Vitamin E, lipids, and lipid peroxidation products in tardive dyskinesia

Antioxidant Properties of Second-Generation Antipsychotics: Focus on Microglia

Recent studies suggest a primary role of oxidative stress in an early phase of the pathogenesis of schizophrenia and a strong neurobiological link has been found between dopaminergic system dysfunction, microglia overactivation, and oxidative stress. Different risk factors for schizophrenia increase oxidative stress phenomena raising the risk of developing psychosis. Oxidative stress induced by first-generation antipsychotics such as haloperidol significantly contributes to the development of extrapyramidal side effects. Haloperidol also exerts neurotoxic effects by decreasing antioxidant enzyme levels then worsening pro-oxidant events. Opposite to haloperidol, second-generation antipsychotics (or atypical antipsychotics) such as risperidone, clozapine, and olanzapine exert a strong antioxidant activity in experimental models of schizophrenia by rescuing the antioxidant system, with an increase in superoxide dismutase and glutathione (GSH) serum levels. Second-generation antipsychotics also improve the antioxidant status and reduce lipid peroxidation in schizophrenic patients. Interestingly, second-generation antipsychotics, such as risperidone, paliperidone, and in particular clozapine, reduce oxidative stress induced by microglia overactivation, decreasing the production of microglia-derived free radicals, finally protecting neurons against microglia-induced oxidative stress. Further, long-term clinical studies are needed to better understand the link between oxidative stress and the clinical response to antipsychotic drugs and the therapeutic potential of antioxidants to increase the response to antipsychotics.

Genetics of tardive dyskinesia: Promising leads and ways forward

Tardive dyskinesia (TD) is a potentially irreversible and often debilitating movement disorder secondary to chronic use of dopamine receptor blocking medications. Genetic factors have been implicated in the etiology of TD. We therefore have reviewed the most promising genes associated with TD, including DRD2, DRD3, VMAT2, HSPG2, HTR2A, HTR2C, and SOD2. In addition, we present evidence supporting a role for these genes from preclinical models of TD. The current understanding of the etiogenesis of TD is discussed in the light of the recent approvals of valbenazine and deutetrabenazine, VMAT2 inhibitors, for treating TD.

Role of immunological factors in the pathophysiology and diagnosis of bipolar disorder: comparison with schizophrenia

Several lines of evidence point to the key role of neurobiological mechanisms and shared genetic background in schizophrenia and bipolar disorder. For both disorders, neurodevelopmental and neurodegenerative processes have been postulated to be relevant for the pathogenesis as well as dysregulation of immuno-inflammatory pathways. Inflammation is a complex biological response to harmful stimuli and it is mediated by cytokines cascades, cellular immune responses, oxidative factors and hormone regulation. Cytokines, in particular, are supposed to play a critical role in infectious and inflammatory processes, mediating the cross-talk between the brain and the immune system; they also possibly contribute to the development of the central nervous system. From this perspective, even though mixed results have been reported, it seems that both schizophrenia and bipolar disorder are associated with an imbalance in inflammatory cytokines; in fact, some of these could represent biological markers of illness and could be possible targets for pharmacological treatments. In light of these considerations, the purpose of the present paper was to provide a comprehensive and critical review of the existing literature about immunological abnormalities in bipolar disorder with particular attention to the similarities and differences with schizophrenia.

Antioxidants as potential therapeutics for neuropsychiatric disorders

Oxidative stress has been implicated in the pathophysiology of many neuropsychiatric disorders such as schizophrenia, bipolar disorder, major depression etc. Both genetic and non-genetic factors have been found to cause increased cellular levels of reactive oxygen species beyond the capacity of antioxidant defense mechanism in patients of psychiatric disorders. These factors trigger oxidative cellular damage to lipids, proteins and DNA, leading to abnormal neural growth and differentiation. Therefore, novel therapeutic strategies such as supplementation with antioxidants can be effective for long-term treatment management of neuropsychiatric disorders. The use of antioxidants and PUFAs as supplements in the treatment of neuropsychiatric disorders has provided some promising results. At the same time, one should be cautious with the use of antioxidants since excessive antioxidants could dangerously interfere with some of the protective functions of reactive oxygen species. The present article will give an overview of the potential strategies and outcomes of using antioxidants as therapeutics in psychiatric disorders.

