration increased insula (SN)-inferior frontal gyrus and superior temporal gyrus connectivity. We also found that greater depression severity was associated with increased PCC (DMN)-cerebellum connectivity after cortisol. These results did not survive Bonferroni correction for seed ROIs and should be interpreted with caution. Our findings indicate that acute cortisol elevation may normalize aberrant connectivity of DMN and SN regions, which could help inform clinical treatments for depression.

Effect of transcutaneous cervical vagus nerve stimulation on declarative and working memory in patients with Posttraumatic Stress Disorder (PTSD): A pilot study

BACKGROUND

Posttraumatic stress disorder (PTSD) is associated with changes in multiple neurophysiological systems, including verbal declarative memory deficits. Vagus Nerve Stimulation (VNS) has been shown in preliminary studies to enhance function when paired with cognitive and motor tasks. The purpose of this study was to analyze the effect of transcutaneous cervical VNS (tcVNS) on attention, declarative and working memory in PTSD patients.

METHODS

Fifteen PTSD patients were randomly assigned to active tcVNS (N = 8) or sham (N = 7) stimulation in a double-blinded fashion. Memory assessment tests including paragraph recall and N-back tests were performed to assess declarative and working memory function when paired with active/sham tcVNS once per month in a longitudinal study during which patients self-administered tcVNS/sham twice daily.

RESULTS

Active tcVNS stimulation resulted in a significant improvement in paragraph recall performance following pairing with paragraph encoding for PTSD patients at two months (p < 0.05). It resulted in a 91 % increase in paragraph recall performance within group (p = 0.03), while sham tcVNS exhibited no such trend in performance improvement. In the N-back study, positive deviations in accuracy, precision and recall measures on different day visits (7,34,64,94) of patients with respect to day 1 revealed a pattern of better performance of the active tcVNS population compared to sham VNS which did not reach statistical significance.

LIMITATIONS

Our sample size was small.

CONCLUSIONS

These preliminary results suggest that tcVNS improves attention, declarative and working memory, which may improve quality of life and productivity for patients with PTSD. Future studies are required to confirm these results.

Younger age and early puberty are associated with cognitive function decline in children with Cushing disease

OBJECTIVE

To investigate the effect of hypercortisolism on the developing brain we performed clinical, cognitive, and psychological evaluation of children with Cushing disease (CD) at diagnosis and 1 year after remission.

STUDY DESIGN

Prospective study of 41 children with CD. Children completed diverse sets of cognitive measures before and 1 year after remission. Neuropsychological evaluation included the Wechsler Intelligence Scale, California Verbal Learning Test, Trail Making Test, the combined subset scores of Wide Range Achievement Test and Woodcock-Johnson Psychoeducational Battery Test of Achievement, and the Behavioral Assessment System for Children.

RESULTS

Comprehensive cognitive evaluations at baseline and 1 year following cure revealed significant decline mostly in nonverbal skills. Decrements occurred in most of the various indices that measure all aspects of cognitive function and younger age and early pubertal stage largely contributed to most of this decline. Results indicated that age at baseline was associated with positive regression weights for changes in scores for verbal, performance, and full intelligence quotient (IQ) scores and for subtests arithmetic, picture completion, coding, block design, scores; indicating that older age at baseline was associated with less of a deterioration in cognitive scores from pre- to posttreatment.

CONCLUSION

Our findings suggest that chronic glucocorticoid excess and accompanying secondary hormonal imbalances followed by eucortisolemia have detrimental effects on cognitive function in the developing brain; younger age and pubertal stage are risk factors for increased vulnerability, while older adolescents have cognitive vulnerabilities like that of adult patients affected with CD.

Differential association of cortisol with visual memory/learning and executive function in Bipolar Disorder

The association of cortisol with cognition has been understudied in Bipolar Disorder (BD); available evidence is inconsistent while it is unknown whether cortisol's effects vary across neurocognitive domains implicating different brain structures. This study aimed to examine the association of cortisol with two cognitive tasks targeting visual memory and executive function (planning) in BD, related to the hippocampus and prefrontal lobe, respectively. Cambridge Neuropsychological Test Automated Battery (CANTAB) tasks targeting paired associative learning (PAL) and planning (Stockings of Cambridge; SOC) were administered to 60 BD type I patients. Basal serum cortisol was also measured. Higher cortisol was associated with worse performance in PAL, but not SOC, after controlling for gender, education, illness duration and treatment with mood stabilizers. This is the first study to examine the association of cortisol with neurocognitive function in BD while controlling for clinicodemographic and treatment-related factors. We found a significant association of cortisol with hippocampal-related visual memory/learning but not with prefrontal lobe-related executive function, suggesting domain-specific underlying mechanisms of cognitive dysfunction in BD. Future studies should further explore cortisol's brain structure-specific effects on cognitive functioning in BD.

Cortisol effects on brain functional connectivity during emotion processing in women with depression

BACKGROUND

Depression is associated with altered functional connectivity and altered cortisol sensitivity, but the effects of cortisol on functional connectivity in depression are unknown. Previous research shows that brief cortisol augmentation (CORT) has beneficial neurocognitive effects in depression.

METHODS

We investigated the effects of CORT (20mg oral cortisol) on functional connectivity during emotion processing in women with depression. Participants included 75 women with no depression or a depressive disorder. In a double-blind, crossover study, we used functional magnetic resonance imaging to measure effects of CORT vs. placebo on task-based functional connectivity during presentation of emotionally-laden images. We performed psychophysiological interaction (PPI) to test interactions among depression severity, cortisol administration, and task-dependent functional connectivity using the hippocampus and amygdala as seeds.

RESULTS

During the presentation of negative images, CORT (vs. placebo) increased functional connectivity between the hippocampus and putamen in association with depression severity. During the presentation of positive pictures CORT increased functional connectivity between the hippocampus and middle frontal gyrus as well as superior temporal gyrus in association with depression.

LIMITATIONS

Because cortisol was pharmacologically manipulated, results cannot be extrapolated to endogenous increases in cortisol levels. The sample did not permit investigation of differences due to race, ethnicity, or sex. Co-morbidities such as anxiety or PTSD were not accounted for.

CONCLUSIONS

The results suggest that CORT has normalizing effects on task-dependent functional connectivity in women with depression during emotion processing. Increasing cortisol availability or signaling may have therapeutic benefits within affective disorders.

