Critical review of GABA-ergic drugs in the treatment of schizophrenia

Emerging Roles of FTO in Neuropsychiatric Disorders

FTO (fat mass and obesity associated) is a recently discovered gene related to obesity and expressed in various tissues of the human body, especially with high expression in the brain. Earlier studies have found that FTO is involved in several biological processes, including brain development and function. In particular, recent studies have found that FTO is a demethylase of N6-methyladenosine (m6A) and it can affect neurological function through the m6A modification of mRNA. At present, a number of studies have shown that FTO is associated with many neuropsychiatric disorders. This paper reviews the discovery, structure, function, and tissue expression of FTO followed by discussing the relationship between FTO and neuropsychiatric diseases. In addition, the potential roles of FTO gene in drug addiction, major depression (MDD), and schizophrenia (SCZ) through regulating m6A modification of dopamine related genes were also highlighted.

Development of MLR and SVM Aided QSAR Models to Identify Common SAR of GABA Uptake Herbal Inhibitors used in the Treatment of Schizophrenia

BACKGROUND

Alterations in GABAnergic system are implicated in the pathophysiology of schizophrenia. Available antipsychotics that target GABA receptor form a desirable therapeutic strategy in the treatment regimen of schizophrenia, unfortunately, suffer serious setback due to their prolonged side effects. The present investigation focuses on developing QSAR models from the biological activity of herbal compounds and their derivatives that promise to be alternative candidates to GABA uptake inhibitors.

METHODS

Three sets of compounds were undertaken in the study to develop QSAR models. The first set consisted of nine compounds which included Magnolol, Honokiol and other GABA acting established compounds. The second set consisted of 16 derivatives of N-diarylalkenylpiperidinecarboxylic acid. The third QSAR dataset was made up of thirty two compounds which were Magnolol and Honokiol derivatives. Multiple linear regressions (MLR) and support vector machine (SVM) supervised quantitative structure-activity relationship (QSAR) models were developed to predict the biological activity of these three sets. The purpose of taking three QSAR sets of diverse chemical structures but identical in their GABA targeting and pharmacological action was to identify common chemical structure features responsible for structure-activity relationship (SAR).

RESULTS

Linear and non-linear QSAR models confirmed that the three sets shared common structural descriptors derived from WHIM (Weighted Holistic Invariant Molecular descriptors), 3D-MoRSE and Eigenvalue classes.

CONCLUSION

It was concluded that properties like electro negativity and polarizability play a crucial role in controlling the activity of herbal compounds against GABA receptor.

Maternal immune activation leads to selective functional deficits in offspring parvalbumin interneurons

Abnormalities in prefrontal gamma aminobutyric acid (GABA)ergic transmission, particularly in fast-spiking interneurons that express parvalbumin (PV), are hypothesized to contribute to the pathophysiology of multiple psychiatric disorders, including schizophrenia, bipolar disorder, anxiety disorders and depression. While primarily histological abnormalities have been observed in patients and in animal models of psychiatric disease, evidence for abnormalities in functional neurotransmission at the level of specific interneuron populations has been lacking in animal models and is difficult to establish in human patients. Using an animal model of a psychiatric disease risk factor, prenatal maternal immune activation (MIA), we found reduced functional GABAergic transmission in the medial prefrontal cortex (mPFC) of adult MIA offspring. Decreased transmission was selective for interneurons expressing PV, resulted from a decrease in release probability and was not observed in calretinin-expressing neurons. This deficit in PV function in MIA offspring was associated with increased anxiety-like behavior and impairments in attentional set shifting, but did not affect working memory. Furthermore, cell-type specific optogenetic inhibition of mPFC PV interneurons was sufficient to impair attentional set shifting and enhance anxiety levels. Finally, we found that in vivo mPFC gamma oscillations, which are supported by PV interneuron function, were linearly correlated with the degree of anxiety displayed in adult mice, and that this correlation was disrupted in MIA offspring. These results demonstrate a selective functional vulnerability of PV interneurons to MIA, leading to affective and cognitive symptoms that have high relevance for schizophrenia and other psychiatric disorders.

Abnormal GABAergic function and face processing in schizophrenia: A pharmacologic-fMRI study

The involvement of the gamma-aminobutyric acid (GABA) system in schizophrenia is suggested by postmortem studies and the common use of GABA receptor-potentiating agents in treatment. In a recent study, we used a benzodiazepine challenge to demonstrate abnormal GABAergic function during processing of negative visual stimuli in schizophrenia. This study extended this investigation by mapping GABAergic mechanisms associated with face processing and social appraisal in schizophrenia using a benzodiazepine challenge. Fourteen stable, medicated schizophrenia/schizoaffective patients (SZ) and 13 healthy controls (HC) underwent functional MRI using the blood oxygenation level-dependent (BOLD) technique while they performed the Socio-emotional Preference Task (SePT) on emotional face stimuli ("Do you like this face?"). Participants received single-blinded intravenous saline and lorazepam (LRZ) in two separate sessions separated by 1-3weeks. Both SZ and HC recruited medial prefrontal cortex/anterior cingulate during the SePT, relative to gender identification. A significant drug by group interaction was observed in the medial occipital cortex, such that SZ showed increased BOLD signal to LRZ challenge, while HC showed an expected decrease of signal; the interaction did not vary by task. The altered BOLD response to LRZ challenge in SZ was significantly correlated with increased negative affect across multiple measures. The altered response to LRZ challenge suggests that abnormal face processing and negative affect in SZ are associated with altered GABAergic function in the visual cortex, underscoring the role of impaired visual processing in socio-emotional deficits in schizophrenia.