Meta-analysis of oxidative stress in schizophrenia

BACKGROUND

Schizophrenia is associated with impaired antioxidant defense, including abnormal serum, plasma, and red blood cell (RBC) oxidative stress parameters. We performed a meta-analysis of these associations, considering the effect of clinical status and antipsychotic treatment after an acute exacerbation of psychosis.

METHODS

We identified articles by searching PubMed, PsychInfo, and Institute for Scientific Information, and the reference lists of identified studies.

RESULTS

Forty-four studies met the inclusion criteria. Total antioxidant status seemed to be a state marker, because levels were significantly decreased in cross-sectional studies of serum and plasma in first-episode psychosis (FEP) and significantly increased in longitudinal studies of antipsychotic treatment for acute exacerbations of psychosis (p < .01 for each). The RBC catalase and plasma nitrite seemed to be state-related markers, because levels in cross-sectional studies were significantly decreased in FEP (p < .01) and significantly increased in stable outpatients (p = .01). In contrast, RBC superoxide dismutase seemed to be a trait marker for schizophrenia, because levels in cross-sectional studies were significantly decreased in acutely relapsed inpatients, FEP, and stable outpatients (p < .01 for each).

CONCLUSIONS

Oxidative stress abnormalities in FEP suggest an effect that might be independent of antipsychotic medications. Although some parameters (total antioxidant status, RBC catalase, and plasma nitrite) might be state markers for acute exacerbations of psychosis, others (RBC superoxide dismutase) might be trait markers; however, more longitudinal studies are needed. Our findings suggest that oxidative stress might serve as a potential biomarker in the etiopathophysiology and clinical course of schizophrenia.

Risperidone reverses phencyclidine induced decrease in glutathione levels and alterations of antioxidant defense in rat brain

Perinatal phencyclidine (PCP) administration to rats represents one of the actual animal models of schizophrenia. Numerous data suggest redox dysregulation in this disease. We have previously demonstrated decreased content of the reduced glutathione (GSH) and complex disbalance of antioxidant enzymes in the brain of rats perinatally treated with PCP. The aim of this study was to elucidate whether chronic risperidone treatment can reverse these changes. The Wistar rats were perinatally treated with either PCP (10mg/kg; PCP, two groups) or saline (0.9% NaCl, two groups). At postnatal day (PN) 35, two groups of rats one NaCl and one PCP have started to receive risperidone in drinking water for nine weeks (NaCl-RSP and PCP-RSP groups). Animals were sacrificed on PN100 and the levels of GSH, the activities of γ-glutamate cysteine ligase (GCL), glutathione peroxidase (GPx), glutathione reductase (GR) and superoxide dismutase (SOD), as well as, the concentration of lipid peroxides were determined in the different brain structures. Risperidone restored decreased GSH levels, as well as decreased γ-GCL activity in cortex and hippocampus of animals perinatally treated with PCP. Alterations in GPx and GR activities caused by perinatal PCP treatment were also reversed by risperidone in most investigated brain structures. Furthermore, chronic risperidone treatment caused the decrease in SOD activity both in control and in PCP perinatally treated groups. Increased levels of lipid peroxides noticed in hippocampus and thalamus were reversed after chronic risperidone treatment. The results of the present study demonstrate that risperidone treatment restores GSH levels and to great measure reverses antioxidant defense alterations in the brain of perinatally PCP treated rats. Further studies are necessary in order to clarify the significance of risperidone influence on oxidative stress parameters in schizophrenia.

