Neuropsychological impairment in bipolar disorder: the relationship with glucocorticoid receptor function

Neural functional connectivity changes to psychosocial stress in young adults with bipolar disorder and preliminary associations with clinical trajectories

BACKGROUND

Stress-related mechanisms are implicated in the pathophysiology of bipolar disorder and may contribute to heterogeneity in illness course. Yet, there is a lack of study investigating the neural mechanisms underlying the stress response in this condition. This study investigated changes in amygdala activation and functional connectivity in response to acute psychosocial stress in young adults with bipolar disorder and explored relations with clinical phenotype and prospective mood symptoms.

METHODS

42 young adults [19 with bipolar disorder, age_mean  ± SD =21.4 ± 2.2 years] completed a modified version of the Montreal Imaging Stress Task. Amygdala activation and functional connectivity with prefrontal cortex (PFC) regions of interest was calculated for control and stress conditions. Main effects of group, condition, and group by condition interaction on amygdala activation and connectivity were modeled. A subset of bipolar participants completed 1-year follow-up assessments. Relations between neural responses to stress with concurrent substance use and prospective mood symptoms were explored.

RESULTS

There were no between-group differences in amygdala activation or functional connectivity during the control condition. Increased right amygdala-right rostral PFC (rPFC) functional connectivity to stress was observed in bipolar disorder, compared to typically developing controls. In bipolar disorder, greater increase in right amygdala-right rPFC functional connectivity to stress was associated with less frequent cannabis use, and prospectively with shorter duration and lower severity of depression symptoms over follow-up.

CONCLUSION

Results from this preliminary study suggest differences in frontolimbic functional connectivity responses to stress in young adults with bipolar disorder and associations with cannabis use and prospective mood symptoms.

Cortisol to Dehydroepiandrosterone Sulphate Ratio and Executive Function in Bipolar Disorder

INTRODUCTION

Bipolar disorder (BD) is associated with impairment in cognitive domains such as verbal memory and executive functions. Very few studies have assessed dehydroepiandrosterone sulphate (DHEA-S) in BD and its relation to cognitive functioning despite evidence showing its regulatory effects on glucocorticoid action. The aim of our study was to explore the association of cortisol, DHEA-S, and cortisol to DHEA-S ratio with visuospatial memory and executive functioning in BD.

METHODS

Cognitive performance of 60 bipolar I patients and 30 healthy subjects was evaluated by using Cambridge Neuropsychological Test Automated Battery tasks targeting visuospatial memory (spatial recognition memory) and executive functions (planning [Stockings of Cambridge; SOC] and attentional set shifting [ID/ED]). Morning serum cortisol and DHEA-S levels were measured in patients. Main effects of cortisol, DHEA-S, and cortisol/DHEA-S ratio for each neurocognitive task were explored in multiple regression analyses correcting for demographic and clinical parameters as well as treatment-related factors (current use of antipsychotic and mood stabilizer medication).

RESULTS

Bipolar patients showed poorer performance than healthy subjects in planning and attentional set shifting but not in visuospatial memory. Cortisol to DHEA-S ratio predicted worse performance in planning (SOC).

CONCLUSIONS

This is the first study to assess memory and executive function in BD in relation to DHEA-S and cortisol to DHEA-S ratio. We report an association of cortisol to DHEA-S ratio with worse performance in planning in bipolar I patients, which warrants further investigation.

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.

Neuroendocrine Stress System in Bipolar Disorder

Hormones have a crucial part in the progress and manifestation of a wide variety of different behaviors. The main influence of the neuroendocrine system on behavior is its action on the neurobiology of neuropsychiatric disorders and its relationship with the pharmacodynamics of medicines. Of all the neuroendocrine axes, the hypothalamic-pituitary-adrenal (HPA) axis has been the most extensively studied. There is evidence that disturbance in the HPA axis, the primary stress hormone system, could increase treatment resistance and relapse, worsen illness outcome, and cause cognitive deficits. Glucocorticoids mediate their actions in negative feedback binding in two different cytoplasmatic receptors described as mineralocorticoid receptors (MRs) and glucocorticoid receptors (GRs). Different psychopathologies underlying bipolar disorders are supposed to involve persistent dysfunctions in the expression and role of both MR and GR in the hippocampus. We review and analyze the evidence related to the correlation between bipolar disorders and the consequences and impact of stressful life events on the HPA axis, exploring the importance of these findings in bipolar disorders and as potential new targets for treatment.

Predicted Cellular and Molecular Actions of Lithium in the Treatment of Bipolar Disorder: An In Silico Study

BACKGROUND

Lithium remains the first-line treatment for bipolar disorder (BD), but patients respond to it variably. While a myriad of studies have attributed many genes and signaling pathways to lithium responsiveness, a comprehensive study with an integrated conclusion is still lacking.

OBJECTIVE

We aim to present an integrated mechanism for the therapeutic actions of lithium in BD.

METHODS

First, a list of lithium responsiveness-associated genes (LRAGs) was collected by searching in the literature. Thereafter, gene set enrichment analysis together with gene-gene interaction network analysis was performed, in order to find the cellular and molecular events related to the LRAGs.

RESULTS

Gene set enrichment analyses showed that the chromosomal regions 3p26, 4p21, 5q34 and 7p13 could be novel associated loci for lithium responsiveness in BD. Also, expression pattern analysis of the LRAGs showed their enrichment in adulthood stages and different cell lineages of brain, blood and immune system. Most of the LRAGs exhibited enriched expression in central parts of human brain, suggesting major contribution of these parts in lithium responsiveness. Beside the prediction of several biological processes and signaling pathways related to lithium responsiveness, an interaction network between these processes was constructed that was found to be regulated by a set of microRNAs. Proteins of the network were mainly classified as transcription factors and kinases, which also highlighted the crucial role of glycogen synthase kinase 3β (GSK3β) in lithium responsiveness.

CONCLUSIONS

The predicted cellular and molecular events in this study could be considered as mechanisms and also determinants of lithium responsiveness in BD.