GABA abnormalities in schizophrenia: a methodological review of in vivo studies

Abnormalities of GABAergic interneurons are some of the most consistent findings from post-mortem studies of schizophrenia. However, linking these molecular deficits with in vivo observations in patients - a critical goal in order to evaluate interventions that would target GABAergic deficits - presents a challenge. Explanatory models have been developed based on animal work and the emerging experimental literature in schizophrenia patients. This literature includes: neuroimaging ligands to GABA receptors, magnetic resonance spectroscopy (MRS) of GABA concentration, transcranial magnetic stimulation of cortical inhibitory circuits and pharmacologic probes of GABA receptors to dynamically challenge the GABA system, usually in combination with neuroimaging studies. Pharmacologic challenges have elicited behavioral changes, and preliminary studies of therapeutic GABAergic interventions have been conducted. This article critically reviews the evidence for GABAergic dysfunction from each of these areas. These methods remain indirect measures of GABAergic function, and a broad array of dysfunction is linked with the putative GABAergic measures, including positive symptoms, cognition, emotion, motor processing and sensory processing, covering diverse brain areas. Measures of receptor binding have not shown replicable group differences in binding, and MRS assays of GABA concentration have yielded equivocal evidence of large-scale alteration in GABA concentration. Overall, the experimental base remains sparse, and much remains to be learned about the role of GABAergic interneurons in healthy brains. Challenges with pharmacologic and functional probes show promise, and may yet enable a better characterization of GABAergic deficits in schizophrenia.

Molecular docking based screening of GABA (A) receptor inhibitors from plant derivatives

The present antipsychotic drugs have known to show serious concerns like extra pyramidal side effects therefore, pursuit for novel antipsychotic GABAnergic drugs has lately focused on the folkloric medicine from plant derivatives as better treatment option of schizophrenia. The present study centers to identify potential inhibitors of plant origin for GABA receptor through in silico approaches. Three compound datasets were undertaken in the study. The first set consisted of seven compounds which included Magnolol, Honokiol and other plant derivatives. The second set consisted of 16 derivatives of N-diarylalkenyl-piperidinecarboxylic acid synthesized by Zheng et al., 2006. The third dataset had thirty two compounds which were Magnolol and Honokiol analogues synthesized by Fuchs et al., 2014. All the compounds were docked at the allosteric site of the GABA (A) receptor. The compounds were further tested for ADMET and biological activity. We observed Honokiol and its derivatives demonstrated superior druglike properties than any compound undertaken in the study. Further, compound 61 [2-(4-methoxyphenyl)-4-propylphenol] of dataset three - a synthetic derivative of honokiol had better profile than its parent compound. In a possible attempt to identify compound with even better efficacious compound than 61, virtual screening was performed, 135 compounds akin to compound 61 were retrieved. Interestingly none of the 135 compounds showed better druggable properties than compound 61. Our in silico pharmacological profiling of compounds is in coherence and is complemented by the findings of Fuchs et al, which also revealed compound 61 to be the good potentiator of GABA receptor.

ABBREVIATIONS

GABA (A) R - Gamma Amino Butyric Acid Receptor, subtype A, GPCR - G Protein Coupled Receptor, OPLS - Optimized Potentials for Liquid Simulations, PDB - Protein Data Bank, PLP - Piece wise Linear Potential, T.E.S.T - Toxicity Estimation Software Tool, TCM - Traditional Chinese Medicine.

Abnormal GABAergic function and negative affect in schizophrenia

Deficits in the γ-aminobutyric acid (GABA) system have been reported in postmortem studies of schizophrenia, and therapeutic interventions in schizophrenia often involve potentiation of GABA receptors (GABAR) to augment antipsychotic therapy and treat negative affect such as anxiety. To map GABAergic mechanisms associated with processing affect, we used a benzodiazepine challenge while subjects viewed salient visual stimuli. Fourteen stable, medicated schizophrenia/schizoaffective patients and 13 healthy comparison subjects underwent functional magnetic resonance imaging using the blood oxygenation level-dependent (BOLD) technique while they viewed salient emotional images. Subjects received intravenous lorazepam (LRZ; 0.01 mg/kg) or saline in a single-blinded, cross-over design (two sessions separated by 1-3 weeks). A predicted group by drug interaction was noted in the dorsal medial prefrontal cortex (dmPFC) as well as right superior frontal gyrus and left and right occipital regions, such that psychosis patients showed an increased BOLD signal to LRZ challenge, rather than the decreased signal exhibited by the comparison group. A main effect of reduced BOLD signal in bilateral occipital areas was noted across groups. Consistent with the role of the dmPFC in processing emotion, state negative affect positively correlated with the response to the LRZ challenge in the dmPFC for the patients and comparison subjects. The altered response to LRZ challenge is consistent with altered inhibition predicted by postmortem findings of altered GABAR in schizophrenia. These results also suggest that negative affect in schizophrenia/schizoaffective disorder is associated-directly or indirectly-with GABAergic function on a continuum with normal behavior.

Sleep and circadian rhythm dysregulation in schizophrenia

Sleep-onset and maintenance insomnia is a common symptom in schizophrenic patients regardless of either their medication status (drug-naive or previously treated) or the phase of the clinical course (acute or chronic). Regarding sleep architecture, the majority of studies indicate that non-rapid eye movement (NREM), N3 sleep and REM sleep onset latency are reduced in schizophrenia, whereas REM sleep duration tends to remain unchanged. Many of these sleep disturbances in schizophrenia appear to be caused by abnormalities of the circadian system as indicated by misalignments of the endogenous circadian cycle and the sleep-wake cycle. Circadian disruption, sleep onset insomnia and difficulties in maintaining sleep in schizophrenic patients could be partly related to a presumed hyperactivity of the dopaminergic system and dysfunction of the GABAergic system, both associated with core features of schizophrenia and with signaling in sleep and wake promoting brain regions. Since multiple neurotransmitter systems within the CNS can be implicated in sleep disturbances in schizophrenia, the characterization of the neurotransmitter systems involved remains a challenging dilemma.

Visual surround suppression in schizophrenia

Compared to unaffected observers patients with schizophrenia (SZ) show characteristic differences in visual perception, including a reduced susceptibility to the influence of context on judgments of contrast – a manifestation of weaker surround suppression (SS). To examine the generality of this phenomenon we measured the ability of 24 individuals with SZ to judge the luminance, contrast, orientation, and size of targets embedded in contextual surrounds that would typically influence the target’s appearance. Individuals with SZ demonstrated weaker SS compared to matched controls for stimuli defined by contrast or size, but not for those defined by luminance or orientation. As perceived luminance is thought to be regulated at the earliest stages of visual processing our findings are consistent with a suppression deficit that is predominantly cortical in origin. In addition, we propose that preserved orientation SS in SZ may reflect the sparing of broadly tuned mechanisms of suppression. We attempt to reconcile these data with findings from previous studies.

