Brisa Simoes Fernandes

Comparison of cytokine levels in depressed, manic and euthymic patients with bipolar disorder

BACKGROUND The neurobiology of bipolar disorder is not completely understood. Cytokines have received increasing attention as potential mediators of the interaction with immune, neuroendocrine system and specific pathways involved in mood, energy, and activity control. Previous reports have suggested the association of mania and bipolar depression with a proinflammatory state. However, they did not compare cytokine levels in all phases of bipolar disorder. METHODS Sixty-one bipolar patients were recruited for assessment of serum cytokine levels. Of these, 14 were in euthymic state, 23 and 24 were in manic and depressive episodes, respectively. A healthy comparison group included 25 healthy volunteers. Cytokines involved in Th1/Th2 balance, such as TNF-alpha, IL-2, IL-4, IL-6, IL-10, IFN-gamma, were examined by flow cytometry. RESULTS During mania, proinflammatory cytokines, IL-2, IL-4 and IL-6, were increased in comparison with healthy subjects. Patients in depressive episode showed only increased IL-6 levels. There were no significant differences in cytokine levels between patients in remission and healthy subjects, except for IL-4. Mood symptoms showed a positive correlation with IL-6 and IL-2. DISCUSSION These findings suggest that mania, and to a less extent, depression are associated with a proinflammatory state. These changes seem to be related to mood state, as changes in cytokine profile were more pronounced during acute episodes than in euthymia. This study provides further support to investigate the immune system as a target for future treatment development.

Serum levels of IL-6, IL-10 and TNF-α in patients with bipolar disorder and schizophrenia: differences in pro- and anti-inflammatory balance

OBJECTIVE Previous reports suggest that cytokines act as potential mediators of the interaction between the immune and neuroendocrine systems, and that a proinflammatory state may be associated with bipolar disorder and schizophrenia. The aim is to compare cytokine levels in both disorders. METHOD Twenty euthymic bipolar disorder patients, 53 chronic stabilized schizophrenia patients and 80 healthy controls were recruited. Subjects were all non-smokers and non-obese. Cytokines TNF-α, IL-6, and IL-10 were examined by sandwich ELISA. RESULTS IL-6 levels were increased in schizophrenia patients when compared to controls (p < 0.0001) and euthymic bipolar disorder patients (p < 0.0001). IL-6 levels were no different in controls compared to euthymic bipolar disorder patients (p = 0.357). IL-10 was lower in controls compared to schizophrenia patients (p = 0.001) or to bipolar disorder patients (p = 0.004). There was no significant difference in TNF-α serum levels among the groups (p = 0.284). Gender-based classification did not significantly alter these findings, and no correlation was found between the antipsychotic dose administered and cytokine levels in patients with schizophrenia. DISCUSSION These findings evidence a chronic immune activation in schizophrenia. Bipolar disorder seems to present an episode-related inflammatory syndrome. Increased anti-inflammatory factor IL-10 in bipolar disorder and schizophrenia suggests different patterns of inflammatory balance between these two disorders. Results further support the need to investigate cytokines as possible biomarkers of disease activity or treatment response.

Biomarkers in bipolar disorder: A positional paper from the International Society for Bipolar Disorders Biomarkers Task Force

Although the etiology of bipolar disorder remains uncertain, multiple studies examining neuroimaging, peripheral markers and genetics have provided important insights into the pathophysiologic processes underlying bipolar disorder. Neuroimaging studies have consistently demonstrated loss of gray matter, as well as altered activation of subcortical, anterior temporal and ventral prefrontal regions in response to emotional stimuli in bipolar disorder. Genetics studies have identified several potential candidate genes associated with increased risk for developing bipolar disorder that involve circadian rhythm, neuronal development and calcium metabolism. Notably, several groups have found decreased levels of neurotrophic factors and increased pro-inflammatory cytokines and oxidative stress markers. Together these findings provide the background for the identification of potential biomarkers for vulnerability, disease expression and to help understand the course of illness and treatment response. In other areas of medicine, validated biomarkers now inform clinical decision-making. Although the findings reviewed herein hold promise, further research involving large collaborative studies is needed to validate these potential biomarkers prior to employing them for clinical purposes. Therefore, in this positional paper from the ISBD-BIONET (biomarkers network from the International Society for Bipolar Disorders), we will discuss our view of biomarkers for these three areas: neuroimaging, peripheral measurements and genetics; and conclude the paper with our position for the next steps in the search for biomarkers for bipolar disorder.

