Loss of striatal cholinergic neurons as a basis for tardive and L-dopa-induced dyskinesias, neuroleptic-induced supersensitivity psychosis and refractory schizophrenia

Development of an individualized risk calculator of treatment resistance in patients with first-episode psychosis (TRipCal) using automated machine learning: a 12-year follow-up study with clozapine prescription as a proxy indicator

About 15-40% of patients with schizophrenia are treatment resistance (TR) and require clozapine. Identifying individuals who have higher risk of development of TR early in the course of illness is important to provide personalized intervention. A total of 1400 patients with FEP enrolled in the early intervention for psychosis service or receiving the standard psychiatric service between July 1, 1998, and June 30, 2003, for the first time were included. Clozapine prescriptions until June 2015, as a proxy of TR, were obtained. Premorbid information, baseline characteristics, and monthly clinical information were retrieved systematically from the electronic clinical management system (CMS). Training and testing samples were established with random subsampling. An automated machine learning (autoML) approach was used to optimize the ML algorithm and hyperparameters selection to establish four probabilistic classification models (baseline, 12-month, 24-month, and 36-month information) of TR development. This study found 191 FEP patients (13.7%) who had ever been prescribed clozapine over the follow-up periods. The ML pipelines identified with autoML had an area under the receiver operating characteristic curve ranging from 0.676 (baseline information) to 0.774 (36-month information) in predicting future TR. Features of baseline information, including schizophrenia diagnosis and age of onset, and longitudinal clinical information including symptoms variability, relapse, and use of antipsychotics and anticholinergic medications were important predictors and were included in the risk calculator. The risk calculator for future TR development in FEP patients (TRipCal) developed in this study could support the continuous development of data-driven clinical tools to assist personalized interventions to prevent or postpone TR development in the early course of illness and reduce delay in clozapine initiation.

Prenatal exposition to haloperidol: A preclinical narrative review

Pre-existing maternal mental disorders may affect the early interactions between mother and baby, impacting the child's psychoemotional development. The typical antipsychotic haloperidol can be used during pregnancy, even with some restrictions. Its prescription is not limited to psychotic disorders, but also to other psychiatric conditions of high incidence and prevalence in the woman's fertile period. The present review focused on the preclinical available data regarding the biological and behavioral implications of embryonic exposure to haloperidol. The understanding of the effects of psychotropic drugs during neurodevelopment is important for its clinical aspect since there is limited evidence regarding the risks of antipsychotic drug treatment in pregnant women and their children. Moreover, a better comprehension of the mechanistic events that can be affected by antipsychotic treatment during the critical period of neurodevelopment may offer insights into the pathophysiology of neurodevelopmental disorders. The findings presented in this review converge to the existence of several risks associated with prenatal exposure to such medication and emphasize the need for further studies regarding its dimensions.

A novel giant non-cholinergic striatal interneuron restricted to the ventrolateral striatum coexpresses Kv3.3 potassium channel, parvalbumin, and the vesicular GABA transporter

The striatum is the main input structure of the basal ganglia. Distinct striatal subfields are involved in voluntary movement generation and cognitive and emotional tasks, but little is known about the morphological and molecular differences of striatal subregions. The ventrolateral subfield of the striatum (VLS) is the orofacial projection field of the sensorimotor cortex and is involved in the development of orofacial dyskinesias, involuntary chewing-like movements that often accompany long-term neuroleptic treatment. The biological basis for this particular vulnerability of the VLS is not known. Potassium channels are known to be strategically localized within the striatum. In search of possible molecular correlates of the specific vulnerability of the VLS, we analyzed the expression of voltage-gated potassium channels in rodent and primate brains using qPCR, in situ hybridization, and immunocytochemical single and double staining. Here we describe a novel, giant, non-cholinergic interneuron within the VLS. This neuron coexpresses the vesicular GABA transporter, the calcium-binding protein parvalbumin (PV), and the Kv3.3 potassium channel subunit. This novel neuron is much larger than PV neurons in other striatal regions, displays characteristic electrophysiological properties, and, most importantly, is restricted to the VLS. Consequently, the giant striatal Kv3.3-expressing PV neuron may link compromised Kv3 channel function and VLS-based orofacial dyskinesias.

