Purinergic dysfunction in mania: an integrative model

Uric Acid as a Biomarker for Mood Disorders: A Comparative Study of Blood Uric Acid Levels Correlating With the Symptom Severity and Treatment Response

Background Bipolar affective disorder (BPAD) and major depressive disorder (MDD) are two mood disorders whose pathophysiology may involve the purinergic system. Elevated uric acid levels, associated with this system, can impact various behaviors in individuals affected by these conditions. In addition to genetic predisposition, blood uric acid levels can be impacted by various factors, including metabolic syndrome, the consumption of psychoactive medications, and other underlying kidney conditions such as gout. Objective The study aims to investigate the relationship between blood uric acid levels and mental health conditions, specifically BPAD subtypes (manic and depressive) and MDD. The study also examines changes in blood uric acid levels following treatment and evaluates the effectiveness of different treatment approaches in reducing uric acid levels. Methodology To be eligible to participate, individuals must have a confirmed diagnosis of BPAD (manic or depressive type) or MDD, according to the International Classification of Diseases (ICD-10). Blood uric acid levels were measured at both baseline and follow-up assessments. Symptoms were assessed weekly using standardized rating scales (Young Mania Rating Scale (YMRS) and Hamilton Rating Scale for Depression (HAM-D)) until treatment response was achieved, which was defined as a 50% reduction in initial scores on both scales. We used ANOVA to examine the differences among the three patient groups and paired sample t-tests to examine the changes in means before and after treatment conditions. Results A significant positive correlation was found between the severity of illness and serum uric acid levels across all three patient groups: those with BPAD-mania, BPAD-depression, and MDD. Notably, patients with BPAD-mania patients had significantly higher serum uric acid levels (5.2±0.9 mg/dL) compared to those with BPAD-depression (4.8±1.0 mg/dL) and MDD (4.0±1.1 mg/dL). After treatment, all patient groups exhibited a decrease in serum uric acid levels. The reduction in serum uric acid levels was pronounced in all patient groups, with decreases of 3.1±0.8 mg/dL in patients with BPAD-mania, 3.1±0.9 mg/dL in those with BPAD-depression, and 3.5±1.1 mg/dL in those with MDD. The study showed that the reduction in serum uric acid levels was significantly correlated with the severity of illness in patients with BPAD-mania, but not in those with BPAD-depression or MDD. Furthermore, the study found that treatment with lithium carbonate, sodium valproate, or carbamazepine was equally effective in reducing serum uric acid levels, regardless of the mood stabilizer used. Conclusion The study supports that dysfunction in the purine system might play a significant role in the development and progression of BPAD, suggesting that this phenomenon is not solely due to chronicity or medication exposure. This study also introduces a fresh perspective on the underlying biological processes that contribute to the development of BPAD and also sheds light on new treatment regimens targeting uric acid reduction in treating patients with bipolar disorder.

The Prevalence of Hyperuricemia and the Association Between Hyperuricemia and Age in Patients with Psychiatric Disorders to a General Hospital: A Cross-Section Study

Purpose

In clinical work, it has been found that the prevalence of hyperuricemia (HUA) is significantly higher in younger patients with psychiatric disorders, but there are few studies in this area. The present study aims to evaluate the prevalence of HUA and the relationship between the HUA and age in hospitalized patients with psychiatric disorders in the real world, and to provide a theoretical basis for clinical staff to pay attention to the metabolic indicators of younger patients and for future related studies.

Methods

This is a cross-sectional evaluation of a cohort of 1761 patients with psychiatric disorders of hospitalized. The categories of disorders designed for study included: Depression, Bipolar disorder, Schizophrenia, Anxiety, Obsessive-Compulsive disorder, Acute and transient psychotic disorder, Dissociative(conversion) disorders, Conduct disorders and Tic disorders. In addition, based on age, the participants are stratified into three groups. The authors used Kruskal-Wallis tests, chi-square tests, and multiple linear logistic regression to verify the relationship between HUA and age among hospitalized patients with psychiatric disorders.

Results

Overall, the estimated prevalence of HUA was 35.4%. The prevalence of HUA was significantly higher in individuals with 17 years and under compared to those with 45 years and above (P < 0.001). After adjusting for confounders, the prevalence of HUA remained higher at 17 years and under than at 45 years and above. Bipolar disorder can lead to an increased prevalence of HUA (P<0.05).

Conclusion

The prevalence of HUA was higher in hospitalized patients with psychiatric disorders, and the prevalence was inversely proportional to age.

Bipolar mania and epilepsy pathophysiology and treatment may converge in purine metabolism: A new perspective on available evidence

Decreased ATPergic signaling is an increasingly recognized pathophysiology in bipolar mania disease models. In parallel, adenosine deficit is increasingly recognized in epilepsy pathophysiology. Under-recognized ATP and/or adenosine-increasing mechanisms of several antimanic and antiseizure therapies including lithium, valproate, carbamazepine, and ECT suggest a fundamental pathogenic role of adenosine deficit in bipolar mania to match the established role of adenosine deficit in epilepsy. The depletion of adenosine-derivatives within the purine cycle is expected to result in a compensatory increase in oxopurines (uric acid precursors) and secondarily increased uric acid, observed in both bipolar mania and epilepsy. Cortisol-based inhibition of purine conversion to adenosine-derivatives may be reflected in observed uric acid increases and the well-established contribution of cortisol to both bipolar mania and epilepsy pathology. Cortisol-inhibited conversion from IMP to AMP as precursor of both ATP and adenosine may represent a mechanism for treatment resistance common in both bipolar mania and epilepsy. Anti-cortisol therapies may therefore augment other treatments both in bipolar mania and epilepsy. Evidence linking (i) adenosine deficit with a decreased need for sleep, (ii) IMP/cGMP excess with compulsive hypersexuality, and (iii) guanosine excess with grandiose delusions may converge to suggest a novel theory of bipolar mania as a condition characterized by disrupted purine metabolism. The potential for disease-modification and prevention related to adenosine-mediated epigenetic changes in epilepsy may be mirrored in mania. Evaluating the purinergic effects of existing agents and validating purine dysregulation may improve diagnosis and treatment in bipolar mania and epilepsy and provide specific targets for drug development.

Non-canonical pathways in the pathophysiology and therapeutics of bipolar disorder

Bipolar disorder (BD) is characterized by extreme mood swings ranging from manic/hypomanic to depressive episodes. The severity, duration, and frequency of these episodes can vary widely between individuals, significantly impacting quality of life. Individuals with BD spend almost half their lives experiencing mood symptoms, especially depression, as well as associated clinical dimensions such as anhedonia, fatigue, suicidality, anxiety, and neurovegetative symptoms. Persistent mood symptoms have been associated with premature mortality, accelerated aging, and elevated prevalence of treatment-resistant depression. Recent efforts have expanded our understanding of the neurobiology of BD and the downstream targets that may help track clinical outcomes and drug development. However, as a polygenic disorder, the neurobiology of BD is complex and involves biological changes in several organelles and downstream targets (pre-, post-, and extra-synaptic), including mitochondrial dysfunction, oxidative stress, altered monoaminergic and glutamatergic systems, lower neurotrophic factor levels, and changes in immune-inflammatory systems. The field has thus moved toward identifying more precise neurobiological targets that, in turn, may help develop personalized approaches and more reliable biomarkers for treatment prediction. Diverse pharmacological and non-pharmacological approaches targeting neurobiological pathways other than neurotransmission have also been tested in mood disorders. This article reviews different neurobiological targets and pathophysiological findings in non-canonical pathways in BD that may offer opportunities to support drug development and identify new, clinically relevant biological mechanisms. These include: neuroinflammation; mitochondrial function; calcium channels; oxidative stress; the glycogen synthase kinase-3 (GSK3) pathway; protein kinase C (PKC); brain-derived neurotrophic factor (BDNF); histone deacetylase (HDAC); and the purinergic signaling pathway.