Proteomic Profiling as a Diagnostic Biomarker for Discriminating Between Bipolar and Unipolar Depression

INTRODUCTION

Affective disorders are a major global burden, with approximately 15% of people worldwide suffering from some form of affective disorder. In patients experiencing their first depressive episode, in most cases it cannot be distinguished whether this is due to bipolar disorder (BD) or major depressive disorder (MDD). Valid fluid biomarkers able to discriminate between the two disorders in a clinical setting are not yet available.

MATERIAL AND METHODS

Seventy depressed patients suffering from BD (bipolar I and II subtypes) and 42 patients with major MDD were recruited and blood samples were taken for proteomic analyses after 8 h fasting. Proteomic profiles were analyzed using the Multiplex Immunoassay platform from Myriad Rules Based Medicine (Myriad RBM; Austin, Texas, USA). Human DiscoveryMAPTM was used to measure the concentration of various proteins, peptides, and small molecules. A multivariate predictive model was consequently constructed to differentiate between BD and MDD.

RESULTS

Based on the various proteomic profiles, the algorithm could discriminate depressed BD patients from MDD patients with an accuracy of 67%.

DISCUSSION

The results of this preliminary study suggest that future discrimination between bipolar and unipolar depression in a single case could be possible, using predictive biomarker models based on blood proteomic profiling.

A pilot investigation of differential neuroendocrine associations with fronto-limbic activation during semantically-cued list learning in mood disorders

BACKGROUND

Decreased volume and disrupted function in neural structures essential for memory formation (e.g. medial temporal lobe and prefrontal cortex) are common among individuals with depression. Hypothalamic-pituitary-axis function, as reflected by measurement of cortisol levels, is linked to neural activity during memory encoding in healthy people. However, it is not as well understood whether cortisol is associated with alterations in fronto-temporal recruitment during memory encoding in depression.

METHODS

In this pilot study, we evaluated associations between cortisol and neural activation during memory encoding in 62 adults (18-65 years) with mood disorders (MD; n = 39, 66.7% female), including major depression (n = 28) and bipolar I disorder (n = 11), and healthy controls (HC; n = 23, 43.5% female). Participants provided salivary cortisol samples before and after completing a semantically-cued list-learning task during 3-Tesla fMRI. Links between pre-scan cortisol (and cortisol change) and activation during encoding were evaluated using block and event-related models.

RESULTS

Overall, pre-scan cortisol level was positively associated with greater engagement of fronto-limbic activation during the encoding block. However, in MD, pre-scan cortisol was associated with attenuated activation during encoding in medial frontal, superior and middle temporal gyri, insula, lingual gyrus, and claustrum relative to HCs. Cortisol-related attenuation of activation in MD was also observed during encoding of words subsequently recalled in the ventral anterior cingulate, hypothalamus, and middle temporal gyrus. By and large, cortisol change (pre/post scan) predicted the same pattern of findings in both block and event-related contrasts.

LIMITATIONS

Although analyses accounted for variations in scanner time of day, circadian alterations in cortisol may have introduced variability into the results.

CONCLUSIONS

Pre-scan cortisol may selectively interfere with recruitment of important fronto-temporal memory circuitry in mood disorders. The inverted associations between cortisol and neural function in MD relative to HC also elucidate potentially unique pathophysiological markers of mood disorders.

Hippocampal subfield volumes in children and adolescents with mood disorders

The hippocampus has been implicated in various mood disorders, with global volume deficits consistently found in patient populations. The hippocampus, however, consists of anatomically distinct subfields, and examination of specific subfield differences may elucidate the possible molecular mechanisms behind psychiatric pathologies. Indeed, adult studies have reported smaller hippocampal subfield volumes in regions within the cornu ammonis (CA1 and CA4), dentate gyrus (DG), and hippocampal tails in both patients with Major Depressive Disorder (MDD) and Bipolar Disorder (BD) compared to healthy controls. Subfield differences in pediatric patients with mood disorders, on the other hand, have not been extensively investigated. In the current study, magnetic resonance imaging scans were acquired for 141 children and adolescents between the ages of eight and eighteen (57 with BD, 30 with MDD, and 54 healthy controls). An automated segmentation method was then used to assess differences in hippocampal subfield volumes. Children and adolescents with BD were found to have significantly smaller volumes in the right CA1, CA4, and right subiculum, as well as the bilateral granule cell layer (GCL), molecular layer (ML), and hippocampal tails. The volume of the right subiculum in BD patients was also found to be negatively correlated with illness duration. Overall, the findings from this cross-sectional study provide evidence for specific hippocampal subfield volume differences in children and adolescents with BD compared to healthy controls and suggest progressive reductions with increased illness duration.

Staging in bipolar disorder: from theoretical framework to clinical utility

Illness staging is widely utilized in several medical disciplines to help predict course or prognosis, and optimize treatment. Staging models in psychiatry in general, and bipolar disorder in particular, depend on the premise that psychopathology moves along a predictable path: an at-risk or latency stage, a prodrome progressing to a first clinical threshold episode, and one or more recurrences with the potential to revert or progress to late or end-stage manifestations. The utility and validity of a staging model for bipolar disorder depend on its linking to clinical outcome, treatment response and neurobiological measures. These include progressive biochemical, neuroimaging and cognitive changes, and potentially stage-specific differences in response to pharmacological and psychosocial treatments. Mechanistically, staging models imply the presence of an active disease process that, if not remediated, can lead to neuroprogression, a more malignant disease course and functional deterioration. Biological elements thought to be operative in bipolar disorder include a genetic diathesis, physical and psychic trauma, epigenetic changes, altered neurogenesis and apoptosis, mitochondrial dysfunction, inflammation, and oxidative stress. Many available agents, such as lithium, have effects on these targets. Staging models also suggest the utility of stage-specific treatment approaches that may not only target symptom reduction, but also impede illness neuroprogression. These treatment approaches range from prevention for at-risk individuals, to early intervention strategies for prodromal and newly diagnosed individuals, complex combination therapy for rapidly recurrent illness, and palliative-type approaches for those at chronic, late stages of illness. There is hope that prompt initiation of potentially disease modifying therapies may preclude or attenuate the cognitive and structural changes seen in the later stages of bipolar disorder. The aims of this paper are to: a) explore the current level of evidence supporting the descriptive staging of the syndromal pattern of bipolar disorder; b) describe preliminary attempts at validation; c) make recommendations for the direction of further studies; and d) provide a distillation of the potential clinical implications of staging in bipolar disorder within a broader transdiagnostic framework.