Antioxidants, redox signaling, and pathophysiology in schizophrenia: an integrative view

Schizophrenia (SZ) is a brain disorder that has been intensively studied for over a century; yet, its etiology and multifactorial pathophysiology remain a puzzle. However, significant advances have been made in identifying numerous abnormalities in key biochemical systems. One among these is the antioxidant defense system (AODS) and redox signaling. This review summarizes the findings to date in human studies. The evidence can be broadly clustered into three major themes: perturbations in AODS, relationships between AODS alterations and other systems (i.e., membrane structure, immune function, and neurotransmission), and clinical implications. These domains of AODS have been examined in samples from both the central nervous system and peripheral tissues. Findings in patients with SZ include decreased nonenzymatic antioxidants, increased lipid peroxides and nitric oxides, and homeostatic imbalance of purine catabolism. Reductions of plasma antioxidant capacity are seen in patients with chronic illness as well as early in the course of SZ. Notably, these data indicate that many AODS alterations are independent of treatment effects. Moreover, there is burgeoning evidence indicating a link among oxidative stress, membrane defects, immune dysfunction, and multineurotransmitter pathologies in SZ. Finally, the body of evidence reviewed herein provides a theoretical rationale for the development of novel treatment approaches.

Genetics of tardive dyskinesia

Tardive dyskinesia (TD) is one of the most serious adverse side effects of antipsychotic drugs and is an important topic of pharmacogenetic studies. Since there is a genetic susceptibility for developing this adverse reaction, and given that it is hard to predict its development prior to or during the early period of medication, the genetic study of TD is a promising research topic that has a direct clinical application. Moreover, such studies would improve our understanding of the genetic mechanism(s) underlying abnormal dyskinetic movement. A substantial number of case-control association studies of TD have been performed, with numbers of studies focusing on the genes involved in antipsychotic drug metabolism, such as those for cytochrome P450 (CYP) and oxidative stress related genes as well as various neurotransmitter related genes. These studies have produced relatively consistent though controversial findings for certain polymorphisms such as CYP2D6*10, DRD2 Taq1A, DRD3 Ser9Gly, HTR2A T102C, and MnSOD Ala9Val. Moreover, the application of the genome-wide association study (GWAS) to the susceptibility of TD has revealed certain associated genes that previously were never considered to be associated with TD, such as the rs7669317 on 4q24, GLI2 gene, GABA pathway genes, and HSPG2 gene. Although a substantial number of genetic studies have investigated TD, many of the positive findings have not been replicated or are inconsistent, which could be due to differences in study design, sample size, and/or subject ethnicity. We expect that more refined research will be performed in the future to resolve these issues, which will then enable the genetic prediction of TD and clinical application thereof.

Winter/summer seasonal changes in malondialdehyde formation as a source of variance in oxidative stress schizophrenia research

BACKGROUND

Malondialdehyde (MDA), an oxidative stress biological marker, is one of the most frequently used markers of lipid peroxidation in schizophrenia research. Data regarding MDA levels in schizophrenia are controversial. Our aim is to study the existence of winter/summer seasonal changes in serum MDA levels in schizophrenic patients.

METHODS

Twenty-three clinically stable treated chronic paranoid schizophrenic outpatients were studied in summer and winter. Blood was sampled between 08:30 and 09:00 h. Serum MDA was determined by the thiobarbituric acid reactive substances technique. The clinical state was assessed by means of the Clinical Global Impression (CGI) scale.

RESULTS

Mean serum MDA levels were significantly higher in summer than winter (2.49+/-0.25 vs. 1.86+/-0.11 nmol/ml, P<0.03). Summer MDA was increased by a 33.9% compared to winter MDA. Age, gender, smoking status, body mass index, psychopharmacological treatment, illness duration, age of illness onset and CGI did not affect significantly MDA levels.

CONCLUSION

Our results show that serum MDA presents a winter/summer rhythm of formation, with higher levels in summer than winter. It is strongly advisable to take into account the summer/winter variation in MDA levels when researching into this field.

