Plasma GABA predicts acute response to divalproex in mania

Neuromolecular Etiology of Bipolar Disorder: Possible Therapeutic Targets of Mood Stabilizers

Bipolar disorder is a mental illness that causes extreme mood swings and has a chronic course. However, the mechanism by which mood episodes with completely opposite characteristics appear repeatedly, or a mixture of symptoms appears, in patients with bipolar disorder remains unknown. Therefore, mood stabilizers are indicated only for single mood episodes, such as manic episodes and depressive episodes, and no true mood-stabilizing drugs effective for treating both manic and depressive episodes currently exist. Therefore, in this review, therapeutic targets that facilitate the development of mood stabilizers were examined by reviewing the current understanding of the neuromolecular etiology of bipolar disorder.

Valproate for acute mania

BACKGROUND

Bipolar disorder is a severe and common mental disorder where patients experience recurrent symptoms of elevated or irritable mood, depression, or a combination of both. Treatment is usually with psychiatric medication, including mood stabilisers, antidepressants and antipsychotics. Valproate is an effective maintenance treatment for bipolar disorder. However, evidence assessing the efficacy of valproate in the treatment of acute mania is less robust, especially when comparing it to some of the newer antipsychotic agents. This review is an update of a previous Cochrane Review (last published 2003) on the role of valproate in acute mania.

OBJECTIVES

To assess the efficacy and tolerability of valproate for acute manic episodes in bipolar disorder compared to placebo, alternative pharmacological treatments, or a combination pharmacological treatments, as measured by the treatment of symptoms on specific rating scales for individual episodes in paediatric, adolescent and adult populations.

SEARCH METHODS

We searched Ovid MEDLINE (1950- ), Embase (1974- ), PsycINFO (1967- ) and the Cochrane Central Register of Controlled Trials (CENTRAL) to 28 September 2018. We had also conducted an earlier search of these databases in the Cochrane Common Mental Disorders Controlled Trials Register (CCMDCTR) (all years to 6 June 2016). We also searched the World Health Organization (WHO) trials portal (ICTRP) and clinicaltrials.gov in September 2018, to identify any additional unpublished or ongoing studies.

SELECTION CRITERIA

Single- and double-blind, randomised controlled trials comparing valproate with placebo, alternative antimanic treatments, or a combination of pharmacological treatments. We also considered studies where valproate was used as an adjunctive treatment in combination with another agent separately from studies where it was used in monotherapy. We included male and female patients of all ages and ethnicity with bipolar disorder.

DATA COLLECTION AND ANALYSIS

Two review authors independently performed data extraction and methodological quality assessment. For analysis, we used the odds ratio (OR) for binary efficacy outcomes and the mean difference (MD) or standardised mean difference (SMD) for continuously distributed outcomes.

MAIN RESULTS

Twenty-five trials (3252 participants) compared valproate with either placebo or alternative antimanic treatments to alleviate the symptoms of acute mania. For efficacy, our primary outcome was response rate. For tolerability, our primary outcome was the number of participants with any adverse effect. This meta-analysis included studies focusing on children, adolescents, as well as adults with a range of severity of manic symptoms. The majority of studies focused on adult men and women (aged 18 and above), were conducted in inpatient settings and completed in the US. Five studies in this review focused on children and adolescents (aged 18 and under) so that the review covers an age range from 3 - 82 years. Seven studies contained outpatient participants in some form. Nine studies included data that has been collected outside the US, namely Iran (4 studies), India (3 studies), China (1 study), or across several international countries (1 study).In adults, high-quality evidence found that valproate induces a slightly higher response compared to placebo (45% vs 29%, OR 2.05, 95% CI 1.32 to 3.20; 4 studies, 869 participants). Moderate-quality evidence found there was probably little or no difference in response rates between valproate and lithium (56% vs 62%, OR 0.80, 95% CI 0.48 to 1.35; 3 studies, 356 participants). In adults, low-quality evidence found there may be little or no difference in response rate between valproate and olanzapine (38% vs 44%, OR 0.77, 95% CI 0.48 to 1.25; 2 studies, 667 participants).In the children and adolescent population, the evidence regarding any difference in response rates between valproate and placebo was uncertain (23% vs 22%, OR 1.11, 95% CI 0.51 to 2.38; 1 study, 151 participants, very low-quality evidence). Low-quality evidence found that the response rate of participants receiving valproate may be lower compared to risperidone (23% vs 66%, OR 0.16, 95% CI 0.08 to 0.29; 1 study, 197 participants). The evidence regarding any difference in response rates between valproate and lithium was uncertain (23% vs 34%, OR 0.57, 95% CI 0.31 to 1.07; 1 study, 197 participants, very low-quality evidence).In terms of tolerability in adults, moderate-quality evidence found that there are probably more participants receiving valproate who experienced any adverse events compared to placebo (83% vs 75%, OR 1.63, 95% CI 1.13 to 2.36; 3 studies, 745 participants). Low-quality evidence found there may be little or no difference in tolerability between valproate and lithium (78% vs 86%, OR 0.61, 95% CI 0.25 to 1.50; 2 studies, 164 participants). We did not obtain primary tolerability outcome data on the olanzapine comparison.Within the children and adolescent population, the evidence regarding any difference between valproate or placebo was uncertain (67% vs 60%, OR 1.39, 95% CI 0.71 to 2.71; 1 study, 150 participants, very low-quality evidence). We did not obtain primary tolerability outcome data on the lithium or risperidone comparisons.