The prevalence and associated clinical correlates of hyperuricemia in patients with bipolar disorder

Objective

The prevalence and clinically associated factors of hyperuricemia (HUA) have been widely studied in the general population but rarely in patients with bipolar disorder (BPD) co-morbid with HUA. This study attempted to investigate the prevalence of HUA in BPD patients and analyze the associated correlates of HUA.

Materials and methods

In this study, 182 outpatients with BPD and 182 healthy controls participated. The demographic and clinical information were collected. The body weight, height, waist circumference (WC), hip circumference (HC), and blood pressure (BP) were measured. The levels of serum uric acid (UA), triglyceride (TG), high-density lipoprotein (HDL-C), and fasting blood glucose (FBG) were also determined.

Results

BPD patients had a significantly higher prevalence of HUA (40.7%) compared to healthy controls (30.2%) (χ² = 4.335, P = 0.037). The systolic blood pressure (SBP), pulse pressure (PP), FBG, UA, and body mass index (BMI) were higher in the BPD group compared with those in the control group, while the diastolic blood pressure (DBP) and HDL-C level were lower (P < 0.05) in BPD patients. The prevalence of HUA was higher in BPD patients who used antipsychotics combined with mood stabilizers than that in BPD subjects receiving the mood stabilizers alone (P < 0.001). The prevalence of HUA and increased serum UA levels were higher in the manic group (62.1%) than in the depressive (34.3%) or euthymia group (17.0%) (P < 0.001). Additionally, the severity of mania was positively correlated with the UA level (r = 0.410, P < 0.001). There were significant differences in terms of MetS (29.7% vs. 14.8%), BMI, HC, WC, TG, and HDL-C between the HUA and the non-HUA groups (P < 0.05). The unconditional logistic regression analysis revealed that high BMI (OR = 1.210; 95%CI: 1.100–1.331) and high TG level (OR = 1.652; 95%CI: 1.058–2.580) were the major risk factorids for HUA in BPD patients.

Conclusion

Our study suggests that patients with BPD are prone to metabolic diseases such as HUA. Higher serum levels of TG and high BMI could be associated with HUA development. Clinicians need to regularly monitor and evaluate BPD patients for their serum UA levels, especially for BPD patients with manic/hypomanic episodes and/or under the treatment of antipsychotics combined with mood stabilizers.

The serum uric acid is longitudinally related to patients global assessment of disease activity in male patients with axial spondyloarthritis

Objectives

To investigate longitudinal relationship between serum uric acid (SUA) and disease activity among Chinese males with axial spondyloarthritis (axSpA).

Methods

Two-year data from the NASA study cohort of male patients with axial spondyloarthritis were analyzed. Patients global assessment of disease activity (PtGA), BASDAI, ASDAS-CRP, BASFI, and SF-36 were used as the outcomes. The autoregressive Generalized Estimation Equation (GEE) model was used to investigate the longitudinal relationship between SUA and the above outcomes. Age and gender and symptom duration were tested as effect modifiers or confounders.

Results

In total, 102 male axSpA patients were included, 33.3% of who were hyperuricemia at baseline. Over time,serum uric acid levels associated with the global assessment of patient global assessment of disease activity (PtGA)[P=0.041, β=-2.059,95%CI(-4.032, -0.086)], SF-36: Vitality (VT) [P=0.01, β=1.751, 95%CI (0.415,3.087)], SF-36: Social Functioning (SF)[P=0.002, β= 2.968,95%CI (1.067,4.869)]). And these relationgships were independent of age, symptom duration, baseline uric acid levels, and medication use.

Conclusions

In summary, SUA levels is longitudinally related to PtGA and mental health assessment. Age, gender and symptom duration do not have an impact on the relationships.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-022-05657-3.

Metabolomic biomarkers related to non-suicidal self-injury in patients with bipolar disorder

BACKGROUND

Non-suicidal self-injury (NSSI) is an important symptom of bipolar disorder (BD) and other mental disorders and has attracted the attention of researchers lately. It is of great significance to study the characteristic markers of NSSI. Metabolomics is a relatively new field that can provide complementary insights into data obtained from genomic, transcriptomic, and proteomic analyses of psychiatric disorders. The aim of this study was to identify the metabolic pathways associated with BD with NSSI and assess important diagnostic and predictive indices of NSSI in BD.

METHOD

Nuclear magnetic resonance spectrometry was performed to evaluate the serum metabolic profiles of patients with BD with NSSI (n = 31), patients with BD without NSSI (n = 46), and healthy controls (n = 10). Data were analyzed using an Orthogonal Partial Least Square Discriminant Analysis and a t-test. Differential metabolites were identified (VIP > 1 and p < 0.05), and further analyzed using Metabo Analyst 3.0 to identify associated metabolic pathways.

RESULTS

Eight metabolites in the serum and two important metabolic pathways, the urea and glutamate metabolism cycles, were found to distinguish patients with BD with NSSI from healthy controls. Eight metabolites in the serum, glycine and serine metabolism pathway, and the glucose-alanine cycle were found to distinguish patients with BD without NSSI from healthy controls. Five metabolites in the serum and the purine metabolism pathway were found to distinguish patients with BD with NSSI from those with BD without NSSI.

CONCLUSIONS

Abnormalities in the urea cycle, glutamate metabolism, and purine metabolism played important roles in the pathogenesis of BD with NSSI.

Oxidative Stress and Psychiatric Disorders: Evidence from the Bidirectional Mendelian Randomization Study

Observational studies have shown that oxidative stress is highly related to psychiatric disorders, while its cause−effect remains unclear. To this end, a Mendelian randomization study was performed to investigate the causal relationship between oxidative stress and psychiatric disorders. On the one hand, all causal effects of oxidative stress injury biomarkers (OSIB) on psychiatric disorders were not significant (p > 0.0006), while the findings suggested that part of OSIB was nominally associated with the risk of psychiatric disorders (causal OR of uric acid (UA), 0.999 for bipolar disorder (BD), and 1.002 for attention-deficit/hyperactivity disorder (ADHD); OR of catalase was 0.903 for anorexia nervosa (AN); OR of albumin was 1.162 for autism; p < 0.05). On the other hand, major depressive disorder (MDD) was significantly associated with decreased bilirubin (p = 2.67 × 10−4); ADHD was significantly associated with decreased ascorbate (p = 4.37 × 10−5). Furthermore, there were also some suggestively causal effects of psychiatric disorders on OSIB (BD on decreased UA and increased retinol; MDD on increased UA and decreased ascorbate; schizophrenia on decreased UA, increased retinol and albumin; ADHD on increased UA, and decreased catalase, albumin, and bilirubin; AN on decreased UA). This work presented evidence of potential causal relationships between oxidative stress and psychiatric disorders.

