A systemic toxicity index developed to assess peripheral changes in mood episodes

The conundrum of the connection between severe psychiatric disorders and dementia

Psychiatric disorders have been recognized as important risk factors for neurodegenerative diseases, especially dementia. The strength of association varies among different psychiatric conditions, being more pronounced in severe mental illnesses, i.e., schizophrenia and bipolar disorder. Multiple mechanisms seem to underlie this association, such as high prevalence of cardiovascular and other physical morbidities, poor lifestyle choices, and accelerated aging, including 'inflammaging'. They all represent opportunities for intervention, but it is still unclear whether current therapeutic approaches for psychiatric disorders can prevent the development of dementia. Other knowledge gaps include whether the risk of dementia applies to all patients with a certain condition, or if subgroups of patients are more vulnerable than others, whether different types of dementia are linked to specific psychiatric disorders.

Exploring Clinical Subgroups of Participants with Major Depressive Disorder that may Benefit from Adjunctive Minocycline Treatment

Objective

: To explore illness-related factors in patients with major depressive disorder (MDD) recipients of adjunctive minocycline (200 mg/day) treatment. The analysis included participants experiencing MDD from a 12-week, double blind, placebo-controlled, randomized clinical trial (RCT).

Methods

: This is a sub-analysis of a RCT of all 71 participants who took part in the trial. The impact of illness chronicity (illness duration and number of depressive episodes), systemic illness (endocrine, cardiovascular and obesity), adverse effects and minocycline were evaluated as change from baseline to endpoint (12-week) using ANCOVA.

Results

: There was a consistent but statistically non-significant trend on all outcomes in favour of the use of adjunctive minocycline for participants without systemic illness, less illness chronicity, and fewer adverse effects.

Conclusion

: Understanding the relationship between MDD and illness chronicity, comorbid systemic illness, and adverse effects, can potentially better characterise those individuals who are more likely to respond to adjunctive anti-inflammatory medications.

Therapeutic Interventions to Mitigate Mitochondrial Dysfunction and Oxidative Stress–Induced Damage in Patients with Bipolar Disorder

Bipolar disorder (BD) is characterized by mood changes, including recurrent manic, hypomanic, and depressive episodes, which may involve mixed symptoms. Despite the progress in neurobiological research, the pathophysiology of BD has not been extensively described to date. Progress in the understanding of the neurobiology driving BD could help facilitate the discovery of therapeutic targets and biomarkers for its early detection. Oxidative stress (OS), which damages biomolecules and causes mitochondrial and dopamine system dysfunctions, is a persistent finding in patients with BD. Inflammation and immune dysfunction might also play a role in BD pathophysiology. Specific nutrient supplements (nutraceuticals) may target neurobiological pathways suggested to be perturbed in BD, such as inflammation, mitochondrial dysfunction, and OS. Consequently, nutraceuticals may be used in the adjunctive treatment of BD. This paper summarizes the possible roles of OS, mitochondrial dysfunction, and immune system dysregulation in the onset of BD. It then discusses OS-mitigating strategies that may serve as therapeutic interventions for BD. It also analyzes the relationship between diet and BD as well as the use of nutritional interventions in the treatment of BD. In addition, it addresses the use of lithium therapy; novel antipsychotic agents, including clozapine, olanzapine, risperidone, cariprazine, and quetiapine; and anti-inflammatory agents to treat BD. Furthermore, it reviews the efficacy of the most used therapies for BD, such as cognitive–behavioral therapy, bright light therapy, imagery-focused cognitive therapy, and electroconvulsive therapy. A better understanding of the roles of OS, mitochondrial dysfunction, and inflammation in the pathogenesis of bipolar disorder, along with a stronger elucidation of the therapeutic functions of antioxidants, antipsychotics, anti-inflammatory agents, lithium therapy, and light therapies, may lead to improved strategies for the treatment and prevention of bipolar disorder.

Differences in mitochondrial DNA copy number between patients with bipolar I and II disorders

Mitochondria play a critical role in energy metabolism. Genetic, postmortem brain, and brain imaging studies of bipolar disorder (BD) patients indicated that mitochondrial dysfunction might explain BD pathophysiology. Mitochondrial function can be indirectly evaluated by measuring mitochondrial DNA (mtDNA) copy numbers. We recruited 186 bipolar I disorder (BD1) and 95 bipolar II disorder (BD2) patients, and age- and sex-matched controls. MtDNA copy numbers in peripheral blood cells were measured via quantitative polymerase chain reaction. We explored parameters (including age and clinical features) that might affect mtDNA copy numbers. We found that BD1 patients had a lower mtDNA copy number than controls and that mtDNA copy number was negatively associated with the number of mood episodes. BD2 patients had a higher mtDNA copy number than controls. Thus, changes in mitochondrial function may influence BD pathophysiology. The opposite directions of the association with mtDNA copy number in BD1 and BD2 patients suggests that the difference in pathophysiology may be associated with mitochondrial function.

Mitochondrial dysfunction as a critical event in the pathophysiology of bipolar disorder

The understanding of the pathophysiology of bipolar disorder (BD) remains modest, despite recent advances in neurobiological research. The mitochondrial dysfunction hypothesis of bipolar disorder has been corroborated by several studies involving postmortem brain analysis, neuroimaging, and specific biomarkers in both rodent models and humans. Evidence suggests that BD might be related to abnormal mitochondrial morphology and dynamics, neuroimmune dysfunction, and atypical mitochondrial metabolism and oxidative stress pathways. Mitochondrial dysfunction in mood disorders is also associated with abnormal Ca2+ levels, glutamate excitotoxicity, an imbalance between pro- and antiapoptotic proteins towards apoptosis, abnormal gene expression of electron transport chain complexes, and decreased ATP synthesis. This paper aims to review and discuss the implications of mitochondrial dysfunction in BD etiology and to explore mitochondria as a potential target for novel therapeutic agents.

Concepts of Neuroinflammation and Their Relationship With Impaired Mitochondrial Functions in Bipolar Disorder

Bipolar disorder (BD) is a chronic psychiatric disease, characterized by frequent behavioral episodes of depression and mania, and neurologically by dysregulated neurotransmission, neuroplasticity, growth factor signaling, and metabolism, as well as oxidative stress, and neuronal apoptosis, contributing to chronic neuroinflammation. These abnormalities result from complex interactions between multiple susceptibility genes and environmental factors such as stress. The neurocellular abnormalities of BD can result in gross morphological changes, such as reduced prefrontal and hippocampal volume, and circuit reorganization resulting in cognitive and emotional deficits. The term "neuroprogression" is used to denote the progressive changes from early to late stages, as BD severity and loss of treatment response correlate with the number of past episodes. In addition to circuit and cellular abnormalities, BD is associated with dysfunctional mitochondria, leading to severe metabolic disruption in high energy-demanding neurons and glia. Indeed, mitochondrial dysfunction involving electron transport chain (ETC) disruption is considered the primary cause of chronic oxidative stress in BD. The ensuing damage to membrane lipids, proteins, and DNA further perpetuates oxidative stress and neuroinflammation, creating a perpetuating pathogenic cycle. A deeper understanding of BD pathophysiology and identification of associated biomarkers of neuroinflammation are needed to facilitate early diagnosis and treatment of this debilitating disorder.