Electrical stimulation of cranial nerves in cognition and disease

The cranial nerves are the pathways through which environmental information (sensation) is directly communicated to the brain, leading to perception, and giving rise to higher cognition. Because cranial nerves determine and modulate brain function, invasive and non-invasive cranial nerve electrical stimulation methods have applications in the clinical, behavioral, and cognitive domains. Among other neuromodulation approaches such as peripheral, transcranial and deep brain stimulation, cranial nerve stimulation is unique in allowing axon pathway-specific engagement of brain circuits, including thalamo-cortical networks. In this review we amalgamate relevant knowledge of 1) cranial nerve anatomy and biophysics; 2) evidence of the modulatory effects of cranial nerves on cognition; 3) clinical and behavioral outcomes of cranial nerve stimulation; and 4) biomarkers of nerve target engagement including physiology, electroencephalography, neuroimaging, and behavioral metrics. Existing non-invasive stimulation methods cannot feasibly activate the axons of only individual cranial nerves. Even with invasive stimulation methods, selective targeting of one nerve fiber type requires nuance since each nerve is composed of functionally distinct axon-types that differentially branch and can anastomose onto other nerves. None-the-less, precisely controlling stimulation parameters can aid in affecting distinct sets of axons, thus supporting specific actions on cognition and behavior. To this end, a rubric for reproducible dose-response stimulation parameters is defined here. Given that afferent cranial nerve axons project directly to the brain, targeting structures (e.g. thalamus, cortex) that are critical nodes in higher order brain networks, potent effects on cognition are plausible. We propose an intervention design framework based on driving cranial nerve pathways in targeted brain circuits, which are in turn linked to specific higher cognitive processes. State-of-the-art current flow models that are used to explain and design cranial-nerve-activating stimulation technology require multi-scale detail that includes: gross anatomy; skull foramina and superficial tissue layers; and precise nerve morphology. Detailed simulations also predict that some non-invasive electrical or magnetic stimulation approaches that do not intend to modulate cranial nerves per se, such as transcranial direct current stimulation (tDCS) and transcranial magnetic stimulation (TMS), may also modulate activity of specific cranial nerves. Much prior cranial nerve stimulation work was conceptually limited to the production of sensory perception, with individual titration of intensity based on the level of perception and tolerability. However, disregarding sensory emulation allows consideration of temporal stimulation patterns (axon recruitment) that modulate the tone of cortical networks independent of sensory cortices, without necessarily titrating perception. For example, leveraging the role of the thalamus as a gatekeeper for information to the cerebral cortex, preventing or enhancing the passage of specific information depending on the behavioral state. We show that properly parameterized computational models at multiple scales are needed to rationally optimize neuromodulation that target sets of cranial nerves, determining which and how specific brain circuitries are modulated, which can in turn influence cognition in a designed manner.

Alterations in Systemic and Cognitive Glucocorticoid Sensitivity in Depression

BACKGROUND

Decades of research point to cortisol insensitivity as a biomarker of depression. Despite a vast literature on cortisol's effects on memory, the role of cortisol insensitivity in core psychological features of depression, such as emotional memory biases, is unknown.

METHODS

Sixty-five premenopausal women with varying levels of depression completed this study involving an at-home low-dose dexamethasone suppression test and four experimental sessions (i.e., two visits for memory encoding of emotionally arousing pictures, each of which was followed 48 hours later by a recall test). Participants received 20 mg of oral cortisol (CORT) or placebo prior to encoding. We tested whether systemic cortisol insensitivity measured with the dexamethasone suppression test predicted cognitive sensitivity to CORT, which was operationalized as the change in negatively biased memory formation for pictures encoded following CORT versus placebo administration.

RESULTS

Cortisol insensitivity was associated with more severe depression and flatter diurnal cortisol levels. Cortisol insensitivity predicted negative memory bias for pictures encoded during the placebo session and reduction in negative memory bias for pictures encoded during the CORT (compared with placebo) session, even after accounting for psychiatric symptomatology.

CONCLUSIONS

Our findings replicate research showing that cortisol insensitivity predicts depression severity and flatter diurnal cortisol levels. The results further suggest that systemic cortisol insensitivity is related to negative memory bias and its alleviation by cortisol administration. These novel cognitive findings tie together knowledge regarding endocrine and psychological dysfunction in depression and suggest that boosting cortisol signal may cognitively benefit individuals with cortisol insensitivity.

Sex-related variation of neurocognitive functioning in bipolar disorder: Focus on visual memory and associative learning

Bipolar disorder (BD) is associated with cognitive deficits in attention, verbal memory and executive functions. However, only few studies have examined sex effects on cognition despite their clinical relevance. Given that visual memory/ learning has been understudied the aim of our study was to investigate sex-related variation in cognition (executive functions and visual memory/ learning) in BD. Cognitive performance of 60 bipolar-I patients and 30 healthy controls was evaluated by using CANTAB battery tasks targeting spatial memory (SRM), paired associative learning (PAL) and executive functions. We fitted a multivariate analysis of covariance (MANCOVA), followed by task-specific ANCOVAs. A significant diagnosis by sex interaction effect was detected (MANCOVA); specifically, diagnosis-specific sex effects were found for SRM and PAL, as healthy males outperformed healthy females but this pattern was attenuated in BD patients. Patients' clinicodemographic characteristics, current psychopathology or medication status did not differ across sexes and were, therefore, unlikely to explain detected sex effects. Our study is one of few studies to assess sex-related variation in cognition in BD and the first to record a diagnosis-specific sex effect for two tasks of visuo-spatial memory/ learning, indicating that sex-related variation in healthy subjects is disrupted in BD.

Effects of cortisol on cognition in major depressive disorder, posttraumatic stress disorder and borderline personality disorder - 2014 Curt Richter Award Winner

Stress hormones influence a wide range of cognitive functions, including memory performance and executive function. It is well established that glucocorticoids enhance memory consolidation but impair memory retrieval. While most of the effects have been attributed to glucocorticoid receptors (GR), the importance of mineralocorticoid receptors (MR) has been also emphasized. Dysfunctions in hypothalamic-pituitary-adrenal (HPA) axis have been reported for several mental disorders. While major depressive disorder (MDD) as well as borderline personality disorder (BPD) seem to be characterized by enhanced cortisol release in concert with a reduced feedback sensitivity of the HPA axis, in posttraumatic stress disorder (PTSD) a contrary picture has been reported. Despite the fact that altered GR function has been discussed for these disorders only very few studies have investigated the effects of glucocorticoids on cognitive performance in these patients so far. In a series of studies, we investigated the effects of glucocorticoids on cognition (i.e. declarative memory, working memory and response inhibition) in different mental disorders such as MDD, PTSD and BPD. While in patients with MDD cortisol administration failed to effect memory retrieval, patients with PTSD and BPD showed enhanced rather than impaired memory retrieval after cortisol administration. These results indicate an altered sensitivity to cortisol in these disorders. Results from one of our recent studies in the field of social cognition underline the importance of the MR. We found that emotional empathy was enhanced through stimulation of the MR via fludrocortisone in healthy participants and women with BPD. This review aims to integrate these findings and discuss potential mechanisms and implications.

[Consistent Declarative Memory with Depressive Symptomatology]

INTRODUCTION

Some studies have suggested that potentiated remembrance of negative events on people with depressive disorders seems to be an important factor in the etiology, course and maintenance of depression.

OBJECTIVE

Evaluate the emotional memory in people with and without depressive symptomatology by means of an audio-visual test.

METHODOLOGY

73 university students were evaluated, male and female, between 18 and 40 years old, distributed in two groups: with depressive symptomatology (32) and without depressive symptomatology (40), using the Scale from the Center of Epidemiologic Studies for Depression (CES-D, English Abbreviation) and a cutting point of 20.