Upregulation of heat-shock protein HSP-70 and glutamate transporter-1/glutamine synthetase in the striatum and hippocampus in haloperidol-induced dopamine-supersensitivity-state rats

BACKGROUND

The excessive blockade of dopamine D2 receptors (DRD2s) with long-term antipsychotic treatment is known to induce a dopamine supersensitivity state (DSS). The mechanism of DSS is speculated to be a compensatory up-regulation of DRD2s, but an excess blockade of DRD2s can also cause glutamatergic neuronal damage. Herein, we investigated whether antipsychotic-induced neuronal damage plays a role in the development of DSS.

METHODS

Haloperidol (HAL; 0.75 mg/kg/day for 14 days) or vehicle was administered to rats via an osmotic mini-pump. Haloperidol-treated rats were divided into groups of DSS rats and non-DSS rats based on their voluntary locomotion data. We then determined the tissue levels of glutamate transporter-1 (GLT-1)/glutamine synthetase (GS) and heat shock protein-70 (HSP-70) in the rats' brain regions.

RESULTS

The levels of HSP-70 in the striatum and CA-3 region of the DSS rats were significantly higher than those of the control and non-DSS rats, whereas the dentate gyrus HSP-70 levels in both the DSS and non-DSS rats were increased versus the controls. The levels of GLT-1/GS in the CA-3 and nucleus accumbens were increased in the DSS rats.

CONCLUSIONS

These results suggest that the DSS rats experienced striatal neuronal damage and indicate that a HAL-induced upregulation of HSP-70 and the GLT-1/GS system in the CA3 may be involved in the development of DSS. It remains unknown why the non-DSS rats did not suffer neuronal damage. In view of the need for therapeutic strategies for treatment-resistant schizophrenia, dopamine supersensitivity psychosis, and tardive dyskinesia, further investigations of our findings are warranted.

Candidate Genes Encoding Dopamine Receptors as Predictors of the Risk of Antipsychotic-Induced Parkinsonism and Tardive Dyskinesia in Schizophrenic Patients

(1) Introduction: Extrapyramidal disorders form the so-called extrapyramidal syndrome (EPS), which is characterized by the occurrence of motor disorders as a result of damage to the basal ganglia and the subcortical-thalamic connections. Often, this syndrome develops while taking medications, in particular antipsychotics (APs). (2) Purpose: To review studies of candidate genes encoding dopamine receptors as genetic predictors of development of AP-induced parkinsonism (AIP) and AP-induced tardive dyskinesia (AITD) in patients with schizophrenia. (3) Materials and Methods: A search was carried out for publications of PubMed, Web of Science, Springer, and e-Library databases by keywords and their combinations over the last 10 years. In addition, the review includes earlier publications of historical interest. Despite extensive searches of these commonly used databases and search terms, it cannot be ruled out that some publications were possibly missed. (4) Results: The review considers candidate genes encoding dopamine receptors involved in pharmacodynamics, including genes DRD1, DRD2, DRD3, and DRD4. We analyzed 18 genome-wide studies examining 37 genetic variations, including single nucleotide variants (SNVs)/polymorphisms of four candidate genes involved in the development of AIP and AITD in patients with schizophrenia. Among such a set of obtained results, only 14 positive associations were revealed: rs1799732 (141CIns/Del), rs1800497 (C/T), rs6275 (C/T), rs6275 (C/T) DRD2; rs167771 (G/A) DRD3 with AIP and rs4532 (A/G) DRD1, rs6277 (C/T), rs6275 (C/T), rs1800497 (C/T), rs1079597 (A/G), rs1799732 (141CIns/Del), rs1045280 (C/G) DRD2, rs6280 (C/T), rs905568 (C/G) DRD3 with AITD. However, at present, it should be recognized that there is no final or unique decision on the leading role of any particular SNVs/polymorphisms in the development of AIP and AITD. (5) Conclusion: Disclosure of genetic predictors of the development of AIP and AITD, as the most common neurological adverse drug reactions (ADRs) in the treatment of patients with psychiatric disorders, may provide a key to the development of a strategy for personalized prevention and treatment of the considered complication of AP therapy for schizophrenia in real clinical practice.