Effect of Probiotic Supplements on Oxidative Stress Biomarkers in First-Episode Bipolar Disorder Patients: A Randomized, Placebo-Controlled Trial

Background: Currently no study has examined the effects of probiotic administration on the symptoms of anxiety, depression, and mania, as well as their correlations with the biomarkers of oxidative stress in patients with bipolar disorder (BPD). The aim of this study is to determine the effects of probiotic supplementation on plasma oxidative stress-related biomarkers and different domains of clinical symptom in patients suffering from BPD. Methods: Eighty first-episode drug-naive patients with BPD were recruited. The subjects were randomized to receive psychotropic drugs supplementing with either probiotic or placebo and scheduled to evaluate with follow-ups for clinical symptom improvements and changes in the oxidative stress biomarkers. The Hamilton Depression Rating Scale, Hamilton Anxiety Rating Scale, and Young Mania Rating Scale were used to assess the clinical symptomatology. The panel of plasma oxidative stress biomarkers were determined by ultra-performance liquid chromatography-mass spectrometry (UPLC-MS/MS) at baseline and for 3 months of follow-up, i.e., at post-treatment month 1, 2, and 3. Results: After 3 months of intervention, decreased levels of plasma lysophosphatidylcholines (LPCs) were found in both placebo and probiotic groups. However, six other oxidative stress biomarkers (i.e., creatine, inosine, hypoxanthine, choline, uric acid, allantoic acid) increased in BPD patients after the two types of therapies. In addition, a positive correlation between changes of LPC (18:0) and YMRS scale was found in BPD patients and this association only existed in the probiotic group. Additionally, the mania symptom greatly alleviated (pretreatment-posttreatment, odds ratio = 0.09, 95%CI = 0.01, 0.64, p= 0.016) in patients who received probiotic supplements as compared with the placebo group. Conclusion: The changes in plasma biomarkers of oxidative stress in patients with BPD have a potential to be trait-like markers, and serve as prognostic indexes for bipolar patients. Daily intakes of probiotics have advantageous effects on BPD patients with certain clinical symptoms, especially manic symptoms. The treatment may be a promising adjunctive therapeutic strategy for BPD patients in manic episode.

Peripheral non-enzymatic antioxidants as biomarkers for mood disorders: Evidence from a machine learning prediction model

BACKGROUND

Oxidative stress is related to the pathogenesis of mood disorders, and the level of oxidative stress may differ between bipolar disorder (BD) and major depressive disorder (MDD). This study aimed to detect the differences in non-enzymatic antioxidant levels between BD and MDD and assess the predictive values of non-enzymatic antioxidants in mood disorders by applying a machine learning model.

METHODS

Peripheral uric acid (UA), albumin (ALB), and total bilirubin (TBIL) were measured in 1,188 participants (discover cohort: 157 with BD and 544 with MDD; validation cohort: 119 with BD and 95 with MDD; 273 healthy controls). An extreme gradient boosting (XGBoost) model and a logistic regression model were used to assess the predictive effect.

RESULTS

All three indices differed between patients with mood disorders and healthy controls; in addition, the levels of UA in patients with BD were higher than those of patients with MDD. After treatment, UA levels increased in the MDD group, while they decreased in the BD group. Finally, we entered age, sex, UA, ALB, and TBIL into the XGBoost model. The area under the curve (AUC) of the XGBoost model for distinguishing between BD and MDD reached 0.849 (accuracy = 0.808, 95% CI = 0.719-0.878) and for distinguishing between BD with depression episode (BD-D) and MDD was 0.899 (accuracy = 0.891, 95% CI = 0.856-0.919). The models were validated in the validation cohort. The most important feature distinguishing between BD and MDD was UA.

CONCLUSION

Peripheral non-enzymatic antioxidants, especially the UA, might be a potential biomarker capable of distinguishing between BD and MDD.

The Influence of Serum Uric Acid on the Brain and Cognitive Dysfunction

Uric acid is commonly known for its bad reputation. However, it has been shown that uric acid may be actively involved in neurotoxicity and/or neuroprotection. These effects could be caused by oxidative stress or inflammatory processes localized in the central nervous system, but also by other somatic diseases or systemic conditions. Our interest was to summarize and link the current data on the possible role of uric acid in cognitive functioning. We also focused on the two putative molecular mechanisms related to the pathological effects of uric acid-oxidative stress and inflammatory processes. The hippocampus is a prominent anatomic localization included in expressing uric acid's potential impact on cognitive functioning. In neurodegenerative and mental disorders, uric acid could be involved in a variety of ways in etiopathogenesis and clinical presentation. Hyperuricemia is non-specifically observed more frequently in the general population and after various somatic illnesses. There is increasing evidence to support the hypothesis that hyperuricemia may be beneficial for cognitive functioning because of its antioxidant effects but may also be a potential risk factor for cognitive dysfunction, in part because of increased inflammatory activity. In this context, gender specificities must also be considered.

The Purinergic System as a Target for the Development of Treatments for Bipolar Disorder

The neurobiological and neurochemical mechanisms underlying the pathophysiology of bipolar disorder are complex and not yet fully understood. From circadian disruption to neuroinflammation, many pathways and signaling molecules are important contributors to bipolar disorder development, some specific to a disease subtype or a cycling episode. Pharmacological agents for bipolar disorder have shown only partial efficacy, including mood stabilizers and antipsychotics. The purinergic hypothesis for bipolar disorder emerges in this scenario as a promising target for further research and drug development, given its role in neurotransmission and neuroinflammation that results in behavioral and mood regulation. Here, we review the basic concepts of purinergic signaling in the central nervous system and its contribution to bipolar disorder pathophysiology. Allopurinol and novel P2X7 receptor antagonists are promising candidates for treating bipolar disorder. We further explore currently available pharmacotherapies and the emerging new purinergic targets for drug development in bipolar disorder.

Individuals with bipolar disorder have a higher level of uric acid than major depressive disorder: a case-control study

At present, no well-established biomarkers were ever found to distinguish unipolar depression and bipolar disorder (BD). This study aimed to provide a clearer comparison of UA levels between BD and major depressive disorder. Peripheral UA of 119 patients with BD in acute stage (AS) and 77 in remission stage (RS), and 95 patients with UD in AS and 61 in RS were measured, so were 180 healthy controls. UA levels in BD group were higher than UD and HC groups regardless of the AS or RS, while differences in UA levels between UD group and HC group were not significant. Differences in UA levels of BD-M (bipolar mania/hypomania) were higher than BD-D (bipolar depression) subgroups, and UA levels of BD-M and BD-D subgroups were higher than UD and HC groups. The comparison of number of participants with hyperuricemia among groups confirmed the above results. There were no significant differences in UA levels of between drug-use and drug-free/naïve subgroups. UA could distinguish BD and UD significantly both in acute and remission stage. The study suggests patients with BD had a higher level of UA than UD, especially in mania episode. UA may be a potential biomarker to distinguish BD from UD.

Inflammatory signaling mechanisms in bipolar disorder

Bipolar disorder is a decidedly heterogeneous and multifactorial disease, with a high individual and societal burden. While not all patients display overt markers of elevated inflammation, significant evidence suggests that aberrant immune signaling contributes to all stages of the disease, and likely explains the elevated rates of comorbid inflammatory illnesses seen in this population. While individual systems have been intensely studied and targeted, a relative paucity of attention has been given to the interconnecting role of inflammatory signals therein. This review presents an updated overview of some of the most prominent pathophysiologic mechanisms in bipolar disorder, from mitochondrial, endoplasmic reticular, and calcium homeostasis, to purinergic, kynurenic, and hormonal/neurotransmitter signaling, showing inflammation to act as a powerful nexus between these systems. Several areas with a high degree of mechanistic convergence within this paradigm are highlighted to present promising future targets for therapeutic development and screening.