RESULTS

There were not meaningful differences between free and voluntary recalls, with and without depressive symptomatology, in spite of the fact that both groups had granted a higher emotional value to the audio-visual test and that they had associated it with emotional sadness.

CONCLUSION

People with depressive symptomatology did not exhibit the effect of mnemonic potentiation generally associated to the content of the emotional version of the test; therefore, the hypothesis of emotional consistency was not validated.

Effects of acute cortisol administration on response inhibition in patients with major depression and healthy controls

Glucocorticoids (GCs) have repeatedly been shown to impair hippocampus-mediated, declarative memory retrieval and prefrontal cortex-based working memory in healthy subjects. However, recent experimental studies indicated that patients with major depressive disorder (MDD) lack these impairing effects. These missing effects have been suggested to result from dysfunctional brain GC receptors. The purpose of the present study was to investigate whether response inhibition, an executive function relying on the integrity of the prefrontal cortex, would be impaired after cortisol administration in patients with MDD. In a placebo-controlled, double blind crossover study, 50 inpatients with MDD and 54 healthy control participants conducted an emotional go/no-go task consisting of human face stimuli (fearful, happy, and neutral) after receiving a dose of 10 mg hydrocortisone and after placebo. GC administration had an enhancing effect on inhibitory performance in healthy control participants, indicated by faster responses, while no GC effect was revealed for the patients group. Moreover, patients showed an overall worse performance than healthy participants. In conclusion, this study further supports the hypothesis of impaired central glucocorticoid receptor function in MDD patients. Regarding the importance of inhibitory functioning for daily living, further studies are needed to examine the impact of glucocorticoids on response inhibition.

Electroconvulsive Treatment: Hypotheses about Mechanisms of Action

No consensus has been reached on the mode of action of electroconvulsive treatment (ECT). We suggest that two features may aid in the delineation of the involved mechanisms. First, when effective, ECT would be likely to affect brain functions that are typically altered in its primary recipient group, people with severe depression. Central among these are the frontal and temporal lobes, the hypothalamus-pituitary-adrenal (HPA) stress axis, and the mesocorticolimbic dopamine system. Second, the involved mechanisms should be affected for a time period that matches the average endurance of clinical effects, which is indicated to be several days to a few weeks. To identify effects upon frontal and temporal lobe functioning we reviewed human studies using EEG, PET, SPECT, and fMRI. Effects upon the HPA axis and the dopamine system were assessed by reviewing both human and animal studies. The EEG studies indicate that ECT decelerates neural activity in the frontal and temporal lobes (increased delta and theta wave activity) for weeks to months. Comparable findings are reported from PET and SPECT studies, with reduced cerebral blood flow (functional deactivation) for weeks to months after treatment. The EEG deceleration and functional deactivation following ECT are statistically associated with reduced depression scores. FMRI studies indicate that ECT flattens the pattern of activation and deactivation that is associated with cognitive task performance and alters cortical functional connectivity in the ultra slow frequency range. A common finding from human and animal studies is that ECT acutely activates both the HPA axis and the dopamine system. In considering this evidence, we hypothesize that ECT affects the brain in a similar manner as severe stress or brain trauma which activates the HPA axis and the dopamine system and may compromise frontotemporal functions.

Cortisol and depression: three questions for psychiatry

BACKGROUND

Cortisol plays a multifaceted role in major depression disorder (MDD). Diurnal rhythms are disturbed, there is increased resistance to the feedback action of glucocorticoids, excess cortisol may induce MDD, basal levels may be higher and the post-awakening cortisol surge accentuated in those at risk for MDD. Does this suggest new avenues for studying MDD or its clinical management?

METHOD

The relevant literature was reviewed.

RESULTS

Cortisol contributes to genetic variants for the risk for MDD and the way that environmental events amplify risk. The corticoids' influence begins prenatally, but continues into adulthood. The impact of cortisol at each phase depends not only on its interaction with other factors, such as psychological traits and genetic variants, but also on events that have, or have not, occurred previously.

CONCLUSIONS

This review suggests that the time is now right for serious consideration of the role of cortisol in a clinical context. Estimates of cortisol levels and the shape of the diurnal rhythm might well guide the understanding of subtypes of MDD and yield additional indicators for optimal treatment. Patients with disturbed cortisol rhythms might benefit from restitution of those rhythms; they may be distinct from those with more generally elevated levels, who might benefit from cortisol blockade. Higher levels of cortisol are a risk for subsequent depression. Should manipulation of cortisol or its receptors be considered as a preventive measure for some of those at very high risk of future MDD, or to reduce other cortisol-related consequences such as long-term cognitive decline?

Associations between cognitive performance and cortisol reaction to the DEX/CRH test in patients recovered from depression

BACKGROUND

Hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis in major depression (MDD) is one of the most reliably reported neurobiological characteristics of affective disorders. Whether these alterations in HPA axis regulation are limited to the acute stage of MDD or whether they persist after recovery, remains ambiguous. A relationship between hypercortisolemia and cognitive dysfunction in acutely depressed patients has been repeatedly observed and it was also demonstrated in a number of studies that a discrete cognitive impairment often persists in the remitted state of depression. In the present study we were interested, whether these subtle impairments in cognitive functioning observed in patients recovered from depression compared to healthy control subjects are associated with HPA axis feedback sensitivity.

METHODS

In 20 recovered patients and 20 matched healthy controls we assessed HPA axis feedback sensitivity with the combined dexamethasone suppression/corticotropin-releasing-hormone (DEX/CRH) challenge test. Furthermore cognitive performance was investigated with respect to the following domains: verbal memory (Auditory Verbal Learning Test, VLMT), attention and executive control (Trail Making Test, TMT-A/B) as well as verbal fluency (Controlled Oral Word Association Test, COWAT).

RESULTS

Recovered patients showed a significantly poorer cognitive performance compared to healthy controls (all p<.05). With regard to HPA-axis activity, no overall difference was observed in the DEX/CRH test between recovered patients and controls. In recovered patients however, a significant association was observed between cortisol response and verbal memory (main effect VLMT trial 1-5: p=.046), attention (main effect TMT-A: p=.015) and executive functioning in terms of set shifting (interaction samples*TMT-B: p=.018). Poorer test performance was related to increased cortisol levels in response to challenge.

CONCLUSIONS

The present findings suggest that patients recovered from MDD are especially vulnerable toward detrimental effects of subtle HPA axis disturbances on cognitive performance.

Biomarkers in an animal model for revealing neural, hematologic, and behavioral correlates of PTSD

Identification of biomarkers representing the evolution of the pathophysiology of Post Traumatic Stress Disorder (PTSD) is vitally important, not only for objective diagnosis but also for the evaluation of therapeutic efficacy and resilience to trauma. Ongoing research is directed at identifying molecular biomarkers for PTSD, including traumatic stress induced proteins, transcriptomes, genomic variances and genetic modulators, using biologic samples from subjects' blood, saliva, urine, and postmortem brain tissues. However, the correlation of these biomarker molecules in peripheral or postmortem samples to altered brain functions associated with psychiatric symptoms in PTSD remains unresolved. Here, we present an animal model of PTSD in which both peripheral blood and central brain biomarkers, as well as behavioral phenotype, can be collected and measured, thus providing the needed correlation of the central biomarkers of PTSD, which are mechanistic and pathognomonic but cannot be collected from people, with the peripheral biomarkers and behavioral phenotypes, which can.