Acute cortisol reactivity attenuates engagement of fronto-parietal and striatal regions during emotion processing in negative mood disorders

OBJECTIVE

Depression and bipolar disorder (negative mood disorders, NMD) are associated with dysregulated hypothalamic-pituitary-adrenal (HPA)-axis function and disrupted emotion processing. The neural networks involved in attenuation of HPA-axis reactivity overlap with the circuitry involved in perception and modulation of emotion; however, direct links between these systems are understudied. This study investigated whether cortisol activity prior to undergoing fMRI was related to neural processing of emotional information in participants with NMD.

METHODS

Forty-one adults (M_age=40.33, SD=15.57) with major depression (n=29) or bipolar disorder (n=12) and 23 healthy control comparisons (M_age=36.43, SD=17.33) provided salivary cortisol samples prior to completing a facial emotion perception test during 3-Tesla fMRI.

RESULTS

Overall, pre-scan cortisol level was positively associated with greater engagement of the dorsal anterior cingulate (dACC), inferior parietal lobule, insula, putamen, precuneus, middle and medial frontal and postcentral gyri, posterior cingulate, and inferior temporal gyrus during emotion processing of all faces. NMD status moderated this effect; in NMD participants' pre-scan cortisol was associated with attenuated activation of the insula, postcentral gyrus, precuneus, and putamen for fearful faces and the medial frontal gyrus for angry faces relative to HCs. Cortisol-related attenuation of activation among NMD participants was also observed for facial identification in the dACC, putamen, middle temporal gyrus, precuneus, and caudate.

CONCLUSIONS

Across all participants, cortisol was associated with greater activation in several regions involved in the perception and control of emotion. However, cortisol responsivity was associated with hypoactivation of several of these regions in the NMD group, suggesting that HPA-axis activity may selectively interfere with the potentially adaptive recruitment of circuits supporting emotion perception, processing and/or regulation in mood disorders.

The HPA axis in bipolar disorder: Systematic review and meta-analysis

OBJECTIVES

To provide a quantitative and qualitative synthesis of the available evidence on the role of Hypothalamic-Pituitary-Adrenal (HPA) axis in the pathophysiology of Bipolar Disorder (BD).

METHODS

Meta-analysis and meta-regression of case-control studies examining the levels of cortisol, ACTH, CRH levels. Systematic review of stress reactivity, genetic, molecular and neuroimaging studies related to HPA axis activity in BD.

RESULTS

Forty-one studies were included in the meta-analyses. BD was associated with significantly increased levels of cortisol (basal and post-dexamethasone) and ACTH, but not of CRH. In the meta-regression, case-control differences in cortisol levels were positively associated with the manic phase (p=0.005) and participants' age (p=0.08), and negatively with antipsychotics use (p=0.001). Reviewed studies suggest that BD is associated with abnormalities of stress-related molecular pathways in several brain areas. Variants of HPA axis-related genes seem not associated with a direct risk of developing BD, but with different clinical presentations. Also, studies on unaffected relatives suggest that HPA axis dysregulation is not an endophenotype of BD, but seems related to environmental risk factors, such as childhood trauma. Progressive HPA axis dysfunction is a putative mechanism that might underlie the clinical and cognitive deterioration of patients with BD.

CONCLUSIONS

BD is associated with dysfunction of HPA axis activity, with important pathophysiological implications. Targeting HPA axis dysfunctions might be a novel strategy to improve the outcomes of BD.

Increased Subsequent Risk of Peptic Ulcer Diseases in Patients With Bipolar Disorders

Previous studies have reported that patients with bipolar disorders (BDs) exhibit increased physical comorbidity and psychological distress. Studies have shown that schizophrenia and anxiety increase the risk of peptic ulcer diseases (PUDs). Therefore, we conducted this study to determine the association between these 2 diseases and examine the possible risk factors. We used patients diagnosed with BDs from the Taiwan National Health Insurance Research Database. A comparison cohort comprising patients without BDs was frequency matched by age, sex, and comorbidities, and the occurrence of PUDs was evaluated in both the cohorts. The BD and non-BD cohort consisted of 21,060 patients with BDs and 84,240 frequency-matched patients without BDs, respectively. The incidence of PUDs (hazard ratio, 1.51; 95% confidence interval, 1.43-1.59; P < 0.001) was higher among the patients with BDs than the control patients. Cox models showed that irrespective of comorbidities, BDs were an independent risk factor for PUDs. Patients with BDs exhibit a substantially higher risk for developing PUDs. According to our data, we suggest that, following a diagnosis of BD, practitioners could notice the occurrence of PUD and associated prevention. Further prospective clinical studies investigating the relationship between BDs and PUDs are warranted.

Hypothalamic-pituitary-adrenal axis dysfunction and illness progression in bipolar disorder

BACKGROUND

Impaired stress resilience and a dysfunctional hypothalamic-pituitary-adrenal (HPA) axis are suggested to play key roles in the pathophysiology of illness progression in bipolar disorder (BD), but the mechanisms leading to this dysfunction have never been elucidated. This study aimed to examine HPA axis activity and underlying molecular mechanisms in patients with BD and unaffected siblings of BD patients.

METHODS

Twenty-four euthymic patients with BD, 18 siblings of BD patients, and 26 healthy controls were recruited for this study. All subjects underwent a dexamethasone suppression test followed by analyses associated with the HPA axis and the glucocorticoid receptor (GR).

RESULTS

Patients with BD, particularly those at a late stage of illness, presented increased salivary post-dexamethasone cortisol levels when compared to controls (p = 0.015). Accordingly, these patients presented reduced ex vivo GR responsiveness (p = 0.008) and increased basal protein levels of FK506-binding protein 51 (FKBP51, p = 0.012), a co-chaperone known to desensitize GR, in peripheral blood mononuclear cells. Moreover, BD patients presented increased methylation at the FK506-binding protein 5 (FKBP5) gene. BD siblings presented significantly lower FKBP51 protein levels than BD patients, even though no differences were found in FKBP5 basal mRNA levels.