Effect of Varenicline on Tardive Dyskinesia: A Pilot Study

Objective

Although evidence implicates striatal cholinergic impairment as a mechanism underlying tardive dyskinesia, trials of nonspecific cholinergic agents have been inconclusive. As a partial agonist at specific nicotinic receptor subtypes, varenicline reduces drug-induced dyskinesias in animal models suggesting promise as a treatment for tardive dyskinesia.

Methods

Three schizophrenia patients with tardive dyskinesia who were smokers underwent an open trial of varenicline. After a 2-week baseline, subjects received varenicline 1 mg twice daily. Changes from baseline on the Abnormal Involuntary Movement Scale were measured after a 4-week varenicline stabilization period, and 6 weeks after the smoking quit date in one patient.

Results

Varenicline had no effect on mean Abnormal Involuntary Movement Scale scores after 4 weeks. Although smoking decreased after 4 weeks on varenicline and diminished further in one patient after 10 weeks, this also appeared to have no effect on ratings of tardive dyskinesia.

Conclusion

In contrast to animal models, no significant change in tardive dyskinesia occurred in response to varenicline replacement in three schizophrenia patients. Further investigations of cholinergic mechanisms in tardive dyskinesia are worthwhile as agents for specific cholinergic targets become available for treatment. In addition, treatment trials of tardive dyskinesia should control for smoking status, while patients on antipsychotics receiving nicotine replacement therapies for smoking should be studied further for changes in movement.

Dopamine: The Neuromodulator of Long-Term Synaptic Plasticity, Reward and Movement Control

Dopamine (DA) is a key neurotransmitter involved in multiple physiological functions including motor control, modulation of affective and emotional states, reward mechanisms, reinforcement of behavior, and selected higher cognitive functions. Dysfunction in dopaminergic transmission is recognized as a core alteration in several devastating neurological and psychiatric disorders, including Parkinson's disease (PD), schizophrenia, bipolar disorder, attention deficit hyperactivity disorder (ADHD) and addiction. Here we will discuss the current insights on the role of DA in motor control and reward learning mechanisms and its involvement in the modulation of synaptic dynamics through different pathways. In particular, we will consider the role of DA as neuromodulator of two forms of synaptic plasticity, known as long-term potentiation (LTP) and long-term depression (LTD) in several cortical and subcortical areas. Finally, we will delineate how the effect of DA on dendritic spines places this molecule at the interface between the motor and the cognitive systems. Specifically, we will be focusing on PD, vascular dementia, and schizophrenia.

Continuous versus extended antipsychotic dosing in schizophrenia: Less is more

Antipsychotic drugs temper psychotic symptoms by interacting with dopamine D2 receptors to reduce dopamine neurotransmission. Currently, the standard of care involves antipsychotic treatment protocols that achieve steady-state levels of medication. Maintaining patients on continuous treatment is thought to be necessary to keep them stabilised. However, continuous antipsychotic exposure increases the risk of adverse effects over time. These effects include metabolic and cardiovascular disorders, extrapyramidal complications, and dopamine receptor supersensitivity, the latter of which could potentially promote both treatment tolerance and psychosis relapse. In the present review, we describe evidence showing that continuous exposure to antipsychotic drugs can not only worsen long-term outcome, but-past acute phase treatment-it is also unnecessary to effectively manage schizophrenia symptoms. We also describe evidence that regular but extended dosing, allowing predictable periods of lower antipsychotic levels/D2 occupancy, is both safe and effective in patients, and it greatly reduces drug exposure overall. Studies in laboratory animals show that compared to continuous antipsychotic exposure, regular but extended dosing actually has superior antipsychotic-like efficacy, and it also substantially reduces the likelihood of both motor side effects and dopamine receptor supersensitivity. We propose that regular, but extended dosing should be considered in the long-term treatment of people with schizophrenia, because the available evidence suggests it can be just as effective as continuous treatment, while decreasing overall drug exposure and potentially reducing harmful side effects.