AUTHORS' CONCLUSIONS

There is evidence that valproate is an efficacious treatment for acute mania in adults when compared to placebo. By contrast, there is no evidence of a difference in efficacy between valproate and placebo for children and adolescents. Valproate may be less efficacious than olanzapine in adults, and may also be inferior to risperidone as a monotherapy treatment for paediatric mania. Generally, there is uncertain evidence regarding whether valproate causes more or less side effects than the other main antimanic therapies. However, evidence suggests that valproate causes less weight gain and sedation than olanzapine.

Co-occurring psychiatric disorders and alcoholism

Alcohol use disorder (AUD), a term that comprises both alcohol abuse and alcohol dependence, is a highly prevalent psychiatric disorder. Over 50% of treated AUD patients also suffer from other psychiatric disorder(s). Detailed study has revealed disorders across multiple psychiatric domains with rates of co-occurrence far greater than chance, suggesting a synergistic relationship. The basis of this synergy is explored along with its multiple forms, including behavioral and neurobiologic. Specific topics include the predisposition to both AUD and co-occurring psychopathology, the vulnerability to environmental risk factors that exacerbate these predispositions, and the nature of reinforcement in acute intoxication. Co-occurrence can also modify and exacerbate the neuroadaptations underpinning chronic dependence and relapse, the manifestations of acute and protracted withdrawal, emergence of medical and psychiatric complications, and ultimately the potential for relapse. The outcomes of co-occurrence as well as the unique impact it has on proper treatment are also discussed. Throughout, the significance of recognizing co-occurrence is emphasized since, both neurobiologically and clinically, the synergies between co-occurring disorders yield a result far more complex than a mere sum of the component disorders.

Elevated plasma γ-aminobutyrate/glutamate ratio and responses to risperidone antipsychotic treatment in schizophrenia

BACKGROUND

γ-aminobutyrate (GABA) and Glutamate (Glu) are respectively two major inhibitory and excitatory neurotransmitters in the central nervous system and recent theories propose that both of their signaling complexes are compromised in patients with schizophrenia.

METHODS

The changes in plasma GABA, Glu and GABA/Glu ratio in schizophrenia have been studied and may be potential clinical markers. Here, we examined if plasma GABA, Glu and GABA/Glu ratio are altered in 32 schizophrenics, including a comprehensive investigation of their involvements with clinical course of a 6-week risperidone antipsychotic treatment.

RESULTS

Plasma levels of GABA and Glu were significantly lower in patients than in controls, while plasma GABA/Glu ratio was significantly elevated. During treatment, a non-significant further decrease of plasma GABA, a significant increase of plasma Glu and a significant reduction of plasma GABA/Glu ratio were observed. The ratio returned to the control level at week 6 even though concentrations of GABA and Glu were still distant from normal. After the Bonferroni correction, partial correlation analyses showed that plasma GABA and GABA/Glu ratio were positively correlated with the dose of risperidone and plasma concentration of 9-hydroxyrisperidone. The reduction of plasma GABA/Glu ratio was positively correlated with the improvement of activation symptom cluster.

CONCLUSIONS

The elevated plasma GABA/Glu ratio reinforces the idea of an abnormal GABA-Glu interaction in schizophrenia. The ratio may be a good peripheral state-like marker in schizophrenia research.