CONCLUSIONS

Our data suggest that the epigenetic modulation of the FKBP5 gene, along with increased FKBP51 levels, is associated with the GR hyporesponsiveness seen in BD patients. Our findings are consistent with the notion that unaffected first-degree relatives of BD patients share biological factors that influence the disorder, and that such changes are more pronounced in the late stages of the illness.

The effects of HPA axis function on cognition and its implications for the pathophysiology of bipolar disorder

Bipolar disorders (BDs) are common and complex diseases. Recent findings have provided the basis for an integrated approach linking seemingly disparate findings, based on a greater understanding of the effects of stress on those vulnerable to these illnesses and the brain's consequent responses. Genes are associated with this disorder, although their integration into current pathophysiological models is unclear. Manic states are associated with enhanced dopaminergic transmission, and experimental stress enhances dopamine neurotransmission and impairs cognition. Stress activates the hypothalamic-pituitary-adrenal axis, and dysfunction of this axis and impairments in neurocognitive function have both been demonstrated in BD. Glucocorticoid receptors are abnormal in postmortem brain studies in BD and play an important role in the HPA axis. The glucocorticoid receptor antagonist RU-486 has been shown to improve aspects of cognitive function in BD. The implications of these findings for models of pathophysiology are discussed. Future efforts should focus on further integrating the current and emerging research findings into a coherent pathophysiological model that generates testable hypotheses.

Applications of blood-based protein biomarker strategies in the study of psychiatric disorders

Major psychiatric disorders such as schizophrenia, major depressive and bipolar disorders are severe, chronic and debilitating, and are associated with high disease burden and healthcare costs. Currently, diagnoses of these disorders rely on interview-based assessments of subjective self-reported symptoms. Early diagnosis is difficult, misdiagnosis is a frequent occurrence and there are no objective tests that aid in the prediction of individual responses to treatment. Consequently, validated biomarkers are urgently needed to help address these unmet clinical needs. Historically, psychiatric disorders are viewed as brain disorders and consequently only a few researchers have as yet evaluated systemic changes in psychiatric patients. However, promising research has begun to challenge this concept and there is an increasing awareness that disease-related changes can be traced in the peripheral system which may even be involved in the precipitation of disease onset and course. Converging evidence from molecular profiling analysis of blood serum/plasma have revealed robust molecular changes in psychiatric patients, suggesting that these disorders may be detectable in other systems of the body such as the circulating blood. In this review, we discuss the current clinical needs in psychiatry, highlight the importance of biomarkers in the field, and review a representative selection of biomarker studies to highlight opportunities for the implementation of personalized medicine approaches in the field of psychiatry. It is anticipated that the implementation of validated biomarker tests will not only improve the diagnosis and more effective treatment of psychiatric patients, but also improve prognosis and disease outcome.

Pattern of heat shock factor and heat shock protein expression in lymphocytes of bipolar patients: increased HSP70-glucocorticoid receptor heterocomplex

Bipolar disorder (BD), a stress-related disease, is characterized by altered glucocorticoid receptor (GR) signalling. Stress response includes activation of heat shock factor (HSF) and subsequent heat shock protein (HSP) synthesis which regulate GR folding and function. The objective of this study was to investigate the possible role of HSFs, HSPs and their interaction with GR in BD. We applied immunoprecipitation, SDS-PAGE/Western blot analysis and electrophoretic mobility shift assay (EMSA) in lymphocytes (whole cell or nuclear extracts) from BD patients and healthy subjects and determined the HSPs (HSP90 and HSP70), the heterocomplexes HSP90-GR and HSP70-GR, the HSFs (HSF1 and HSF4) as well as the HSF-DNA binding. The HSP70-GR heterocomplex was elevated (p < 0.05) in BD patients vs healthy subjects, and nuclear HSP70 was reduced (p ≤ 0.01) in bipolar manic patients. Protein levels of HSF1, HSF4, HSP90, HSP90-GR heterocomplex, and HSF-DNA binding remained unaltered in BD patients vs healthy subjects. The corresponding effect sizes (ES) indicated a large ES for HSP70-GR, HSP70, HSF-DNA binding and HSF4, and a medium ES for HSP90, HSF1 and HSP90-GR between healthy subjects and bipolar patients. Significant correlations among HSFs, HSPs, GR and HSP70-GR heterocomplex were observed in healthy subjects, which were abrogated in bipolar patients. The higher interaction between GR and HSP70 and the disturbances in the relations among heat shock response parameters and GR as observed in our BD patients may provide novel insights into the contribution of these factors in BD aetiopathogenesis.

Hippocampal and amygdala volumes in an older bipolar disorder sample

BACKGROUND

Brain volumetric magnetic resonance imaging (MRI) studies of adult bipolar disorder samples, compared with healthy controls, have reported conflicting results in hippocampal and amygdala volumes. Among these, few have studied older bipolar samples, which would allow for examination of the effects of greater duration in mood episodes on brain volumes. The aim of this study was to compare hippocampal and amygdala volumes in older bipolar patients with controls.

METHODS

High-resolution MRI scans were used to determine hippocampal and amygdala volumes that were manually traced using established protocols in 18 euthymic patients with DSM-IV bipolar I disorder (mean age 57 years) and 21 healthy controls (mean age 61 years). Analysis of covariance (ANCOVA) was used to explore group differences while controlling for intracranial volume (ICV), age, sex, and years of education.

RESULTS

While gray matter, white matter, and cerebrospinal fluid volumes did not differ between the groups, bipolar disorder patients had smaller ICV (t = 2.54, p = 0.015). After correcting for ICV, the bipolar group had smaller hippocampal (left hippocampus F = 13.944, p = 0.001; right hippocampus F = 10.976, p = 0.002; total hippocampus F = 13.566; p = 0.001) and right amygdala (F = 13.317, p = 0.001) volumes. Total hippocampal volume was negatively associated with the duration of depressive (r = -0.636; p = 0.035) and manic (r = -0.659; p = 0.027) episodes, but not lithium use. Amygdala volumes were not associated with the duration of mood episodes.