Modulation of ion channels in clinical psychopharmacology: adults and younger people

This review focuses on the use of Na(+), Ca(2+) and Cl(-) channel modulators in psychiatric disease. Drugs that modulate ion channels have been used in psychiatry for more than a century, and in this review we critically evaluate clinical research that reports the therapeutic effects of drugs acting on GABA(A), voltage-gated Na(+) and voltage-gated Ca(2+) channels in pediatric and adult patients. As in other fields, the evidence underpinning the use of medicines in younger people is far less robust than for adults. In addition, we discuss some current developments and highlight clinical disorders in which current molecules could be further tested. Notable success stories, such as benzodiazepines (in sleep and anxiety disorders) and antiepileptics (in bipolar disorder), have been the result of serendipitous discoveries or refinements of serendipitous discoveries, as in all other major treatments in psychiatry. Genomic, high-throughput screening and molecular pharmacology discoveries may, however, guide further developments in the future. This could include increased research in promising targets that have been perceived as commercially risky, such as selective α-subunit GABA(A) receptors.

Pharmacologic treatment of first-episode schizophrenia: a review of the literature

OBJECTIVE

To review the evidence base for the efficacy and tolerability of antipsychotic medication for the treatment of the first episode of schizophrenia.

DATA SOURCE

MEDLINE databases were searched for published articles in English over the last 25 years, from January 1986 to January 2011, on choice of antipsychotic treatment for the first episode of schizophrenia, with an emphasis on efficacy and tolerability of antipsychotic drugs in the acute phase of psychotic illness.

STUDY SELECTION

The keywords antipsychotic drugs and schizophrenia were used in combination with drug treatment, pharmacologic treatment, efficacy, and tolerability in addition to atypical antipsychotics, first-generation antipsychotics, second-generation antipsychotics, first-episode psychosis, and acute psychotic episode.

DATA SYNTHESIS

At present, there is no convincing evidence to guide clinicians in choosing a single first-line antipsychotic that is effective in treating the positive and negative symptoms of the first episode of schizophrenia. Even though second-generation antipsychotic drugs offer potential benefits in terms of less extrapyramidal side effects and some benefits in treating negative, affective, and cognitive symptoms, these drugs are not without their own side effects.

CONCLUSIONS

With the introduction of a number of second-generation antipsychotic drugs there have been significant advances in antipsychotic drug treatment over the last decade. Despite these advances, there are still a number of limitations in continued use of some antipsychotic medications due to their efficacy and tolerability issues in the acute and early maintenance phases of psychosis. Active research in this area would provide more promising results of improved efficacy and tolerability of antipsychotic medication.

The neurochemistry of human aggression

Various data from scientific research studies conducted over the past three decades suggest that central neurotransmitters play a key role in the modulation of aggression in all mammalian species, including humans. Specific neurotransmitter systems involved in mammalian aggression include serotonin, dopamine, norepinephrine, GABA, and neuropeptides such as vasopressin and oxytocin. Neurotransmitters not only help to execute basic behavioral components but also serve to modulate these preexisting behavioral states by amplifying or reducing their effects. This chapter reviews the currently available data to present a contemporary view of how central neurotransmitters influence the vulnerability for aggressive behavior and/or initiation of aggressive behavior in social situations. Data reviewed in this chapter include emoiric information from neurochemical, pharmaco-challenge, molecular genetic and neuroimaging studies.

Gabapentin adjunctive to risperidone or olanzapine in partially responsive schizophrenia: an open-label pilot study

BACKGROUND

There is a great need in the treatment of schizophrenia for a drug, or drug combinations, to improve clinical response with fewer serious side effects. The objective of this study was to explore the therapeutic effects and tolerability of the anticonvulsant gabapentin as an adjunctive in the treatment of patients with partially responsive schizophrenia.

METHODS

Ten consenting patients with a confirmed Diagnostic and Statistical Manual of Mental Disorders, 4th Edition, Text Revision diagnosis of schizophrenia were identified. All patients failed at least one 12-week treatment trial with risperidone or olanzapine. Gabapentin was added to ongoing antipsychotic treatment with olanzapine or risperidone for eight weeks. The primary outcome measure was the Positive and Negative Syndrome Scale (PANSS). Other scales included the Calgary Depression Scale (CDSS) and the Abnormal Involuntary Movement Scale (AIMS). Repeated-measures multivariate analysis of variance was utilized to examine changes in outcome measures over time with adjunctive treatment with gabapentin.

RESULTS

There was a significant drop in the PANSS and CDSS scores at endpoint (week 8). There were no significant differences between the two treatment groups with regard to changes in all outcome measures or in AIMS score. The adjunctive treatments were well tolerated and side effects were transient.

CONCLUSION

Gabapentin could be used successfully as an adjunct to novel antipsychotics in partially responsive schizophrenia. However, large controlled studies are needed to examine the effectiveness of gabapentin in psychotic disorders.

Clonazepam withdrawal-induced catatonia

BACKGROUND

Catatonia is a often a complex syndrome. It has been divided into categories of simple and malignant, with the latter being a more severe form involving autonomic instability and/or fever and having a higher mortality rate.

OBJECTIVE

There have been only two cases presented in the literature postulating benzodiazepine-withdrawal as a possible trigger for malignant catatonia. Here, the authors present a case of catatonia likely caused by abrupt benzodiazepine discontinuation; they also discuss neurobiological mechanisms relating to catatonia.

METHOD

The authors report on a 60-year-old man with a history of depression and posttraumatic stress disorder who was brought to the emergency department with acute confusion, grimacing, stereotypy, refusal of food and water, muscle rigidity, mutism, and extreme negativism. He had recently and abruptly discontinued all psychotropic medication.

RESULTS

After administration of lorazapam, the patient was re-started on clonazepam, after which there was a complete and sustained resolution of catatonic symptoms and autonomic instability.