Neuroprogression as an Illness Trajectory in Bipolar Disorder: A Selective Review of the Current Literature

Bipolar disorder (BD) is a chronic and disabling psychiatric condition that is linked to significant disability and psychosocial impairment. Although current neuropsychological, molecular, and neuroimaging evidence support the existence of neuroprogression and its effects on the course and outcome of this condition, whether and to what extent neuroprogressive changes may impact the illness trajectory is still poorly understood. Thus, this selective review was aimed toward comprehensively and critically investigating the link between BD and neurodegeneration based on the currently available evidence. According to the most relevant findings of the present review, most of the existing neuropsychological, neuroimaging, and molecular evidence demonstrates the existence of neuroprogression, at least in a subgroup of BD patients. These studies mainly focused on the most relevant effects of neuroprogression on the course and outcome of BD. The main implications of this assumption are discussed in light of specific shortcomings/limitations, such as the inability to carry out a meta-analysis, the inclusion of studies with small sample sizes, retrospective study designs, and different longitudinal investigations at various time points.

Biological Pathways Associated with Neuroprogression in Bipolar Disorder

There is evidence suggesting clinical progression in a subset of patients with bipolar disorder (BD). This progression is associated with worse clinical outcomes and biological changes. Molecular pathways and biological markers of clinical progression have been identified and may explain the progressive changes associated with this disorder. The biological basis for clinical progression in BD is called neuroprogression. We propose that the following intertwined pathways provide the biological basis of neuroprogression: inflammation, oxidative stress, impaired calcium signaling, endoplasmic reticulum and mitochondrial dysfunction, and impaired neuroplasticity and cellular resilience. The nonlinear interaction of these pathways may worsen clinical outcomes, cognition, and functioning. Understanding neuroprogression in BD is crucial for identifying novel therapeutic targets, preventing illness progression, and ultimately promoting better outcomes.

Exploring the Evidence Implicating the Renin-Angiotensin System (RAS) in the Physiopathology of Mood Disorders

Mood disorders include Major Depressive Disorder (MDD), Bipolar Disorder (BD) and variations of both. Mood disorders has a public health significance with high comorbidity, suicidal mortality and economic burden on the health system. Research related to mood disorders has evolved over the years to relate it with systemic conditions. The Renin Angiotensin System (RAS) has been noticed to play major physiological roles beyond renal and cardiovascular systems. Recent studies have linked RAS not only with neuro-immunological processes, but also with psychiatric conditions like mood and anxiety disorders. In this comprehensive review, we integrated basic and clinical studies showing the associations between RAS and mood disorders. Animal studies on mood disorders models - either depression or mania - were focused on the reversal of behavioral and/or cognitive symptoms through the inhibition of RAS components like the Angiotensin- Converting Enzyme (ACE), Angiotensin II Type 1 receptor (AT1) or Mas receptors. ACE polymorphisms, namely insertion-deletion (I/D), were linked to mood disorders and suicidal behavior. Hypertension was associated with neurocognitive deficits in mood disorders, which reversed with RAS inhibition. Low levels of RAS components (renin activity or aldosterone) and mood symptoms improvement with ACE inhibitors or AT1 blockers were also observed in mood disorders. Overall, this review reiterates the strong and under-researched connection between RAS and mood disorders.

Association of pro-inflammatory cytokines with clinical features in euthymic patients with Bipolar-I-Disorder

BACKGROUND

A chronic low-grade inflammatory state appears to be a relevant mechanism in the pathophysiology of bipolar disorder. Pro-inflammatory cytokines may influence disease course and individual symptomatology; and biological markers correlating with illness features may be of utility in clinical decision making during euthymia.

METHODS

51 euthymic outpatients with Bipolar-I-Disorder (BD-I) and 93 healthy controls (HC) were investigated. Comparisons between groups, and correlations with clinical features were performed. Serum concentrations of interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and soluble interleukin-6 receptor (sIL-6R) were evaluated by ELISA under highly standardized conditions. Clinical features included duration of illness, number of previous suicide attempts and mood episodes (manic, hypomanic, depressive), scores of the Young Mania Rating Scale (YMRS), the Inventory of Depressive Symptoms (IDS-30), the Pittsburg Sleep Quality Index (PSQI), and the Global Assessment of Functioning (GAF).

RESULTS

No significant difference in serum concentrations of IL-1β, TNF-α, and sIL-6R between BD-I euthymic patients and HC could be identified. Among euthymic BD-I patients, a positive correlation of r_s = 0.47 (p = 0.004) between levels of IL-1β and IDS-30 score was identified.

LIMITATIONS

The design was cross-sectional, most patients were receiving medication, only 3 cytokines were assessed, only euthymic BD-I patients were evaluated.

CONCLUSIONS

The findings suggest that elevated pro-inflammatory cytokine concentrations are likely state rather than trait markers of BD-I. It also seems unlikely that cytokine concentrations are clinically informative interepisode. An inflammatory component might possibly be involved in the pathophysiology of subsyndromic depression in BD-I, and conceivably of bipolar depression per se.

Relationship between allostatic load and clinical outcomes in youth at ultra-high risk for psychosis in the NEURAPRO study

Individuals at ultra-high risk (UHR) for psychosis have an elevated risk of developing psychosis and other psychiatric outcomes. Risk biomarkers can assist in delineating individual risk and allow better prediction of longer-term outcomes. The aim of the present study was to examine if allostatic load (AL), a multisystem index of neuroendocrine, cardiovascular, immune and metabolic dysregulation, is associated with clinical outcomes in youth at UHR for psychosis. AL was measured in 106 participants of the NEURAPRO study (n = 70 female, n = 36 male; mean age 17.21, SD 2.37), a multicentre randomized-controlled trial of long-chain omega-3 polyunsaturated fatty acids versus placebo in people at UHR for psychosis. Psychiatric symptoms and social and occupational functioning were assessed at baseline and 6 and 12 months after study intake. Multivariate linear and logistic regression models were used to test the relationship between AL and clinical outcomes. High AL at baseline was associated with poor social and occupational functioning at 6 months (β = -0.224, p = 0.025) and with more severe manic symptoms at 6 months (β = 0.207, p = 0.026), taking into account relevant covariates including age and smoking status. No significant associations were observed at the 12-month follow-up assessment or with any other clinical outcome measures. Our data provide initial evidence for a link between AL and impaired functioning in individuals at UHR for psychosis. Further studies are needed to evaluate AL as a potential predictor of early treatment response.