CONCLUSIONS

Older bipolar disorder patients had smaller hippocampal and amygdala volumes. That smaller hippocampal volume was associated with the duration of mood episodes may suggest a neuroprogressive course related to the severity of the disorder.

A randomized trial to examine the effect of mifepristone on neuropsychological performance and mood in patients with bipolar depression

BACKGROUND

Deficits in neuropsychological performance are found in patients with bipolar disorder and represent a potential treatment target for novel therapeutic strategies. We have previously demonstrated a beneficial effect on spatial working memory (SWM) of treatment for 1 week with the progesterone and glucocorticoid receptor antagonist mifepristone, evident 2 weeks after the cessation of treatment.

METHODS

We examined the longer-term efficacy of 600 mg/day of mifepristone as an adjunctive treatment, for 1 week, in a placebo-controlled, randomized, double-blind trial in 60 patients with bipolar depression, with SWM as the primary outcome measure. A comparator group of healthy control subjects was also recruited.

RESULTS

At baseline, neuropsychological performance of patients was impaired, but hypothalamic-pituitary-adrenal axis function did not differ from that of control subjects. Mifepristone treatment was associated with a time-limited increase in cortisol awakening response and with a sustained improvement in SWM performance, which was evident 7 weeks after the cessation of treatment. The magnitude of this neuropsychological response was predicted by the magnitude of the cortisol response to mifepristone. The response occurred in the absence of a significant improvement in depressed mood.

CONCLUSIONS

These data accord with the findings of animal studies and demonstrate that brief treatment with mifepristone is associated with a sustained improvement in SWM, an effect that might be mediated by a persistent enhancement in hippocampal mineralocorticoid receptor function.

Bipolar disorder: clinical perspectives and implications with cognitive dysfunction and dementia

Introduction. Cognitive dysfunction as a core feature in the course of bipolar affective disorder (BPD) is a current subject of debate and represents an important source of psychosocial and functional burden. Objectives. To stand out the connection and clinical implications between cognitive dysfunction, dementia, and BPD. Methods. A nonsystematic review of all English language PubMed articles published between 1995 and 2011 using the terms "bipolar disorder," "cognitive dysfunction," and "dementia". Discussion. As a manifestation of an affective trait or stage, both in the acute phases and in remission, the domains affected include attention, executive function, and verbal memory. The likely evolution or overlap with the behavioural symptoms of an organic dementia allows it to be considered as a dementia specific to BPD. This is named by some authors, as BPD type VI, but others consider it a form of frontotemporal dementia. It is still not known if this process is neurodevelopmental or neurodegenerative in nature, or both simultaneously. The assessment should consider the iatrogenic effects of medication, the affective symptoms, and a neurocognitive evaluation. Conclusion. More specific neuropsychological tests and functional imaging studies are needed and will assume an important role in the near future for diagnosis and treatment.

Glucocorticoid receptors in the prefrontal cortex regulate stress-evoked dopamine efflux and aspects of executive function

Enhanced dopamine efflux in the prefrontal cortex is a well-documented response to acute stress. However, the underlying mechanism(s) for this response is unknown. Using in vivo microdialysis, we demonstrate that blocking glucocorticoid receptors locally within the rat prefrontal cortex results in a reduction in stress-evoked dopamine efflux. In contrast, blocking glucocorticoid receptors in the ventral tegmental area did not affect stress-evoked dopamine efflux in the prefrontal cortex. Additionally, local administration of corticosterone into the prefrontal cortex increased prefrontal dopamine efflux. The functional impact of enhanced dopamine efflux evoked by acute stress was demonstrated using a cognitive task dependent on the prefrontal cortex and sensitive to impairment in working memory. Notably, stress-induced impairments in cognition were attenuated by blockade of glucocorticoid receptors in the prefrontal cortex. Taken together, these data demonstrate that glucocorticoids act locally within the prefrontal cortex to modulate mesocortical dopamine efflux leading to the cognitive impairments observed during acute stress.

11β-hydroxysteroid dehydrogenases and the brain: from zero to hero, a decade of progress

Glucocorticoids have profound effects on brain development and adult CNS function. Excess or insufficient glucocorticoids cause myriad abnormalities from development to ageing. The actions of glucocorticoids within cells are determined not only by blood steroid levels and target cell receptor density, but also by intracellular metabolism by 11β-hydroxysteroid dehydrogenases (11β-HSD). 11β-HSD1 regenerates active glucocorticoids from their inactive 11-keto derivatives and is widely expressed throughout the adult CNS. Elevated hippocampal and neocortical 11β-HSD1 is observed with ageing and causes cognitive decline; its deficiency prevents the emergence of cognitive defects with age. Conversely, 11β-HSD2 is a dehydrogenase, inactivating glucocorticoids. The major central effects of 11β-HSD2 occur in development, as expression of 11β-HSD2 is high in fetal brain and placenta. Deficient feto-placental 11β-HSD2 results in a life-long phenotype of anxiety and cardiometabolic disorders, consistent with early life glucocorticoid programming.

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.

Hypothalamic-pituitary-adrenal axis abnormalities in response to deletion of 11beta-HSD1 is strain-dependent

Inter-individual differences in hypothalamic-pituitary-adrenal (HPA) axis activity underlie differential vulnerability to neuropsychiatric and metabolic disorders, although the basis of this variation is poorly understood. 11beta-Hydroxysteroid dehydrogenase type 1 (11beta-HSD1) has previously been shown to influence HPA axis activity. 129/MF1 mice null for 11beta-HSD1 (129/MF1 HSD1(-/-)) have greatly increased adrenal gland size and altered HPA activity, consistent with reduced glucocorticoid negative feedback. On this background, concentrations of plasma corticosterone and adrenocorticotrophic hormone (ACTH) were elevated in unstressed mice, and showed a delayed return to baseline after stress in HSD1-null mice with reduced sensitivity to exogenous glucocorticoid feedback compared to same-background genetic controls. In the present study, we report that the genetic background can dramatically alter this pattern. By contrast to HSD1(-/-) mice on a 129/MF1 background, HSD1(-/-) mice congenic on a C57Bl/6J background have normal basal plasma corticosterone and ACTH concentrations and exhibit normal return to baseline of plasma corticosterone and ACTH concentrations after stress. Furthermore, in contrast to 129/MF1 HSD1(-/-) mice, C57Bl/6J HSD1(-/-) mice have increased glucocorticoid receptor expression in areas of the brain involved in glucocorticoid negative feedback (hippocampus and paraventricular nucleus), suggesting this may be a compensatory response to normalise feedback control of the HPA axis. In support of this hypothesis, C57Bl/6J HSD1(-/-) mice show increased sensitivity to dexamethasone-mediated suppression of peak corticosterone. Thus, although 11beta-HSD1 appears to contribute to regulation of the HPA axis, the genetic background is crucial in governing the response to (and hence the consequences of) its loss. Similar variations in plasticity may underpin inter-individual differences in vulnerability to disorders associated with HPA axis dysregulation. They also indicate that 11beta-HSD1 inhibition does not inevitably activate the HPA axis.