CONCLUSION

Catatonia may result from a wide variety of etiologies. Catatonia due to benzodiazepine-withdrawal is a rare but serious condition that may be difficult to distinguish from other causes of catatonia. The mechanism by which catatonia may be precipitated by benzodiazepine-withdrawal is unknown, but likely involves a rapid decrease in GABA transmission in the central nervous system.

Association study of the gamma-aminobutyric acid type a receptor gamma2 subunit gene with schizophrenia

Schizophrenia (SCZ) is a severe neuropsychiatric disorder with a strong genetic basis. We analyzed eight GABRG2 and one DRD5 tag single-nucleotide polymorphisms for association with SCZ in 109 small nuclear families and 229 independent SCZ case-control pairs. The marker rs183294 in the 5' region of GABRG2 was found to be associated with SCZ in both samples with the C allele over-represented in SCZ cases and over-transmitted in SCZ families (combined z=9.18; p<1 x 10(-3)). Taken together, the results of the present study suggest that GABRG2 may be involved in SCZ susceptibility, but further studies are required.

Adjunct extended-release valproate semisodium in late life schizophrenia

OBJECTIVE

Adjunctive anticonvulsant medications may benefit some individuals with schizophrenia, however data on adjunct anticonvulsants in older adults with schizophrenia is limited. This prospective, 12-week open label study evaluated adjunct extended-release valproate semisodium (divalproex) in 20 older adults with schizophrenia.

METHODS

The study was conducted at an academic psychiatry clinic in the mid-western United States. Participants were self-referred from posted advertisements or referred by clinic practitioners. Extended-release valproate semisodium was added onto antipsychotic treatment. Individuals with active substance use disorders or active significant medical comorbidity were excluded. Primary outcome measures included the Positive and Negative Syndrome Scale (PANSS), Geriatric Depression Scale (GDS) and Global Assessment Scale (GAS). Tolerability was evaluated via patient self-reported side effects, change from baseline in body weight and change on abnormal movement scales.

RESULTS

Patients (mean age 61 years, range 49.8-79.2 years) had significant reductions in psychosis scores as measured by the Positive and Negative Syndrome Scale (PANSS) p<0.01, as well as in global functioning as measured by the Global Assessment Scale (GAS) p<0.01 and depression as measured by the Geriatric Depression Scale (GDS) p<0.05. Mean dose of extended-release valproate semisodium was 587.50 mg/day SD+/-247.02. Extended-release valproate semisodium was well tolerated in this older adult population. The primary adverse effect was sedation, which appeared to be relatively dose and titration-speed dependent. Weight change was not significant.

CONCLUSION

While extended-release valproate semisodium appears efficacious and well tolerated in older adults with schizophrenia, data from larger, controlled trials is needed.

[Benzodiazepines and schizophrenia, a review of the literature]

AIn this work, the authors have analysed the principal studies on the interest in the use of benzodiazepines in schizophrenia. The first double-controlled study concerning this question was conducted in 1961. The results of the first studies are criticisable due to the variability of the diagnostic and clinical assessment criteria, as well as to the divergences between the different conclusions. Through this review of literature, the authors wish to clarify the questions and hypothesis raised specify certain therapeutic strategies. MECHANISM OF GABA-ERGIC TREATMENTS: The analysis of the principle works on this question provides evidence on the use of benzodiazepines in schizophrenia. By fixing on their receptors, benzodiazepines facilitate GABA-ergic transmission. GABA is an inhibitor neurotransmitter. The GABA stimulation induced by benzodiazepines may be at the origin of a reduction of the pre-synaptic release of dopamine in the mesolimbic region. The GABA stimulation may also delay the post-synaptic adaptation of the dopaminergic neurons to neuroleptics. This phenomenon may enhance the activity of neuroleptics in resistant schizophrenia. Benzodiazepines would also have an effect on the mesoprefrontocortical regions where neuroleptics may be less efficient. It is interesting to note that this cerebral region is particularly sensitive to stress. This effect of benzodiazepines on the mesoprefrontocortical region might explain a preferentially beneficial effect in patients who have radiographic signs consistent with prefroncortical atrophy, although this observation remains preliminary. BENZODIAZEPINES IN MONOTHERAPY: In monotherapy their action on productive and deficient psychotic symptoms is greatly discussed and not very convincing. The main studies in the use of benzodiazepines alone ) are heterogeneous for their diagnosis criteria, their methodology and their results. The conclusions of the publications are not totally clear, and different points are to be criticized: heterogeneity of assessment criteria, heterogeneity and variability of methodology, use of non standardized scales, most of the studies are open studies, variability of benzodiazepines dose. BENZODIAZEPINES IN ASSOCIATION WITH NEUROLEPTICS: In few controlled studies, most authors have underlined ) the advantage of the association of benzodiazepines with neuroleptics. This association may act either on positive symptoms (hallucinations, delusions) or on negative symptoms. The latent period and the length of the effect of benzodiazepines in the treatment of psychotic patients remain unclear. According to certain studies, the therapeutic effect may appear in a short time, and then disappear within the fourth week. The association of benzodiazepines with neuroleptics is particularly helpful for patients with great anxiety, whether they have neuroleptic intolerance or not. There is no robust convergence about the type of benzodiazepines and their optimal dose in the treatment of schizophrenia. Their use may permit a reduction in the neuroleptic dose. They could increase the plasma concentration of neuroleptics and they might act on the mesoprefrontocortical regions where there are fewer dopaminergic auto receptors. BENZODIAZEPINES AND ANXIETY IN SCHIZOPHRENIA: States of anxiety, and in particular panic disorders that would participate in the exacerbation of psychotic symptoms, would benefit from the use of benzodiazepines. Anxiety can be considered as a major symptom of schizophrenia: insecure feelings and impressions of threatening events are frequent during schizophrenia. Interpretations or brutal hallucinations can lead to the feeling of imminent catastrophe or anxiety. Nevertheless, anxious phenomenons are under-estimated for many reasons: on the one hand, positive symptoms may hide anxiety, and on the other, the symptoms that are observed in patients treated with neuroleptics are often attributed to the neuroleptic side effects rather than linked to anxiety. Benzodiazepines and catatonia - Lorazepam has demonstrated its efficacy on catatonia. This effect seems to be specific of small doses of lorazepam (<5 mg/day). It should be compared to the effect of zolpidem in the same conditions. This prescription should be limited to acute catatonia, with no effect on chronic catatonia. Benzodiazepines and neuroleptic side effects - The use of benzodiazepines to treat some side effects of neuroleptics such as akathesia is reported by certain authors but remains little explained. They may have no effect or only small effects on tardive dyskinesia, but could reduce their incidence with the use of the smallest doses of neuroleptics in association with benzodiazepines. Safety of use - The safety of use of benzodiazepines in schizophrenia, particularly in association with neuroleptics is admitted, however recommended precautions with clozapine are to be noted. Benzodiazepine combined with clozapine clearly increases the frequency of cardiovascular and respiratory accidents. Some studies point out the risk of behavioural desinhibition and dysphoria. Their use should also be limited to patients with good compliancy, in order to avoid exacerbation of symptoms in the case of brutal interruption of the treatment. Dependency, which is an important issue in the use of benzodiazepines, seems much lesser in schizophrenia than in personality disorders and anxiety. Conversely, some studies point out the benefits of benzodiazepine use in schizophrenia, with their efficacy in the treatment and prevention of drug abuse. Finally, benzodiazepines contribute to the establishment of a good patient-doctor relationship, and may guarantee enhanced treatment compliancy.