Oxidative stress in tardive dyskinesia: genetic association study and meta-analysis of NADPH quinine oxidoreductase 1 (NQO1) and Superoxide dismutase 2 (SOD2, MnSOD) genes

INTRODUCTION

Tardive dyskinesia (TD) is a potentially irreversible side effect of antipsychotic medication treatment that occurs in approximately 25% of chronically treated schizophrenia patients. Oxidative stress has been one of the proposed mechanisms influencing TD risk. Pae et al. (2004) originally reported a significant association between TD and the NADPH quinine oxidoreductase 1 (NQO1) gene Pro187Ser (C609T, rs1800566) polymorphism in Korean schizophrenia patients; however, subsequent studies have not consistently replicated these findings. Similarly, Hori et al. (2000) reported an association between TD and the Manganese superoxide dismutase SOD2 (MnSOD) gene Ala9Val (rs4880) polymorphism in a Japanese sample, but most research groups failed to replicate their positive findings.

AIMS

We investigated the role of the NQO1 polymorphism Pro187Ser and SOD2 (Ala9Val) in a group of well-characterized schizophrenia patients (N=223) assessed for TD. We also performed a meta-analysis of all the previously published TD studies, including data from our sample, on these polymorphisms, Pro187Ser (N=5 studies) and Ala9Val (N=9 studies).

RESULTS

We did not observe a significant association of the Pro187Ser or Ala9Val polymorphism with TD occurrence or AIMS scores in our Caucasian and African American samples when analyzed independently. Meta-analysis did not reveal a significant association of the Pro187Ser/Ala9Val alleles or genotypes with TD occurrence.

CONCLUSIONS

Neither the NQO1 Pro187Ser nor the SOD2 Ala9Val appear to play a major role in TD risk, although additional polymorphisms should be tested before the role of NQO1 and SOD2 in TD can be completely excluded.

Manganese superoxide dismutase gene Ala-9Val polymorphism might be related to the severity of abnormal involuntary movements in Korean schizophrenic patients

OBJECTIVE

This study examined whether the manganese superoxide dismutase (MnSOD) gene Ala-9Val single-nucleotide polymorphism (SNP) is associated with neuroleptic-induced tardive dyskinesia (TD) and the severity of the abnormal involuntary movements in Korean schizophrenic patients.

METHOD

We investigated whether the MnSOD gene Ala-9Val SNP is associated with TD in Korean schizophrenic patients with (n=83) and without (n=126) TD who were matched for exposure to antipsychotics and other relevant variables.

RESULTS

Logistic regression analysis revealed that being older (p=0.026) was a risk factor for TD, but that there was no significant association between MnSOD gene and TD. Abnormal involuntary movements were more severe in carriers of the Ala allele than in noncarriers (p=0.044).

CONCLUSION

These findings do not support that the MnSOD gene Ala-9Val SNP is associated with TD in Korean schizophrenic patients. However, this polymorphism might be related to the severity of abnormal involuntary movements in this population.

Valeriana officinalis does not alter the orofacial dyskinesia induced by haloperidol in rats: role of dopamine transporter

Chronic treatment with classical neuroleptics in humans can produce a serious side effect, known as tardive dyskinesia (TD). Here, we examined the effects of V. officinalis, a medicinal herb widely used as calming and sleep-promoting, in an animal model of orofacial dyskinesia (OD) induced by long-term treatment with haloperidol. Adult male rats were treated during 12 weeks with haloperidol decanoate (38 mg/kg, i.m., each 28 days) and with V. officinalis (in the drinking water). Vacuous chewing movements (VCMs), locomotor activity and plus maze performance were evaluated. Haloperidol treatment produced VCM in 40% of the treated rats and the concomitant treatment with V. officinalis did not alter either prevalence or intensity of VCMs. The treatment with V. officinalis increased the percentage of the time spent on open arm and the number of entries into open arm in the plus maze test. Furthermore, the treatment with haloperidol and/or V. officinalis decreased the locomotor activity in the open field test. We did not find any difference among the groups when oxidative stress parameters were evaluated. Haloperidol treatment significantly decreased [(3)H]-dopamine uptake in striatal slices and V. officinalis was not able to prevent this effect. Taken together, our data suggest a mechanism involving the reduction of dopamine transport in the maintenance of chronic VCMs in rats. Furthermore, chronic treatment with V. officinalis seems not produce any oxidative damage to central nervous system (CNS), but it also seems to be devoid of action to prevent VCM, at least in the dose used in this study.

