Common biological mechanisms between bipolar disorder and type 2 diabetes: Focus on inflammation

Schisandrin A Alleviates Spatial Learning and Memory Impairment in Diabetic Rats by Inhibiting Inflammatory Response and Through Modulation of the PI3K/AKT Pathway

Clinical and epidemiological research shows that people with diabetes mellitus frequently experience diabetic cognitive impairment. Schisandrin A (SchA), one of the lignans found in the dried fruit of Schisandra chinensis, has a variety of pharmacological effects on immune system control, apoptosis suppression, anti-oxidation and anti-inflammation. The goal of the current investigation was to clarify the probable neuro-protective effects of SchA against streptozotocin-induced diabetes deficiencies of the spatial learning and memory in rats. The outcomes show that SchA therapy effectively improved impaired glucose tolerance, fasting blood glucose level and serum insulin level in diabetic rats. Additionally, in the Morris water maze test, diabetic rats showed deficits in spatial learning and memory that were ameliorated by SchA treatment. Moreover, giving diabetic rats SchA reduced damage to the hippocampus structure and increased the production of synaptic proteins. Further research revealed that SchA therapy reduced diabetic-induced hippocampus neuron damage and the generation of Aβ, as demonstrated by the upregulated phosphorylation levels of insulin signaling pathway connected proteins and by the decreased expression levels of inflammatory-related factors. Collectively, these results suggested that SchA could improve diabetes-related impairments in spatial learning and memory, presumably by reducing inflammatory responses and regulating the insulin signaling system.

Psychiatric disorders and Type 2 diabetes mellitus: A bidirectional Mendelian randomization

BACKGROUND

Extensive observational evidence put forward the association between psychiatric disorders and type 2 diabetes mellitus (T2DM). However, causal relationships between these two diseases required further research. Thus, we evaluated the bidirection casual effect between five psychiatric disorders and T2DM using two-sample mendelian randomization (MR).

METHODS

By selecting single nucleotide polymorphisms associated with T2DM and five psychiatric disorders (attention-deficit hyperactivity disorder (ADHD), major depressive disorder (MDD), schizophrenia, anxiety disorder and panic disorder), a bidirectional two-sample MR was applied to evaluate causality between these diseases. The inverse-variance weighted (IVW) method was used as the primary analysing approach for estimating possible causal effects. MR-Egger and weighted median were also conducted to verify the results. The funnel plot, Cochran's Q test and MR-Egger intercept test were used for sensitivity analyses. In addition, potential mediators were investigated by risk factor analyses.

RESULTS

Genetic susceptibilities of ADHD and MDD would increase the risk of T2DM (ADHD: OR = 1.14, 95%CI 1.08-1.20; p = 5.7 × 10 - 6 ; MDD: OR = 1.22, 95%CI 1.09-1.36; p = 0.0004 ). In addition, genetic predisposition to T2DM was also associated with ADHD (OR = 1.09, 95%CI 1.04-1.14; p = 0.0004). Several risk factors of T2DM were implicated in the above causal associations, including smoking, high body mass index, waist-to-hip ratio and elevated serum triglycerides.

CONCLUSION

Our studies indicated a causal effect of ADHD and MDD on increasing the risk of T2DM, which was potentially mediated by smoking and obesity-related phenotypes. Meanwhile, we found a causal effect of T2DM on ADHD. Thus, prevention strategies for T2DM should also include mental health and vice versa.

Low-grade inflammation as mediator between diet and behavioral disinhibition: A UK Biobank study

BACKGROUND

Dietary patterns have been associated with variations in behavior. However, evidence has been limited and mixed, and the underlying mechanism remains unclear.

OBJECTIVE

Extend a previous study reporting significant associations between food patterns and behavioral disinhibition and explore whether low-grade inflammation is linked to behaviors and mediates the association between diet and behavioral disinhibition.

DESIGN

Among participants of the UK Biobank (UKB) we extracted a single behavioral disinhibition principal component using the UKB touchscreen questionnaire, Mental Health Questionnaire (MHQ), and registered diagnoses. We identified four dietary patterns (prudent diet, elimination of wheat/dairy/eggs, meat-based diet, full-cream dairy consumption) by using the Food Frequency Questionnaire (FFQ). Immune biomarkers and an aggregated inflammation score (INFLA-score) were used to characterize low-grade inflammation. Associations between dietary patterns and immune biomarkers, between immune biomarkers and disinhibition were assessed, with adjustment for demographics, lifestyle factors, and somatic health conditions. Next, mediation analyses were run to examine whether the association between dietary patterns and disinhibition was partially explained by inflammatory levels. We also conducted subgroup analyses to explore whether associations and the mediation effect differed by sex, age, ethnicity/race, body-mass-index (BMI), and socioeconomic status (SES).