Phosphorylation status of glucocorticoid receptor, heat shock protein 70, cytochrome c and Bax in lymphocytes of euthymic, depressed and manic bipolar patients

Bipolar disorder (BD), a severe mental illness, has been correlated with alterations in glucocorticoid receptor (GR) signaling. Since it is phosphorylated GR that contributes to receptor function and determines its transcriptional activity, the Ser211 being a biomarker for activated GR in vivo, it is pertinent that we seek to determine the putative role of the total phosphorylation status of GR and site-specific phosphorylation at serine 211 (S211) in BD and their possible association with parameters of apoptosis. In lymphocytes from 48 BD patients under multiple psychotropic therapy and 20 healthy subjects, we measured whole cell GR, total GR phosphorylation, and phosphorylation of GR at serine 211 in nucleus, using immunoprecipitation, phosphospecific antibody and Western-blot analysis. Cytosolic cytochrome c and Bax and whole cell HSP70 were determined by immunoblot analysis. One-way ANOVA statistical analysis was carried out. Total phosphorylated GR was lower (P<0.001) while the GR S211 was higher (P<0.001) in all BD patients as compared to healthy subjects. HSP70 was reduced in euthymic (P<0.05), depressed (P<0.001) and manic (P<0.001) as compared to healthy subjects. Cytochrome c was higher in all-patient groups as compared to healthy subjects, however without reaching statistical significance (P>0.05). Bax levels were lower in the cytosolic fraction of all three BD groups. We provide the first evidence of altered GR phosphorylation joined with signs of apoptosis in lymphocytes of BD patients and suggest that the phosphorylation status of GR may play a role in the pathophysiology of bipolar disorder.

Neurobiological trait abnormalities in bipolar disorder

Dissecting trait neurobiological abnormalities in bipolar disorder (BD) from those characterizing episodes of mood disturbance will help elucidate the aetiopathogenesis of the illness. This selective review highlights the immunological, neuroendocrinological, molecular biological and neuroimaging abnormalities characteristic of BD, with a focus on those likely to reflect trait abnormalities by virtue of their presence in euthymic patients or in unaffected relatives of patients at high genetic liability for illness. Trait neurobiological abnormalities of BD include heightened pro-inflammatory function and hypothalamic-pituitary-adrenal axis dysfunction. Dysfunction in the intracellular signal transduction pathway is indicated by elevated protein kinase A activity and altered intracellular calcium signalling. Consistent neuroimaging abnormalities include the presence of ventricular enlargement and white matter abnormalities in patients with BD, which may represent intermediate phenotypes of illness. In addition, spectroscopy studies indicate reduced prefrontal cerebral N-acetylaspartate and phosphomonoester concentrations. Functional neuroimaging studies of euthymic patients implicate inherently impaired neural networks subserving emotional regulation, including anterior limbic, ventral and dorsal prefrontal regions. Despite heterogeneous samples and conflicting findings pervading the literature, there is accumulating evidence for the existence of neurobiological trait abnormalities in BD at various scales of investigation. The aetiopathogenesis of BD will be better elucidated by future clinical research studies, which investigate larger and more homogenous samples and employ a longitudinal design to dissect neurobiological abnormalities that are underlying traits of the illness from those related to episodes of mood exacerbation or pharmacological treatment.

Cellular mechanisms underlying affective resiliency: the role of glucocorticoid receptor- and mitochondrially-mediated plasticity

Bipolar disorder (BPD) is a devastating psychiatric illness marked by recurrent episodes of mania and depression. While the underlying pathophysiology of BPD remains elusive, an abnormal hypothalamic-pituitary-adrenal (HPA) axis and dysfunctional glucocorticoid receptor (GR) signaling are considered hallmarks. This review will examine how targeting resiliency signaling cascades at the cellular level may serve as a mechanism to treat BPD. Here, cellular resiliency is defined as the ability of a cell to adapt to an insult or stressor. Such resiliency at the cellular level could confer resiliency at the systems level and, ultimately, help individuals to cope with stressors or recover from depressive or manic states. This review will focus on four molecular targets of mood stabilizers that are known to play integral roles in these cellular resiliency signaling pathways: (1) B-cell CLL/lymphoma 2 (Bcl-2), (2) Bcl-2-associated athanogene (BAG-1), (3) glucocorticoid receptors (GRs), and (4) 51 kDa FK506-binding protein (FKBP5). These targets have emerged from neurobiological and human genetic studies and employ mechanisms that modulate GR function or promote anti-apoptotic processes critical to affective resilience. Future research should focus on elucidating sustainable treatments that target resiliency factors-such as BAG-1 or FKBP5-which could ultimately be used to treat individuals suffering from BPD and prevent relapses in afflicted individuals. Further identification of resiliency and susceptibility factors will also be vital. Ultimately, these developments would allow for the treatment of susceptible individuals prior to the development of BPD.

Effect of aspirin on hypothalamic-pituitary-adrenal function and on neuropsychological performance in healthy adults: a pilot study

RATIONALE

Hypothalamic-pituitary-adrenal axis dysregulation predicts poor clinical and biochemical response to antidepressants. Antiglucocorticoids have therapeutic benefits but most have a troublesome adverse event profile. Aspects of neuropsychological performance, notably working memory, are susceptible to corticosteroid modulation and are impaired in depression. Aspirin has been shown to attenuate the adrenocorticotropic hormone (ACTH) and cortisol response to physiological challenge suggesting its potential to act as an augmenting agent in depression.