Purines and Pyrimidines: Metabolism, Function and Potential as Therapeutic Options in Neurodegenerative Diseases

Various neurodegenerative disorders have various molecular origins but some common molecular mechanisms. In the current scenario, there are very few treatment regimens present for advanced neurodegenerative diseases. In this context, there is an urgent need for alternate options in the form of natural compounds with an ameliorating effect on patients. There have been individual scattered experiments trying to identify potential values of various intracellular metabolites. Purines and Pyrimidines, which are vital molecules governing various aspects of cellular biochemical reactions, have been long sought as crucial candidates for the same, but there are still many questions that go unanswered. Some critical functions of these molecules associated with neuromodulation activities have been identified. They are also known to play a role in foetal neurodevelopment, but there is a lacuna in understanding their mechanisms. In this review, we have tried to assemble and identify the importance of purines and pyrimidines, connecting them with the prevalence of neurodegenerative diseases. The leading cause of this class of diseases is protein misfolding and the formation of amyloids. A direct correlation between loss of balance in cellular homeostasis and amyloidosis is yet an unexplored area. This review aims at bringing the current literature available under one umbrella serving as a foundation for further extensive research in this field of drug development in neurodegenerative diseases.

Intracellular Signaling Cascades in Bipolar Disorder

Bipolar spectrum disorders carry a significant public health burden. Disproportionately high rates of suicide, incarceration, and comorbid medical conditions necessitate an extraordinary focus on understanding the intricacies of this disease. Elucidating granular, intracellular details seems to be a necessary preamble to advancing promising therapeutic opportunities. In this chapter, we review a wide range of intracellular mechanisms including mitochondrial energetics, calcium signaling, neuroinflammation, the microbiome, neurotransmitter metabolism, glycogen synthase kinase 3-beta (GSK3β), protein kinase C (PKC) and diacylglycerol (DAG), and neurotrophins (especially BDNF), as well as the glutamatergic, dopaminergic, purinergic, and neurohormonal systems. Owing to the relative lack of understanding and effective therapeutic options compared to the rest of the spectrum, special attention is paid in the chapter to the latest developments in bipolar depression. Likewise, from a therapeutic standpoint, special attention should be paid to the pervasive mechanistic actions of lithium as a means of amalgamating numerous, disparate cascades into a digestible cognitive topology.

Chronic nicotine, but not suramin or resveratrol, partially remediates the mania-like profile of dopamine transporter knockdown mice

Bipolar disorder (BD) is a severe mental illness affecting 2% of the global population. Current pharmacotherapies provide incomplete symptom remediation, highlighting the need for novel therapeutics. BD is characterized by fluctuations between mania and depression, likely driven by shifts between hyperdopaminergia and hypercholinergia, respectively. Hyperdopaminergia may result from insufficient activity of the dopamine transporter (DAT), the primary mediator of synaptic dopamine clearance. The DAT knockdown (DAT KD) mouse recreates this mechanism and exhibits a highly reproducible hyperexploratory profile in the cross-species translatable Behavioral Pattern Monitor (BPM) that is: (a) consistent with that observed in BD mania patients; and (b) partially normalized by chronic lithium and valproate treatment. The DAT KD/BPM model of mania therefore exhibits high levels of face-, construct-, and predictive-validity for the pre-clinical assessment of putative anti-mania drugs. Three different drug regimens - chronic nicotine (nicotinic acetylcholine receptor (nAChR) agonist; 40 mg/kg/d, 26 d), subchronic suramin (anti-purinergic; 20 mg/kg, 1 × /wk, 4 wks), and subchronic resveratrol (striatal DAT upregulator; 20 mg/kg/d, 4 d) - were administered to separate cohorts of male and female DAT KD- and wildtype (WT) littermate mice, and exploration was assessed in the BPM. Throughout, DAT KD mice exhibited robust hyperexploratory profiles relative to WTs. Nicotine partially normalized this behavior. Resveratrol modestly upregulated DAT expression but did not normalize DAT KD behavior. These results support the mania-like profile of DAT KD mice, which may be partially remediated by nAChR agonists via restoration of disrupted catecholaminergic/cholinergic equilibrium. Delineating the precise mechanism of action of nicotine could identify more selective therapeutic targets.

A Single Nucleotide Polymorphism Within Molybdenum Cofactor Sulfurase Gene Is Associated With Neuropsychiatric Conditions

Background

Molybdenum cofactor sulfurase (MOCOS) is an enzyme participating in purine metabolism. The aim of current study was to evaluate the role of a single nucleotide polymorphism (SNP) in the coding gene (rs594445) in mood disorders and methamphetamine addiction.

Methods

This SNP was genotyped in 200 persons with methamphetamine addiction, 85 patients with bipolar disorder 1 (BP1), 78 patients with BP2, 33 patients with major depressive disorder (MDD) and 200 age-/sex-matched normal subjects using the tetra-primer amplification-refractory mutation system (ARMS)-PCR technique.

Results

The rs594445 was associated with methamphetamine addiction in co-dominant model [A/A vs C/C: OR (95% CI) = 0.466 (0.252–0.864), P-value = 0.014; C/A vs C/C: OR (95% CI) = 0.641 (0.418–0.981), P-value = 0.04]. This SNP was also associated with this trait in dominant model [OR (95% CI) = 0.591 (0.398–0.879), P-value = 0.009]. The A allele of rs594445 had a protective role against methamphetamine addiction [A vs C: OR (95% CI) = 0.645 (0.48–0.866), P-value = 0.004]. The rs594445 was associated with BP1 in co-dominant model [C/A vs C/C: OR (95% CI) = 0.423 (0.230–0.778), P-value = 0.005]. However, the associations were insignificant in other inheritance models.

Conclusion

Finally, there were no significant associations between the mentioned SNP and risk of BP2 or MDD in any inheritance model. The present project highlights the role rs594445 in two psychiatric conditions and implies the presence of common genetic factors for these disorders.

Comparison of Serum Uric Acid in Major Depressive Disorder and Bipolar Disorder: a Retrospective Chart Review Study

BACKGROUND

Uric acid (UA) has been suggested as a possible biomarker of bipolar disorder (BD) in recent studies. We aimed to provide a clearer comparison of UA levels between BD and major depressive disorder (MDD).

METHODS

We retrospectively reviewed the medical chart records of psychiatric inpatients aged 19-60 years, whose main discharge diagnoses were either MDD or BD, with an admission between January 1, 2015 and December 31, 2018 at Seoul National University Hospital. Data such as sex, age, body mass index (BMI), medication usage, and serum UA levels were extracted. Patients with medical conditions or on medications that could influence UA levels were excluded. Age, sex, BMI, and psychiatric drug usage were considered in the comparison of serum UA between MDD and BD patients.

RESULTS

Our sample consisted of 142 MDD patients and 234 BD patients. The BD patients had significantly higher serum UA levels compared to the MDD patients, without accounting for other confounding variables (5.75 ± 1.56 mg/dL vs. 5.29 ± 1.59 mg/dL, P = 0.006). T-test comparisons between psychiatric medication users and non-users revealed that mood stabilizers and antipsychotics may be relevant confounding factors in our sample analysis. The likelihood of BD diagnosis was significantly correlated with higher UA levels (odds ratio, 1.410; 95% confidence interval, 1.150-1.728; P = 0.001) when accounting for sex, age, and BMI in the logistic regression analysis. Also, accounting for mood stabilizers or antipsychotics, the likelihood of BD diagnosis was still significantly correlated with higher UA levels.

CONCLUSION

Our study confirms that BD patients are significantly more likely to show higher serum UA levels than MDD patients. The high UA levels in BD point to purinergic dysfunction as an underlying mechanism that distinguishes BD from MDD. Further research is recommended to determine whether UA is a trait or a state marker and whether UA correlates with the symptoms and severity of BD.