Recent Advances in the Pharmacology of Tardive Dyskinesia

Tardive dyskinesia (TD) is a syndrome of abnormal involuntary movements that follows treatment with dopamine D2-receptor antagonists. Recent approval of vesicular monoamine transporter-2 (VMAT2) inhibitors offers hope for reducing the impact of TD. Although these drugs represent a significant advance in patient care and a practical step forward in providing relief for patients with TD, understanding of the pharmacology of TD that could inform future research to prevent and reverse TD remains incomplete. This review surveys evidence for the effectiveness of VMAT2 inhibitors and other agents in the context of theories of pathogenesis of TD. In patients for whom VMAT2 inhibitors are ineffective or intolerable, as well as for extending therapeutic options and insights regarding underlying mechanisms, a review of clinical trial results examined as experimental tests of etiologic hypotheses is worthwhile. There are still compelling reasons for further investigations of the pharmacology of TD, which could generate alternative preventive and potentially curative treatments. Finally, benefits from novel drugs are best realized within an overall treatment strategy addressing the condition and needs of individual patients.

A unifying theory for the pathoetiologic mechanism of tardive dyskinesia

INTRODUCTION

Chronic treatment with dopamine D2 receptor antagonists has been proposed to lead to dopamine receptor supersensitivity. Frequently, this is conceptualized as upregulation or changes in the structure or function of the post-synaptic D2 receptor. However, the measured 1.4-fold increase in D2 receptor density and the lack of actual receptor supersensitivity are probably inadequate to explain outcomes such as tardive dyskinesia (TD) and dopamine supersensitivity psychosis.

HYPOTHESIS

Recent data suggest that TD may result from a combination of presynaptic, synaptic, and postsynaptic changes.

DISCUSSION

Presynaptic increase in dopamine release occurs when super-therapeutic blockade of postsynaptic D2 receptors results in excess synaptic unbound dopamine which ultimately ends up being reuptaken by the presynaptic neuron through the dopamine transporter. The increased availability of recycled dopamine results in higher vesicular dopamine concentrations. Since the quantity of neurotransmitter released (known as quanta) is determined by the number of presynaptic neurotransmitter vesicles, the increase in the number (concentration) of dopamine molecules in the vesicles results in a higher concentration of synaptic dopamine with successive depolarization events. Synaptic changes such as the appearance of perforated synapses which is an early step in new synapse formation have been shown in animal models of TD. Finally, postsynaptic increases in D2 receptor expression without demonstration of increased sensitivity or potency has been demonstrated.

CONCLUSION

TD likely develops due to changes across the synapse and terminology such as 'dopamine receptor supersensitivity' can be misleading. 'Synaptic upregulation' may be a more correct term.

[Antipsychotic-induced motor symptoms in schizophrenic psychoses-Part 3 : Tardive dyskinesia]

The treatment of schizophrenic psychoses with antipsychotic drugs (AP) is often associated with an increased risk of delayed occurrence of antipsychotic-associated movement disorders. Persistence and chronicity of such symptoms are very frequent. The risk of developing tardive dyskinesia (TD) is associated with the pharmacological effect profile of a particular AP, with treatment duration and age. This systematic review article summarizes the current study situation on prevalence, risk factors, prevention and treatment options and instruments for early prediction of TD in schizophrenic psychoses. The current data situation on treatment strategies for TD is very heterogeneous. For the treatment of TD there is preliminary evidence for reduction or discontinuation of the AP, switching to clozapine, administration of benzodiazepines (clonazepam) and treatment with vesicular monoamine transporter (VMAT2) inhibitors, ginkgo biloba, amantadine or vitamin E. Although TD can be precisely diagnosed it cannot always be effectively treated. Early detection and early treatment of TD can have a favorable influence on the prognosis and the clinical outcome.