Corticotropin-Releasing Hormone, Glutamate, and γ-Aminobutyric Acid in Depression

Stress response and depression have a significant impact on modern society. Although the symptoms are well characterized, the molecular mechanisms underlying depression are largely unknown. The monoamine hypothesis, which postulates dysfunctional noradrenergic and serotonergic systems as the underlying primary cause of depression, has been valuable for the development of conventional antidepressants, which can reverse these dysfunctional states to some degree. However, recent data from various neuroscience disciplines have questioned the major role of amines in the pathogenesis of depression. A considerable amount of evidence has accumulated that suggests that normalization of the hypothalamo—pituitary—adrenal (HPA) system might be the final step necessary for a remission of depression. In addition, an increasing body of clinical and postmortem evidence is pointing to a role played by γ-aminobutyric acid (GABA) and glutamate in the etiology of depression. This review examines the evidence, mainly obtained from clinical studies or from postmortem brain material, for a major role of the HPA axis, glutamatergic, and GABAergic systems in the pathogenesis of major and bipolar depression. The authors hope that these insights will stimulate further studies with the final aim of developing new types of antidepressants that combine increased efficacy with a shorter delay of the onset of action and reduced side-effect profiles.

GABA and homovanillic acid in the plasma of Schizophrenic and bipolar I patients

We have determined the plasma (p) concentration of gamma-aminobutyric acid (GABA) and the dopamine metabolite homovanillic acid (HVA), and the pHVA/pGABA ratio in schizophrenic and bipolar patients. The research was undertaken in a geographic area with an ethnically homogeneous population. The HVA plasma concentrations were significantly elevated in the schizophrenic patients compared to the bipolar patients. The levels of pGABA was significantly lower in the two groups of patients compared to the control group, while the pHVA/pGABA ratio was significantly greater in the both groups of patients compared to the controls. As the levels of pHVA and pGABA are partially under genetic control it is better to compare their concentrations within an homogeneous population. The values of the ratio pHVA/pGABA are compatible with the idea of an abnormal dopamine-GABA interaction in schizophrenic and bipolar patients. The pHVA/pGABA ratio may be a good peripheral marker in psychiatric research.

Cortical inhibitory dysfunction in bipolar disorder: a study using transcranial magnetic stimulation

OBJECTIVE

Neuroanatomic evidence suggests that patients with bipolar disorder (BD) have impaired cortical inhibition (CI). However, there is little in vivo neurophysiological evidence supporting the occurrence of such impairments in this disorder. Using 3 transcranial magnetic stimulation paradigms, known as short-interval CI (SICI), cortical silent period (SP), and interhemispheric inhibition (IHI), the authors measured inhibition in the motor cortex.

METHOD

Fifteen patients with BD and 15 healthy subjects were enrolled. Short-interval CI involves stimulating with a subthreshold pulse a few milliseconds before a suprathreshold pulse, thereby inhibiting the size of the motor-evoked potential (MEP) produced by the suprathreshold pulse. In the SP paradigm, inhibition is reflected by the SP duration (ie, the duration of electromyographic activity cessation following a transcranial magnetic stimulation-induced MEP). Interhemispheric inhibition involves a subthreshold conditioning stimulus applied to the right motor cortex several milliseconds before a suprathreshold test stimulus is applied to the left motor cortex which inhibits the size of the MEP produced by the test stimulus by 50% to 75%.

RESULTS

Patients with BD demonstrated deficits in all 3 paradigms: SICI (F1,28 = 5.55, P = 0.03; Cohen d = 0.86), SP (F1,28 = 5.24, P = 0.03; Cohen d = 0.84), and IHI (F1,28 = 3.41, P = 0.02; Cohen d = 0.77) compared with healthy volunteers with a large effect size.

CONCLUSIONS

Our study supports the hypothesis that CI is decreased in BD. Further understanding of the neurophysiology of such deficiencies may help to elucidate future treatment options.

Open-label adjunctive topiramate in the treatment of unstable bipolar disorder

OBJECTIVE

To assess open-label adjunctive topiramate in the treatment of outpatients with unstable bipolar disorder (BD).

METHOD

Outpatients with DSM-IV-defined BD (I or II) exhibiting mood instability were enrolled in this 16-week, open-label, multicentre study. Topiramate was added to existing mood stabilizers and other psychotropic treatments. The primary effectiveness measure was the Clinical Global Impression of Severity (CGI-S) scale; other scales included the Young Mania Rating Scale (YMRS) and the Montgomery-Asberg Depression Rating Scale (MADRS). Safety assessments included monitoring adverse events, measuring tremor, monitoring vital signs and weight, and laboratory indices. We also evaluated patient satisfaction with treatment.