Our animal model of PTSD employs restraint and tail shocks repeated for three continuous days - the inescapable tail-shock model (ITS) in rats. This ITS model mimics the pathophysiology of PTSD ^{17, 7, 4, 10}. We and others have verified that the ITS model induces behavioral and neurobiological alterations similar to those found in PTSD subjects ^{17, 7, 10, 9}. Specifically, these stressed rats exhibit (1) a delayed and exaggerated startle response appearing several days after stressor cessation, which given the compressed time scale of the rat's life compared to a humans, corresponds to the one to three months delay of symptoms in PTSD patients (DSM-IV-TR PTSD Criterian D/E ¹³), (2) enhanced plasma corticosterone (CORT) for several days, indicating compromise of the hypothalamopituitary axis (HPA), and (3) retarded body weight gain after stressor cessation, indicating dysfunction of metabolic regulation.

The experimental paradigms employed for this model are: (1) a learned helplessness paradigm in the rat assayed by measurement of acoustic startle response (ASR) and a charting of body mass; (2) microdissection of the rat brain into regions and nuclei; (3) enzyme-linked immunosorbent assay (ELISA) for blood levels of CORT; (4) a gene expression microarray plus related bioinformatics tools ¹⁸. This microarray, dubbed rMNChip, focuses on mitochondrial and mitochondria-related nuclear genes in the rat so as to specifically address the neuronal bioenergetics hypothesized to be involved in PTSD.

Perinatal exposure to 50 ppb sodium arsenate induces hypothalamic-pituitary-adrenal axis dysregulation in male C57BL/6 mice

Over the past two decades, key advancements have been made in understanding the complex pathology that occurs following not only high levels of arsenic exposure (>1 ppm) but also levels previously considered to be low (<100 ppb). Past studies have characterized the deleterious effects of arsenic on the various functions of cardiovascular, pulmonary, immunological, respiratory, endocrine and neurological systems. Other research has demonstrated an elevated risk of a multitude of cancers and increased rates of psychopathology, even at very low levels of arsenic exposure. The hypothalamic-pituitary-adrenal (HPA) axis represents a multisite integration center that regulates a wide scope of biological and physiological processes: breakdown within this system can generate an array of far-reaching effects, making it an intriguing candidate for arsenic-mediated damage. Using a mouse model, we examined the effects of perinatal exposure to 50 ppb sodium arsenate on the functioning of the HPA axis through the assessment of corticotrophin-releasing factor (CRF), proopiomelanocortin (Pomc) mRNA, adrenocorticotrophin hormone (ACTH), corticosterone (CORT), 11β-hydroxysteroid dehydrogenase Type 1 (11β-HSD 1), and glucocorticoid receptor (GR) protein and mRNA. Compared to controls, we observed that the perinatal arsenic-exposed offspring exhibit an increase in hypothalamic CRF, altered CORT secretion both at baseline and in response to a stressor, decreased hippocampal 11β-HSD 1 and altered subcellular GR distribution in the hypothalamus. These data indicate significant HPA axis impairment at post-natal day 35 resulting from perinatal exposure to 50 ppb sodium arsenate. Our findings suggest that the dysregulation of this critical regulatory axis could underlie important molecular and cognitive pathology observed following exposure to arsenic.

Increased stress reactivity is associated with reduced hippocampal activity and neuronal integrity along with changes in energy metabolism

Patients suffering from major depression have repeatedly been reported to have dysregulations in hypothalamus-pituitary-adrenal (HPA) axis activity along with deficits in cognitive processes related to hippocampal and prefrontal cortex (PFC) malfunction. Here, we utilized three mouse lines selectively bred for high (HR), intermediate, or low (LR) stress reactivity, determined by the corticosterone response to a psychological stressor, probing the behavioral and functional consequences of increased vs. decreased HPA axis reactivity on the hippocampus and PFC. We assessed performance in hippocampus- and PFC-dependent tasks and determined the volume, basal activity, and neuronal integrity of the hippocampus and PFC using in vivo manganese-enhanced magnetic resonance imaging and proton magnetic resonance spectroscopy. The hippocampal proteomes of HR and LR mice were also compared using two-dimensional gel electrophoresis and mass spectrometry. HR mice were found to have deficits in the performance of hippocampus- and PFC-dependent tests and showed decreased N-acetylaspartate levels in the right dorsal hippocampus and PFC. In addition, the basal activity of the hippocampus, as assessed by manganese-enhanced magnetic resonance imaging, was reduced in HR mice. The three mouse lines, however, did not differ in hippocampal volume. Proteomic analysis identified several proteins that were differentially expressed in HR and LR mice. In accordance with the notion that N-acetylaspartate levels, in part, reflect dysfunctional mitochondrial metabolism, these proteins were found to be involved in energy metabolism pathways. Thus, our results provide further support for the involvement of a dysregulated HPA axis and mitochondrial dysfunction in the etiology and pathophysiology of affective disorders.

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.

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.

A double dissociation of memory impairments in major depression

Sleep benefits the consolidation of both declarative and nondeclarative memories, however the question if these two memory systems profit from sleep in more or less similar ways is still under debate. Studying the on-line and off-line consolidation of declarative and nondeclarative memory tasks in depressed patients and healthy controls, we here present a clear double dissociation between memory systems and consolidation phases, suggesting radically different ways how sleep benefits memory consolidation. 37 medicated inpatients with an acute episode of major depression and 31 healthy controls were assessed using a nondeclarative (sequential finger tapping) memory task before and after a night with polysomnography, 27 of the depressed and 22 of the control subjects additionally performed a declarative (paired associates) task. Although depressed patients and control subjects did not differ in practice-dependent learning of the nondeclarative motor task in the wake state, healthy subjects showed overnight improvements in tapping performance of 11.4%, while the patients' performance decreased overnight by 11.5%. This pattern was reversed for the declarative task: While patients learned 33.5% less word pairs than controls in the wake state, overnight changes did not differ between the two groups. These results suggest a double dissociation of memory consolidation processes in major depression: Off-line memory consolidation in major depression is impaired for nondeclarative, but not declarative tasks. The same tasks in the wake state show a reversed pattern, with performance in declarative but not nondeclarative tasks being impaired in major depression.

Hydrocortisone impairs working memory in healthy humans, but not in patients with major depressive disorder

OBJECTIVE

Several studies have shown that stress or the administration of glucocorticoids can impair hippocampus-based declarative memory retrieval and prefrontal dependent working memory performance in healthy subjects. Major Depressive Disorder (MDD) is often characterized by memory impairment and increased cortisol secretion. Studies indicate that the impairing effects of glucocorticoids on declarative memory performance are missing in patients with MDD. The purpose of our study was to investigate whether the finding of missing effects of acute cortisol administration on memory performance in MDD is also seen when examining prefrontal-based working memory.