Tardive dyskinesia update: treatment and management

The development of rational treatments for tardive dyskinesia has been held back by limitations to our understanding of its aetiology, which even now does not extend far beyond its association with centrally acting dopamine-blocking drugs. This article reviews briefly the major aetiological theories and addresses general management and specific treatment options. Primary prevention and early recognition remain the crucial management issues because, once the condition is established, there are no satisfactory treatments. The article considers two newly developed drugs, valbenazine and deutetrabenazine, in some detail as, although they are not yet licensed in Europe, they have largely been responsible for an upsurge in interest in tardive dyskinesia in the North American literature and are likely to be widely promoted in the future. Although possessed of undoubted benefits, the evidence suggests that these represent small steps rather than large leaps forward in treatment.

LEARNING OBJECTIVES

•

DECLARATION OF INTEREST

D.C.O. is psychiatric commissioner on the Commission on Human Medicines, the UK drug regulator, and chair of its expert advisory group on CNS drugs. He is also a member of the psychiatry Scientific Advisory Group of the European Medicines Agency.

Systematic review of interventions for treating or preventing antipsychotic-induced tardive dyskinesia

BACKGROUND

Antipsychotic medication can cause tardive dyskinesia (TD) - late-onset, involuntary, repetitive movements, often involving the face and tongue. TD occurs in > 20% of adults taking antipsychotic medication (first-generation antipsychotics for > 3 months), with this proportion increasing by 5% per year among those who continue to use these drugs. The incidence of TD among those taking newer antipsychotics is not different from the rate in people who have used older-generation drugs in moderate doses. Studies of TD have previously been found to be limited, with no treatment approach shown to be effective.

OBJECTIVES

To summarise the clinical effectiveness and safety of treatments for TD by updating past Cochrane reviews with new evidence and improved methods; to undertake public consultation to gauge the importance of the topic for people living with TD/the risk of TD; and to make available all data from relevant trials.

DATA SOURCES

All relevant randomised controlled trials (RCTs) and observational studies.

REVIEW METHODS

Cochrane review methods, network meta-analysis (NMA).

DESIGN

Systematic reviews, patient and public involvement consultation and NMA.

SETTING

Any setting, inpatient or outpatient.

PARTICIPANTS

For systematic reviews, adults with TD who have been taking a stable antipsychotic drug dose for > 3 months.

INTERVENTIONS

Any, with emphasis on those relevant to UK NHS practice.

MAIN OUTCOME MEASURES

Any measure of TD, global assessments and adverse effects/events.

RESULTS

We included 112 studies (nine Cochrane reviews). Overall, risk of bias showed little sign of improvement over two decades. Taking the outcome of 'TD symptoms improved to a clinically important extent', we identified two trials investigating reduction of antipsychotic dose [n = 17, risk ratio (RR) 0.42, 95% confidence interval (CI) 0.17 to 1.04; very low quality]. Switching was investigated twice in trials that could not be combined (switching to risperidone vs. antipsychotic withdrawal: one RCT, n = 42, RR 0.45, 95% CI 0.23 to 0.89; low quality; switching to quetiapine vs. haloperidol: one RCT, n = 45, RR 0.80, 95% CI 0.52 to 1.22; low quality). In addition to RCTs, six observational studies compared antipsychotic discontinuation with decreased or increased dosage, and there was no clear evidence that any of these strategies had a beneficial effect on TD symptoms (very low-quality evidence). We evaluated the addition to standard antipsychotic care of several treatments, but not anticholinergic treatments, for which we identified no trials. We found no clear effect of the addition of either benzodiazepines (two RCTs, n = 32, RR 1.12, 95% CI 0.6 to 2.09; very low quality) or vitamin E (six RCTs, n = 264, RR 0.95, 95% CI 0.89 to 1.01; low quality). Buspirone as an adjunctive treatment did have some effect in one small study (n = 42, RR 0.53, 95% CI 0.33 to 0.84; low quality), as did hypnosis and relaxation (one RCT, n = 15, RR 0.45, 95% CI 0.21 to 0.94; very low quality). We identified no studies focusing on TD in people with dementia. The NMA model found indirect estimates to be imprecise and failed to produce useful summaries on relative effects of interventions or interpretable results for decision-making. Consultation with people with/at risk of TD highlighted that management of TD remains a concern, and found that people are deeply disappointed at the length of time it has taken researchers to address the issue.