RESULTS

A total of 109 patients were enrolled. Intent-to-treat analysis showed significant improvement from baseline in the CGI-S, YMRS, and MADRS, starting at Week 2 (P < 0.001), with further accrual of benefit between Week 2 and Week 16 (P < 0.001). The mean modal dosage of topiramate during the stable dosing period was 180 mg daily. There was a mean 1.8 kg decrease in patient weight from topiramate initiation to Week 16 (P < 0.001). Topiramate was well tolerated by most patients; 11% withdrew from the study owing to adverse events. We noted a significant reduction in the mean severity score for preexisting tremor by Week 8 of treatment (P < 0.005); no notable changes in vital signs were observed. At Week 16, 50% of the patients were "completely satisfied" with topiramate treatment.

CONCLUSIONS

Adjunctive topiramate treatment can reduce the severity of manic and depressive symptoms, as well as reducing tremor and weight in outpatients with BD I or II.

GABA and glutamate systems as therapeutic targets in depression and mood disorders

Advances made in diverse areas of neuroscience suggest that neurotransmitter systems, additional to the monoaminergic, contribute to the pathophysiology of mood disorders. This ever accruing body of preclinical and clinical research is providing increased recognition of the contribution made by amino acid neurotransmitters to the neurobiology of mood disorders. This review examines evidence supporting the role of GABA and glutamate in these processes and explores the potential to target these systems in the development of novel compounds; the viability of these agents for treatment-related co-morbidities will also be considered.

Response to flumazenil in the late luteal phase and follicular phase of the menstrual cycle in healthy control females

RATIONALE

Animal studies of short-term progesterone administration and withdrawal model the natural increase and abrupt decrease in progesterone levels which occur in the late luteal phase (LP) of the human menstrual cycle (MC). Previously, studies in animals have shown that abrupt cessation of chronic or short-term progesterone administration results in pharmacological changes at the GABAA receptor, resulting in altered sensitivity to GABAA receptor neuromodulators such as benzodiazepines and flumazenil, a GABAA receptor antagonist.

OBJECTIVES

This study's goal was to compare the response to flumazenil in the follicular phase (FP) and late LP in female healthy controls (HCs). We postulated that HC females would exhibit a greater psychological and somatic response to flumazenil in the late LP, a period of progesterone withdrawal, compared to the FP.

METHODS

Twelve healthy females, without history of psychiatric disorder, were randomized to receive two injections of a 2 mg bolus injection of flumazenil (one in the late LP and one in the FP) and two injections of placebo (one in the late LP and one in the FP). Following injection, subjects were asked to rate the occurrence and intensity of panic symptoms on the panic symptom scale (PSS).

RESULTS

A main treatment effect was detected for the PSS score response after flumazenil injection (P=0.008). However, there was no significant treatment-by-phase interaction observed (P=0.449).

CONCLUSIONS

These findings indicate that MC phase did not affect the response to flumazenil in HC females. This result is contrary to our hypothesis of altered sensitivity to flumazenil in the late LP.

Risperidone Does Not Affect Steady-State Pharmacokinetics of Divalproex Sodium in Patients with Bipolar Disorder

OBJECTIVE

Divalproex sodium can interact with many drugs in which combination treatments are used; it can increase plasma concentrations of some drugs by inhibiting metabolism and can increase the free fractions of other medications by displacing them from plasma proteins. The combination of risperidone and divalproex sodium is used to treat the manic phase of bipolar disorder. However, the effect of risperidone on the pharmacokinetics of valproate has not previously been systematically studied. The aims of this study were to determine the effect of repeated doses of oral risperidone on the pharmacokinetics of valproate in subjects stabilised on divalproex sodium and to document the safety of this combination.

STUDY DESIGN

A multicentre, observational, randomised, parallel group, single-blind, placebo-controlled drug interaction study.

PATIENTS

Twenty-two patients with bipolar disorder, in remission, were studied.

METHODS

All subjects were treated with divalproex sodium 1000 mg/day monotherapy on days 1-14. Thereafter, subjects continued to take divalproex sodium for days 15-28; they also received adjunctive treatment with either placebo (n = 11) or risperidone (n = 11) 2mg once daily on days 15 and 16, and 4 mg once daily on days 17-28. Serial blood sampling was performed throughout to determine the plasma concentrations of valproate, risperidone and 9-hydroxy-risperidone.