Are remitted affective disorders and familial risk of affective disorders associated with metabolic syndrome, inflammation and oxidative stress? - a monozygotic twin study

BACKGROUND

Metabolic syndrome (MetS) is associated with reduced life expectancy in patients with affective disorders, however, whether MetS also plays a role before the onset of affective disorder is unknown. We aimed to investigate whether MetS, inflammatory markers or oxidative stress act as risk factors for affective disorders, and whether MetS is associated with increased inflammation and oxidative stress.

METHODS

We conducted a high-risk study including 204 monozygotic (MZ) twins with unipolar or bipolar disorder in remission or partial remission (affected), their unaffected co-twins (high-risk) and twins with no personal or family history of affective disorder (low-risk). Metabolic Syndrome was ascertained according to the International Diabetes Federation (IDF) criteria. Inflammatory markers and markers of oxidative stress were analyzed from fasting blood and urine samples, respectively.

RESULTS

The affected and the high-risk group had a significantly higher prevalence of MetS compared to the low-risk group (20% v. 15% v. 2.5%, p = 0.0006), even after adjusting for sex, age, smoking and alcohol consumption. No differences in inflammatory and oxidative markers were seen between the three groups. Further, MetS was associated with alterations in inflammatory markers, and oxidative stress was modestly correlated with inflammation.

CONCLUSION

Metabolic syndrome is associated with low-grade inflammation and may act as a risk factor and a trait marker for affective disorders. If confirmed in longitudinal studies, this suggests the importance of early intervention and preventive approaches targeted towards unhealthy lifestyle factors that may contribute to later psychopathology.

Number of episodes in bipolar disorder: The case for more thoughtful conceptualization and measurement

OBJECTIVES

Number of mood episodes (NoE) may be an important prognostic indicator in bipolar disorder, with implications for treatment. However, NoE has been conceptualized and measured inconsistently throughout the literature. This review examines the construct of NoE in bipolar disorder, with the aim of enhancing its conceptualization and measurement.

METHODS

A critical evaluation of literatures on important correlates of NoE, conceptually and phenomenologically overlapping features, and previous studies considering and measuring this construct was undertaken.

RESULTS

The literature indicates that despite frequent use, NoE has been inconsistently defined and measured. Multiple studies have linked NoE with important clinical factors, including relapse, functioning, cognitive impairment and the effectiveness of both pharmacological and psychosocial interventions, yet conclusions are limited by its inconsistent treatment. Additionally, it seems evident that that NoE may best be treated as a fuzzy construct (rather than precise figure), with yet to be defined overlaps with clinical variables such as age at onset and severity. Attempts to measure this construct have varied in comprehensiveness and structure.

CONCLUSIONS

The NoE construct may have important implications for individuals with bipolar disorders. However, more consistent and systematic definition and assessment of NoE is required to advance this literature and clarify its role. Recommendations aimed at advancing the conceptualization and the measurement of NoE are provided. Conceptualization may be advanced by considering and exploring relationships between NoE and factors with which it overlaps, while measurement may best be improved with increased consistency and balancing accuracy with feasibility.

Differential biomarker signatures in unipolar and bipolar depression: A machine learning approach

OBJECTIVE

This study used machine learning techniques combined with peripheral biomarker measurements to build signatures to help differentiating (1) patients with bipolar depression from patients with unipolar depression, and (2) patients with bipolar depression or unipolar depression from healthy controls.

METHODS

We assessed serum levels of interleukin-2, interleukin-4, interleukin-6, interleukin-10, tumor necrosis factor-α, interferon-γ, interleukin-17A, brain-derived neurotrophic factor, lipid peroxidation and oxidative protein damage in 54 outpatients with bipolar depression, 54 outpatients with unipolar depression and 54 healthy controls, matched by sex and age. Depressive symptoms were assessed using the Hamilton Depression Rating Scale. Variable selection was performed with recursive feature elimination with a linear support vector machine kernel, and the leave-one-out cross-validation method was used to test and validate our model.

RESULTS

Bipolar vs unipolar depression classification achieved an area under the receiver operating characteristics (ROC) curve (AUC) of 0.69, with 0.62 sensitivity and 0.66 specificity using three selected biomarkers (interleukin-4, thiobarbituric acid reactive substances and interleukin-10). For the comparison of bipolar depression vs healthy controls, the model retained five variables (interleukin-6, interleukin-4, thiobarbituric acid reactive substances, carbonyl and interleukin-17A), with an AUC of 0.70, 0.62 sensitivity and 0.7 specificity. Finally, unipolar depression vs healthy controls comparison retained seven variables (interleukin-6, Carbonyl, brain-derived neurotrophic factor, interleukin-10, interleukin-17A, interleukin-4 and tumor necrosis factor-α), with an AUC of 0.74, a sensitivity of 0.68 and 0.70 specificity.

CONCLUSION

Our findings show the potential of machine learning models to aid in clinical practice, leading to more objective assessment. Future studies will examine the possibility of combining peripheral blood biomarker data with other biological data to develop more accurate signatures.

Emotional memory in bipolar disorder: Impact of multiple episodes and childhood trauma

BACKGROUND

Emotional memory is a critical amygdala-dependent cognitive function characterized by enhanced memory for emotional events coupled with retrograde amnesia. Our study aims to assess the influence of bipolar disorder (BD), trauma, and the number of mood episodes on emotional memory.

METHODS

53 subjects (33 euthymic patients with BD and 20 healthy controls) answered a clinical assessment, childhood trauma questionnaire (CTQ), and an emotional memory test composed of lists of nouns, including neutral words, one emotional (E), one preceding (E-1) and one following word (E + 1). We assessed for the influence of type, position, diagnosis, trauma, and number of mood episodes in word recall using generalized estimating equations.

RESULTS

Controlling for neutral words, BD had a higher recall for E-1 (p = 0.038) and a trend for a higher recall of E (p = 0.055). There was no difference between patients with and without trauma. Patients with BD who suffered multiple mood episodes had a higher recall of E compared to patients with fewer episodes (p = 0.016).

LIMITATIONS

Cross-sectional design and small sample size.

CONCLUSION

Our results indicate dysfunction in emotional memory in patients with BD, particularly after multiple mood episodes. While we expected an impaired emotional memory, patients with BD showed an increased recall for emotional stimuli and events preceding them. Childhood trauma does not seem to interfere with emotional memory changes in patients with BD. Emotional memory enhancement seems to be a promising marker of progression in BD.