RESULTS

The prudent diet was negatively, and the meat-based diet was positively associated with several pro-inflammatory biomarkers. Most immune biomarkers were positively associated with disinhibition (numbers of lymphocytes (β_standardized = 0.082, p < 0.001), monocytes (β_standardized = 0.043, p < 0.001), neutrophils (β_standardized = 0.071, p < 0.001), platelets (β_standardized = 0.022, p < 0.001), leukocytes (β_standardized = 0.093, p < 0.001), C-reactive protein (β_standardized = 0.051, p < 0.001), and for INFLA-score (β_standardized = 0.074, p < 0.001). In the mediation model, the INFLA-score mediated the association between prudent diet and meat-based diet and disinhibition score, with a significant indirect effect of low-grade inflammation for the prudent diet-disinhibition association (β_standardized = -0.007, p < 0.001) and for meat-disinhibition association (β_standardized = 0.001, p < 0.001)). Although all effects were small, covariates and interaction term adjustments did not attenuate the effects, and neither did most subgroup-only analyses.

CONCLUSIONS

The prudent diet was associated with a lower disinhibition score and this effect was partially mediated by the lower inflammation. Reversely, the meat-based diet was linked to more inflammation, which was associated with more disinhibition. Our findings suggest mediating effects of immune function in the relationship between diet and behavioral disinhibition. However further alternative designs such as interventional trials are needed to establish causal effects.

Homocysteine as a peripheral biomarker in bipolar disorder: A meta-analysis

Background:

Bipolar disorder (BD) is a psychiatric disorder with an uncertain aetiology. Recently, special attention has been given to homocysteine (Hcy), as it has been suggested that alterations in 1-carbon metabolism might be implicated in diverse psychiatric disorders. However, there is uncertainty regarding possible alterations in peripheral Hcy levels in BD.

Methods:

This study comprises a meta-analysis comparing serum and plasma Hcy levels in persons with BD and healthy controls. We conducted a systematic search for all eligible English and non-English peer-reviewed articles.

Results:

Nine cross-sectional studies were included in the meta-analyses, providing data on 1547 participants. Random-effects meta-analysis showed that serum and plasma levels of Hcy were increased in subjects with BD in either mania or euthymia when compared to healthy controls, with a large effect size in the mania group (g= 0.98, 95% CI: 0.8–1.17,P< 0.001,n= 495) and a small effect in the euthymia group (g= 0.3, 95% CI: 0.11–0.48,P= 0.002,n= 1052).

Conclusions:

Our meta-analysis provides evidence that Hcy levels are elevated in persons with BD during mania and euthymia. Peripheral Hcy could be considered as a potential biomarker in BD, both of trait (since it is increased in euthymia), and also of state (since its increase is more accentuated in mania). Longitudinal studies are needed to clarify the relationship between bipolar disorder and Hcy, as well as the usefulness of peripheral Hcy as both a trait and state biomarker in BD.

Association between diabetes and mood disorders and the potential use of anti-hyperglycemic agents as antidepressants

Epidemiological and mechanistic studies support the association between Diabetes Mellitus and mood disorders, such as Major Depressive Disorder and Bipolar Disorder. This association is especially relevant in specific domains of depressive psychopathology, such as disturbances in reward systems and cognitive functions. Several anti-hyperglycemic agents have demonstrated effects on depressive symptoms and cognitive decline and this efficacy is probably the result of an action in shared brain targets between these two groups of conditions. These medications include subcutaneous insulin, intranasal insulin, metformin, and liraglutide. The study of the mechanisms involved in the relationship between Diabetes Mellitus and mood disorders offers a new avenue of investigation, and this understanding can be applied when examining whether antidiabetic agents can be repurposed as antidepressants and mood stabilizers. The objective of this narrative review is to critically appraise the literature surrounding drugs commonly used as anti-hyperglycemic agents and their effects on the brain, while discussing their potential as a new treatment for mental illnesses, and specifically, mood disorders.

Elevated Familial Cardiovascular Burden Among Adolescents With Familial Bipolar Disorder