OBJECTIVES

To examine the effect of sub-acute (300 mg daily for 7 days) aspirin pre-treatment on the cortisol awakening response and the effect of acute (600 mg) and sub-acute aspirin on the neuroendocrine and neuropsychological response to the arginine vasopressin analogue, desmopressin.

RESULTS

We demonstrated that aspirin pre-treatment did not attenuate the cortisol or ACTH response to desmopressin but, as hypothesised, significantly reduced the cortisol awakening response and improved working memory.

CONCLUSIONS

Further studies to examine the impact of aspirin on neuropsychological performance and HPA axis function are warranted.

Neurocognitive impairment in bipolar disorder patients: functional implications

BACKGROUND

Functional recovery among treated bipolar disorder (BPD) patients is far less likely than syndromal and even symptomatic recovery. We hypothesized that increasingly well-documented aspects of cognitive impairment may contribute to poor functional outcomes in BPD patients, and reviewed the available research on the topic.

METHODS

Computerized literature searching identified 12 studies with 13 comparisons that simultaneously evaluated cognitive and functional status in euthymic (n = 8) or non-euthymic (n = 5 comparisons) adult BPD patients versus otherwise similar healthy controls.

RESULTS

In 6/8 studies of euthymic BPD patients and 5/5 studies of non-euthymic BPD patients, neurocognitive impairment was significantly associated with impaired psychosocial functioning, even after adjusting for residual mood symptoms and relevant demographic and clinical variables. Cognitive status was consistently assessed with standardized, performance-based neuropsychological tests, but functional status usually was based on subjective self-appraisals. Approximately 55% of BPD patients were unemployed.

CONCLUSIONS

Available studies are limited by subjective assessments of functional status rather than objective, performance-based measures. Nevertheless, they support the hypothesis that enduring aspects of cognitive impairment found even in euthymic BPD patients are associated with inferior functioning. These findings encourage further studies with better assessment methods and greater rehabilitative efforts in BPD patients.

Suicide behavior and neuropsychological assessment of type I bipolar patients

BACKGROUND

Neuropsychological deficits are often described in patients with bipolar disorder (BD). Some symptoms and/or associated characteristics of BD can be more closely associated to those cognitive impairments. We aimed to explore cognitive neuropsychological characteristics of type I bipolar patients (BPI) in terms of lifetime suicide attempt history.

METHOD

We studied 39 BPI outpatients compared with 53 healthy controls (HC) matched by age, educational and intellectual level. All subjects were submitted to a neuropsychological assessment of executive functions, decision-making and declarative episodic memory.

RESULTS

When comparing BDI patients, regardless of suicide attempt history or HC, we observed that bipolar patients performed worse than controls on measures of memory, attention, executive functions and decision-making. Patients with a history of suicide attempt performed worse than non-attempters on measures of decision-making and there were a significant negative correlation between the number of suicide attempts and decision-making results (block 3 and net score). We also found significant positive correlation between the number of suicide attempts and amount of errors in Stroop Color Word Test (part 3).

LIMITATIONS

The sample studied can be considered small and a potentially confounding variable - medication status - were not controlled.

CONCLUSION

Our results show the presence of neuropsychological deficits in memory, executive functions, attention and decision-making in BPI patients. Suicide attempts BPI scored worse than non-suicide attempt BPI on measures of decision-making. More suicide attempts were associated with a worse decision-making process. Future research should explore the relationship between the association between this specific cognitive deficits in BPIs, serotonergic function and suicide behavior in bipolar patients as well other diagnostic groups.

Cognitive dysfunction in bipolar disorder: future place of pharmacotherapy

Bipolar disorder is an episodic affective illness, once believed to involve complete inter-episode remission. More recent data have highlighted the presence of persistent symptoms during purported periods of wellness, including subsyndromal affective symptoms and neurocognitive impairment. These unremitting symptoms are of extreme clinical importance, as they are directly related to a worsening of clinical course, functional impairments and psychosocial difficulties in patients with bipolar disorder. Although there is now substantial evidence demonstrating the prevalence of neurocognitive impairment during euthymia, there have been few studies, to date, targeting this disabling aspect of the illness using pharmacological strategies. While treatment approaches have previously focused on primary affective and psychotic symptoms of the disease, it is important to consider the debilitating impact that impaired cognition has on patients with bipolar disorder. A recent focus has been placed on the significant need for large-scale clinical trials designed to specifically target cognitive impairment in patients with schizophrenia, with a parallel need existing in the field of bipolar research. There is now early evidence for the presence of neurocognitive deficits in patients with bipolar disorder and a relationship between these impairments and functional disability, making this a symptom domain that requires immediate clinical attention. Convergent data indicate a compelling need for formal assessment of cognition in patients with bipolar disorder, and for researchers and clinicans alike to consider the necessity for treatment specific to cognition in this population. Although limited data exist from cognitive enhancement trials in this population, there are a number of potential pharmacotherapy targets based on evidence from neuroimaging, molecular genetic, pharmacological and animal studies related to the pathophysiology of bipolar disorder. Future directions for potential cognitive enhancement strategies in bipolar disorder may include medications that influence dopaminergic or glutamatergic neurotransmission; however, further work is needed to adequately assess the safety and effectiveness of these agents in bipolar patients. Finally, psychosocial intervention and/or cognitive remediation should be considered as alternatives to medications, although these techniques will also require additional systematic study.

Genotype and childhood sexual trauma moderate neurocognitive performance: a possible role for brain-derived neurotrophic factor and apolipoprotein E variants

BACKGROUND

Limited success in the identification of genetic variants underpinning psychiatric illness has prompted attempts to elucidate gene-environment interactions and illness-associated endophenotypes. Here we measured childhood sexual abuse, a potential environmental risk factor, and verbal and visual recall and recognition memory, a possible illness-associated endophenotype in a cohort of bipolar disorder (BPD) subjects and their relatives. We predicted that memory would be affected by sexual trauma and that a number of functional polymorphisms previously implicated in BPD and cognition would moderate the effect of psychological trauma on memory.