A review on shared clinical and molecular mechanisms between bipolar disorder and frontotemporal dementia

Mental disorders are highly prevalent and important causes of medical burden worldwide. Co-occurrence of neurological and psychiatric symptoms are observed among mental disorders, representing a challenge for their differential diagnosis. Psychiatrists and neurologists have faced challenges in diagnosing old adults presenting behavioral changes. This is the case for early frontotemporal dementia (FTD) and bipolar disorder. In its initial stages, FTD is characterized by behavioral or language disturbances in the absence of cognitive symptoms. Consequently, patients with the behavioral subtype of FTD (bv-FTD) can be initially misdiagnosed as having a psychiatric disorder, typically major depression disorder (MDD) or bipolar disorder (BD). Bipolar disorder is associated with a higher risk of dementia in older adults and with cognitive impairment, with a subset of patients presents a neuroprogressive pattern during the disease course. No mendelian mutations were identified in BD, whereas three major genetic causes of FTD have been identified. Clinical similarities between BD and bv-FTD raise the question whether common molecular pathways might explain shared clinical symptoms. Here, we reviewed existing data on clinical and molecular similarities between BD and FTD to propose biological pathways that can be further investigated as common or specific markers of BD and FTD.

White matter volume is decreased in bipolar disorder at early and late stages

Abstract Introduction: Bipolar disorder (BD) is a debilitating mood condition that affects approximately 1.3% of people worldwide, although some studies report up to 3.9% lifetime prevalence and 4-6% in adults when broad diagnostic criteria are applied. Objective: To compare differences in total white matter (WM), corpus callosum (CC) and total gray matter (GM) volumes in patients with type I BD at early and late stages compared with controls. Methods: Fifty-five subjects were enrolled in this study protocol. The double case-control design included 14 patients with BD at early stage; 15 patients at late stage; and their respective matched controls (14 and 12 subjects). Results: CC and total WM volumes were significantly smaller in patients with BD at early and late stages vs. controls. There was no difference for total GM volume in the early stage group, but in patients at late stage total GM volume was significantly smaller than in controls. The total GM volume reduction in patients at late stage is in agreement with the neuroprogression theory of BD. The reduction of WM volumes in total WM and in the CC at early and late stages supports the possibility that an early demyelination process could occur underlying the clinical manifestation of BD. Conclusion: Our findings may direct to the investigation of WM abnormalities in populations at high risk to develop BD, perhaps as early biomarkers before the overt syndrome.

Biomarkers for bipolar disorder: current status and challenges ahead

INTRODUCTION

Bipolar disorder (BD) is a chronic psychiatric disorder marked by clinical and pathophysiological heterogeneity. There is a high expectation that personalized approaches can improve the management of patients with BD. For that, identification and validation of potential biomarkers are fundamental. Areas covered: This manuscript will critically review the current status of different biomarkers for BD, including peripheral, genetic, neuroimaging, and neurophysiological candidates, discussing the challenges to move the field forward. Expert commentary: There are no lab or complementary tests currently recommended for the diagnosis or management of patients with BD. Panels composed by multiple biomarkers will probably contribute to stratifying patients according to their clinical stage, therapeutic response, and prognosis.

The Staging of Major Mood Disorders: Clinical and Neurobiological Correlates

OBJECTIVE

Staging of psychiatric disorders is gaining momentum and the purpose of this review is to examine whether major mood disorders can be defined according to stages.

METHODS

In April 2018 the PubMed electronic data base was scrutinized by a combination of various search terms like "major depressive disorder and staging," "bipolar disorder and neuroprogression," etc. To incorporate the latest findings the search was limited to the last 10 years. Both original and review articles were examined by reading the abstracts, and papers which were found to be particularly applicable were read in full and their reference lists were also consulted.

RESULTS

A significant increase occurred in the number of papers published on the topic of staging of mood disorders. Staging formats were found for both major mood disorders, with the caveat that many more articles were discovered for bipolar disorder. Current evidence points to allostatic load and neuroprogression as the basis for staging of mood disorders.

CONCLUSION

Principal affective illnesses may be characterized by distinct stages, for instance early, intermediate and late. These phases inform the management so that clinicians should incorporate the staging schema into everyday practice and implement treatment strategies according to the phase of the illness.

Differential mitochondrial DNA copy number in three mood states of bipolar disorder

BACKGROUND

Accumulating evidences indicated that mitochondrial abnormalities were associated with bipolar disorder. As a sensitive index of mitochondrial function and biogenesis, Mitochondrial DNA copy number (mtDNAcn) may be involved in the pathophysiology of bipolar disorder.

METHODS

Leukocyte relative mtDNAcn was measured by quantitative polymerase chain reaction in subjects with BD (n = 131) in manic, depressive, and euthymic symptoms. Thirty-four healthy individuals were used as comparison control. BD clinical symptomatology was evaluated by Young Mania Rating Scale (YMRS), Hamilton Depression Scale (HAM-D), Clinical Global Impression-Bipolar Disorder-Severity of Illness Scale (CGI-BD-S), and the Positive and Negative Syndrome Scale (PANSS).

RESULTS

Compared to healthy controls, BD patients with manic and depressive symptoms presented significantly decreased mtDNAcn levels (p-value = 0.009 and 0.041, respectively). No significant differences were detected in mtDNAcn between euthymic patients and healthy controls. The mtDNAcn was negatively correlated with the number of relapses in manic patients (β = - 0.341, p = 0.044).

CONCLUSIONS

Our study described the first evidence of (1) a significant decline of mtDNAcn in manic BD patients, (2) a similar decreased level of mtDNAcn between manic and depressed BD patients, (3) a negative correlation of mtDNAcn with number of relapses in patients suffering from manic states. Alterations of mtDNAcn in manic and depressed patients, which may reflect disturbances of energy metabolism, supported the role of mitochondrial abnormalities in the pathophysiology of BD.

Allostatic load is associated with psychotic symptoms and decreases with antipsychotic treatment in patients with schizophrenia and first-episode psychosis

Current pathophysiological models of schizophrenia suggest that stress contributes to the etiology and trajectory of the disorder. We investigated if allostatic load (AL), an integrative index of neuroendocrine, immune and metabolic dysregulation in response to chronic stress, is elevated in patients with schizophrenia (SCZ) and first-episode psychosis (FEP) and related to psychotic symptoms and social and occupational functioning. Additionally, we assessed the temporal dynamics of AL in response to treatment with second-generation antipsychotics. AL, psychotic symptoms and psychosocial functioning were assessed in a longitudinal design in patients with SCZ (n = 28), FEP (n = 28), and healthy controls (n = 53) at baseline and 6 and 12 weeks after commencement of antipsychotic therapy. AL at baseline was higher in patients with SCZ and FEP relative to controls, but not different between patients with SCZ and FEP. Adjusting for age and smoking, we found that positive symptoms were positively correlated with AL and psychosocial functioning was negatively correlated with AL at trend level. Linear mixed model analysis demonstrated that AL decreased after treatment was commenced in patients with SCZ and FEP between the baseline assessment and the 6 and 12-week follow-up. AL was not predictive of treatment response or symptomatic remission. Our data provide evidence for cumulative physiological dysregulation in patients with SCZ and FEP that is linked to the experience of current positive psychotic symptoms. AL could be a useful tool to monitor biological signatures related to chronic stress and unhealthy behaviors in schizophrenia.