METHODS

In a placebo-controlled study, 57 patients with MDD and 56 sex- and age-matched healthy control subjects received either placebo or 10 mg of hydrocortisone orally before memory testing. To test the verbal modality of working memory, the Word Suppression Test was applied with one negative and one neutral test part.

RESULTS

After hydrocortisone intake, healthy subjects showed a significantly poorer working memory performance compared to placebo treatment when negative interference words were administered. In contrast, memory performance of MDD patients was not affected by hydrocortisone treatment.

CONCLUSIONS

The missing effects of glucocorticoid administration on working memory in MDD might be interpreted in the context of reduced central glucocorticoid receptor function.

Cognitive correlates of hypothalamic-pituitary-adrenal axis in major depression

Depressive disorder has become a major health problem and is ranked among the leading causes of disability worldwide. Depression-related cognitive impairment contributes to loss of economic productivity and psychosocial functioning and calls for more efficient treatment strategies. Although the pathogenesis of cognitive impairments in patients with major depressive disorder (MDD) is still insufficiently understood, increasing evidence implicates hypothalamus-pituitary-adrenal (HPA) axis as an important neurobiological determinant of cognitive impairment in depression. In this article, major findings of both HPA axis function abnormalities and cognitive impairments in depressed patients are summarized, focusing on their inter-relationship. Novel approaches in pharmacotherapy and psychotherapy have emerged which will be discussed with regard to their ability to reinstate normal HPA axis function in MDD and to treat cognitive impairments in MDD.

HPA axis alterations in mental disorders: impact on memory and its relevance for therapeutic interventions

Dysfunctions in hypothalamic-pituitary-adrenal (HPA) axis have been reported for several mental disorders that are also often characterized by memory disturbances. It is now well established that glucocorticoids influence cognitive processes by enhancing memory consolidation and impairing memory retrieval. There is further evidence for an association between HPA axis related disturbances and memory function in mental disorders. The present selective review provides a brief overview of HPA axis dysfunction and its impact on memory function in major depressive disorder, posttraumatic stress disorder, and borderline personality disorder. Furthermore, the relevance of these findings for therapeutic intervention is discussed.

Hydrocortisone responsiveness in Gulf War veterans with PTSD: effects on ACTH, declarative memory hippocampal [(18)F]FDG uptake on PET

Neuroendocrine, cognitive and hippocampal alterations have been described in Gulf War (GW) veterans, but their inter-relationships and significance for posttraumatic stress disorder (PTSD) have not been described. Hydrocortisone (Hcort) was administered to GW veterans with (PTSD+ n=12) and without (PTSD- n=8) chronic PTSD in a randomized, placebo-controlled, double-blind challenge. Changes in plasma ACTH, memory, and hippocampal [(18)F]FDG uptake on positron emission tomography were assessed. The low-dose dexamethasone suppression test was also administered. The PTSD+ group showed greater cortisol and ACTH suppression, reflecting greater peripheral glucocorticoid receptor (GR) responsiveness, and did not show an Hcort-induced decrement in delayed recall or retention. The groups had comparable relative regional hippocampal [(18)F]FDG uptake at baseline, but only the PTSD- group had an Hcort-associated decrease in hippocampal [(18)F]FDG uptake. Asymmetry in hippocampal hemispheric volumes differed between PTSD+ and PTSD- groups. This asymmetry was associated with cortisol, ACTH, retention and functional hippocampal asymmetry before, but not after, Hcort administration. Differences in brain metabolic responses between GW veterans with and without PTSD may reflect differences in peripheral and central GR responsiveness.

Beneficial Effects of Tianeptine on Hippocampus-Dependent Long-Term Memory and Stress-Induced Alterations of Brain Structure and Function

Tianeptine is a well-described antidepressant which has been shown to prevent stress from producing deleterious effects on brain structure and function. Preclinical studies have shown that tianeptine blocks stress-induced alterations of neuronal morphology and synaptic plasticity. Moreover, tianeptine prevents stress from impairing learning and memory, and, importantly, demonstrates memory-enhancing properties in the absence of stress. Recent research has indicated that tianeptine works by normalizing glutamatergic neurotransmission, a mechanism of action that may underlie its effectiveness as an antidepressant. These findings emphasize the value in focusing on the mechanisms of action of tianeptine, and specifically, the glutamatergic system, in the development of novel pharmacotherapeutic strategies in the treatment of depression.

Impaired off-line memory consolidation in depression

Sleep is critically involved in the consolidation of procedural memory. In major depression (MD) and during antidepressant pharmacotherapy, changes in sleep EEG are well documented. Here, we test if off-line motor memory consolidation is impaired in MD. 50 medicated patients with an acute episode of MD, 50 normal controls and 12 patients with a remitted episode of MD were assessed using a sequential finger tapping task before and after a night of sleep. Although depressed patients and control subjects did not differ in practice-dependent learning, healthy subjects showed markedly overnight improvements in tapping performance of 18% while patients failed to show any improvement. This pattern became even more striking when the subjects were divided by an age threshold of 30years: In the 30+yrs group the healthy subjects showed 16% overnight increase in motor performance, whereas the patients showed -10% overnight decrease. In contrast, patients and controls in the </=30yrs group showed virtually the same motor performance, as well as remitted patients and controls in the 30+yrs group. In addition, the younger controls showed stronger overnight improvements than the older controls. This pattern might be interpreted as a synergistic interaction between age and depression: Off-line motor memory consolidation is not affected in young patients, but severely impaired in older patients with an acute episode of MD. This impairment seems to recover after remission from depression.

Neuropsychological profiles in MCI and in depression: Differential cognitive dysfunction patterns or similar final common pathway disorder?

The concept of "mild cognitive impairment" (MCI) refers to alterations in cognition in the transition between normal aging and dementia. However, from a neuropsychological point of view the conventional diagnostic criteria appear not sufficiently valid. In particular, it is still difficult to differentiate between subjects with MCI and subjects with depression plus cognitive deficits on the basis of their neuropsychological profiles. The aim of this study is to compare cognitive deficit patterns of subjects with MCI and with depression. 24 subjects with MCI, 50 subjects with depression (DEP) and 20 healthy control subjects were included (age: 55-74years). The neuropsychological assessment consisted of standardized tests to assess attention, memory, and executive functions. Compared to healthy controls both subject groups showed significantly lower performance in all cognitive domains. However, we did not find significant differences in cognitive performance between MCI and DEP subjects, neither at baseline nor at follow-up. In addition, preliminary results of follow-up assessments after 2 (DEP) and 6months (MCI), respectively, revealed no significant changes in cognition in subjects with depression, regardless of whether depressive symptoms had improved. Subjects with MCI also showed no changes in cognition at follow-up. The comparable neuropsychological patterns identified in the two subject groups may be understood as a consequence of similar alterations in cognitive systems, supporting the idea of a final common pathway disorder. Thus, the cognitive deficits present in a subgroup of subjects with depression may possibly better be understood in the context of MCI.