Background: Bipolar disorder (BD) is one of the most heritable medical conditions, and certain phenotypic characteristics are especially familial in BD. BD is also strongly associated with elevated and premature cardiovascular disease (CVD) morbidity and mortality. Thus, far, little is known regarding the familiality of cardiovascular risk in BD. We therefore examined the extent of CVD-related conditions among relatives of: adolescents with BD with a family history of BD (familial BD), adolescents with BD without a family history of BD (non-familial BD) and healthy controls (HC). Materials and Methods: The sample included 372 adolescents; 75 with familial BD, 96 with non-familial BD, and 201 HC. Parents of the adolescents completed the CARDIA Family Medical History interview regarding the adolescents' first- and second- degree adult relatives. We computed a "cardiovascular risk score" (CRS) for each relative, based on the sum of the presence of diabetes, hypertension, obesity, dyslipidemia, stroke, angina, and myocardial infarction (range 0-7). Primary analyses examined for group differences in mean overall CRS scores among first and second- degree relatives combined, controlling for age, sex, and race. Secondary analyses examined first- and second-degree relatives separately, controlling for age, sex, and race. Results: There were significant between-group differences in CRS in first- and second- degree relatives combined, following the hypothesized ordering: CRS was highest among adolescents with familial BD (1.14 ± 0.78), intermediate among adolescents with non-familial BD (0.92 ± 0.79) and lowest in HC (0.76 ± 0.79; F = 6.23, df = 2, p = 0.002, ηp 2 = 0.03). There was a significant pairwise difference between adolescents with familial BD and HC (p = 0.002, Cohen's d = 0.49). A similar pattern of between-group differences was identified when first-degree and second-degree relatives were examined separately. Limitations: familial cardiovascular burden was determined based on parent interview, not evaluated directly. Conclusions: Adolescents with BD with a family history of BD have elevated rates of CVD-related conditions among their relatives. This may be related to genetic overlap between BD and CVD-related conditions, shared environmental factors that contribute to both BD and CVD-related conditions, or a combination of these factors. More research is warranted to better understand the interaction between familial risk for BD and CVD, and to address this risk using family-wide preventive approaches.

A qualitative study investigating bipolar patients' expectations of a lifestyle intervention: A self-management program

BACKGROUND

There is some evidence supporting the efficacy of lifestyle interventions in changing unhealthy habits and reduce the risk of developing comorbid conditions in Bipolar Disorder (BD).

AIMS

This qualitative study aimed to identify what an optimal lifestyle intervention would look like for individuals with BD.

METHODS

The current findings are based on one focus group and two paired interviews including a total of 10 individuals with BD (44.20 ± 11.11 years; 6 females). Groups' transcripts were analyzed using a narrative approach. Primary themes included facilitating factors and barriers, general content, outcomes, format of the intervention, and background factors.

RESULTS

Participants were in favor of a group-based lifestyle intervention as part of their usual treatment. The optimal group format would include 4 to 10 individuals, and comprise of 12 to 18 sessions lasting 1 to 1.5 h each. Accountability, motivation, interaction, and group activities were identified as contributing to the success of a lifestyle intervention.

CONCLUSIONS

This qualitative study provides important information regarding aspects of lifestyle intervention format and delivery for individuals with BD. We identified barriers and facilitating factors that should be addressed in health promotion interventions delivered within community mental health settings.

Bipolar disorder and obsessive compulsive disorder: The comorbidity does not further impair the neurocognitive profile

BACKGROUND

The comorbidity of bipolar disorder (BD) and obsessive-compulsive disorder (OCD) has been widely described. Several studies have investigated the cognitive profiles of BD and OCD patients, but studies that compare BD, BD-OCD, and OCD patients in neuropsychological domains do not exist. The purpose of this study was to compare set-shifting, decision making, and central coherence among BD, BD-OCD, and OCD patients.

METHODS

A battery of neuropsychological tests was administered to 68 patients (22 BD, 26 BD-OCD, 20 OCD). The Young Mania Rating Scale and Hamilton Depression Rating Scale were used to evaluate manic and depressive symptoms, and OCD severity was assessed with the Yale Brown Obsessive Compulsive Scale.

RESULTS

No significant differences emerged in decision-making and cognitive flexibility, whereas BD patients had lower scores in the Accuracy Index on Rey-Osterrieth Complex Figure Test and poor response speed on Hayling Sentence Completion Test Part A than OCD patients.

LIMITATIONS

The small sample size with different BD patients, the cross-sectional design, and the study clinical nature.

CONCLUSIONS

The most striking result is that, contrary to our hypothesis, comorbidity does not further impair the neurocognitive profile. The clinical relevance of our work could be a shift from the current cognitive rehabilitation model focusing on individualized pathways towards a new overlapping model for all three patient groups. This could make the cognitive rehabilitation faster and less costly. Notwithstanding, these disorders do not only need cognitive training but also various psycho-educative approaches and treatment according to their different clinical profile.