RESULTS

On analysis, steady-state pharmacokinetic parameters (peak plasma concentrations [C(max)], time to C(max,) area under the concentration-time curve) of valproate were of the same order of magnitude on day 14 (monotherapy) and day 28 (valproate plus risperidone or placebo), with no period effect. The parameters on day 28 were similar in the risperidone and placebo treatment groups, showing that risperidone, as adjunctive treatment, had no influence on the steady-state pharmacokinetics of valproate. Although there were more adverse events reported in the risperidone group compared with the placebo group (ten vs seven, respectively), none of them were serious or necessitated withdrawal. No clinically relevant changes in laboratory parameters, vital signs or ECG-tracings were observed in either group.

CONCLUSION

These results indicate that adjunctive risperidone treatment had no influence on the steady-state pharmacokinetics of valproate and this combination was safe and well tolerated.

GABAergic dysfunction in mood disorders

The authors review the available literature on the preclinical and clinical studies involving GABAergic neurotransmission in mood disorders. Gamma-aminobutyric acid (GABA) is an inhibitory neurotransmitter present almost exclusively in the central nervous system (CNS), distributed across almost all brain regions, and expressed in interneurons modulating local circuits. The role of GABAergic dysfunction in mood disorders was first proposed 20 years ago. Preclinical studies have suggested that GABA levels may be decreased in animal models of depression, and clinical studies reported low plasma and CSF GABA levels in mood disorder patients. Also, antidepressants, mood stabilizers, electroconvulsive therapy, and GABA agonists have been shown to reverse the depression-like behavior in animal models and to be effective in unipolar and bipolar patients by increasing brain GABAergic activity. The hypothesis of reduced GABAergic activity in mood disorders may complement the monoaminergic and serotonergic theories, proposing that the balance between multiple neurotransmitter systems may be altered in these disorders. However, low GABAergic cortical function may probably be a feature of a subset of mood disorder patients, representing a genetic susceptibility. In this paper, we discuss the status of GABAergic hypothesis of mood disorders and suggest possible directions for future preclinical and clinical research in this area.

Effects of chronic lithium and sodium valproate on concentrations of brain amino acids

The present study was designed to determine if the mood stabilizers, lithium and valproate, have common effects on concentrations of amino acid neurotransmitters which may be related to their mechanisms of action. Two separate groups of rats were administered therapeutic doses of lithium, sodium valproate, or saline for 2 weeks. Whole brain extracts were then examined using either high-field 1H NMR spectroscopy or HPLC. Both drugs decreased whole brain concentrations of aspartate, glutamate, and taurine while brain concentrations of gamma-aminobutyric acid (GABA) and alanine decreased following chronic sodium valproate administration but not following chronic lithium administration. These findings indicate that lithium and sodium valproate share common effects on the concentrations of certain amino acid neurotransmitters in whole brain which may be related to their mechanisms of action in bipolar disorder.

Effect of lamotrigine on plasma GABA levels in healthy humans

Lamotrigine, a new anticonvulsant, has been reported to be useful in treating bipolar depression, rapid cycling, and other phases of bipolar disorder. However, the mechanism of action underlying its efficacy in mood disorders is still not known. Since there is evidence for gamma-aminobutyric acid (GABA) involvement in the pathophysiology and treatment response of patients with bipolar disorder, this study was designed to examine the effect of lamotrigine on plasma GABA levels in healthy humans. Eleven healthy volunteers with no lifetime history of psychiatric illness or family history in first-degree relatives were recruited. Each subject received lamotrigine 100 mg/day for 1 week. Blood samples for assay of plasma levels of GABA were taken from each subject before and after administration of lamotrigine. Plasma GABA levels were analyzed using high-pressure liquid chromatography (HPLC) with fluorescence detection after derivatization with o-phthaldialdehyde (OPA). We found no significant difference in the plasma GABA levels of the study subjects before and after treatment with lamotrigine. The finding of this study suggests that lamotrigine in the dose used in this study does not appear to enhance GABA levels in humans.

Valproate for acute mood episodes in bipolar disorder

BACKGROUND

Bipolar disorder is a common debilitating illness, characterised by acute affective episodes with full or partial inter-episode remission. Effective and acceptable treatment of acute episodes is required. Valproate has become a leading adjunctive and alternative mood stabilising treatment to lithium in bipolar disorder.

OBJECTIVES

To determine the efficacy and acceptability of valproate in the treatment of acute episodes of bipolar disorder.