Increased stress reactivity is associated with cognitive deficits and decreased hippocampal brain-derived neurotrophic factor in a mouse model of affective disorders

Cognitive deficits are a common feature of major depression (MD), with largely unknown biological underpinnings. In addition to the affective and cognitive symptoms of MD, a dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis is commonly observed in these patients. Increased plasma glucocorticoid levels are known to render the hippocampus susceptible to neuronal damage. This structure is important for learning and memory, creating a potential link between HPA axis dysregulation and cognitive deficits in depression. In order to further elucidate how altered stress responsiveness may contribute to the etiology of MD, three mouse lines with high (HR), intermediate (IR), or low (LR) stress reactivity were generated by selective breeding. The aim of the present study was to investigate whether increased stress reactivity is associated with deficits in hippocampus-dependent memory tests. To this end, we subjected mice from the HR, IR, and LR breeding lines to tests of recognition memory, spatial memory, and depression-like behavior. In addition, measurements of brain-derived neurotrophic factor (BDNF) in the hippocampus and plasma of these animals were conducted. Our results demonstrate that HR mice exhibit hippocampus-dependent memory deficits along with decreased hippocampal, but not plasma, BDNF levels. Thus, the stress reactivity mouse lines are a promising animal model of the cognitive deficits in MD with the unique feature of a genetic predisposition for an altered HPA axis reactivity, which provides the opportunity to explore the progression of the symptoms of MD, predisposing genetic factors as well as new treatment strategies.

The effects of perceived emotional distress on language performance in intractable epilepsy

We evaluated the potential moderating effect of emotional distress (Minnesota Multiphasic Personality Inventory 2, scales D and Pt) on language functioning (i.e., Boston Naming Test, phonemic paraphasic error production on the Boston Naming Test, Controlled Oral Word Association Task, Animal Naming, Token Test) in patients with left (N=43) and right (N=34) mesial temporal lobe epilepsy (MTLE) and frontal lobe epilepsy (FLE) (N=30). Video/EEG and brain imaging results confirmed localization. Logistic regression models revealed that perceived emotional distress moderated language performance. Performance of patients with left MTLE and that of patients with FLE were equally poor across language measures. Performance of patients with right MTLE was intact. Depression and anxiety differentially moderated performance. Anxiety was associated with better performance in patients with FLE on classically temporal lobe-mediated tasks (Boston Naming Test). Depression was associated with worse language performance on measures for which impaired performance was traditionally intrinsic to the underlying epileptogenic lesion (word fluency in FLE). Emotional distress influences language performance. Adequate treatment of mood should be considered when managing pharmacoresistant epilepsy.

Effects of acute cortisol administration on autobiographical memory in patients with major depression and healthy controls

OBJECTIVE

Overgeneral autobiographical memory has become a well established phenomenon within major depressive disorder (MDD). Neuroendocrinologically, MDD is often characterized by a dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis, i.e. hypercortisolemia and reduced feedback sensitivity. In healthy participants cortisol administration has been found to impair autobiographical memory retrieval. The purpose of this study was to compare the effects of acute cortisol administration on autobiographical memory in MDD patients with the effects observed in healthy controls. We hypothesized that in contrast to healthy control subjects acute cortisol administration would not affect autobiographical memory performance in MDD due to reduced central glucocorticoid sensitivity.

METHODS

In a placebo-controlled, double-blind crossover study, 16 patients with MDD and 16 healthy control subjects received a placebo or 10mg of hydrocortisone orally before autobiographical memory testing (AMT).

RESULTS

In the placebo condition depressed patients performed poorer than controls. After hydrocortisone intake, healthy subjects reported significantly fewer specific memories on the AMT compared to placebo treatment. In contrast, memory specificity of MDD patients was not affected by hydrocortisone treatment.

CONCLUSIONS

The present findings replicate previous findings of impaired autobiographical memory retrieval after hydrocortisone treatment in healthy subjects and of impaired AMT performance in depressed patients. We speculate that the missing acute impairing effect of hydrocortisone on autobiographical memory in depressed patients might reflect reduced central glucocorticoid sensitivity. However alternative explanations cannot be ruled out.

Effects of glucocorticoids on mood, memory, and the hippocampus. Treatment and preventive therapy

Corticosteroids, such as prednisone and dexamethasone, are commonly prescribed medications that suppress the immune system and decrease inflammation. Common side effects of long-term treatment with corticosteroids include weight gain, osteoporosis, and diabetes mellitus. This paper reviews the literature on psychiatric and cognitive changes during corticosteroid therapy and potential treatment options. Hypomania and mania are the most common mood changes during acute corticosteroid therapy, although depression has also been reported. However, depression is reported to be more common than mania during long-term treatment with corticosteroids. A decline in declarative and working memory is also reported during corticosteroid therapy. Corticosteroids are associated with changes in the temporal lobe, detected by structural, functional, and spectroscopic imaging. The mood and cognitive symptoms are dose dependent and frequently occur during the first few weeks of therapy. Other risk factors are not well characterized. Controlled trials suggest that lithium and phenytoin can prevent mood symptoms associated with corticosteroids. Lamotrigine and memantine also have been shown to reverse, at least partially, the declarative memory effects of corticosteroids. Uncontrolled trials suggest that antipsychotics, anti-seizure medications, and perhaps some antidepressants can also be useful for normalizing mood changes associated with corticosteroids. Thus, both the symptoms and treatment response are similar to those of bipolar disorder. Moreover, corticosteroid-induced mood and cognitive alterations have been shown to be reversible with dose reduction or discontinuation of treatment.

Risk factors for development of depression and psychosis. Glucocorticoid receptors and pituitary implications for treatment with antidepressant and glucocorticoids

Increased levels of glucocorticoid hormones-the main product of the hypothalamic-pituitary-adrenal (HPA) axis-have been considered to be "depressogenic," but this notion has largely derived from studies in patients with endocrine conditions, such as Cushing's syndrome or exogenous treatment with synthetic glucocorticoids. In these conditions, it is likely that the full impact of the high glucocorticoid levels is felt on the brain, through over-stimulation of the glucocorticoid receptors (GRs); indeed, normalizing these high levels leads to an improvement of mood in these patients. However, a completely different mechanism may be operating in major depression, where the increased levels of glucocorticoid hormones are conceptualized as driven by an impairment in GR function (glucocorticoid resistance), and therefore as a "compensatory" mechanism. Moreover, clinical and experimental studies have shown that antidepressants increase GR function, thus leading to resolution of glucocorticoid resistance. Interestingly, a number of studies have also demonstrated that manipulating GR function with both agonists and antagonists has an antidepressant effect, and indeed that other drugs targeting the HPA axis and cortisol secretion-even drugs with opposite effects on the HPA axis-have antidepressant effects. These studies do not support the notion that "high levels of glucocorticoids" always have a depressogenic effect, nor that decreasing the effects of these hormones always has an antidepressant effects.