Hyperglycemia elicits anxiety-like behaviors in zebrafish: Protective role of dietary diphenyl diselenide

Diabetes mellitus (DM) is a chronic metabolic disease that may comorbid with various psychiatric disorders, such as anxiety and depression. The search for effective therapeutics to alleviate hyperglycemia and complications resulting from DM is continuous. Here we investigate the effects of diphenyl diselenide (DD), an organoselenium compound with several pharmacological properties, in a zebrafish model of hyperglycemia. Fish were fed for 74 days with a diet containing 3 mg/Kg DD, a concentration chosen after experiments based in a dose-response curve (DD 1, 2 and 3 mg/Kg) that did not cause overt toxicity (mortality, weight loss and neurobehavioral deficits). In the last 14 days of the experimental period, fish were concomitantly exposed to a glucose solution (111 mM). Afterwards, blood glucose levels, brain selenium (Se) content, and behavioral analysis aiming to assess anxiety-like behaviors and locomotor/exploratory activities were performed. In the novel tank diving test, glucose decreased vertical exploration and fish spent less time in the lit area when tested in the light-dark test, suggesting increased anxiety-like behavior. Moreover, DD decreased blood glucose levels in hyperglycemic fish as well as prevented the development of anxiety-related symptoms. DD diet alone did not change glycemia and behavioral parameters, but increased Se levels in the brain without affecting the cellular viability. Collectively, our findings highlight the growing utility of this zebrafish hyperglycemia model as a valuable strategy for further research in DM field and neuroprotective approaches.

Peroxisome Proliferator-Activated Receptor Gamma Coactivator-1 Alpha as a Novel Target for Bipolar Disorder and Other Neuropsychiatric Disorders

Peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1 alpha) is a protein that regulates metabolism and inflammation by activating nuclear receptors, especially the family of peroxisome proliferator-activated receptors (PPARs). PGC-1 alpha and PPARs also regulate mitochondrial biogenesis, cellular energy production, thermogenesis, and lipid metabolism. Brain energy metabolism may also be regulated in part by the interaction between PGC-1 alpha and PPARs. Because neurodegenerative diseases (Huntington's disease, Parkinson's disease, and amyotrophic lateral sclerosis) and bipolar disorder have been associated with dysregulated mitochondrial and brain energy metabolism, PGC-1 alpha may represent a potential drug target for these conditions. The purpose of this article is to review the physiology of PGC-1 alpha, PPARs, and the role of PPAR agonists to target PGC-1 alpha to treat neurodegenerative diseases and bipolar disorder. We also review clinical trials of repurposed antidiabetic thiazolidines and anti-triglyceride fibrates (PPAR agonists) for neurodegenerative diseases and bipolar disorder. PGC-1 alpha and PPARs are innovative potential targets for bipolar disorder and warrant future clinical trials.

Biological aspects and candidate biomarkers for rapid-cycling in bipolar disorder: A systematic review

Rapid-cycling bipolar disorder represents a frequent severe subtype of illness which has been associated with poor response to pharmacological treatment. Aim of the present article is to provide an updated review of biological markers associated with rapid-cycling bipolar disorder. A research in the main database sources has been conducted to identify relevant papers about the topic. Rapid-cycling bipolar disorder patients seem to have a more frequent family history for bipolar spectrum disorders (d range: 0.44-0.74) as well as an increased susceptibility to DNA damage or mRNA hypo-transcription (d range: 0.78-1.67) than non rapid-cycling ones. A susceptibility to hypothyroidism, which is exacerbated by treatment with lithium, is possible in rapid-cycling bipolar disorder, but further studies are needed to draw definitive conclusions. Rapid-cycling bipolar patients might have more insuline resistance as well as more severe brain changes in frontal areas (d range: 0.82-0.94) than non rapid-cycling ones. Many questions are still open about this topic. The first is whether the rapid-cycling is inheritable or is more generally the manifestation of a severe form of bipolar disorder. The second is whether some endocrine dysfunctions (diabetes and hypothyroidism) predispose to rapid-cycling or rapid-cycling is the consequence of drug treatment or medical comorbidities (e.g. obesity).

Indices of insulin resistance and glucotoxicity are not associated with bipolar disorder or major depressive disorder, but are differently associated with inflammatory, oxidative and nitrosative biomarkers

BACKGROUND

Insulin resistance (IR) is a key factor in diabetes mellitus, metabolic syndrome (MetS) and obesity and may occur in mood disorders and tobacco use disorder (TUD), where disturbances of immune-inflammatory, oxidative and nitrosative stress (IO&NS) pathways are important shared pathophysiological pathways.

METHODS

This study aimed to a) examine IR and β-cell function as measured by the homeostasis model assessment of insulin resistance (HOMA-IR) and insulin sensitivity and β cell function (HOMA-B) and glucotoxicity (conceptualized as increased glucose levels versus lowered HOMA-B values) in 74 participants with major depressive disorder (MDD) and bipolar disorder, with and or without MetS and TUD, versus 46 healthy controls, and b) whether IR is associated with IO&NS biomarkers, including nitric oxide metabolites (NOx), lipid hydroperoxides (LOOH), plasma advanced oxidation protein products (AOPP), C-reactive protein (CRP), haptoglobin (Hp) and uric acid.