Diphenyl diselenide decreases the prevalence of vacuous chewing movements induced by fluphenazine in rats

RATIONALE

Chronic treatment with neuroleptics causes, as a side effect, tardive dyskinesia in humans; however, the mechanisms involved in its pathophysiology remain unclear.

OBJECTIVES

The purpose of this study was to examine the effects of diphenyl diselenide, an organoselenium compound with antioxidant properties, in an animal model of vacuous chewing movements (VCMs) induced by long-term treatment with fluphenazine.

RESULTS

Adult male rats were treated during 24 weeks with fluphenazine (25 mg/kg, intramuscularly [i.m.], once every 21 days) and diphenyl diselenide (1 mg/kg, subcutaneously, three times a week). VCMs and body weight gain were quantified every 3 weeks. The fluphenazine treatment produced VCMs in the majority of the treated rats (87% after 24 weeks). Concomitant treatment with diphenyl diselenide decreased the prevalence of VCMs to 50%. Additionally, we separated the rats that developed or did not develop VCMs. We did not find any statistical differences among the groups when oxidative stress parameters were evaluated. Chronic fluphenazine treatment significantly decreased [(3)H]-dopamine uptake. Concomitant treatment with diphenyl diselenide was not able to prevent this decrease in those rats that developed VCMs.

CONCLUSIONS

Our data suggest that the reduction in dopamine transport can be a possible mechanism related to the maintenance of VCMs in rats. Moreover, diphenyl diselenide seems to be a promising pharmacological agent in the reduction in the prevalence of VCMs in rats.

Association between the MnSOD Ala-9Val polymorphism and development of schizophrenia and abnormal involuntary movements in the Xhosa population

Reactive oxygen species (ROS)-mediated damage has been hypothesized to play a role in the development and poor outcome of schizophrenia, as well as the development of neuroleptic-induced abnormal involuntary movements. Recently, the functional polymorphism (Ala-9Val) in the manganese superoxide dismutase (MnSOD) gene (part of the antioxidant defense mechanism) was found to be associated with schizophrenia in a Turkish population. This study was aimed at replicating this finding in a Xhosa population. In addition, the role of Ala-9Val in abnormal involuntary movement and tardive dyskinesia development in the Xhosa population was also investigated. The schizophrenic patient group (n=286) and a healthy control group (n=243) were genotyped for the Ala-9Val polymorphism using heteroduplex-single stranded conformational polymorphism (HEX-SSCP) analysis. No significant difference in genotype or allele frequency could be observed between the schizophrenia and control group (P=0.294 and P=0.528 respectively). In addition no association could be found between the polymorphism and symptom severity (SANS and SAPS). The Xhosa schizophrenia patient group with abnormal involuntary movements (n=54) and a subgroup with tardive dyskinesia (n=30) was found to significantly differ in Ala-9Val genotype frequency (P=0.008 and P=0.011 respectively) compared to the Xhosa schizophrenia patient group without abnormal involuntary movements (n=204). However, no significant difference was found for the allele frequencies (P=0.955 and P=0.161). Further, using ANCOVA no association was found between AIMS score and genotype in the group with abnormal involuntary movements (P=0.1234). However, in the patient group with tardive dyskinesia an association was observed between genotype and AIMS score (P=0.0365). These results do not support a major role of the MnSOD Ala-9Val polymorphism in the development of schizophrenia or symptom severity in the Xhosa population. Yet it seems to be involved in the development of abnormal involuntary movements and tardive dyskinesia and may even modulate the severity of tardive dyskinesia.