Blood-based biomarkers predicting response to antidepressants

Major depressive disorder is a common, serious and in some cases, life-threatening condition and affects approximately 350 million people globally. Although there is effective treatment available for it, more than 50% of the patients fail to respond to the first antidepressant they receive. The selection of a distinct treatment is still exclusively based on clinical judgment without incorporating lab-derived objective measures. However, there is growing evidence of biomarkers that it helps to improve diagnostic processes and treatment algorithms. Here genetic markers and blood-based biomarkers of the monoamine pathways, inflammatory pathways and the hypothalamic-pituitary-adrenal (HPA) axis are reviewed. Promising findings arise from studies investigating inflammatory pathways and immune markers that may identify patients suitable for anti-inflammatory based treatment regimes. Next, an early normalization of a disturbed HPA axis or depleted neurotrophic factors may predict stable treatment response. Genetic markers within the serotonergic system may identify patients who are vulnerable because of stressful life events, but evidence for guiding treatment regimes still is inconsistent. Therefore, there is still a great need for studies investigating and validating biomarkers for the prediction of treatment response to facilitate the treatment selection and shorten the time to remission and thus provide personalized medicine in psychiatry.

Neuron-glia Interaction as a Possible Pathophysiological Mechanism of Bipolar Disorder

Accumulating evidence has shown the importance of glial cells in the neurobiology of bipolar disorder. Activated microglia and inflammatory cytokines have been pointed out as potential biomarkers of bipolar disorder. Indeed, recent studies have shown that bipolar disorder involves microglial activation in the hippocampus and alterations in peripheral cytokines, suggesting a potential link between neuroinflammation and peripheral toxicity. These abnormalities may also be the biological underpinnings of outcomes related to neuroprogression, such as cognitive impairment and brain changes. Additionally, astrocytes may have a role in the progression of bipolar disorder, as these cells amplify inflammatory response and maintain glutamate homeostasis, preventing excitotoxicity. The present review aims to discuss neuron-glia interactions and their role in the pathophysiology and treatment of bipolar disorder.

Neuroimmune Biomarkers in Mental Illness

Exploration of neuroimmune mechanisms is vital to the understanding of the pathogenesis and pathophysiology of mental disorders. Inflammatory and immune mechanisms are increasingly understood to underpin a number of neuropsychiatric disorders, with an ever-expanding evidence base drawn from basic science to large-scale epidemiological data. Unravelling of these mechanisms should lead to biomarker discovery and potential new avenues for therapeutics that modulate immunological mechanisms. Identification of neuroimmune biomarkers is vital to improving diagnosis, stratification and treatment of mental disorders. There is an urgent clinical need for new therapeutic approaches with poor treatment response and treatment resistance a major problem for many psychiatric disorders including depression and schizophrenia. Neurodegenerative psychiatric disorders such as Alzheimer's also have clear neuroimmune underpinnings and manifest an urgent clinical need for improvements in diagnosis and research towards transformative disease-modifying treatments. This chapter provides some background on the role of the neuroimmune system in mental illness, exploring the role for biomarkers, in addition to reviewing the current state of knowledge in this exciting field. We also reflect on the inherent challenges and methodological pitfalls faced by research in this field, including the complexity of conceptualising multidimensional mental disorders and the dynamic shifting sands of the immune system.

On the transdiagnostic nature of peripheral biomarkers in major psychiatric disorders: A systematic review

The search for biomarkers has been a leading endeavor in biological psychiatry. To analyze its evolution over the years, we performed a systematic review to evaluate (a) the most studied peripheral molecular markers in major psychiatric disorders, (b) the main features of studies proposing them as biomarkers and (c) whether their patterns of variation are similar across disorders. Of the six molecules most commonly studied as plasmatic markers of schizophrenia, major depressive disorder or bipolar disorder, five (BDNF, TNF-alpha, IL-6, C-reactive protein and cortisol) were the same across diagnoses. An analysis of this literature showed that, while 66% of studies compared patients and controls, only 34% were longitudinal, and only 10% presented a measure of diagnostic or prognostic efficacy. Meta-analyses showed variation in the levels of these molecules to be robust across studies, but similar among disorders, suggesting them to reflect transdiagnostic systemic consequences of psychiatric illness. Based on this, we discuss how current publication practices have led to research fragmentation across diagnoses, and suggest approaches to face this issue.

Peripheral insulin-like growth factor 1 in bipolar disorder

Bipolar disorder is a recurrent and highly incapacitating illness, related to inflammation and changes in the insulin-like growth factor 1 (IGF-1). The objective of this study was to evaluate serum levels of IGF-1 in bipolar disorder patients and its relation to inflammation. We included 31 patients with bipolar disorder and 33 healthy controls. Serum concentrations of IGF-1, growth hormone (GH), insulin and tumor necrosis factor α (TNF-α) were analyzed. The serum levels of IGF-1 seem to be increased in bipolar disorder patients (248.84±104.91ng/mL) compared to controls (169.18±74.16ng/mL). Comparing reference values of IGF serum concentrations between groups, we found that 32% of patients had increased IGF-1 serum concentrations while only 3% of subjects are above normal range. We did not find statistically significant differences between groups in the concentration of insulin, GH, and TNF-α. This study suggests an association between IGF-1 in the pathophysiology of bipolar disorder. It is possible that this peripheral increase is related to a central nervous system increased resistance to IGF-1, thus reducing its neuroprotective action.

Medical comorbidity in bipolar disorder: The link with metabolic-inflammatory systems

BACKGROUND

Bipolar disorder (BD) is associated with chronic low-grade inflammation, several medical comorbidities and a decreased life expectancy. Metabolic-inflammatory changes have been postulated as one of the main links between BD and medical comorbidity, although there are few studies exploring possible mechanisms underlying this relationship. Therefore, the aims of the current narrative review were 1) synthesize the evidence for metabolic-inflammatory changes that may facilitate the link between medical comorbidity and BD and 2) discuss therapeutic and preventive implications of these pathways.