RESULTS

Mood disorders are not associated with changes in IR or glucotoxicity, although the number of mood episodes may increase IR. 47.8% of the variance in HOMA-IR is explained by AOPP and body mass index (BMI, both positively) and NOx, Hp and TUD (all inversely). 43.2% of the variance in HOMA-B is explained by NOx, Hp and age (all inversely associated) and higher BMI and sex. The glucotoxic index is strongly associated with NOx, Hp and BMI (positively), male gender and lower education.

LIMITATIONS

This is a cross-sectional study and therefore we cannot draw firm conclusions on causal associations.

CONCLUSIONS

Activated IO&NS pathways (especially increased Hp and NOx) increase glucotoxicity and exert very complex effects modulating IR. Mood disorders are not associated with increased IR.

Associated illness severity in schizophrenia and diabetes mellitus: A systematic review

OBJECTIVE

We aimed to elucidate whether schizophrenia and type II diabetes mellitus may present with associated illness severity, in light of accumulating evidence to suggest both conditions have important shared inflammatory components with many shared inflammatory genetic factors.

METHODS

We conducted a systematic review employing PRISMA criteria, searching EMBASE, Ovid MEDLINE, PsychInfo, Web of Science and Google Scholar to February 1st, 2017, for clinical studies assessing schizophrenia severity alongside dysglycaemia. A narrative synthesis was employed to discuss and compare findings between studies.

RESULTS

Eleven observational studies were included in the analysis. Ten presented evidence in support of an association between schizophrenia severity and dysglycaemia. This association appeared particularly strong regarding negative symptomatology and impaired cognitive function, between which there may be some overlap. Studies examining positive symptomatology returned mixed results.

CONCLUSION

Whilst study design varied amongst the included studies, the results suggest that further work examining the effect of hyperglycaemia on schizophrenia severity may be relevant, particularly longitudinal studies assessing negative symptomatology and cognitive function. To the authors' knowledge, this is the first systematic review conducted to address this question.

The regulation of tetraspanin 8 gene expression-A potential new mechanism in the pathogenesis of bipolar disorder

In a previous study, we identified the single nucleotide polymorphism (SNP) rs4500567, located in the upstream region of tetraspanin 8 (TSPAN8), to be associated with bipolar disorder (BD). Due to its proximal position, the SNP might have an impact on promoter activity, thus on TSPAN8 gene expression. We investigated the impact of rs4500567 on TSPAN8 expression in vitro with luciferase-based promoter assays in human embryonic kidney (HEK293) and neuroblastoma cells (SH-SY5Y), and its effect on expression of downstream associated genes by microarray-based transcriptome analyses. Immunohistochemical localization studies on murine brain slices served to identify possible target regions of altered TSPAN8 expression in the brain. Promoter assays revealed decreased TSPAN8 expression in presence of the minor allele. Transcriptome analyses of TSPAN8-knockdown cells, mirroring the effects of putatively reduced TSPAN8 expression in minor allele carriers, resulted in 231 differentially expressed genes with enrichments of relevant signaling pathways for psychiatric disorders and neuronal development. Finally, we demonstrate Tspan8 abundance in mouse cerebellum and hippocampus. These findings point to a role of TSPAN8 in neuronal function or development. Considering a rather protective effect of the minor allele of rs4500567, our findings reveal a possible novel mechanism that contributes to the development of BD.

A systematic review of evidence for the role of inflammatory biomarkers in bipolar patients

Bipolar disorder (BD) is a neuropsychiatric disorder that is characterized by a phasic course of affective episodes interspersed with a euthymic state. Epidemiological, clinical, genetic, post-mortem and preclinical studies have shown that inflammatory reactions and immune modulation play a pivotal role in the pathophysiology of BD. It is conceptualized that biomarkers of inflammation and immune responses should be employed to monitor the disease process in bipolar patients. The objective of this systematic review is to analyse the inflammatory markers involved in human studies and to explore each individual marker for its potential clinical application and summarize evidence regarding their role in BD. A systematic review of human studies to measure inflammatory markers was conducted, and the studies were identified by searching PubMed/MEDLINE, PsycINFO, EMBASE, and Web of Science databases for peer-reviewed journals that were published until September 2015. In this review, we included peripheral markers, genetic, post-mortem and cell studies with inflammatory biomarker analysis in BD. One hundred and two (102) papers met the inclusion criteria. The pro-inflammatory cytokines were elevated and the anti-inflammatory cytokines were reduced in BD patients, particularly during manic and depressive phases when compared to the controls. These changes tend to disappear in euthymia, indicating that inflammation may be associated with acute phases of BD. Even though there are promising findings in this field, further clinical studies using more established detection techniques are needed to clearly show the benefit of using inflammatory markers in the diagnosis, follow-up and prognosis of patients with BD.