Pharmacological management of acute agitation

Acute agitation occurs in a variety of medical and psychiatric conditions, and when severe can result in behavioural dyscontrol. Rapid tranquillisation is the assertive use of medication to calm severely agitated patients quickly, decrease dangerous behaviour and allow treatment of the underlying condition. Intramuscular injections of typical antipsychotics and benzodiazepines, given alone or in combination, have been the treatment of choice over the past few decades. Haloperidol and lorazepam are the most widely used agents for acute agitation, are effective in a wide diagnostic arena and can be used in medically compromised patients. Haloperidol can cause significant extrapyramidal symptoms, and has rarely been associated with cardiac arrhythmia and sudden death. Lorazepam can cause ataxia, sedation and has additive effects with other CNS depressant drugs.Recently, two fast-acting preparations of atypical antipsychotics, intramuscular ziprasidone and intramuscular olanzapine, have been developed for treatment of acute agitation. Intramuscular ziprasidone has shown significant calming effects emerging 30 minutes after administration for acutely agitated patients with schizophrenia and other nonspecific psychotic conditions. Intramuscular ziprasidone is well tolerated and has gained widespread use in psychiatric emergency services since its introduction in 2002. In comparison with other atypical antipsychotics, ziprasidone has a relatively greater propensity to increase the corrected QT (QTc) interval and, therefore, should not be used in patients with known QTc interval-associated conditions. Intramuscular olanzapine has shown faster onset of action, greater efficacy and fewer adverse effects than haloperidol or lorazepam in the treatment of acute agitation associated with schizophrenia, schizoaffective disorder, bipolar mania and dementia. Intramuscular olanzapine has been shown to have distinct calming versus nonspecific sedative effects. The recent reports of adverse events (including eight fatalities) associated with intramuscular olanzapine underscores the need to follow strict prescribing guidelines and avoid simultaneous use with other CNS depressants. Both intramuscular ziprasidone and intramuscular olanzapine have shown ease of transition to same-agent oral therapy once the episode of acute agitation has diminished. No randomised, controlled studies have examined either agent in patients with severe agitation, drug-induced states or significant medical comorbidity. Current clinical experience and one naturalistic study with intramuscular ziprasidone suggest that it is efficacious and can be safely used in such populations. These intramuscular atypical antipsychotics may represent a historical advance in the treatment of acute agitation.

Novel oral drug administration in an animal model of neuroleptic therapy

A novel method of oral drug administration was used in a neuroleptic animal study. Seventy male Sprague-Dawley rats were randomly subdivided into four groups, which were treated with clozapine, haloperidol, diazepam or a vehicle solution (5% sucrose solution). Oral drug treatment was achieved by training the rats to drink the drug of choice mixed with five percent sucrose or vehicle solution from a syringe. Within 3-4 weeks the haloperidol group developed vacuous chewing movement, which did not disappear with discontinuation of the drug. Significant weight gain was observed for all drug groups in relation to the control group, whereas only the diazepam group showed a significant increase in response latency on the disengage test of sensorimotor function, which disappeared with drug withdrawal. A novel means of testing the motivational status showed that all drug-treated groups engaged in eating chocolate before grooming (t=11.69, p<0.001), whereas the control group showed no specific tendency towards either task. Furthermore, there was a significant delay in grooming for the haloperidol group compared to the other drug groups and controls. In conclusion, a novel method of oral drug administration with minimum stress was introduced that was sufficient to cause the described changes in behavioural parameters. Additionally, the combination of tests used provided an efficient discrimination between the behavioural effects of clozapine, haloperidol and diazepam in rodents.

Cortical excitability in cocaine-dependent patients: a replication and extension of TMS findings

Cortical excitability can be assessed by transcranial magnetic stimulation (TMS). Previously we observed that TMS motor threshold (MT) was elevated in abstinent cocaine-dependent subjects. In the current study we aimed at replicating our initial finding, exploring other TMS-based measures of excitability, and examining association with personality characteristics. Nineteen cocaine-dependent and 12 healthy control subjects were examined. Resting and activated motor thresholds (RMT and AMT) and duration of the cortical silent period (CSP) were examined. The Cocaine Experience Questionnaire (CEQ) was administered to assess cocaine-induced psychotic symptoms. The relationship between Minnesota Multiphasic Personality Inventory (MMPI) scales and cortical excitability measures was also examined. AMT was significantly elevated in cocaine-dependent subjects on both hemispheres. RMT was also significantly elevated on the right hemisphere. No CSP changes were noted. Patients with cocaine-induced paranoia had longer CSPs on the right hemisphere compared to subjects reporting no paranoid experiences. The patients displayed significantly elevated scores on several MMPI scales, though the scale scores did not correlate with cortical excitability measures. These data support our initial finding of decreased cortical excitability in abstinent cocaine-dependent subjects. We interpret this finding as a compensatory mechanism against the stimulating and epileptogenic effects of cocaine.