METHODS

The PubMed and Google Scholar databases were searched for relevant studies.

RESULTS

Identified studies suggested that there is an increased risk of medical comorbidities, such as autoimmune disorders, obesity, diabetes and cardiovascular disease in patients with BD. The association between BD and general medical comorbidities seems to be bidirectional and potentially mediated by immune dysfunction. Targeting the metabolic-inflammatory-mood pathway may potential yield improved outcomes in BD; however, further study is needed to determine which specific interventions may be beneficial.

LIMITATIONS

The majority of identified studies had cross-sectional designs, small sample sizes and limited measurements of inflammation.

CONCLUSIONS

Treatment and prevention of general medical comorbidities in mood disorders should include preferential prescribing of metabolically neutral agents and adjunctive lifestyle modifications including increased physical activity, improved diet and decreased substance abuse. In addition, the use of anti-inflammatory agents could be a relevant therapeutic target in future research.

Peripheral adenosine levels in euthymic patients with bipolar disorder

Recent evidence points to the involvement of the purinergic signaling in the pathophysiology of bipolar disorder. The aim of this study was to assess the serum levels of adenosine and to evaluate its relation to functioning in 24 euthymic patients with bipolar disorder type I and in 25 matched healthy controls. Subjects were evaluated using the functioning assessment short test. Serum purine levels were measured by high pressure liquid chromatography. Our results show a decrease in serum adenosine levels in bipolar disorder patients compared with controls (t= -4.8, df= 43.96, p<0.001). Moreover, a significant negative correlation was found between patient adenosine levels and depression scale scores (r= -0.642, p= 0.001). Higher functional impairment was linked to lower levels of adenosine in patients (rho= -0.551, p= 0.008). Taken together, our results provide evidence for a purinergic imbalance in bipolar disorder, specifically an adenosinergic dysfunction. Our results also indicate a relation between adenosine levels and the functional impairment caused by the disorder, which could demonstrate a potential relation of adenosine levels in worsening of symptoms.

Dentate gyrus-cornu ammonis (CA) 4 volume is decreased and associated with depressive episodes and lipid peroxidation in bipolar II disorder: Longitudinal and cross-sectional analyses

OBJECTIVES

Reduced dentate gyrus volume and increased oxidative stress have emerged as potential pathophysiological mechanisms in bipolar disorder. However, the relationship between dentate gyrus volume and peripheral oxidative stress markers remains unknown. Here, we examined dentate gyrus-cornu ammonis (CA) 4 volume longitudinally in patients with bipolar II disorder (BD-II) and healthy controls and investigated whether BD-II is associated with elevated peripheral levels of oxidative stress.

METHODS

We acquired high-resolution structural 3T-magnetic resonance imaging (MRI) images and quantified hippocampal subfield volumes using an automated segmentation algorithm in individuals with BD-II (n=29) and controls (n=33). The participants were scanned twice, at study inclusion and on average 2.4 years later. In addition, we measured peripheral levels of two lipid peroxidation markers (4-hydroxy-2-nonenal [4-HNE] and lipid hydroperoxides [LPH]).

RESULTS

First, we demonstrated that the automated hippocampal subfield segmentation technique employed in this work reliably measured dentate gyrus-CA4 volume. Second, we found a decreased left dentate gyrus-CA4 volume in patients and that a larger number of depressive episodes between T1 and T2 predicted greater volume decline. Finally, we showed that 4-HNE was elevated in BD-II and that 4-HNE was negatively associated with left and right dentate gyrus-CA4 volumes in patients.

CONCLUSIONS

These results are consistent with a role for the dentate gyrus in the pathophysiology of bipolar disorder and suggest that depressive episodes and elevated oxidative stress might contribute to hippocampal volume decreases. In addition, these findings provide further support for the hypothesis that peripheral lipid peroxidation markers may reflect brain alterations in bipolar disorders.

Update on bipolar disorder biomarker candidates

INTRODUCTION

Bipolar disorder is a chronic and disabling mood disorder with a complex pathophysiological basis. A significant percentage of patients do not receive correct diagnosis which directly influences therapeutic response, rendering recovery troublesome. There is a long-standing need for proper non-clinically based tools for diagnosis, treatment selection and follow-up of such patients. Areas covered: In the past decade, the scientific community has shown a great interest in biomarker development. Here, we highlight the different potential biomarkers and we discuss their feasibility and their possible clinical relevance. Expert commentary: To date, despite the major ongoing trials and consortia with promising future perspectives, no reliable biomarker of bipolar disorder has been fully defined.

Challenges and developments in research of the early stages of bipolar disorder

Recently, attention in the field of bipolar disorder (BD) has focused on prevention, including early detection and intervention, as these strategies have the potential to delay, lessen the severity, or even prevent full-blown episodes of BD. Although knowledge of the neurobiology of BD has advanced substantially in the last two decades, most research was conducted with chronic patients. The objective of this paper is to comprehensively review the literature regarding the early stages of BD, to explore recent discoveries on the neurobiology of these stages, and to discuss implications for research and clinical care. The following databases were searched: PubMed, PsycINFO, Cochrane Library, and SciELO. Articles published in English from inception to December 2015 were retrieved. Several research approaches were used, including examination of offspring studies, retrospective studies, prospective studies of clinical high-risk populations, and exploration of the progression after the first manic episode. Investigations with neuroimaging, cognition assessments, and biomarkers provide promising (although not definitive) evidence of alterations in the neural substrate during the at-risk stage. Research on BD should be expanded to encompass at-risk states and aligned with recent methodological progress in neuroscience.

Reduced Neurite Density in Neuronal Cell Cultures Exposed to Serum of Patients with Bipolar Disorder

BACKGROUND

Increased inflammatory markers and oxidative stress have been reported in serum among patients with bipolar disorder (BD). The aim of this study is to assess whether biochemical changes in the serum of patients induces neurotoxicity in neuronal cell cultures.

METHODS

We challenged the retinoic acid-differentiated human neuroblastoma SH-SY5Y cells with the serum of BD patients at early and late stages of illness and assessed neurite density and cell viability as neurotoxic endpoints.

RESULTS

Decreased neurite density was found in neurons treated with the serum of patients, mostly patients at late stages of illness. Also, neurons challenged with the serum of late-stage patients showed a significant decrease in cell viability.

CONCLUSIONS

Our findings showed that the serum of patients with bipolar disorder induced a decrease in neurite density and cell viability in neuronal cultures.