Berberine Ameliorates Diabetes-Associated Cognitive Decline through Modulation of Aberrant Inflammation Response and Insulin Signaling Pathway in DM Rats

Background: Memory-impairment was one of the common characteristics in patients with diabetes mellitus. The release of chronic inflammation mediators and insulin resistance in diabetic brain gave rise to the generation of toxic factor Aβ42 which was the marker of Alzheimer’s disease. In addition, the impairment of memory in diabetes mellitus was also correlated predominantly with uptake/metabolism of glucose in medial prefrontal cortex (mPFC). Previously, anti-inflammation and hypoglycemic effects of berberine (BBr) have been described in peripheral tissues. For better understanding the effects of BBr on cognitive action in diabetics, we investigated the functions of BBr involved in anti-inflammation and ameliorating insulin resistance in prefrontal cortex of diabetic rats.

Methods: Intragastric administration of BBr (187.5 mg/Kg/d) was used in diabetic rats. Fear-condition assay was applied for cognitive assessment, and relative protein expressions were detected by western-blot. The glucose uptake in prefrontal cortex of diabetic rats was tested by Positron-Emission Tomography imaging. The levels of inflammation mediators were determined by commercial ELISA kits.

Results: The inflammation mediator release and insulin resistance in the mPFC of diabetic rats was inhibited by BBr. The activation of PI3K/Akt/mTOR and MAPK signaling pathway, as well as two novel isoforms PKCη and PKC𝜀 and the translocation of NF-κB in neuron were also down-regulated by BBr; furthermore, the neuron specific glucose transporter GLUT3 was remarkably augmented by 2–3 times when compared with diabetic group; meanwhile, BBr also promoted glucose uptake in the brain. Additionally BBr decreased the expressions of amyloid precursor protein and BACE-1, and the production of oligomeric Aβ42. Finally, it accelerates the reinforcement of the information and ameliorates cognitive impairment.

Conclusion: BBr inhibited the activation of inflammation pathway and insulin resistance in the mPFC of diabetic rats. Finally, it improved the lesion of cognition in diabetic rats.

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.

Bipolar disorder and diabetes mellitus: evidence for disease-modifying effects and treatment implications

BACKGROUND

Bipolar disorder refers to a group of chronic psychiatric disorders of mood and energy levels. While dramatic psychiatric symptoms dominate the acute phase of the diseases, the chronic course is often determined by an increasing burden of co-occurring medical conditions. High rates of diabetes mellitus in patients with bipolar disorder are particularly striking, yet unexplained. Treatment and lifestyle factors could play a significant role, and some studies also suggest shared pathophysiology and risk factors.

OBJECTIVE

In this systematic literature review, we explored data around the relationship between bipolar disorder and diabetes mellitus in recently published population-based cohort studies with special focus on the elderly.

METHODS

A systematic search in the PubMed database for the combined terms "bipolar disorder" AND "elderly" AND "diabetes" in papers published between January 2009 and December 2015 revealed 117 publications; 7 studies were large cohort studies, and therefore, were included in our review.

RESULTS

We found that age- and gender- adjusted risk for diabetes mellitus was increased in patients with bipolar disorder and vice versa (odds ratio range between 1.7 and 3.2).

DISCUSSION

Our results in large population-based cohort studies are consistent with the results of smaller studies and chart reviews. Even though it is likely that heterogeneous risk factors may play a role in diabetes mellitus and in bipolar disorder, growing evidence from cell culture experiments and animal studies suggests shared disease mechanisms. Furthermore, disease-modifying effects of bipolar disorder and diabetes mellitus on each other appear to be substantial, impacting both treatment response and outcomes.

CONCLUSIONS

The risk of diabetes mellitus in patients with bipolar disorder is increased. Our findings add to the growing literature on this topic. Increasing evidence for shared disease mechanisms suggests new disease models that could explain the results of our study. A better understanding of the complex relationship between bipolar disorder and diabetes mellitus could lead to novel therapeutic approaches and improved outcomes.

The association between first-episode psychosis and abnormal glycaemic control: systematic review and meta-analysis

BACKGROUND

Schizophrenia might share intrinsic inflammatory disease pathways with type 2 diabetes. We aimed to assess whether first-episode psychosis, which could be described as developing schizophrenia, is associated with prediabetic markers, or developing diabetes, to determine whether intrinsic disease links could cause the disorders to develop in unison. We hypothesised that biochemical measures of prediabetic states would be more common in antipsychotic naive patients with first-episode psychosis than in healthy matched controls.