The efficacy of N-acetylcysteine as an adjunctive treatment in bipolar depression: An open label trial

BACKGROUND Evidence is accumulating to support the presence of redox dysregulation in a number of psychiatric disorders, including bipolar disorder. This dysregulation may be amenable to therapeutic intervention. Glutathione is the predominant non-enzymatic intracellular free radical scavenger in the brain, and the most generic of all endogenous antioxidants in terms of action. N-acetylcysteine (NAC) is a glutathione precursor that effectively replenishes brain glutathione. Given the failure of almost all modern trials of antidepressants in bipolar disorder to demonstrate efficacy, and the limited efficacy of mood stabilisers in the depressive phase of the disorder, this is a major unmet need. METHOD This study reports data on the treatment of 149 individuals with moderate depression during the 2 month open label phase of a randomised placebo controlled clinical trial of the efficacy of 1g BID of NAC that examined the use of NAC as a maintenance treatment for bipolar disorder. RESULTS In this trial, the estimated mean baseline Bipolar Depression Rating Scale (BDRS) score was 19.7 (SE=0.8), and the mean BDRS score at the end of the 8 week open label treatment phase was 11.1 (SE=0.8). This reduction was statistically significant (p<0.001). Improvements in functioning and quality of life were similarly evident. CONCLUSION These open label data demonstrate a robust decrement in depression scores with NAC treatment. Large placebo controlled trials of acute bipolar depression are warranted.

Peripheral cytokine and chemokine alterations in depression: a meta-analysis of 82 studies

To conduct a systematic review and meta‐analysis of studies that measured cytokine and chemokine levels in individuals with major depressive disorder (MDD) compared to healthy controls (HCs).

Decreased brain-derived neurotrophic factor in medicated and drug-free bipolar patients

Bipolar disorder (BD) has been associated with abnormalities in neuroplasticity and previous studies suggest an important role for BDNF in the pathophysiology of BD. The confounding effect of the use of medication in these studies has been considered a limitation. Thus, studies with both drug-free and medicated patients are necessary to assess the role of medication in serum BDNF levels. Twenty-two manic and depressed drug-free and 22 medicated BD type I patients were matched to 22 controls according to sex and age in a cross-sectional study. BDNF serum levels were assessed using sandwich-ELISA. Serum BDNF levels in drug-free (0.23+/-0.09), and medicated (0.29+/-0.19) BD patients were decreased when compared to controls (0.40+/-0.12) - drug-free/medicated vs. control p<0.001. The BDNF levels did not differ between medicated and drug-free BD patients. When analyzing patients according to mood states, serum BDNF levels were lower in BD patients during both manic (0.28+/-0.11) and depressive episodes (0.22+/-0.17), as compared with healthy controls (0.40+/-0.12) - manic/depressed patients vs. controls p<0.001. Results suggest that the association of lower serum BDNF and BD mood episodes is kept even in medicated patients, which strengthens the notion that BDNF serum levels may be considered a biomarker of mood episodes in BD.

C-reactive protein is increased in schizophrenia but is not altered by antipsychotics: meta-analysis and implications.

The inflammatory hypothesis of schizophrenia (SZ) posits that inflammatory processes and neural–immune interactions are involved in its pathogenesis, and may underpin some of its neurobiological correlates. SZ is the psychiatric disorder causing the most severe burden of illness, not just owing to its psychiatric impairment, but also owing to its significant medical comorbidity. C-reactive protein (CRP) is a commonly used biomarker of systemic inflammation worldwide. There are some conflicting results regarding the behaviour of CRP in SZ. The aims of this study were to verify whether peripheral CRP levels are indeed increased in SZ, whether different classes of antipsychotics divergently modulate CRP levels and whether its levels are correlated with positive and negative symptomatology. With that in mind, we performed a meta-analysis of all cross-sectional studies of serum and plasma CRP levels in SZ compared to healthy subjects. In addition, we evaluated longitudinal studies on CRP levels before and after antipsychotic use. Our meta-analyses of CRP in SZ included a total of 26 cross-sectional or longitudinal studies comprising 85 000 participants. CRP levels were moderately increased in persons with SZ regardless of the use of antipsychotics and did not change between the first episode of psychosis and with progression of SZ (g=0.66, 95% confidence interval (95% CI) 0.43 to 0.88, P<0.001, 24 between-group comparisons, n=82 962). The extent of the increase in peripheral CRP levels paralleled the increase in severity of positive symptoms, but was unrelated to the severity of negative symptoms. CRP levels were also aligned with an increased body mass index. Conversely, higher age correlated with a smaller difference in CRP levels between persons with SZ and controls. Furthermore, CRP levels did not increase after initiation of antipsychotic medication notwithstanding whether these were typical or atypical antipsychotics (g=0.01, 95% CI −0.20 to 0.22, P=0.803, 8 within-group comparisons, n=713). In summary, our study provides further evidence of the inflammatory hypothesis of SZ. Whether there is a causal relationship between higher CRP levels and the development of SZ and aggravation of psychotic symptoms, or whether they are solely a marker of systemic low-grade inflammation in SZ, remains to be clarified.