DNA Damage in Major Psychiatric Diseases

Human cells are exposed to exogenous insults and continuous production of different metabolites. These insults and unwanted metabolic products might interfere with the stability of genomic DNA. Recently, many studies have demonstrated that different psychiatric disorders show substantially high levels of oxidative DNA damage in the brain accompanied with morphological and functional alterations. It reveals that damaged genomic DNA may contribute to the pathophysiology of these mental illnesses. In this article, we review the roles of oxidative damage and reduced antioxidant ability in some vastly studied psychiatric disorders and emphasize the inclusion of treatment options involving DNA repair. In addition, while most currently used antidepressants are based on the manipulation of the neurotransmitter regulation in managing different mental abnormalities, they are able to prevent or reverse neurotoxin-induced DNA damage. Therefore, it may be plausible to target on genomic DNA alterations for psychiatric therapies, which is of pivotal importance for future antipsychiatric drug development.

Staging Models in Bipolar Disorder: A Systematic Review of the Literature

Bipolar disorder is manifested as severe dysregulation of mood with recurrent manic and major depressive episodes. It is associated with psychiatric and medical comorbidities, inadequate response to currently available pharmacological agents and a progressively deteriorating course in many patients. The index episode is often depressive in nature, while the first manic or hypomanic episode may occur several years later in the course of the disorder causing delay in diagnosis and use of inappropriate treatment strategies. Staging has been used to great advantage in other branches of medicine like cardiology and oncology. There is growing realization that major mental disorders are fundamentally progressive, with simpler treatment requirements and better prognosis during initial stages of the illness. Defining these conditions into clinically applicable stages not only helps in better understanding the trajectory of a particular disorder, but also assists in management. Patients with a chronic, recalcitrant condition like bipolar disorder are likely to greatly benefit from this approach. If the illness is correctly identified early in its course, proper treatment can be instigated arresting progression to latter phases which are associated with myriad complications in the biopsychosocial realm. With these considerations, a search of the MEDLINE data base was conducted to seek out literature pertaining to staging models in bipolar disorder. A thorough scrutiny of the existing research work revealed that a number of investigators have endeavored to stage define bipolar disorder. This paper outlines staging proposals for bipolar disorder which have the greatest supporting evidence in the literature.

Peripheral blood brain-derived neurotrophic factor in bipolar disorder: a comprehensive systematic review and meta-analysis

Peripheral blood brain-derived neurotrophic factor (BDNF) has been proposed as a potential biomarker related to disease activity and neuroprogression in bipolar disorder, speculated to mirror alterations in brain expression of BDNF. The research area is rapidly evolving; however, recent investigations have yielded conflicting results with substantial variation in outcomes, highlighting the need to critically assess the state of current evidence. The aims of the study were to investigate differences in peripheral blood BDNF concentrations between bipolar disorder patients and healthy control subjects and between affective states in bipolar disorder patients, including assessment of the effect of treatment of acute episodes on BDNF levels. A systematic review of English language studies without considering publication status was conducted in PubMed (January 1950-November 2014), Embase (1974-November 2014) and PsycINFO (1806-November 2014), and 35 studies comprising a total of 3798 participants were included in the meta-analysis. The results indicated that crude peripheral blood BDNF levels may be lower in bipolar disorder patients overall (Hedges' g=-0.28, 95% CI: -0.51 to -0.04, P=0.02) and in serum of manic (g=-0.77, 95% CI: -1.36 to -0.18, P=0.01) and depressed (g=-0.87, 95% CI: -1.42 to -0.32, P=0.002) bipolar disorder patients compared with healthy control subjects. No differences in peripheral BDNF levels were observed between affective states overall. Longer illness duration was associated with higher BDNF levels in bipolar disorder patients. Relatively low study quality, substantial unexplained between-study heterogeneity, potential bias in individual studies and indications of publication bias, was observed and studies were overall underpowered. It could thus not be excluded that identified differences between groups were due to factors not related to bipolar disorder. In conclusion, limitations in the evidence base prompt tempered conclusions regarding the role of peripheral BDNF as a biomarker in bipolar disorder and substantially improving the quality of further research is warranted.

Interaction between BDNF rs6265 Met allele and low family cohesion is associated with smaller left hippocampal volume in pediatric bipolar disorder

BACKGROUND

Genetic and environmental factors are implicated in the onset and evolution of pediatric bipolar disorder, and may be associated to structural brain abnormalities. The aim of our study was to assess the impact of the interaction between the Brain-Derived Neurotrophic Factor (BDNF) rs6265 polymorphism and family functioning on hippocampal volumes of children and adolescents with bipolar disorder, and typically-developing controls.

METHODS

We evaluated the family functioning cohesion subscale using the Family Environment Scale-Revised, genotyped the BDNF rs6265 polymorphism, and performed structural brain imaging in 29 children and adolescents with bipolar disorder, and 22 healthy controls.

RESULTS

We did not find significant differences between patients with BD or controls in left or right hippocampus volume (p=0.44, and p=0.71, respectively). However, we detected a significant interaction between low scores on the cohesion subscale and the presence of the Met allele at BNDF on left hippocampal volume of patients with bipolar disorder (F=3.4, p=0.043). None of the factors independently (BDNF Val66Met, cohesion scores) was significantly associated with hippocampal volume differences.

LIMITATIONS

small sample size, cross-sectional study.

CONCLUSIONS

These results may lead to a better understanding of the impact of the interaction between genes and environment factors on brain structures associated to bipolar disorder and its manifestations.

Cumulative stress pathophysiology in schizophrenia as indexed by allostatic load

BACKGROUND

The etiopathophysiology of schizophrenia has long been linked to stress and the influence of stress is important in all stages of the illness. Previous examinations of perceived stress and acute stress responses may not capture this longitudinal stress pathophysiology. We hypothesized that the cumulative negative effects of stress, indexed by allostatic load (AL), would be elevated in schizophrenia, and that the AL paradigm would be relevant to our understanding of pathophysiology in schizophrenia.

METHODS

We assessed allostatic load in 30 patients with schizophrenia (SZ; mean age = 33; 17 males) and 20 healthy controls (HC; mean age = 35; 12 males) using 13 cardiovascular, metabolic, neuroendocrine and immune biomarkers. Participants' perceived stress over the past month, functional capacity and psychiatric symptoms were also measured.

RESULTS

Controlling for age, SZ had significantly higher AL as compared to HC (p = 0.007). Greater AL was present in both early course and chronic SZ, and was associated with reduced functional capacity (p = 0.006) and more psychotic symptoms (p = 0.048) in SZ. Current level of perceived stress was not significantly elevated in SZ or associated with AL in either group.

CONCLUSIONS

The higher AL found in SZ may reflect increased bodily "wear and tear", possibly caused by more chronic stress exposure or maladaptive responses to stress over time, although additional research is required to differentiate these causes. The higher AL is similarly present in early and chronic SZ, suggesting primary maladaptive stress physiology rather than secondary effects from medications or chronic illness.