A linkage study between the GABAA beta2 and GABAA gamma2 subunit genes and major psychoses

BACKGROUND

Alterations of the gamma-aminobutyric acid (GABA) system have been implicated in the pathophysiology of major psychoses.

OBJECTIVE

Restriction fragment length polymorphisms associated with the human gamma-aminobutyric acid type A (GABAA) beta2 and GABAA gamma2 subunit genes on chromosome 5q32-q35 were tested to determine whether they confer susceptibility to major psychoses.

METHODS

Thirty-two schizophrenic families and 25 bipolar families were tested for linkage.

RESULTS

Nonparametric linkage (NPL) analysis performed by GENEHUNTER showed no significant NPL scores for both genes in schizophrenia (GABAA beta2: NPL narrow= -0.450; NPL broad= -0.808; GABAA gamma2: NPL narrow=0.177; NPL broad= -0.051) or bipolar disorder (GABAA beta2: NPL narrow=0.834; NPL broad=0.783; GABAA gamma2: NPL narrow= -0.159; NPL broad=0.070).

CONCLUSION

Linkage analysis does not support the hypothesis that variants within the GABAA beta2 and GABAA gamma2 genes are significantly linked to major psychoses in a Portuguese population.

Neonatal lesions of the ventral hippocampal formation alter GABA-A receptor subunit mRNA expression in adult rat frontal pole

BACKGROUND

Gamma-aminobutyric acid (GABA)-ergic function is altered in schizophrenia. Of particular interest is the altered central nervous system expression of GABA-A receptor subunits, as changes in subunit expression account for recognized differences in mammalian brain function making them inviting targets for novel psychotropic agents. Excitotoxic neonatal lesions of the ventral hippocampal formation (NVHL) in rats reproduce numerous aspects of schizophrenia, including decreased mRNA expression of the GABA synthesizing enzyme glutamic acid decarboxylase-67, though their impact on subunit expression is unknown.

METHODS

We utilized quantitative reverse transcription polymerase chain reaction to investigate mRNA expression of the alpha1, alpha5, and gamma2s GABA-A receptor subunits in the frontal pole of water-deprived adult NVHL and SHAM-lesioned animals.

RESULTS

Messenger RNA expression for all three GABA-A subunits (alpha1-NVHL: 18.5 +/- 1.6 pg/mug total pooled RNA, SHAM: 11.3 +/- .4; alpha5-NVHL: 5.1 +/- .6; SHAM: 3.5 +/- .7; and gamma2s-NVHL: 10.8 +/- 1.7; SHAM: 7.2 +/- 1.5) was higher in NVHL, though only levels of alpha1 differed significantly after correction for multiple comparisons. Levels of a control mRNA, neuronal specific enolase, were similar in the two groups.

CONCLUSIONS

These data indicate that NVHL reproduce changes in cortical GABA-A receptor subunit expression seen in schizophrenia, suggesting this animal model may facilitate efforts to clarify the physiologic significance of altered GABA function and to develop novel targets for therapeutic interventions.

Results of a naturalistic study of treatment options: Switching atypical antipsychotic drugs or augmenting with valproate

BACKGROUND

Combination therapy with atypical antipsychotic agents has not been well studied. Duration of persistence with a prescribed treatment regimen can be used to estimate overall treatment success.

OBJECTIVE

The aim of this study was to determine whether valproate augmentation improved treatment efficacy (ie, persistence with the prescribed regimen) and efficacy (ie, reduction of antipsychotic dose) with atypical antipsychotic drugs for older and younger patients, using a retrospective database analysis.

METHODS

Prescription refill data for atypical antipsychotics during calendar-year 2001 from a national pharmacy chain was used for longitudinal analyses. The database was used to identify patients aged 15 to 64 years and > or =65 years taking risperidone, quetiapine, or olanzapine (but not valproate). Patients who switched to another atypical antipsychotic (group A) or added valproate (group B) were followed after the index prescription to determine the duration of persistence with the treatment regimen and dose changes.

RESULTS

We identified 10,262 patients who were prescribed an atypical antipsychotic, of whom 1022 patients switched to an alternative atypical and 1651 added valproate to the index atypical. The addition of valproate provided significantly longer duration of treatment regimen (mean, 155-159 days) than switching from any atypical antipsychotic drug (mean, 127-130 days) for patients aged 15 to 64 years or > or =65 years (all P<0.001). Atypical antipsychotic doses did not change significantly from baseline to final prescription in groups A or B. The final mean (SD) dose of valproate added to risperidone (389.1 [130.7] mg/d) was significantly lower than valproate added to quetiapine (424.6 [117.1] mg/d; P=0.002) or olanzapine (411.6 [122.8] mg/d; P=0.007).

CONCLUSIONS

In this naturalistic study, the addition of valproate to an atypical antipsychotic increased the duration of treatment compared with switching among atypical antipsychotics. Valproate augmentation may be a good treatment strategy for patients whose atypical antipsychotic monotherapy is inadequate.

GABA and schizophrenia: a review of basic science and clinical studies

BACKGROUND

A converging body of evidence implicates the gamma-aminobutyric acid (GABA) neurotransmitter system in the pathogenesis of schizophrenia.

METHODS

The authors review neuroscience literature and clinical studies investigating the role of the GABA system in the pathophysiology of schizophrenia. First, a background on the GABA system is provided, including GABA pharmacology and neuroanatomy of GABAergic neurons. Results from basic science schizophrenia animal models and human studies are reviewed. The role of GABA in cognitive dysfunction in schizophrenia is then presented, followed by a discussion of GABAergic compounds used in monotherapy or adjunctively in clinical schizophrenia studies.

RESULTS

In basic studies, reductions in GABAergic neuronal density and abnormalities in receptors and reuptake sites have been identified in several cortical and subcortical GABA systems. A model has been developed suggesting GABA's role (including GABA-dopamine interactions) in schizophrenia. In several clinical studies, the use of adjunctive GABA agonists was associated with greater improvement in core schizophrenia symptoms.