Inosine prevents hyperlocomotion in a ketamine-induced model of mania in rats

Bipolar Disorder is a disorder characterized by alternating episodes of depression, mania or hypomania, or even mixed episodes. The treatment consists on the use of mood stabilizers, which imply serious adverse effects. Therefore, it is necessary to identify new therapeutic targets to prevent or avoid new episodes. Evidence shows that individuals in manic episodes present a purinergic system dysfunction. In this scenario, inosine is a purine nucleoside known to act as an agonist of A₁ and A_2A adenosine receptors. Thus, we aimed to elucidate the preventive effect of inosine on locomotor activity, changes in purine levels, and adenosine receptors density in a ketamine-induced model of mania in rats. Inosine pretreatment (25 mg/kg, oral route) prevented the hyperlocomotion induced by ketamine (25 mg/kg, intraperitoneal route) in the open-field test; however, there was no difference in hippocampal density of A₁ and A_2A receptors, where ketamine, as well as inosine, were not able to promote changes in immunocontent of the adenosine receptors. Likewise, no effects of inosine pretreatments or ketamine treatment were observed for purine and metabolic residue levels evaluated. In this sense, we suggest further investigation of signaling pathways involving purinergic receptors, using pharmacological strategies to better elucidate the action mechanisms of inosine on bipolar disorder. Despite the limitations, inosine administration could be a promising candidate for bipolar disorder treatment, especially by attenuating maniac phase symptoms, once it was able to prevent the hyperlocomotion induced by ketamine in rats.

Serum uric acid as a predictor of bipolarity in individuals with a major depressive episode

OBJECTIVES

There are no well-established biomarkers to predict the risk of conversion to bipolar disorder (BD) in patients with depression. Given the putative role of purinergic neurotransmission dysfunction in BD, the purpose of our study was to evaluate if higher serum uric acid (UA) levels could predict BD conversion in depressed inpatients.

METHODS

We reviewed retrospectively the records of subjects hospitalized between June 2007 and June 2010 with a diagnosis of major depressive disorder (MDD) who had undergone routine UA levels testing at admission. At an approximate 10-year follow-up we identified subjects with a subsequent diagnosis of BD. We compared UA levels between the BD-converter and non-BD converter groups, performed Receiver operating characteristic curve analysis to evaluate the prognostic accuracy of serum UA levels and calculated the clinical utility index (CUI) as a risk biomarker for conversion to BD.

RESULTS

The study included 250 subjects (55 "BD-converters" and 195 "No BD-converters"). "BD-converters" had significantly higher plasma UA levels compared to "No BD-converters" in their index hospitalization irrespective of gender (males: 403.84 ± 91.76 vs 270.81 ± 53.58 µmol/L; U = 94.5, P < 0.001 and females 302.19 ± 52.64 vs 202.69 ± 48.93 µmol/L; t = 10.75, P < 0.001). Serum UA levels showed a very good to excellent accuracy for predicting conversion to BD in inpatients with MDD (area under the curve [AUC]: 0.90; 95% CI: 0.86, 0.94) and had a good to excellent CUI- and a moderate to good CUI+ grading for discriminating BD-converter cases from non-BD converters.

CONCLUSIONS

Our study suggests that depressed patients with higher levels of serum UA are at greater risk of a subsequent manic or hypomanic episode. The purinergic system could prove a promising path for the search of biomarkers in BD.

Therapeutic Potential of Exogenous Ketone Supplement Induced Ketosis in the Treatment of Psychiatric Disorders: Review of Current Literature

Globally, psychiatric disorders, such as anxiety disorder, bipolar disorder, schizophrenia, depression, autism spectrum disorder, and attention-deficit/hyperactivity disorder (ADHD) are becoming more prevalent. Although the exact pathological alterations are not yet clear, recent studies have demonstrated that widespread changes of very complex metabolic pathways may partially underlie the pathophysiology of many psychiatric diseases. Thus, more attention should be directed to metabolic-based therapeutic interventions in the treatment of psychiatric disorders. Emerging evidence from numerous studies suggests that administration of exogenous ketone supplements, such as ketone salts or ketone esters, generates rapid and sustained nutritional ketosis and metabolic changes, which may evoke potential therapeutic effects in cases of central nervous system (CNS) disorders, including psychiatric diseases. Therefore, the aim of this review is to summarize the current information on ketone supplementation as a potential therapeutic tool for psychiatric disorders. Ketone supplementation elevates blood levels of the ketone bodies: D-β-hydroxybutyrate (βHB), acetoacetate (AcAc), and acetone. These compounds, either directly or indirectly, beneficially affect the mitochondria, glycolysis, neurotransmitter levels, activity of free fatty acid receptor 3 (FFAR3), hydroxycarboxylic acid receptor 2 (HCAR2), and histone deacetylase, as well as functioning of NOD-like receptor pyrin domain 3 (NLRP3) inflammasome and mitochondrial uncoupling protein (UCP) expression. The result of downstream cellular and molecular changes is a reduction in the pathophysiology associated with various psychiatric disorders. We conclude that supplement-induced nutritional ketosis leads to metabolic changes and improvements, for example, in mitochondrial function and inflammatory processes, and suggest that development of specific adjunctive ketogenic protocols for psychiatric diseases should be actively pursued.

Serum uric acid levels in first episode mania, effect on clinical presentation and treatment response: Data from a case control study

Bipolar disorder (BD) patients have increased serum Uric Acid (UA) levels as compared to their healthy counterparts. They also demonstrate higher impulsivity - while symptomatic, as well as when in remission. Impulsivity adds a risk of self-harming behavior to BD, and studies show that it increases with UA levels. Given this complex relationship, the current project aimed at comparing UA levels in first-episode mania patients with matched controls, and analyzes its relationship with impulsivity, symptom severity and disease prognosis. Thirty-one first-episode mania patients were assessed on BIS-11 and YMRS, serum uric acid levels were measured, and compared to matched controls. A follow up YMRS was rated after one month to evaluate the effects of treatment. We found significantly higher levels of UA in patients, which showed positive correlation with impulsivity and a negative correlation with symptom improvement at 1 month. The results of the study support a purinergic system dysfunction hypothesis in first-episode mania, and suggest its influence on impulsivity in this patient group. Further, the mentioned dysfunction appears to have a negative impact on treatment outcomes in such cases.

Allopurinol augmentation in acute mania: A meta-analysis of placebo-controlled trials

BACKGROUND

Allopurinol is a xanthine oxidase inhibitor commonly used in the treatment of gout. Recent studies have also shown its promise as an adjunctive treatment for manic episodes in bipolar 1 disorder, possibly through mechanisms involving the purinergic pathway. However, its efficacy across studies has been inconsistent, so we conducted a meta-analysis of the published controlled studies with the goal of determining the efficacy profile of allopurinol as an adjunctive treatment for mania in bipolar disorder.

METHODS

An online search was conducted using PubMed for placebo-controlled, randomized, double-blind, clinical trials (RCTs) using the terms "allopurinol," "bipolar," "mania," "manic," and "YMRS" and a meta-analysis was conducted in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses statement.

RESULTS

Five studies met the criteria for inclusion. Three of the five studies were inpatient treatments, one study was outpatient treatment, and one study had a mixture of both. All studies used allopurinol as an adjunct in treating acute mania in bipolar disorder subjects. Four of the studies showed efficacy in the primary outcome measure between allopurinol vs. placebo groups with significantly reduced YMRS scores while one showed no significant effect size between the allopurinol and placebo groups. The overall effect size for the four studies is d = 0.294. No significant difference in side effects were found between groups for any of the studies.