SEARCH STRATEGY

The search included the Cochrane Collaboration Depression, Anxiety and Neurosis Controlled Trials Registrar (CCDANCTR), the Cochrane Controlled Clinical Trials Register (CCTR), reference lists of relevant papers and books, and contact with authors of trials, experts and pharmaceutical companies.

SELECTION CRITERIA

Randomised controlled trials comparing valproate with placebo, other mood stabilisers and antipsychotic medication in the treatment of any bipolar affective episode. Participants were of both sexes, of all ages, with a diagnosis of bipolar affective disorder approximating to ICD 10 Code F31 and DSM IV 296.

DATA COLLECTION AND ANALYSIS

Methodological quality was assessed independently by two reviewers blind to the authorship and source of papers. Ten randomised controlled trials were found comparing valproate with other interventions in mania. None was found examining its use in depression or mixed affective episodes. Data were extracted on the main outcome 'failure to respond by the end of the study' assessed by a less than 50% reduction in the Young Mania Rating Scale or the SADS-S mania scale. Three trials (316 participants) compared valproate with placebo. Three trials (158 participants) compared valproate with lithium. Two trials (363 participants) compared valproate with olanzapine. One trial (36 participants) compared valproate with haloperidol. Two trials (59 patients) compared valproate with carbamazepine. Acceptability of treatment was estimated using the outcome measure 'total number of subjects withdrawing from the study'. Three trials (321 patients) contributed to the comparison between valproate and placebo, two studies (144 patients) contributed to the comparison with lithium. One study (30 patients) provided data on this outcome in the comparison between valproate and carbamazepine. Pooled relative risks (with 95% confidence intervals) were calculated using fixed effect approaches.

MAIN RESULTS

Valproate was more efficacious than placebo (RRR 38%; RR 0.62; 95% C.I. 0.51 to 0.77) in the treatment of mania. There was no significant difference between valproate and lithium (RRI 5%; RR 1.05; 95% C.I. 0.74-1.50) or between valproate and carbamazepine (RRR 34%; RR 0.66; 95% C.I. 0.38 to 1.16). Valproate was less effective than olanzapine (failure to achieve clinical response; RRI 25%; RR 1.25, 95% C.I. 1.01 to 1.54; average of 2.8 point less change on the Mania Rating Scale (95% CI 0.83 to 4.79). There were no significant differences in acceptability as measured by total number of subjects withdrawing from the study. There were significant differences in the side effect profiles of valproate and olanzapine, with more sedation and weight gain on olanzapine.

REVIEWER'S CONCLUSIONS

There is consistent, if limited, evidence to suggest that valproate is an efficacious treatment for acute mania. Valproate may be less effective than olanzapine but may cause less sedation and weight gain. More well designed, randomised controlled trials investigating the relative efficacy and acceptability of valproate in the treatment of the full range of acute affective episodes occurring in bipolar disorder are required.

The comorbidity of bipolar and anxiety disorders: prevalence, psychobiology, and treatment issues

BACKGROUND

Although symptoms of anxiety as well as anxiety disorders commonly occur in patients with bipolar disorder, the pathophysiologic, theoretical, and clinical significance of their co-occurrence has not been well studied.

METHODS

The epidemiological and clinical studies that have assessed the overlap of bipolar and anxiety disorders are reviewed, with focus on panic disorder and obsessive-compulsive disorder (OCD), and to a lesser extent, social phobia and post-traumatic stress disorder. Potential neural mechanism and treatment response data are also reviewed.

RESULTS

A growing number of epidemiological studies have found that bipolar disorder significantly co-occurs with anxiety disorders at rates that are higher than those in the general population. Clinical studies have also demonstrated high comorbidity between bipolar disorder and panic disorder, OCD, social phobia, and post-traumatic stress disorder. Psychobiological mechanisms that may account for these high comorbidity rates likely involve a complicated interplay among various neurotransmitter systems, particularly norepinephrine, dopamine, gamma-aminobutyric acid (GABA), and serotonin. The second-messenger system constituent, inositol, may also be involved. Little controlled data are available regarding the treatment of bipolar disorder complicated by an anxiety disorder. However, adequate mood stabilization should be achieved before antidepressants are used to treat residual anxiety symptoms so as to minimize antidepressant-induced mania or cycling. Moreover, preliminary data suggesting that certain antimanic agents may have anxiolytic properties (e.g. valproate and possibly antipsychotics), and that some anxiolytics may not induce mania (e.g. gabapentin and benzodiazepines other than alprazolam) indicate that these agents may be particularly useful for anxious bipolar patients.