CONCLUSIONS

Alterations in the GABA neurotransmitter system are found in clinical and basic neuroscience schizophrenia studies as well as animal models and may be involved in the pathophysiology of schizophrenia. The interaction of GABA with other well-characterized neurotransmitter abnormalities remains to be understood. Future studies should elucidate the potential therapeutic role for GABA ligands in schizophrenia treatment.

New developments in the pharmacotherapy of schizophrenia

This review summarizes current key research strategies and the most prominently pursued new potential treatments for schizophrenia. First, new routes of administration for second generation antipsychotics are presented. These include rapidly dissolving tablets, drops and sirups as well as new intramuscular formulations. Newly available short acting and long acting (depot) antipsychotics complement oral antipsychotics so that the full spectrum of routes of administration is now available for second generation antipsychotics. Next to antipsychotic polypharmacy, in which two or more antipsychotics are combined, pharmacological add-on treatments, mainly with benzodiazepines, antidepressants and mood stabilizers enjoy increasing popularity. Most of this practice is driven by personal preferences, clinical experience and marketing rather than evidence based medicine. New pharmacological mechanisms currently utilized in advanced states of development include partial dopamine D2-receptor agonism, supplementation with glutamatergic agents, estrogen and omega-3-fatty acids. While the concept of partial D1-agonism has already led to the successful launch of a new antipsychotic, aripiprazole, the other attempts to improve therapeutic response in schizophrenia patients have so far provided equivocal results. It is argued that they may be helpful for certain subgroups or specific symptoms of schizophrenia patients. In conclusion, many exciting new pharmacological leads are currently pursued and this will very likely augment the options for treating patients with schizophrenia.

Effect of divalproex combined with olanzapine or risperidone in patients with an acute exacerbation of schizophrenia

This double-blind, randomized, multicenter study investigated the use of divalproex with an antipsychotic agent in patients hospitalized for acute exacerbation of schizophrenia. Patients (n = 249) who met DSM-IV criteria for schizophrenia were randomly assigned to receive olanzapine monotherapy, risperidone monotherapy, divalproex plus olanzapine, or divalproex plus risperidone for 28 days. Divalproex was initiated at 15 mg/kg/day and titrated over 12 days to a maximum dosage of 30 mg/kg/day. Olanzapine and risperidone, were, respectively, initiated at 5 and 2 mg/day and were titrated over the first 6 days to respective target fixed daily dosages of 15 and 6 mg/day. Improvements from baseline were observed at all evaluation points throughout the 28-day treatment period in the two combination therapy and the two antipsychotic monotherapy groups, with statistically significant treatment differences favoring combination therapy as soon as day 3 for Positive and Negative Syndrome Scale (PANSS) total score, derived Brief Psychiatric Rating Scale (BPRSd) total score, as well as PANSS and BPRSd subscales. These findings were confirmed in post hoc repeated-measures analyses of variance in which treatment differences favoring combination therapy were observed for PANSS total (p = 0.020) and PANSS positive scale scores (p = 0.002). Both combination therapy and antipsychotic monotherapy were well tolerated. Treatment with divalproex in combination with an atypical antipsychotic agent resulted in earlier improvements in a range of psychotic symptoms among acutely hospitalized patients with schizophrenia. Further evaluation is warranted to confirm these findings.

Antiepileptic drugs in schizophrenia: a review

The first choice group of psychotropic agents in schizophrenia is neuroleptics. However, this treatment is not effective in all patients and with every symptom. We summarize papers published on the role of antiepileptic drugs in treatment-resistant schizophrenia. We have searched the computer database system MEDLINE for relevant articles including reviews, reports of drug studies and case histories. Antiepileptic drugs can change symptoms of schizophrenia by their action on GABA-ergic neurotransmission or via anti-glutamatergic mechanisms. High doses of adjunctive benzodiazepines reduce positive symptoms, anxiety, and agitation. Carbamazepine is effective in affective symptoms of schizophrenia and influences violent behavior in psychotic patients. Its anti-kindling action may represent a promising treatment strategy for some patients with chronic course of schizophrenia. Valproate treatment leads to a decrease in positive symptoms as well as hostility. Lamotrigine is expected to influence the positive, negative, affective, and cognitive symptoms of schizophrenia. New antiepileptics (e.g., gabapentin, oxcarbazepine, topiramate, vigabatrin) present a promise as potential adjuncts to neuroleptic treatment in resistant symptoms of schizophrenia.

Benzodiazepines in schizophrenia: prefrontal cortex atrophy predicts clinical response to alprazolam augmentation

Benzodiazepines augment clinical responses to neuroleptics in some, but not all, treatment-refractory schizophrenic patients; however the biological predictors of response have remained unclear. Since patients with prefrontal cortex (PFC) volume loss demonstrate exaggerated subcortical dopamine responses to stress, and since benzodiazepines curtail stress-induced subcortical dopamine release in PFC-lesioned animals, we reasoned that patients with PFC volume loss might show preferential clinical responses to benzodiazepine augmentation. Five patients, who were participating in a larger four-week double-blind study of alprazolam augmentation of neuroleptics in treatment-resistant or partially treatment-resistant schizophrenia, had brain MRI scans prior to entry into the study. MRI scans were morphometrically analyzed to yield estimates of PFC grey and white matter volumes and PFC cerebrospinal fluid (CSF) volume, and these were correlated with clinical responses to alprazolam augmentation. PFC grey matter volume (adjusted for overall cranial capacity) was significantly correlated (r = 0.96, p < 0.01), in the predicted direction, with alprazolam-associated changes in total Brief Psychiatric Rating Scale ratings. PFC volume loss may represent a biological marker for benzodiazepine responsivity in schizophrenia, although the present findings are considered preliminary because of the small sample size. Mechanistic considerations and suggestions for future research are discussed.