Peripheral brain-derived neurotrophic factor in schizophrenia and the role of antipsychotics: meta-analysis and implications

It has been postulated that schizophrenia (SZ) is related to a lower expression of brain-derived neurotrophic factor (BDNF). In the past few years, an increasing number of divergent clinical studies assessing BDNF in serum and plasma have been published. It is now possible to verify the relationship between BDNF levels and severity of symptoms in SZ as well as the effects of antipsychotic drugs on BDNF using meta-analysis. The aims of this study were to verify if peripheral BDNF is decreased in SZ, whether its levels are correlated with positive and negative symptomatology and if BDNF levels change after antipsychotic treatment. This report consists of two distinct meta-analyses of peripheral BDNF in SZ including a total of 41 studies and more than 7000 participants: (1) peripheral BDNF levels in serum and plasma were moderately reduced in SZ compared with controls. Notably, this decrease was accentuated with the disease duration. However, the extent of peripheral BDNF level decrease did not correlate with the severity of positive and negative symptoms. (2) In plasma, but not serum, peripheral BDNF levels are consistently increased after antipsychotic treatment irrespective of the patient’s response to medication. In conclusion, there is compelling evidence that there are decreased levels of peripheral BDNF in SZ, in parallel to previously described reduced cerebral BDNF expression. It remains unclear whether these systemic changes are causally related to the development of SZ or if they are merely a pathologic epiphenomenon.

Improvement of Negative and Positive Symptoms in Treatment-Refractory Schizophrenia: A Double-Blind, Randomized, Placebo-Controlled Trial With Memantine as Add-On Therapy to Clozapine

BACKGROUND Glutamate deregulation may be involved in the neuropathology of schizophrenia, mainly through N-methyl-d-aspartate (NMDA) receptor dysfunction. Memantine, a drug approved by the FDA for the treatment of moderate to severe Alzheimers disease, acts as a weak nonselective NMDA receptor antagonist. The aim of this study was to examine the efficacy of memantine as an adjunctive treatment to clozapine in patients with refractory schizophrenia. METHOD In this double-blind, placebo-controlled study, outpatients with refractory schizophrenia according to DSM-IV clinical criteria were randomly assigned, from March 2005 to February 2008, to receive either 20 mg/d memantine (n = 10) or placebo (n = 11), in addition to clozapine, for 12 weeks. The primary outcome measure was the total score on the 18-item Brief Psychiatry Rating Scale (BPRS) and BPRS subscales of positive and negative symptoms. Secondary outcomes were global severity of disease as measured by the Clinical Global Impressions scale (CGI), cognition as assessed by the Mini-Mental State Examination (MMSE), and extrapyramidal symptoms as assessed by the Simpson-Angus Scale (SAS). RESULTS Twenty-one participants completed the study and were used in the analysis. Significant improvement (P < .01) on the total BPRS score, its subscales of positive (effect size [ES] = -1.38) and negative (ES = -3.33) symptoms, the CGI score (ES = 1.56), and the MMSE score was observed with memantine as compared with placebo. No significant changes in extrapyramidal symptoms were observed. CONCLUSIONS Memantine add-on to clozapine therapy was associated with improvement in negative and positive symptoms in refractory schizophrenia patients. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT00757978.

Peripheral brain-derived neurotrophic factor (BDNF) as a biomarker in bipolar disorder: a meta-analysis of 52 studies

BackgroundThe neurotrophic hypothesis postulates that mood disorders such as bipolar disorder (BD) are associated with a lower expression of brain-derived neurotrophic factor (BDNF). However, its role in peripheral blood as a biomarker of disease activity and of stage for BD, transcending pathophysiology, is still disputed. In the last few years an increasing number of clinical studies assessing BDNF in serum and plasma have been published. Therefore, it is now possible to analyse the association between BDNF levels and the severity of affective symptoms in BD as well as the effects of acute drug treatment of mood episodes on BDNF levels.MethodsWe conducted a systematic review and meta-analysis of all studies on serum and plasma BDNF levels in bipolar disorder.ResultsThrough a series of meta-analyses including a total of 52 studies with 6,481 participants, we show that, compared to healthy controls, peripheral BDNF levels are reduced to the same extent in manic (Hedges’ g = −0.57, P = 0.010) and depressive (Hedges’ g = −0.93, P = 0.001) episodes, while BDNF levels are not significantly altered in euthymia. In meta-regression analyses, BDNF levels additionally negatively correlate with the severity of both manic and depressive symptoms. We found no evidence for a significant impact of illness duration on BDNF levels. In addition, in plasma, but not serum, peripheral BDNF levels increase after the successful treatment of an acute mania episode, but not of a depressive one.ConclusionsIn summary, our data suggest that peripheral BDNF levels, more clearly in plasma than in serum, is a potential biomarker of disease activity in BD, but not a biomarker of stage. We suggest that peripheral BDNF may, in future, be used as a part of a blood protein composite measure to assess disease activity in BD.