Neuropsychological functioning in health and mood disorder: Modulation by glucocorticoids and their receptors

Numerous studies have shown that disturbances in hypothalamic-pituitary-adrenal (HPA) axis function and consequent hypercortisolaemia occur in a significant proportion of patients with mood disorders. This dysfunction has been proposed to be an exacerbating factor of depressive symptoms and may predict symptomatic relapse. Glucocorticoids are also known to have a specific role in learning and memory processes. In this review we present a brief overview of the relationship between HPA axis dysfunction and neuropsychological impairment in mood disorders and the specific links between glucocorticoids and cognition in health and illness states. Finally we examine the neuropsychological effects of drugs that specifically target glucocorticoid receptor function.

Prenatal psychosocial stress exposure is associated with subsequent working memory performance in young women

The aim of the present study was to examine the association between prenatal psychosocial stress exposure and subsequent prefrontal cortex-dependent working memory performance in human adults. Working memory performance was assessed using an item-recognition task under 10 mg hydrocortisone (cortisol) and placebo conditions in a sample of 32 healthy young women (mean age = 25 +/- 4.34 years) whose mothers experienced a major negative life event during their pregnancy (Prenatal Stress, PS group), and in a comparison group of 27 healthy young women (mean age = 24 +/- 3.4 years). The two groups did not differ in the placebo condition, however, subjects in the PS group showed longer reaction times after hydrocortisone administration compared with subjects in the comparison group (p = .02). These findings provide support for an association between prenatal stress exposure and the potential modulatory effect of cortisol on working memory performance in young adults, which may reflect compromised development of the prefrontal cortex in prenatal life.

Effects of major depression diagnosis and cortisol levels on indices of neurocognitive function

Although many studies have examined separately the effects of depression and cortisol on cognition, no study has examined their relative or potentially additive effects. Our study simultaneously investigated the contributions of clinical status [major depression (MD) versus psychiatrically healthy controls (HC)] and cortisol on a hippocampal/mediotemporal mediated verbal memory task (Paragraph Recall) and a prefrontal cortex/cingulate mediated executive functioning task (Stroop). Thirty-seven unmedicated nondelusional MDs and 18 HCs underwent psychiatric ratings, hourly assessments of cortisol activity over 24 h, and neuropsychological assessments. Hierarchical multiple regressions indicated a significant effect of cortisol but not of diagnosis on verbal memory. Greater cortisol levels were related to poorer memory performance independent of group. In contrast, a significant interaction between cortisol and diagnosis was found for a color-word index of response inhibition. This interaction suggests that the detrimental effect of elevated cortisol level on this type of executive functioning exists only in the healthy control group but not in MDs. On an Interference score, another measure of response inhibition, cortisol had a significant independent effect, but neither the effects of diagnosis and the interaction attained full significance. Our study suggests that cortisol has an independent effect on verbal memory. Also, our study produced evidence of an interaction between diagnosis and cortisol on response inhibition.

Cognitive impairment in unipolar depression is persistent and non-specific: further evidence for the final common pathway disorder hypothesis

BACKGROUND

Cognitive performance is often impaired in depression, and these impairments can persist even after remission from psychopathological symptoms. However, it is still unclear whether cognitive dysfunction is associated with psychopathological symptoms or represents a genuine disorder. This study examined cognitive performance in acute depression, after remission, and 6 months after remission in order to determine the nature and specificity of cognitive dysfunction as well as its relevance for the further course of depression.

METHOD

Assessments of cognitive function and psychopathology were carried out on admission and prior to discharge in 53 in-patients with unipolar depression. Twenty patients were retested 6 months after discharge. To correct for practice effects, 13 healthy subjects were included and assessed twice with the same cognitive tests.

RESULTS

In acute depression, we found impairments of information processing/attention, memory, and executive functions. Cognitive impairments remained in a high proportion of patients, even after remission of psychopathological symptoms. After correcting for practice effects, a significant improvement was observed only for some tests of executive functioning. Severity of depression was only weakly correlated with one single cognitive measure, indicating that psychopathological and neuropsychological symptoms are dissociable. Furthermore, we found no evidence for specific cognitive dysfunction.

CONCLUSIONS

Our results support the hypothesis that cognitive impairments in depression are neither selective nor specific; they have trait-like features and are, therefore, not merely an epiphenomenon of depression. Whether or not cognitive dysfunction is a prognostic marker for the course of depression remains still an open issue.

Emanuel Miller Lecture: early onset depressions--meanings, mechanisms and processes

BACKGROUND

Depressive syndromes in children and adolescents constitute a serious group of mental disorders with considerable risk for recurrence. A more precise understanding of aetiology is necessary to improve treatment and management.

METHODS

Three neuroactive agents are purported to be involved in the aetiology of these disorders: serotonin, brain-derived neurotrophic factor and cortisol. A literature review was conducted to determine their contributions to the emergence of unipolar depressions in the adolescent years.

RESULTS

Serotonin, brain-derived neurotrophic factor and cortisol may operate in concert within two distinct functional frameworks: atypical early epigenesis arising in the first few years of life and resulting in the formation of a vulnerable neuronal network involving in particular the amygdala and ventral prefrontal cortex. Individuals with this vulnerability are likely to show impaired mood regulation when faced with environmental demands during adolescence and over the subsequent decades; and acquired neuroendangerment, a pathological brain process leading to reduced synaptic plasticity, in particular in the hippocampus and perhaps the nucleus accumbens and ventral tegmentum. This may result in motivational, cognitive and behavioural deficits at any point in the lifespan most apparent at times of environmental demand.

CONCLUSIONS

The characteristics, course and outcome of a depressive episode may depend on the extent of the involvement of both atypical early neurogenesis and acquired neuroendangerment.

The impact of environmental risk factors on HIV-associated cognitive decline in children

Both the human immunodeficiency virus (HIV) and environmental stress have been independently associated with decreased cognitive functioning in children. Given that they are also known to have a strong relationship with each other, the present study sought to test the hypothesis that children in conditions of high environmental risk would be at greater risk for the cognitive complications related to immunosuppression. A retrospective review was conducted to examine the records of 141 children treated at a large pediatric AIDS clinic from 1993 to 2000. CD4+ lymphocyte levels were recorded from laboratory results and IQ scores were recorded from routine psychological evaluations. Key indicators of environmental risk were collected and combined into one measure of overall environmental risk. Pearson product moment correlations were conducted to examine the relationship between environmental risk, age-adjusted CD4 and IQ. Results indicated a significant correlation between CD4 and IQ, with higher levels of immunocompetence predicting higher IQ scores. When subjects were dichotomized based on their environmental risk score, there was no relationship between CD4 count and IQ in the low environmental risk group. In contrast, CD4 was positively associated with IQ in the high environmental risk group. It is proposed that this may be due to gp120 levels in immunocompromised children being particularly toxic to the hippocampus and cortex under conditions of high stress but not so under conditions of low stress.