CONCLUSIONS

Comorbid anxiety symptoms and disorders must be considered when diagnosing and treating patients with bipolar disorder. Conversely, patients presenting with anxiety disorders must be assessed for comorbid mood disorders, including bipolar disorder. Pathophysiological, theoretical, and clinical implications of the overlap of bipolar and anxiety disorders are discussed.

Antiepileptic drugs: affective use in autism spectrum disorders

Antiepileptic drugs are widely administered to individuals with autistic spectrum disorders. There are several reasons for the use of antiepileptic drugs in autistic spectrum disorders, including the high incidence of epilepsy in these individuals, the anecdotal reports suggesting an improvement of communication and behavior in autistic subjects with epileptic discharges, and the increased awareness that some disruptive behaviors may be manifestations of an associated affective disorder. In this study, data on the current use of antiepileptic drugs in the treatment of autism, and on the association of affective disorders with epilepsy and autism, are reviewed. The evidence supporting the hypothesis that there may be a subgroup of autistic children with epilepsy and affective disorders that preferentially respond to antiepileptic drugs is still very preliminary, and further investigations with double-blind controlled studies are needed. Although the role of antiepileptic drugs at the present time is not established, there is evidence that autism, epilepsy, and affective disorders commonly co-occur, and that they may share a common neurochemical substrate, which is the common target of the psychotropic mechanism of action of different antiepileptic drugs.

GABA-A receptor beta3 and alpha5 subunit gene cluster on chromosome 15q11-q13 and bipolar disorder: a genetic association study

There is accumulated evidence that the genes coding for the receptor of gamma aminobutyric acid (GABA), the most important inhibitory neurotransmitter in the CNS, may be involved in the pathogenesis of affective disorders. In a previous study, we have found a genetic association between the GABA-A receptor alpha5 subunit gene locus (GABRA5) on chromosome 15q11-of 13 and bipolar affective disorder. The aim of the present study was to examine the same subjects to see if there exists a genetic association between bipolar affective disorder and the GABA receptor beta3 subunit gene (GABRB3), which is located within 100 kb from GABRA5. The sample consisted of 48 bipolar patients compared to 44 controls (blood donors). All subjects were Greek, unrelated, and personally interviewed. Diagnosis was based on DSM-IV and ICD-10 criteria. The marker used was a dinucleotide (CA) repeat polymorphism with 12 alleles 179 to 201 bp long; genotyping was successful in all patients and 43 controls. The distribution of GABRB3 genotypes among the controls did not deviate significantly from the Hardy-Weinberg equilibrium. No differences in allelic frequencies between bipolar patients and controls were found for GABRB3, while this locus and GABRA5 did not seem to be in significant linkage disequilibrium. In conclusion, the GABRB3 CA-repeat polymorphism we investigated does not present the observed association between bipolar affective illness and GABRA5. This could be due to higher mutation rate in the GABRB3 CA-repeat polymorphism, but it might also signify that GABRA5 is the gene actually associated with the disease.

Open-label adjunctive topiramate in the treatment of bipolar disorders

BACKGROUND

To preliminarily explore the spectrum of effectiveness and tolerability of the new antiepileptic drug topiramate in bipolar disorder, we evaluated the response of 56 bipolar outpatients in the Stanley Foundation Bipolar Outcome Network (SFBN) who had been treated with adjunctive topiramate in an open-label, naturalistic fashion.

METHODS

In this case series, response to topiramate was assessed every 2 weeks for the first 3 months according to standard ratings in the SFBN, and monthly thereafter while patients remained on topiramate. Patients' weights, body mass indices (BMIs), and side effects were also assessed.

RESULTS

Of the 54 patients who completed at least 2 weeks of open-label, add-on topiramate treatment, 30 had manic, mixed, or cycling symptoms, 11 had depressed symptoms, and 13 were relatively euthymic at the time topiramate was begun. Patients who had been initially treated for manic symptoms displayed significant reductions in standard ratings scores after 4 weeks, after 10 weeks, and at the last evaluation. Those patients who were initially depressed or treated while euthymic showed no significant changes. Patients as a group displayed significant decreases in weight and BMI from topiramate initiation to week 4, to week 10, and to the last evaluation. The most common adverse side effects were neurologic and gastrointestinal.

CONCLUSIONS

These preliminary open observations of adjunctive topiramate treatment suggest that it may have antimanic or anticycling effects in some patients with bipolar disorder, and may be associated with appetite suppression and weight loss that is often viewed as beneficial by the patient and clinician. Controlled studies of topiramate's acute and long-term efficacy and side effects in bipolar disorder appear warranted.