Assessment of malondialdehyde levels in schizophrenia: a meta-analysis and some methodological considerations

Oxidative stress has long been suggested to participate in the pathophysiology of schizophrenia. Most of the published data on the subject rely on malondialdehyde levels assessment through thiobarbituric acid reactive substances (TBARS), despite significant methodological concerns. The present paper reports on a meta-analysis of studies published up to July 2006. Relevant studies were identified through PubMed search and the References section of experimental and review papers on the subject. Studies were retained for analysis if they provided adequate methods description, controls and subjects numbers, means and standard deviations. Using a random effect model, an effect size of 1.22 (CI: 0.64-1.80) was found, with significant bias and high heterogeneity. Inspection of the bias assessment plot suggested a lower value in the order of d approximately 0.5, in line with the results of the larger studies. The heterogeneity of the results appeared to be unrelated to assay type or biological sample. However a meta-regression analysis suggested an association, at trend level, between the precision-weighted effect size and the proportion of drug-free patients, which might therefore account for some of the heterogeneity.

Oxidative mechanisms and tardive dyskinesia

Tardive dyskinesia has been and continues to be a significant problem associated with long-term antipsychotic use, but its pathophysiology remains unclear. In the last 10 years, preclinical studies of the administration of antipsychotics to animals, as well as clinical studies of oxidative processes in patients given antipsychotic medications, with and without tardive dyskinesia, have continued to support the possibility that neurotoxic free radical production may be an important consequence of antipsychotic treatment, and that such production may relate to the development of dyskinetic phenomena. In line with this hypothesis, evidence has accumulated for the efficacy of antioxidants, primarily vitamin E (alpha-tocopherol), in the treatment and prevention of tardive dyskinesia. Early studies suggested a modest effect of vitamin E treatment on existing tardive dyskinesia, but later studies did not demonstrate a significant effect. Because evidence has continued to accumulate for increased oxidative damage from antipsychotic medications, but less so for the effectiveness of vitamin E, especially in cases of long-standing tardive dyskinesia, alternative antioxidant approaches to the condition may be warranted. These approaches may include the use of antioxidants as a preventive measure for tardive dyskinesia or the use of other antioxidants or neuroprotective drugs, such as melatonin, for established tardive dyskinesia.

The increased activity of plasma manganese superoxide dismutase in tardive dyskinesia is unrelated to the Ala-9Val polymorphism

That tardive dyskinesia (TD) may have its origins in free-radical toxicity has stimulated investigations into one enzyme important in the control of oxidative free radicals: superoxide dismutase (SOD). The manganese-containing form of this enzyme (MnSOD) is the major superoxide scavenger in mitochondria; a weak association between a functional genetic polymorphism (Ala-9Val) in the mitochondrial targeting sequence (MTS) of this enzyme and TD has been reported in a Japanese population. We have undertaken to determine both the plasma activity of MnSOD and the association of the Ala-9Val polymorphism in a well-matched series of male Chinese schizophrenic patients with (n=42) and without (n=59) TD, and normal male controls (n=50). MnSOD activity was elevated in the TD subjects over those without TD (P<0.05) and normal controls (P<0.05), an effect that was independent of age, age at first antipsychotic treatment, drug dosage and duration of illness. A significant positive correlation between total AIMS score and MnSOD activity was also observed (P<0.0001). No significant reduction in the frequency of the Ala allele was observed in the TD group (0.14) below non-TD (0.18) or control subjects (0.17); nor was there any relationship between MnSOD activity and the polymorphism. There was no difference between the mean AIMS scores for the two genotypes (V/V and A/V) in the TD group. We conclude that while we have further evidence of a disturbance in the mechanisms regulating oxidative free radicals in TD, this effect is not under the control of the genetic polymorphism investigated here.

Oxidative damage and schizophrenia: an overview of the evidence and its therapeutic implications

Free radicals are highly reactive chemical species generated during normal metabolic processes. which in excess can lead to membrane damage. Elaborate antioxidant defence systems exist to protect against oxidative stress. There is accumulating evidence of altered antioxidant capacity in schizophrenia. Membrane dysfunction can be secondary to free radical-mediated pathology, and may contribute to specific aspects of schizophrenic symptomatology and complications of its treatment. Specifically, free radical-mediated abnormalities may contribute to the development of a number of clinically significant consequences, including prominent negative symptoms, tardive dyskinesia, neurological 'soft' signs and parkinsonian symptoms. Our previous results showing altered membrane dynamics and antioxidant enzyme activities in schizophrenia, and findings from other investigators, are consistent with the notion of free radical-mediated neurotoxicity in schizophrenia. These findings provide a theoretical basis from which the development of novel therapeutic strategies such as fatty acid and antioxidant supplementation can occur in the future.