METHODS

For this systematic review and meta-analysis, using PRISMA criteria, we searched Embase, MEDLINE, PsycINFO, Web of Science, and Google Scholar for clinical studies published between database inception and Jan 6, 2016. We assessed case-control studies with biochemical assessment of prediabetic states in patients with first-episode psychosis alongside matched controls. We sought data at the summary estimate level. Several measurements were used to test for prediabetes, including fasting plasma glucose, insulin resistance (measured by the Homeostatic Model Assessment), and impaired glucose tolerance. We calculated standardised mean differences for each outcome. We used the inverse variance method, for which the weight given to each study was the inverse of the variance of the effect estimate. For dichotomous outcomes, we entered the number of events and number in each group into RevMan 5.3 and used the Mantel-Haenszel method to pool studies.

FINDINGS

We identified 1436 studies, of which 12 were included in final analysis, including 1137 participants. Pooled analyses found first-episode psychosis to be related to insulin resistance (mean difference 0·30 [95% CI 0·18 to 0·42]), impaired glucose tolerance (mean difference 1·31 [0·37 to 2·25]), and the number of patients with impaired glucose tolerance (odds ratio 5·44 [2·63 to 11·27]), but not fasting plasma glucose (mean difference 0·03 mmol/L [-0·04 to 0·09]).

INTERPRETATION

Our findings suggest a potential link between prediabetic markers, in particular impaired glucose tolerance and insulin resistance, and first-episode psychosis. However, we cannot establish causality, and the studies contributing to this review were at some risk of bias. Nevertheless, the findings might help to explain the increased prevalence of type 2 diabetes in patients with schizophrenia and could have implications for the management of patients with schizophrenia.

FUNDING

None.

Modeling mania in preclinical settings: A comprehensive review

The current pathophysiological understanding of mechanisms leading to onset and progression of bipolar manic episodes remains limited. At the same time, available animal models for mania have limited face, construct, and predictive validities. Additionally, these models fail to encompass recent pathophysiological frameworks of bipolar disorder (BD), e.g. neuroprogression. Therefore, there is a need to search for novel preclinical models for mania that could comprehensively address these limitations. Herein we review the history, validity, and caveats of currently available animal models for mania. We also review new genetic models for mania, namely knockout mice for genes involved in neurotransmission, synapse formation, and intracellular signaling pathways. Furthermore, we review recent trends in preclinical models for mania that may aid in the comprehension of mechanisms underlying the neuroprogressive and recurring nature of BD. In conclusion, the validity of animal models for mania remains limited. Nevertheless, novel (e.g. genetic) animal models as well as adaptation of existing paradigms hold promise.

Lifestyle interventions targeting dietary habits and exercise in bipolar disorder: A systematic review

BACKGROUND

Bipolar disorder (BD) is a serious mental illness associated with a high risk of medical comorbidities, long-term disability and premature death. This systematic review examined the current literature on therapeutic interventions targeting nutrition, physical activity and wellness in BD and collecting health-related measures such as mood and course of illness.

METHODS

Scopus (all databases), Pubmed and Ovid Medline were systematically searched with no language or year restrictions, up to June 2015, for studies focusing on lifestyle interventions in BD. Search terms were related to bipolar disorder, nutrition, physical activity, wellbeing, psychosocial interventions and course of illness. We hand searched content pages of Bipolar Disorders and Journal of Affective Disorders and checked references of relevant reviews and dissertations to identify additional papers.

RESULTS

After applying inclusion and exclusion criteria to identified hits, this literature search retrieved six papers. Overall findings point towards a beneficial role of lifestyle interventions on mood, weight, blood pressure, lipid profile, physical activity and overall wellbeing. Methodological limitations include small sample size, gender ratio imbalance, inconsistencies in terms of laboratory measures, and lack of randomized controlled trials and absence of follow-up and longitudinal studies to determine the benefits of these factors on clinical and functional outcomes over time

CONCLUSIONS

Lifestyle interventions in BD targeting nutrition, exercise, wellbeing alongside beliefs, coping strategies and attitudes towards health show promise in reducing the risk of comorbid ailments in BD. There is still a strong need for studies a) developing interventions which are informed by the patient's input and b) examining the effectiveness of such interventions targeting general wellness using well-controlled trials.

Antioxidant treatment ameliorates experimental diabetes-induced depressive-like behaviour and reduces oxidative stress in brain and pancreas