Inhibitory deficit in schizophrenia is not necessarily a GABAergic deficit

1. Current evidence strongly supports the idea of an inhibitory deficit as a central pathophysiological mechanism in schizophrenia. This deficit has been well documented in sensory gating and paired-pulse studies and may be related to decreases in inhibitory interneurons found in schizophrenic patients. 2. The GABAergic system has been repeatedly postulated to mediate this deficit, but the findings are controversial, at least in some areas, and mostly negative regarding treatment with drugs enhancing GABAergic activity. Therefore, the scope of mediators of this inhibitory deficit should be widened and the neuromodulator adenosine is proposed as a candidate to be further studied. 3. A state of adenosinergic hypoactivity in schizophrenia is compatible not only with the inhibitory deficit but also with symptoms, clinical response to antipsychotics, impaired sensory gating, deteriorating course, increased smoking, and sleep alterations reported in schizophrenia. 4. It is concluded that although the GABAergic system should be further studied, especially in sensory gating model in humans, emphasis on other inhibitory mechanisms may prove useful and provide more effective treatment.

The effects of benzodiazepines on event-related potential indices of automatic and controlled processing in schizophrenia: a preliminary report

The effects of benzodiazepines on cognitive function in schizophrenic patients were investigated using event-related potential (ERP) measurement during an auditory selective attention task. In this study, the authors compared the mismatch negativity (MMN) and N2b components between two subgroups of schizophrenic patients: one is comprised of patients who received no benzodiazepines (NT group, n = 7) and the other is comprised of those administered benzodiazepines in the daytime (T group, n = 7). There were no significant differences in MMN and N2b amplitudes between the two subgroups, whereas the N2b latency was significantly prolonged in the T group relative to the NT group. This suggested that benzodiazepines induce delayed stimulus classification processing in schizophrenic patients.

Psychosis: pathological activation of limbic thalamocortical circuits by psychomimetics and schizophrenia?

Non-competitive NMDA receptor antagonists, such as phencyclidine, ketamine and MK801, produce psychosis in humans. These drugs also produce injury to cingulate-retrosplenial cortex in adult rodents that can be prevented by GABA-receptor agonists and antipsychotics such as haloperidol and clozapine. MK801 injections into anterior thalamus reproduce limbic cortex injury, and GABA-receptor agonist injections into anterior thalamus prevent injury produced by systemic MK801. Inhibition of NMDA receptors on GABAergic thalamic reticular nucleus neurons might activate thalamocortical 'injury' circuits in animals. Pathological activation of thalamocortical circuits might also mediate the psychosis produced by NMDA-receptor antagonists in humans, and might contribute to psychosis in schizophrenia.

Divalproex sodium augmentation of haloperidol in hospitalized patients with schizophrenia: clinical and economic implications

Divalproex sodium has been approved for use in treating bipolar disorder. Its usefulness in schizophrenia has yet to be adequately assessed. Three days after initiating haloperidol treatment, patients who were hospitalized for an acute exacerbation of schizophrenia received either valproate augmentation (early-augmentation group) or continued to receive haloperidol alone (no-augmentation group). Patients in the no-augmentation group who failed to respond 14 days after the dose of haloperidol reached 20 mg/day received valproate augmentation (delayed-augmentation group). By day 14, the early-augmentation group improved 32.4% more than the no-augmentation group. Fifty percent of the patients in the no-augmentation group failed to respond to haloperidol alone for 2 weeks. They improved by 29% upon the addition of valproate. Compared with those who received no or delayed augmentation, the early-augmentation group required 44.8% fewer inpatient days from the initiation of haloperidol treatment. Patient response to treatment was particularly noted in suspiciousness, hallucinations, unusual thought content, and emotional withdrawal. Early augmentation with valproate may reduce the length of inpatient stays and provide substantially better therapeutic outcomes. It is, however, premature to recommend changes in the standard clinical management of schizophrenia on the basis of the data provided herein, in view of the small sample and open-label nature of the report.

Randomized, placebo-controlled pilot study of divalproex sodium in the treatment of acute exacerbations of chronic schizophrenia

Experimental and clinical data suggest that GABA-ergic drugs such as valproate may have a potential role in the treatment of schizophrenia. The authors designed a 21-day prospective, double-blind, randomized, placebo-controlled pilot study of divalproex sodium as add-on treatment to haloperidol in 12 hospitalized patients with acute exacerbations of chronic schizophrenia. All patients received haloperidol 10 mg/day for 3 days and 15 mg/day for the remaining 18 days. In addition, five patients were randomly assigned to receive divalproex augmentation and seven to receive placebo. The divalproex dose was adjusted to a target serum concentration of 75 microg/mL for 2 weeks; placebo replaced divalproex during the third and last weeks to determine any carryover effect. Psychiatric rating scales were administered at baseline and on days 7, 14, and 21. Although the placebo group improved with haloperidol treatment, the divalproex group demonstrated greater improvement. On day 21, the divalproex group had greater improvement from baseline on the Clinical Global Impression Scale (p < or = 0.04), Brief Psychiatric Rating Scale (p < or = 0.13), and Schedule for Assessment of Negative Symptoms scores (p < or = 0.007). After divalproex withdrawal on day 15, a carryover effect was observed during week 3. The authors concluded that the addition of divalproex sodium to standard antipsychotic drugs may prove effective in relieving the symptoms of acute schizophrenia. Future studies may benefit from the design of this pilot study. However, it is premature to apply this augmentation strategy in the clinical setting just yet because of the small sample size and the likely heterogeneity of the disorder.

Imidazenil prevention of alprazolam-induced acquisition deficit in patas monkeys is devoid of tolerance

The partial allosteric modulators (PAMs) of gamma-aminobutyric acid-gated Cl(-) current intensities at gamma-aminobutyric acid type A receptors have high affinity but low intrinsic efficacy on benzodiazepine recognition sites. Unlike the full allosteric modulators (FAM), like alprazolam, triazolam, and diazepam, PAMs are virtually devoid of unwanted side effects, including tolerance. Imidazenil (IMD) is a PAM that elicits potent anxiolytic and anticonvulsant actions in rodents and nonhuman primates and retains its anticonvulsant and anxiolytic effects, even in rodents that are tolerant to FAMs. IMD antagonizes the side effects of FAMs in rodents and nonhuman primates. Using patas monkeys and a multiple schedule with repeated acquisition and performance of chain responses, we report that IMD administration for 17 days antagonized without showing tolerance ALP-induced disruption of acquisition.

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.