Enhanced effects of cortisol administration on episodic and working memory in aging veterans with PTSD

Though both glucocorticoid alterations and memory impairments have been noted in posttraumatic stress disorder (PTSD), it is not clear if these phenomena are causally linked. As there is emerging evidence that these domains become further altered in PTSD with increasing age, it is of interest to examine these relationships in an older cohort. Aging (mean age, 62.7+/-8.9; range, 52-81) combat veterans with (n=13) and without (n=17) PTSD received an intravenous bolus of 17.5 mg hydrocortisone (cortisol), a naturally occurring glucocorticoid, or placebo in a randomized, double-blind manner, on two mornings approximately 1-2 weeks apart. Neuropsychological testing to evaluate episodic and working memory performance was performed 75 min later. Cortisol enhanced episodic memory performance in both groups of subjects, but enhanced elements of working memory performance only in the PTSD+ group. The preferential effect of cortisol administration on working memory in PTSD may be related to the superimposition of PTSD and age, as cortisol had impairing effects on this task in a previously studied, younger cohort. The findings suggest that there may be opportunities for developing therapeutic strategies using glucocorticoids in the treatment of aging combat veterans.

Persistent cognitive impairment in depression: the role of psychopathology and altered hypothalamic-pituitary-adrenocortical (HPA) system regulation

BACKGROUND

Dysregulation of the hypothalamic-pituitary-adrenocortical (HPA) system and cognitive impairment are consistent findings in depression. This study examines the associations between HPA system regulation, cognitive functioning, and psychopathology in depressed inpatients on admission and at discharge.

METHODS

The HPA system dysregulation was evaluated with the dexamethasone (DEX)/corticotropin-releasing hormone (CRH) test. Cognitive assessment included speed of information processing, divided and selective attention, as well as short-term and working memory. Psychopathology was evaluated with the Hamilton Rating Scale for Depression (HAMD). Data from 75 depressed inpatients are reported, 51 (68%) of them achieved remission.

RESULTS

Despite a significant reduction of depressive symptoms between admission and discharge, a high rate of patients remained cognitively impaired. Selective attention improved significantly in remitters and nonremitters, while speed of information processing increased only in remitters. The cortisol response to the DEX/CRH test decreased significantly only in remitters, which was uncorrelated with cognitive performance. In nonremitters, severity of depression was significantly correlated with information processing time while improvement in short-term memory was negatively associated with the cortisol response at discharge.

CONCLUSIONS

Our data support the assumption that psychopathological symptoms and the HPA system dysregulation can be dissociated in their impact on cognitive functioning in depressed patients.

Glucocorticoids Decrease Hippocampal and Prefrontal Activation during Declarative Memory Retrieval in Young Men

Glucocorticoids (GCs, cortisol in human) are associated with impairments in declarative memory retrieval. Brain regions hypothesized to mediate these effects are the hippocampus and prefrontal cortex (PFC). Our aim was to use fMRI in localizing the effects of GCs during declarative memory retrieval. Therefore, we tested memory retrieval in 21 young healthy males in a randomized placebo-controlled crossover design. Participants encoded word lists containing neutral and emotional words 1 h prior to ingestion of 20 mg hydrocortisone. Memory retrieval was tested using an old/new recognition paradigm in a rapid event-related design. It was found that hydrocortisone decreased brain activity in both the hippocampus and PFC during successful retrieval of neutral words. These observations are consistent with previous animal and human studies suggesting that glucocorticoids modulate both hippocampal and prefrontal brain regions that are crucially involved in memory processing. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s11682-007-9003-2) contains supplementary material, which is available to authorized users.

Structural and functional plasticity of the human brain in posttraumatic stress disorder

Posttraumatic stress disorder (PTSD) is associated with long-term changes in neurobiology. Brain areas involved in the stress response include the medial prefrontal cortex, hippocampus, and amygdala. Neurohormonal systems that act on the brain areas to modulate PTSD symptoms and memory include glucocorticoids and norepinephrine. Dysfunction of these brain areas is responsible for the symptoms of PTSD. Brain imaging studies show that PTSD patients have increased amygdala reactivity during fear acquisition. Other studies show smaller hippocampal volume. A failure of medial prefrontal/anterior cingulate activation with re-experiencing of the trauma is hypothesized to represent a neural correlate of the failure of extinction seen in PTSD. The brain has the capacity for plasticity in the aftermath of traumatic stress. Antidepressant treatments and changes in environment can reverse the effects of stress on hippocampal neurogenesis, and humans with PTSD showed increased hippocampal volume with both paroxetine and phenytoin.

The glucocorticoid receptor: part of the solution or part of the problem?

Clinical studies have demonstrated hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis and increased levels of cortisol in patients with major depression, because of an impairment of glucocorticoid receptor (GR)-mediated negative feedback (glucocorticoid resistance). Moreover, clinical and experimental studies have shown that antidepressants increase GR function, thus leading to resolution of glucocorticoid resistance. Interestingly, a number of studies have also demonstrated that manipulating GR function with both agonists and antagonists has an antidepressant effect, and indeed that other drugs targeting the HPA axis and cortisol secretion - even drugs with opposite effects on the HPA axis - have antidepressant effects. These studies do not support the notion that cortisol has 'negative' effects on the brain. On the contrary, this paper concludes that a lack of the 'positive' effects of cortisol on the brain, because of glucocorticoid resistance, is likely to be involved in the pathogenesis of depression.

Do corticosteroids damage the brain?

Corticosteroids are an essential component of the body's homeostatic system. In common with other such systems, this implies that corticosteroid levels in blood and, more importantly, in the tissues remain within an optimal range. It also implies that this range may vary according to circumstance. Lack of corticosteroids, such as untreated Addison's disease, can be fatal in humans. In this review, we are principally concerned with excess or disturbed patterns of circulating corticosteroids in the longer or shorter term, and the effects they have on the brain.

Effect of two prednisone exposures on mood and declarative memory

Corticosteroids are essential for life and an integral part of the stress response. However, in excess, corticosteroids can be associated with a variety of effects on the brain including hippocampal atrophy and even neuronal death, mood changes, and declarative memory impairment. The magnitude of mood change in patients receiving prednisone is reportedly associated with previous lifetime corticosteroid exposure, consistent with a sensitization or kindling process whereby greater effects are observed with repeated exposure. To our knowledge, the effect of multiple corticosteroid exposures on mood and memory has not been previously examined prospectively in animals or humans. In this study, 30 human volunteers, with no history of systemic prescription corticosteroid therapy, were given (in random order using a crossover design) two 3-day exposures of prednisone (60 mg/day) and one of identical placebo, with 11-day washouts between each medication exposure. Before and after each 3-day prednisone/placebo exposure, declarative memory was assessed using different versions of the Rey Auditory Verbal Learning Test (RAVLT) to minimize practice or learning effects, while mood was assessed with the 21-item Hamilton Rating Scale for Depression, Young Mania Rating Scale and Internal State Scale. No significant mood changes were found. However, a significant decrease in aspects of RAVLT performance was observed after the first prednisone exposure consistent with a decline in declarative memory performance. The decline in RAVLT performance was significantly smaller after the second prednisone exposure as compared to the initial prednisone exposure. Thus, a second prednisone exposure was associated with an attenuated prednisone-effect on declarative memory. These data suggest tolerance or habituation, rather than sensitization, to prednisone effects on declarative memory during a second exposure. Implications and possible explanations for the findings are discussed.