Abnormal age-related changes of plasma antioxidant proteins in schizophrenia

Albumin and bilirubin are metal-binding proteins, shown to possess free radical scavenging properties, and may thus be selective antioxidants. In the present study we examined whether individual plasma antioxidants such as albumin and bilirubin, which significantly contribute to total antioxidant status (TAS), are reduced in patients with schizophrenia. We prospectively studied plasma antioxidant proteins, i.e. albumin and bilirubin, in male veteran schizophrenic patients using a within-subject, repeated measures, on-off-on haloperidol treatment design, as well as age- and sex-matched healthy volunteers. Male patients with schizophrenia either during haloperidol treatment (n=46) or in a drug-free condition (n=35) had significantly lower levels of both plasma albumin and bilirubin compared with age- and sex-matched healthy volunteers (n=31). Such reductions of plasma antioxidant proteins in schizophrenic patients appear to be age-related changes, in contrast to those observed in healthy volunteers. On the other hand, levels of plasma albumin and bilirubin were not significantly affected by haloperidol treatment, haloperidol withdrawal, or length of drug-free period. Moreover, plasma TAS was not influenced significantly by cigarette smoking, even though it may selectively decrease plasma bilirubin but not albumin levels. The present findings, taken together with our previous results of reduced plasma TAS and uric acid, as well as an increased Red blood cell superoxide dismutase, lend further support to the hypothesis that a defect in the antioxidant defense system exists in schizophrenia that may lead to oxidative damage.

Neurotoxicity associated with neuroleptic-induced oral dyskinesias in rats. Implications for tardive dyskinesia?

Tardive dyskinesia is a serious motor side effect of long-term treatment with neuroleptics, with an unknown pathophysiologic basis. Brain damage and aging are prominent risk-factors, and together with the persistent character of the disorder, it is likely that long-lasting neuronal changes are involved in the pathogenesis. It has been hypothesized that striatal neurodegeneration caused by excitotoxic mechanisms and oxidative stress may play an important role in the development of the disorder, and the scope of the present work is to review the evidence supporting this hypothesis. The rat model of tardive dyskinesia has been used extensively in the field, and the usefulness of this model will be discussed. Neuroleptics are able to induce oxidative stress in vitro and increase striatal glutamatergic activity in rats, which may lead to toxic effects in the striatum. Drugs that block excitotoxicity inhibit the development of persistent oral dyskinesia in the rat model, and impaired energy metabolism leads to increased frequency of oral dyskinesia. There are also signs of altered striatal histology in rats with high frequency of oral dyskinesia. Furthermore, markers of increased oxidative stress and glutamatergic neurotransmission have been found in the cerebrospinal fluid of patients with tardive dyskinesia. In conclusion, several lines of evidence implicate neurotoxic events in the development of neuroleptic induced tardive dyskinesia.

The current status of tardive dystonia

Tardive dystonia (TDt), a persistent dystonia associated with exposure to neuroleptic drugs, is an uncommon disorder. It differs from tardive dyskinesia (TDk) in epidemiology, clinical features, risk factors, pathophysiology, course, prognosis, and treatment outcome. TDt seems to develop faster and is more painful, distressing, and disabling than tardive dyskinesia. In this article, evidence is reviewed on the face, descriptive, construct, and predictive validity of this iatrogenic complication of antipsychotic drugs. It is suggested that TDt should not be lumped together with TDk. It deserves a separate nosological status as an independent diagnostic category. The subclassification of TDt into various subtypes based on coexistence of other movement disorders is suggested.