CONCLUSION

The data suggest that allopurinol may have some efficacy as an adjunct in reducing mania symptoms during acute manic episodes in patients with bipolar disorder. Adjunctive allopurinol efficacy may be related to the mood stabilizer used. Additional controlled trials with greater sample sizes, homogenous dosing, and consistent treatment modalities are needed to determine optimal clinical application.

Purinergic system in psychiatric diseases

Psychiatric disorders are debilitating diseases, affecting >80 million people worldwide. There are no causal cures for psychiatric disorders and available therapies only treat the symptoms. The etiology of psychiatric disorders is unknown, although it has been speculated to be a combination of environmental, stress and genetic factors. One of the neurotransmitter systems implicated in the biology of psychiatric disorders is the purinergic system. In this review, we performed a comprehensive search of the literature about the role and function of the purinergic system in the development and predisposition to psychiatric disorders, with a focus on depression, schizophrenia, bipolar disorder, autism, anxiety and attention deficit/hyperactivity disorder. We also describe how therapeutics used for psychiatric disorders act on the purinergic system.

Purinergic system dysfunctions in subjects with bipolar disorder: A comparative cross-sectional study

BACKGROUND

Subjects with bipolar mania may have increased uric acid levels, based on a purinergic system dysfunction with reduced neurotransmission of adenosine. We investigated whether there were differences in uric acid levels between individuals with bipolar disorder (in manic or depressive phases) and those with major depressive disorder.

METHODS

We conducted a cross-sectional study recruiting 128 subjects with bipolar disorder and 118 with major depressive disorder, admitted to a psychiatric inpatient unit. Standard demographic and clinical information were retrieved from electronic charts and relevant clinical records. Fasting serum values of uric acid, as well as metabolic (total cholesterol, triglycerides, and glycaemia), oxidative stress (albumin, bilirubin), and kidney function (creatinine), parameters, were collected.

RESULTS

Subjects with bipolar mania (5.27±1.63mg/dL), but not those with bipolar depression (4.89±1.94mg/dL), had higher levels of serum uric acid (p<0.05), as compared with individuals with major depressive disorder (4.59±1.62mg/dL). Relevant linear regression analyses, controlling for metabolic profile, oxidative stress markers, kidney function, and comorbid alcohol use disorder, showed a significant association between bipolar mania (p<0.01) and increased uric acid.

CONCLUSIONS

Findings of this study add evidence to the role of uric acid as state, rather than trait, marker in bipolar disorders. Explored, relevant, confounders do not seem to influence these results. The current study supports the hypothesis of a purinergic system dysfunction associated with manic phases of bipolar disorder.

Allopurinol as add-on treatment for mania symptoms in bipolar disorder: systematic review and meta-analysis of randomised controlled trials

BACKGROUND

Since bipolar disorder seems to be associated with purinergic system dysfunction, allopurinol might be effective in treating symptoms of mania.

AIMS

To estimate the efficacy and tolerability of allopurinol as adjunctive treatment for mania symptoms in people with bipolar affective disorder.

METHOD

We conducted a systematic review and meta-analysis of randomised controlled trials (RCTs) comparing the effects of adjunctive allopurinol and placebo on mania symptom changes.

RESULTS

Five RCTs were included in the meta-analysis. Participants with allopurinol augmentation had a significantly greater decrease in mania symptoms than those with placebo (SMD = -0.34, P = 0.007), especially in people with the most severe forms of mania. Remission rates, although based on only two studies (n = 177), were significantly higher among individuals receiving allopurinol, whereas for discontinuation and side-effects no difference was found.

CONCLUSIONS

Our finding of a small to moderate effect size and overall low evidence for add-on allopurinol in reducing mania symptoms indicate that its use in routine practice needs further elucidation.

Uric acid levels in subjects with bipolar disorder: A comparative meta-analysis

Previous research has hypothesised increased uric acid levels, possibly because of an amplified purinergic metabolism and a reduced adenosine activity, in subjects with bipolar disorder. This systematic review and meta-analysis aimed at estimating if individuals with bipolar disorder had uric acid levels higher than both healthy controls and subjects with major depression (trait marker hypothesis). It also tested if uric acid levels could differ in different phases of bipolar disorder (state marker hypothesis). Meta-analyses were carried out generating pooled standardized mean differences (SMDs), using random-effects models. Heterogeneity between studies was estimated using the I(2) index. Relevant sensitivity and meta-regression analyses were conducted. We searched main Electronic Databases, identifying twelve studies that met our inclusion criteria. Meta-analyses showed increased uric acid levels in individuals with bipolar disorder as compared with both healthy controls (SMD = 0.65, p < 0.001, I(2) = 82.9%) and those with major depression (SMD = 0.46, p < 0.001; I(2) = 68.7%). However, meta-regression analyses confirmed this association only as compared with healthy controls. Finally, though uric acid levels were higher in manic/mixed phases as compared with depressive ones (SMD = 0.34; p = 0.04, I(2) = 58.8%), a sensitivity analysis did not confirm the association. In sum, our meta-analysis shows that subjects with bipolar disorder have uric acid levels higher than healthy controls. The potential role of factors that might clarify the nature of this association deserves additional research.

Uric acid excretion predicts increased aggression in urban adolescents

Elevated levels of uric acid have been linked with impulsive and disinhibited behavior in clinical and community populations of adults, but no studies have examined uric acid in relation to adolescent aggression. This study examined the prospective role of uric acid in aggressive behavior among urban, low income adolescents, and whether this relationship varies by gender. A total of 84 adolescents (M age 13.36years; 50% male; 95% African American) self-reported on their physical aggression at baseline and 1.5years later. At baseline, the youth also completed a 12-h (overnight) urine collection at home which was used to measure uric acid excretion. After adjusting for baseline aggression and age, greater uric acid excretion predicted more frequent aggressive behavior at follow up, with no significant gender differences. The results suggest that lowering uric acid levels may help reduce youth aggression.

Exploring the association between bipolar disorder and uric acid: A mediation analysis

OBJECTIVE

Recent evidence shows that bipolar disorder might be associated with a purinergic system dysfunction. This study aimed at (i) testing the association between bipolar disorder and uric acid serum levels, and (ii) clarifying whether this relationship is mediated by metabolic syndrome and other relevant metabolic parameters.

METHODS

Patients consecutively admitted to a Mental Health Inpatient Unit, with a diagnosis of bipolar disorder or other severe mental disorders, and an appropriate healthy control sample, were included in this cross-sectional, exploratory study. We performed linear regression analyses, to explore factors associated with uric acid levels, and formal tests of mediation to assess mediating effect of candidate variables.

RESULTS

176 individuals with mental disorders and 89 healthy controls met inclusion criteria. Bipolar disorder was the only diagnostic subgroup significantly associated with increased uric acid levels. Furthermore, male gender, metabolic syndrome, as well as abdominal circumference and triglycerides levels, had a significant effect on uric acid. Relevant mediation analyses showed that the estimated effect between bipolar disorder and uric acid levels was only partially mediated by metabolic abnormalities.

CONCLUSION

This study suggests a direct association between bipolar disorder and uric acid levels, only partially mediated by metabolic abnormalities. It seems consistent with results of previous studies highlighting a purinergic dysfunction in bipolar disorder and the role that purinergic modulators, lowering uric acid levels, could have in clinical practice.