METHODS

A cohort of 350 individuals from 47 BPD families was recruited, tested with a neuropsychological battery, and given the Childhood Trauma Questionnaire (CTQ). Eleven different genetic variants previously found to be relevant to BPD or memory dysfunction were typed.

RESULTS

As predicted, scores on the sexual abuse scale of the CTQ were negatively associated with memory performance. Furthermore, the low-activity Met allele of the brain-derived neurotrophic factor (BDNF) gene and the epsilon4 allele of the apolipoprotein E gene interacted with sexual abuse scores to result in reduced memory test performance.

CONCLUSIONS

Apolipoprotein E and BDNF exert a neurotrophic effect in response to cellular injury. Their possible moderation of the association between sexual abuse and memory performance might indicate that there is some degree of overlap in the pathophysiological mechanisms by which psychological and physical trauma impact brain function. The finding of an environmental effect on memory performance and a gene-environment interaction on this hypothetical endophenotype of BPD illustrates the difficulty of identifying genetically and phenotypically simple intermediate traits for molecular genetic studies.

Overexpressing the glucocorticoid receptor in forebrain causes an aging-like neuroendocrine phenotype and mild cognitive dysfunction

Repeated stress enhances vulnerability to neural dysfunction that is cumulative over the course of the lifespan. This dysfunction contributes to cognitive deficits observed during aging. In addition, aging is associated with dysregulation of the limbic-hypothalamic-pituitary-adrenal (LHPA) axis, leading to a delayed termination of the stress response. This delay, in turn, increases exposure to glucocorticoids and exacerbates the likelihood of neural damage. Here we asked whether similar effects could emerge at an early age as a result of genetic variations in the level or function of the brain glucocorticoid receptor (GR). We investigated the effect of forebrain-specific overexpression of GR on LHPA axis activity. Transgenic mice with GR overexpression in forebrain (GRov) display normal basal circulating adrenocorticotropic hormone and corticosterone levels. However, young GRov mice exhibit a number of LHPA alterations, including a blunted initial response to acute restraint stress followed by a delayed turn-off of the stress response. This deficit in negative feedback is paradoxical in the face of elevated GR levels, resembles the stress response in aged animals, and continues to worsen as GRov mice age. The neuroendocrine dysregulation in young GRov mice is coupled with a mild cognitive deficit, also consistent with the accelerated aging hypothesis. The molecular basis of this phenotype was examined using microarray analysis of the hippocampus, which revealed a broad downregulation of glutamate receptor signaling in GRov mice. Thus, even in the absence of chronic stress, elevation of GR gene expression can lead to an increased allostatic load and result in an "aging-like" phenotype in young animals.

Neuropsychological impairment in major depression: its nature, origin and clinical significance

Neuropsychological impairment is well established as a feature of major depressive disorder (MDD) but studies have shown a variable pattern of impairment. This paper seeks first to clarify this by examining methodological and clinical factors that give rise to variability in study findings. Second, it examines theories of the origin of these neuropsychological abnormalities. Third, it reviews evidence regarding the clinical significance of different patterns of deficit. A selective review was undertaken of the literature with a particular emphasis on methodological factors, the influence of clinical subtypes and prevalent theories of neuropsychological abnormality. Methodological issues and the heterogeneity of MDD account for considerable variability in results. Specific investigation of the subtypes of psychotic MDD, melancholic MDD and bipolar depression reduces this heterogeneity and results are more consistent in the elderly. Hypothalamic-pituitary-adrenal axis dysfunction is associated with neuropsychological dysfunction in MDD although evidence of direct causation is not definitive at present. Impairment of executive and psychomotor function is a consistent finding, particularly in the elderly, and may reflect frontostriatal-limbic dysfunction. There is growing evidence that this may have clinical significance. It is suggested that future research take very careful account of the exact phenotype of MDD. Classification based on neuropsychological profile may, in fact, be useful. Further research should examine further the clinical importance of patterns of neuropsychological impairment.

Abnormalities of the HPA axis in affective disorders: clinical subtypes and potential treatments

BACKGROUND

New evidence is emerging regarding abnormalities of hypothalamic-pituitary-adrenal (HPA) axis function in subtypes of affective disorders. Adverse effects of HPA axis dysregulation may include dysfunction of monoaminergic transmitter systems, cognitive impairment and peripheral effects. Newer treatments specifically targeting the HPA axis are being developed.

OBJECTIVE

To review these developments focusing particularly on the glucocorticoid receptor (GR) antagonist mifepristone.

METHOD

A selective review of the literature.

RESULTS

The function of GRs is increasingly being defined. The role of corticotrophin-releasing hormone (CRH) and dehydroepiandrosterone (DHEA) in the brain is also increasingly understood. HPA axis function is particularly likely to be abnormal in psychotic depression and bipolar disorder, and it is in these conditions that trials of the GR antagonist mifepristone are being focused. CRH antagonists and DHEA are also being investigated as potential treatments.

CONCLUSION

Initial studies of mifepristone and other HPA-axis-targeting agents in psychotic depression and bipolar disorder are encouraging and confirmatory studies are awaited.

Rational approaches to the neurobiologic study of youth at risk for bipolar disorder and suicide

OBJECTIVES

The aims of this paper are to provide an overview of neuroimaging findings specific to bipolar disorder and suicide, and to consider rational approaches to the design of future in vivo studies in youth at risk.

METHODS

Neuroimaging and related neurobiological literature pertaining to bipolar disorder and suicide in adult and pediatric samples was reviewed in a non-quantitative manner.

RESULTS

Specific structural and functional brain findings in bipolar disorder are described, where possible in the context of relevant current neurobiological theories of etiology. Diagnostic and prognostic implications are discussed.

CONCLUSIONS

The simultaneous use of complementary neurobiological approaches may be a powerful way of identifying and validating factors reliably associated with bipolar disorder and suicide. A profile of neurobiological markers with which to screen for bipolar disorder and suicide risk may provide for earlier and more accurate diagnosis, perhaps even in the pre- or subsyndromal stages in high-risk youth.