Studies have shown a relationship between diabetes mellitus (DM) and the development of major depressive disorder. Alterations in oxidative stress are associated with the pathophysiology of both diabetes mellitus and major depressive disorder. This study aimed to evaluate the effects of antioxidants N-acetylcysteine and deferoxamine on behaviour and oxidative stress parameters in diabetic rats. To this aim, after induction of diabetes by a single dose of alloxan, Wistar rats were treated with N-acetylcysteine or deferoxamine for 14 days, and then depressive-like behaviour was evaluated. Oxidative stress parameters were assessed in the prefrontal cortex, hippocampus, amygdala, nucleus accumbens and pancreas. Diabetic rats displayed depressive-like behaviour, and treatment with N-acetylcysteine reversed this alteration. Carbonyl protein levels were increased in the prefrontal cortex, hippocampus and pancreas of diabetic rats, and both N-acetylcysteine and deferoxamine reversed these alterations. Lipid damage was increased in the prefrontal cortex, hippocampus, amygdala and pancreas; however, treatment with N-acetylcysteine or deferoxamine reversed lipid damage only in the hippocampus and pancreas. Superoxide dismutase activity was decreased in the amygdala, nucleus accumbens and pancreas of diabetic rats. In diabetic rats, there was a decrease in catalase enzyme activity in the prefrontal cortex, amygdala, nucleus accumbens and pancreas, but an increase in the hippocampus. Treatment with antioxidants did not have an effect on the activity of antioxidant enzymes. In conclusion, animal model of diabetes produced depressive-like behaviour and oxidative stress in the brain and periphery. Treatment with antioxidants could be a viable alternative to treat behavioural and biochemical alterations induced by diabetes.

Glucagon-like peptide-1 (GLP-1) receptor agonist prevents development of tolerance to anti-anxiety effect of ethanol and withdrawal-induced anxiety in rats

Despite major advances in the understanding about ethanol actions, the precise underlying neurobiological mechanisms for ethanol dependence remain largely elusive. We recently reported that inhibition of dipeptidyl-peptidase IV (DPP-IV), an enzyme responsible for metabolism of endogenous glucagon-like peptide-1 (GLP-1), delays tolerance to anti-anxiety effect of ethanol and withdrawal-induced anxiety in rats. Intrigued with this report, present study examined the role of glucagon-like peptide-1 (GLP-1) receptor agonist, liraglutide in (1) acute anti-anxiety effect of ethanol; (2) tolerance to ethanol's anti-anxiety-effect and (3) ethanol withdrawal-induced anxiety using elevated plus maze (EPM) test in rats. Ethanol (2 g/kg, i.p.; 8 % w/v) and liraglutide (50 μg/kg, i.p.) treatments exhibited anti-anxiety effect in EPM test. Doses of ethanol (1.0 or 1.5 g/kg, i.p.) that were not effective per se elicited anti-anxiety when combined with sub-effective dose of liraglutide (25 μg/kg, i.p.). Rats consuming ethanol-diet (6 % v/v) exhibited tolerance to anti-anxiety effect of ethanol from day-7 of ethanol consumption. Peak ethanol withdrawal-induced anxiety was observed at 8-10 h upon abstinence from ethanol-diet after 15-days consumption. Rats on simultaneous once-daily liraglutide treatment (50 μg/kg, i.p.) neither had any signs of tolerance to anti-anxiety effect of ethanol nor did they exhibit withdrawal-induced anxiety.

IN CONCLUSION

(1) GLP-1 agonist, liraglutide exhibited anti-anxiety effect per se; (2) potentiated anti-anxiety effect of ethanol; (3) prevented development tolerance to anti-anxiety effect of ethanol and (4) prevented withdrawal-induced anxiety. Further studies examining intracellular cascade of events contributing to these effects may help to improve understanding about role of GLP-1 receptors in ethanol mediated behaviors.

Chronic Stimulation of Alpha-2A-Adrenoceptors With Guanfacine Protects Rodent Prefrontal Cortex Dendritic Spines and Cognition From the Effects of Chronic Stress

The prefrontal cortex (PFC) provides top-down regulation of behavior, cognition, and emotion, including spatial working memory. However, these PFC abilities are greatly impaired by exposure to acute or chronic stress. Chronic stress exposure in rats induces atrophy of PFC dendrites and spines that correlates with working memory impairment. As similar PFC grey matter loss appears to occur in mental illness, the mechanisms underlying these changes need to be better understood. Acute stress exposure impairs PFC cognition by activating feedforward cAMP-calcium-K+ channel signaling, which weakens synaptic inputs and reduces PFC neuronal firing. Spine loss with chronic stress has been shown to involve calcium-protein kinase C signaling, but it is not known if inhibiting cAMP signaling would similarly prevent the atrophy induced by repeated stress. The current study examined whether inhibiting cAMP signaling through alpha-2A-adrenoceptor stimulation with chronic guanfacine treatment would protect PFC spines and working memory performance during chronic stress exposure. Guanfacine was selected due to 1) its established effects on cAMP signaling at post-synaptic alpha-2A receptors on spines in PFC, and 2) its increasing clinical use for the treatment of pediatric stress disorders. Daily guanfacine treatment compared to vehicle control was found to prevent dendritic spine loss in layer II/III pyramidal neurons of prelimbic PFC in rats exposed to chronic restraint stress. Guanfacine also protected working memory performance; cognitive performance correlated with dendritic spine density. These findings suggest that chronic guanfacine use may have clinical utility by protecting PFC gray matter from the detrimental effects of stress.