High Risk of Depressive Disorders in Patients With Gout: A Nationwide Population-Based Cohort Study

Metabolic abnormalities are common in patients with depressive disorders. However, the relationship between gout and depression is unclear. We explored the causal relationship among gout, antigout medication, and the associated risk of incidental depressive disorders.In this nationwide cohort study, we sampled data from the National Health Insurance Research Database to recruit 34,050 patients with gout as the gout cohort and 68,100 controls (without gout) as the nongout cohort. Our primary endpoint was the diagnosis of depressive disorders during follow-up. The overall study population was followed up until depression diagnosis, withdrawal from the NHI program, or the end of the study. The differences in demographic and clinical characteristics between both cohorts were determined using the Chi-square test for categorical variables and the t-test for continuous variables. Cox proportional hazard regression models were used to examine the effect of gout on the risk of depression, represented using the hazard ratio with the 95% confidence interval.Patients with gout exhibited a higher risk of depressive disorders than controls did. The risk of depressive disorders increased with age and was higher in female patients and those with hypertension, stroke, and coronary artery disease. Nonsteroidal antiinflammatory drug and prednisolone use was associated with a reduced risk of depression. Patients with gout who had received antigout medication exhibited a reduced risk of depressive disorders compared with nongout patients.Our findings support that gout increases the risk of depressive disorders, and that antigout medication use reduces the risk.

Purinergic system dysfunction in mood disorders: a key target for developing improved therapeutics

Uric acid and purines (such as adenosine) regulate mood, sleep, activity, appetite, cognition, memory, convulsive threshold, social interaction, drive, and impulsivity. A link between purinergic dysfunction and mood disorders was first proposed a century ago. Interestingly, a recent nationwide population-based study showed elevated risk of gout in subjects with bipolar disorder (BD), and a recent meta-analysis and systematic review of placebo-controlled trials of adjuvant purinergic modulators confirmed their benefits in bipolar mania. Uric acid may modulate energy and activity levels, with higher levels associated with higher energy and BD spectrum. Several recent genetic studies suggest that the purinergic system - particularly the modulation of P1 and P2 receptor subtypes - plays a role in mood disorders, lending credence to this model. Nucleotide concentrations can be measured using brain spectroscopy, and ligands for in vivo positron emission tomography (PET) imaging of adenosine (P1) receptors have been developed, thus allowing potential target engagement studies. This review discusses the key role of the purinergic system in the pathophysiology of mood disorders. Focusing on this promising therapeutic target may lead to the development of therapies with antidepressant, mood stabilization, and cognitive effects.

Increased uric acid levels in bipolar disorder subjects during different phases of illness

BACKGROUND

Recent evidence indicates the possible involvement of adenosine and the purinergic system in the pathophysiology of bipolar disorder (BD). The aim of this study is to compare serum uric acid (UA) levels in a large group of BD patients (in mania, depression and euthymia) vs. a control group of patients with different psychiatric disorders.

METHODS

150 BD (SCID-I; DSM-IV) patients were compared to 150 age- and gender-matched subjects with MDD, OCD, or Schizophrenia. Mean serum UA values were compared with the ANOVA, with Bonferroni's post-hoc tests.

RESULTS

Mean serum UA levels (5.06 ± 1.45 vs. 4.17 ± 1.05 mg/dL) and rates of hyperuricaemia (30.7% vs. 6.7%) were significantly higher in the bipolar than in the control group. No differences were detected between bipolars in different phases of illness, with all three groups (manic, depressive and euthymic bipolars) showing significantly higher UA levels as compared to controls. No correlations were found between UA levels and YMRS or HAM-D scores. Mean UA levels were also higher in bipolars never exposed to mood stabilizers vs. controls (5.08 ± 1.43 vs. 4.17 ± 1.05 mg/dL), with no differences compared to other bipolars.

LIMITATIONS

Our study suffers from the lack of a healthy comparison group; moreover, longitudinal data are missing.

CONCLUSIONS

Our study provides further evidence of a purinergic dysfunction associated with BD, in all phases of the illness. It is possible that increased UA levels are a trait marker of higher vulnerability to bipolar disorder, and are even more increased during mania (mostly in the first manic episode of drug-naïve patients).

Serum uric acid levels and different phases of illness in bipolar I patients treated with lithium

Recent findings support the role of purinergic system dysfunction in the pathophysiology of bipolar disorder (BD). The present study aimed to evaluate the pattern of serum uric acid levels in a sample of 98 BD I patients followed-up prospectively in a naturalistic study and treated with lithium monotherapy or in association with other mood stabilizers (valproate or carbamazepine), in relation to different phases of illness and to pharmacological treatment. The results showed that uric acid levels were significantly higher in patients suffering from a manic/mixed episode, than in those euthymic or during a depressive phase. Further, these levels were related to the Clinical Global Impression-Bipolar Version (CGI-BP) scale score for the severity of manic symptoms. A positive correlation was found also with male sex and with serum lithium levels. These findings suggest that a dysregulation of the purinergic system may occur during manic/mixed episodes, and they support a possible role of serum uric acid levels as a state-dependent marker of BD manic phases.

Are Uric Acid Levels Different from Healthy Subjects in Bipolar Affective Disorder and Schizophrenia?: Relationship Between Clinical Improvement and Episode Severity in Male Patients

INTRODUCTION

Purinergic system dysfunction has been shown both in patients with bipolar disorder (BD) and those with schizophrenia. The aim of this study was to evaluate whether uric acid levels in male BD patients with manic episode and schizophrenia patients with psychotic relapse differ from healthy male subjects. Secondly to assess whether uric acid levels in both patient groups correlate with episode severity and if a decrease in uric acid levels correlate with clinical improvement.

METHOD

A total of 55 BD patients with manic episode and 59 schizophrenic patients with psychotic relapse were evaluated at baseline and at weeks 1, 2, 3 using the Young Mania Rating Scale (YMRS) and the Positive and Negative Syndrome Scale (PANSS), and their plasma uric acid levels were measured. 60 age-matched healthy males without history of any previous or current psychiatric diagnosis and treatment constituted the control group. In order to determine plasma uric acid levels, blood samples were centrifuged at 3000 × g for 15 minutes, stored at -80°C and measured in milligrams per deciliter.

RESULTS

Uric acid levels in both patient groups with manic episode and psychotic relapse were found higher than in healthy controls (f=6.122, p=.027). The difference between repeated measurements of uric acid levels in BD patient group was found to be between baseline and first week measurements (after Bonferroni correction) (p<.001). No correlation was found between YMRS and PANSS scores and uric acid levels at 4 assessment times.

CONCLUSION

Uric acid levels in male BD and schizophrenia patients with manic episode and psychotic relapse were similar with each other, and higher than in healthy males. No correlation was found between uric acid levels and episode severity in both groups. However, for patients with BD, a decrease in uric acid levels between baseline and first week seems to be correlated with clinical improvement.

Adenosine hypothesis in schizophrenia and bipolar disorder: a systematic review and meta-analysis of randomized controlled trial of adjuvant purinergic modulators

OBJECTIVE

Adenosine has been reported to interact with dopamine and glutamate of which are currently central pathophysiology of schizophrenia. Further, there have been emerging reports that patients with bipolar disorder (BD) have pathophysiological changes of the purinergic system. Thus, we performed a systematic review and meta-analysis of adenosine modulators in these disorders.

METHOD

We searched PubMed, EMBASE, the Cochrane Library databases, CINAHL, and PsycINFO up to April 25, 2013. Randomized controlled trials comparing adenosine modulator adjuvant therapy with placebo in patients with schizophrenia and BD were included. Primary outcome measures were Positive and Negative Syndrome Scale (PANSS) and Young Mania Rating Scales (YMRS). The risk ratio, 95% confidence interval, and standardized mean differences (SMD) were used.