Comprehensive review of the psychiatric uses of valproate

The therapeutic effects of valproate in psychiatric conditions are most substantially recognized in bipolar disorder. However, this well-tolerated medication may be beneficial in the treatment of other mental illnesses. In this article, the authors comprehensively review studies of valproate as treatment for psychiatric conditions, including bipolar, depressive, anxiety, and psychotic disorders; alcohol withdrawal and dependence; tardive dyskinesia; agitation associated with dementia; and borderline personality disorder. Valproate shows the most promising efficacy in treating mood and anxiety disorders, with possible efficacy in the treatment of agitation and impulsive aggression, and less convincing therapeutic response in treating psychosis and alcohol withdrawal or dependence. The authors conclude with a brief summary of its mechanism of action and therapeutic spectrum.

Mania: gender, transmitter function, and response to treatment

Noradrenergic and GABA systems may be involved in mania, but there is little information about relationships between the function of these systems and response to specific antimanic treatments. We investigated relationships between indices of catecholamine or GABA system function, pretreatment mania severity and antimanic response to divalproex, lithium, or placebo. Plasma GABA and urinary excretion of catecholamine metabolites were measured before randomization to lithium, divalproex or placebo in patients hospitalized for manic episodes. Severity of mania was evaluated using the Manic Syndrome, Behavior and Ideation and Mania Rating Scale scores from the SADS-C. Multiple regression analysis showed that pretreatment plasma GABA was related to severity of manic symptoms. This relationship seemed stronger in women. Multiple regression analysis showed that pretreatment levels of urinary MHPG correlated with improvement in manic syndrome scores. These data suggest that GABA and norepinephrine may be related to different aspects of the manic state and to its pharmacologic sensitivity.

GABA function in mood disorders: an update and critical review

Over the past twenty years, several lines of evidence from preclinical and clinical studies has accumulated suggesting that a GABA deficit may be involved in mood disorders, particularly in depression, and that increasing GABAergic neurotransmission may exert an antidepressant effect and perhaps a mood stabilizing effect. Given that GABA has an inhibitory effect on biogenic amine neurotransmitters such as norepinephrine and serotonin and this inhibition may be involved in local circuits and interneurons, it has been suggested that the hypothesis of a GABA deficit in mood disorders does not compete with but complements the well-established hypotheses of alterations in noradrenergic and serotonergic function in mood disorders. In this paper, we systematically reviewed the results from preclinical and clinical studies of GABA function in the pathophysiology of mood disorders and in the mechanism of action of mood stabilizers, antidepressants and electroconvulsive therapy. We also discussed the unifying theory of the neurochemistry of mood disorders, which integrates the GABA hypothesis into the biogenic amine hypotheses, and indicated future directions for research.

Incorporation of [3H]valproic acid into lipids in GT1-7 neurons

Valproic acid (2-propylpentanoic acid, valproate, VPA), an 8-carbon, branched chain fatty acid, is effectively used in the treatment of mania and epilepsy. The biochemical mechanisms by which this drug has its therapeutic effects are not yet established. The purpose of this study was to partially characterize the incorporation of [3H]VPA into phospholipids of GT1-7 neurons, an immortalized hypothalamic cell line. GT1-7 neurons were grown to confluence in culture dishes, and then were incubated with various concentrations of [3H]VPA between 10 and 400 microg/mL for various times up to 20 hr. Total lipids were extracted and phospholipids were separated from neutral lipids using TLC. Our results indicate that [3H]VPA (10 microg/mL) was incorporated into phospholipids of GT1-7 neurons in a time-dependent and saturable manner over 300 min. Subsequent separation of the lipid fraction by TLC indicated that 44.4% of the radioactivity taken up by the cells was incorporated into phospholipids and neutral lipids. One of the phospholipids migrated with a slightly lower Rf value than authentic phosphatidylcholine. Our results show that the incorporation of VPA into phospholipids and glycerides was linear with VPA concentrations from 10 to 400 microg/mL. Finally, we synthesized 1-acyl-2-valproyl-sn-glycero-3-phosphocholine and validated its structure with nuclear magnetic resonance and electrospray mass spectrometry to verify the structure of this compound, confirming that this compound is structurally possible. We conclude that VPA is incorporated into lipids in GT1-7 neurons and discuss the possible effects of valproyl phospholipids on neuronal functional properties.