Damage-associated molecular patterns and immune activation in bipolar disorder

OBJECTIVE

Immune activation in bipolar disorder (BD) has been frequently reported. Damage-associated molecular patterns (DAMPs) are key players in the immune activation reaction. The aim of this study was to assess DAMP levels in drug-free patients with BD during acute episodes.

METHOD

Serum levels of a predetermined set of DAMPs were assessed in drug-free patients with BD (n = 20) during an acute mood episode. We also included two control groups: healthy subjects, used as a negative control (n = 20); and patients with sepsis, used as a positive control for severe immune activation (n = 20).

RESULTS

Multivariate analysis using generalized linear mixed model indicated that all DAMPs differed as a function of group membership after controlling for age and addressing multiplicity (P < 0.0006 for all comparisons). Follow-up analyses showed higher levels in BD subjects of circulating cell-free (ccf) nuclear (n)DNA (P = 0.02), HSP70 (P = 0.03) and HSP90α (P = 0.02) as compared to healthy subjects. Also, patients with BD showed lower levels of ccf nDNA (P = 0.04), HSP60 (P = 0.03), HSP70 (P = 0.01), and HSP90α (P = 0.002) as compared to patients with sepsis and higher levels of ccf mitochondrial DNA (P < 0.0001).

CONCLUSION

The present findings may be linked to the inflammatory activity previously described among patients with BD and may help in the development of more targeted and personalized treatments for patients under acute episodes of BD.

Oxidative stress in older patients with bipolar disorder

OBJECTIVE

Increases in oxidative stress have been consistently reported in younger patients with bipolar disorder (BD) in postmortem brain and blood samples studies. Changes in oxidative stress are also associated with the natural aging process. Thus, the investigation of oxidative stress across the life span of patients with BD is crucial.

METHODS

We compared the levels of oxidative damage to proteins and lipids in plasma from 110 euthymic older patients with BD I or II (mean±SD age: 63.9±9.7 years) and 75 older healthy individuals (66.0±9.6 years). To assess protein oxidation, we measured the plasma levels of protein carbonyl (PC) and 3-nitrotyrosine (3-NT) using the ELISA technique. To assess lipid peroxidation, we measured plasma levels of lipid hydroperoxide (LPH) and 4-hydroxynonenal (4-HNE) using spectrophotometric assays.

RESULTS

LPH levels were higher in patients than in the comparison healthy individuals, whereas there were no significant differences for PC, 3-NT, and 4-HNE between the two groups.

CONCLUSIONS

The increased levels of an early component of the peroxidation chain (LPH) in euthymic older patients with BD support the hypothesis of a persistent effect of reactive species of oxygen in patients with BD into late life.

Towards a classification of biomarkers of neuropsychiatric disease: from encompass to compass

There is currently considerable imprecision in the nosology of biomarkers used in the study of neuropsychiatric disease. The neuropsychiatric field lags behind others such as oncology, wherein, rather than using 'biomarker' as a blanket term for a diverse range of clinical phenomena, biomarkers have been actively classified into separate categories, including prognostic and predictive tests. A similar taxonomy is proposed for neuropsychiatric diseases in which the core biology remains relatively unknown. This paper divides potential biomarkers into those of (1) risk, (2) diagnosis/trait, (3) state or acuity, (4) stage, (5) treatment response and (6) prognosis, and provides illustrative exemplars. Of course, biomarkers rely on available technology and, as we learn more about the neurobiological correlates of neuropsychiatric disorders, we will realize that the classification of biomarkers across these six categories can change, and some markers may fit into more than one category.

Reduced mRNA expression of PTGDS in peripheral blood mononuclear cells of rapid-cycling bipolar disorder patients compared with healthy control subjects

BACKGROUND

Disturbances related to the arachidonic acid cascade and prostaglandin metabolism may be involved in the pathophysiology of bipolar disorder, as supported by a recent genome-wide association study meta-analysis; however, evidence from clinical studies on a transcriptional level is lacking. Two enzymes in the arachidonic acid cascade are the prostaglandin D synthase (PTGDS), which catalyzes the conversion of prostaglandin H2 to prostaglandin D2 (PGD2), and the aldo-keto reductase family 1 member C3 (AKR1C3), which catalyzes the reduction of PGD2. We aimed to test the hypothesis that mRNA expression of PTGDS and AKR1C3 is deregulated in rapid-cycling disorder patients in a euthymic or current affective state compared with healthy control subjects, and that expression alters with affective states.

METHODS

PTGDS and AKR1C3 mRNA expression in peripheral blood mononuclear cells was measured in 37 rapid-cycling bipolar disorder patients and 40 age- and gender-matched healthy control subjects using reverse transcription quantitative real-time polymerase chain reaction. Repeated measurements of PTGDS and AKR1C3 mRNA expression were obtained in various affective states during 6-12 months and compared with repeated measurements in healthy control subjects.

RESULTS

Adjusted for age and gender, PTGDS mRNA expression was down-regulated in rapid-cycling bipolar disorder patients in a euthymic, depressive, and manic/hypomanic state compared with healthy control subjects. No difference in PTGDS mRNA expression was observed between affective states. AKR1C3 mRNA expression did not differ between bipolar disorder patients in any affective state or in comparison with healthy control subjects.

CONCLUSIONS

The results suggest a role for aberrantly-regulated PTGDS mRNA expression in rapid-cycling bipolar disorder. The sample size was limited; replication of the findings in larger, independent samples is warranted to further explore the role of the arachidonic acid cascade and prostaglandin metabolism as a potential therapeutic target in bipolar disorder.

Biomarkers and staging of bipolar disorder: a systematic review

INTRODUCTION

A growing body of evidence suggests that bipolar disorder (BD) is a progressive disease according to clinical, biochemical and neuroimaging findings. This study reviewed the literature on the relationship between specific biomarkers and BD stages.

METHODS

A comprehensive literature search of MEDLINE and PubMed was conducted to identify studies in English and Portuguese using the keywords biomarker, neurotrophic factors, inflammation, oxidative stress, neuroprogression and staging models cross-referenced with bipolar disorder.

RESULTS

Morphometric studies of patients with BD found neuroanatomic abnormalities, such as ventricular enlargement, grey matter loss in the hippocampus and cerebellum, volume decreases in the prefrontal cortex and variations in the size of the amygdala. Other studies demonstrated that serum concentrations of neurotrophic factors, inflammatory mediators and oxidative stress may be used as BD biomarkers.

CONCLUSIONS

The analysis of neurobiological changes associated with BD progression and activity may confirm the existence of BD biomarkers, which may be then included in staging models that will lead to improvements in treatment algorithms and more effective, individually tailored treatment regimens. Biomarkers may also be used to define early interventions to control disease progression.