RESULTS

Nine studies, including six studies in schizophrenia (total n=457) and three studies in BD (total n=289) were included. Overall, adenosine modulators were superior to placebo in PANSS total scores (SMD=-1.07, p=0.01) and positive and general but not negative symptom subscale scores in schizophrenia. Individually, allopurinol failed to show its superiority to placebo in all primary outcome measures in schizophrenia. In BD, data from pooled adenosine modulators indicated significant reduction of YMRS scores in comparison to placebo (SMD=-0.39, p=0.004).

CONCLUSIONS

Our results suggest that adenosine modulator adjuvant therapy is more beneficial in overall psychopathology (especially positive symptoms) in schizophrenia and in treating mania episodes of BD in comparison to placebo. The limited sample size of available studies suggests that more research should be done to evaluate both efficacy and tolerability of these medications.

Antidepressant effect of aminophylline after ethanol exposure

This work investigated the association of acute ethanol and aminophylline administration on behavioral models of depression and prefrontal monoamine levels (i.e. norepinephrine and dopamine) in mice. The animals received a single dose of ethanol (2 g/kg) or aminophylline (5 or 10 mg/kg) alone or in association. Thirty minutes after the last drug administration, the animals were assessed in behavioral models by the forced swimming and tail suspension tests. After these tests, the animals were sacrificed and the prefrontal cortices dissected to measure monoamine content. Results showed that ethanol presented depression-like activity in the forced swimming and tail suspension tests. These effects were reversed by the association with aminophylline in all tests. Norepinephrine and dopamine levels decreased, while an increase in the dopamine metabolite, (4-hydroxy-3-methoxyphenyl)acetic acid (DOPAC), after ethanol administration was observed. On the contrary, the association of ethanol and aminophylline increased the norepinephrine and dopamine content, while it decreased DOPAC when compared to the ethanol group, confirming the alterations observed in the behavioral tests. These data reinforce the involvement of the adenosinergic system on ethanol effects, highlighting the importance of the norepinephrine and dopamine pathways in the prefrontal cortex to the effects of ethanol.

Electroconvulsive therapy: a novel hypothesis for the involvement of purinergic signalling

It is proposed that ATP is released from both neurons and glia during electroconvulsive therapy (ECT) and that this leads to reduction of depressive behaviour via complex stimulation of neurons and glia directly via P2X and P2Y receptors and also via P1 receptors after extracellular breakdown of ATP to adenosine. In particular, A(1) adenosine receptors inhibit release of excitatory transmitters, and A(2A) and P2Y receptors may modulate the release of dopamine. Sequential ECT may lead to changes in purinoceptor expression in mesolimbic and mesocortical regions of the brain implicated in depression and other mood disorders. In particular, increased expression of P2X7 receptors on glial cells would lead to increased release of cytokines, chemokines and neurotrophins. In summary, we suggest that ATP release following ECT involves neurons, glial cells and neuron-glial interactions acting via both P2 and after breakdown to adenosine via P1 receptors. We suggest that ecto-nucleotidase inhibitors (increasing available amounts of ATP) and purinoceptor agonists may enhance the anti-depressive effect of ECT.

Proof of concept trials in bipolar disorder and major depressive disorder: a translational perspective in the search for improved treatments

A better understanding of the neurobiology of mood disorders, informed by preclinical research and bi-directionally translated to clinical research, is critical for the future development of new and effective treatments. Recently, diverse new targets/compounds have been specifically tested in preclinical models and in proof-of-concept studies, with potential relevance as treatments for mood disorders. Most of the evidence comes from case reports, case series, or controlled proof-of-concept studies, some with small sample sizes. These include (1) the opioid neuropeptide system, (2) the purinergic system, (3) the glutamatergic system, (4) the tachykinin neuropeptide system, (5) the cholinergic system (muscarinic system), and (6) intracellular signaling pathways. These targets may be of substantial interest in defining future directions in drug development, as well as in developing the next generation of therapeutic agents for the treatment of mood disorders. Overall, further study of these and similar drugs may lead to a better understanding of relevant and clinically useful drug targets in the treatment of these devastating illnesses.

Increased risk of gout among patients with bipolar disorder: a nationwide population-based study

This study aims to explore the association between bipolar disorder and the risk of gout using a nationwide population-based dataset. We used the 1996-2006 data from the Taiwan National Health Insurance Research Database. The study cohort comprised 24,262 patients who had visited outpatient departments for the treatment of bipolar disorder in the year 2000. A total of 121,310 enrollees matched with the study group in terms of age and gender, and were selected as the comparison cohort. Each patient was tracked 6 years from the index outpatient visit in 2000 until 2006 to identify all who had developed gout. Cox proportional hazard regressions were performed to compute the 6-year gout-free survival rate, adjusting for other variables. We found that gout occurred among 16.4% of the patients with bipolar disorder and 13.6% of the patients in the comparison cohort between 2000 and 2006 (P<0.001). After adjusting for potential confounders, the regression analysis shows that the hazard of developing gout during the 6-year follow-up period was 1.19 greater (95% confidence interval (CI)=1.10-1.24, P<0.001) for patients with bipolar disorder than their counterparts in the comparison cohort. We conclude that patients with bipolar disorder had increased risk of developing gout even after adjusting for possible confounding factors.

Adenosine receptors and brain diseases: neuroprotection and neurodegeneration

Adenosine acts in parallel as a neuromodulator and as a homeostatic modulator in the central nervous system. Its neuromodulatory role relies on a balanced activation of inhibitory A(1) receptors (A1R) and facilitatory A(2A) receptors (A2AR), mostly controlling excitatory glutamatergic synapses: A1R impose a tonic brake on excitatory transmission, whereas A2AR are selectively engaged to promote synaptic plasticity phenomena. This neuromodulatory role of adenosine is strikingly similar to the role of adenosine in the control of brain disorders; thus, A1R mostly act as a hurdle that needs to be overcame to begin neurodegeneration and, accordingly, A1R only effectively control neurodegeneration if activated in the temporal vicinity of brain insults; in contrast, the blockade of A2AR alleviates the long-term burden of brain disorders in different neurodegenerative conditions such as ischemia, epilepsy, Parkinson's or Alzheimer's disease and also seem to afford benefits in some psychiatric conditions. In spite of this qualitative agreement between neuromodulation and neuroprotection by A1R and A2AR, it is still unclear if the role of A1R and A2AR in the control of neuroprotection is mostly due to the control of glutamatergic transmission, or if it is instead due to the different homeostatic roles of these receptors related with the control of metabolism, of neuron-glia communication, of neuroinflammation, of neurogenesis or of the control of action of growth factors. In spite of this current mechanistic uncertainty, it seems evident that targeting adenosine receptors might indeed constitute a novel strategy to control the demise of different neurological and psychiatric disorders.

Increased uric acid levels in drug-naïve subjects with bipolar disorder during a first manic episode

Recent evidence suggests that purinergic system dysfunction may play a role in the pathophysiology and therapeutics of bipolar disorder (BPD). Uric acid is a key nitrogenous end product of purine metabolism. In addition to being a potential marker of treatment response, high levels of uric acid may represent a state marker during mania. In this study, we assessed the presence of purinergic dysfunction in 20 treatment-naïve first episode patients with BPD who were experiencing a manic episode. Patients were matched with 24 healthy controls. We found that acutely manic patients had significantly higher levels of plasma uric acid (4.85+/-1.60 mg/dL) compared to healthy controls (2.96+/-0.63 mg/dL, p<0.001; F=28.1). No association between uric acid levels with severity of manic symptoms was observed. These results support the role of purinergic system dysfunction in BPD early in the course of illness, and suggest that this phenomenon is not the result of chronicity or medication exposure. Overall, our findings suggest a novel mechanism in the pathophysiology of BPD.