LIMITATIONS

Most studies remain small and poorly reported.

CONCLUSIONS

Clinicians, policy-makers and people with/at risk of TD are little better informed than they were decades ago. Underpowered trials of limited quality repeatedly fail to provide answers.

FUTURE WORK

TD reviews have data from current trials extracted, tabulated and traceable to source. The NMA highlights one context in which support for this technique is ill advised. All relevant trials, even if not primarily addressing the issue of TD, should report appropriate binary outcomes on groups of people with this problem. Randomised trials of treatments for people with established TD are indicated. These should be large (> 800 participants), necessitating accrual through accurate local/national registers, including an intervention with acceptable treatments and recording outcomes used in clinical practice.

STUDY REGISTRATION

This study is registered as PROSPERO CRD4201502045.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

A new outlook on cholinergic interneurons in Parkinson's disease and L-DOPA-induced dyskinesia

Traditionally, dopamine (DA) and acetylcholine (ACh) striatal systems were considered antagonistic and imbalances or aberrant signaling between these neurotransmitter systems could be detrimental to basal ganglia activity and pursuant motor function, such as in Parkinson's disease (PD) and L-DOPA-induced dyskinesia (LID). Herein, we discuss the involvement of cholinergic interneurons (ChIs) in striatally-mediated movement in a healthy, parkinsonian, and dyskinetic state. ChIs integrate numerous neurotransmitter signals using intrinsic glutamate, serotonin, and DA receptors and convey the appropriate transmission onto nearby muscarinic and nicotinic ACh receptors to produce movement. In PD, severe DA depletion causes abnormal rises in ChI activity which promote striatal signaling to attenuate normal movement. When treating PD with L-DOPA, hyperkinetic side effects, or LID, develop due to increased striatal DA; however, the role of ChIs and ACh transmission, until recently has been unclear. Fortunately, new technology and pharmacological agents have facilitated understanding of ChI function and ACh signaling in the context of LID, thus offering new opportunities to modify existing and discover future therapeutic strategies in movement disorders.

Antipsychotic-Induced Dopamine Supersensitivity Psychosis: Pharmacology, Criteria, and Therapy

The first-line treatment for psychotic disorders remains antipsychotic drugs with receptor antagonist properties at D2-like dopamine receptors. However, long-term administration of antipsychotics can upregulate D2 receptors and produce receptor supersensitivity manifested by behavioral supersensitivity to dopamine stimulation in animals, and movement disorders and supersensitivity psychosis (SP) in patients. Antipsychotic-induced SP was first described as the emergence of psychotic symptoms with tardive dyskinesia (TD) and a fall in prolactin levels following drug discontinuation. In the era of first-generation antipsychotics, 4 clinical features characterized drug-induced SP: rapid relapse after drug discontinuation/dose reduction/switch of antipsychotics, tolerance to previously observed therapeutic effects, co-occurring TD, and psychotic exacerbation by life stressors. We review 3 recent studies on the prevalence rates of SP, and the link to treatment resistance and psychotic relapse in the era of second-generation antipsychotics (risperidone, paliperidone, perospirone, and long-acting injectable risperidone, olanzapine, quetiapine, and aripiprazole). These studies show that the prevalence rates of SP remain high in schizophrenia (30%) and higher (70%) in treatment-resistant schizophrenia. We then present neurobehavioral findings on antipsychotic-induced supersensitivity to dopamine from animal studies. Next, we propose criteria for SP, which describe psychotic symptoms and co-occurring movement disorders more precisely. Detection of mild/borderline drug-induced movement disorders permits early recognition of overblockade of D2 receptors, responsible for SP and TD. Finally, we describe 3 antipsychotic withdrawal syndromes, similar to those seen with other CNS drugs, and we propose approaches to treat, potentially prevent, or temporarily manage SP.

[Antipsychotic-induced tardive syndromes]

Tardive dyskinesia (TD) remains a relevant clinical problem despite the increasing use of new-generation antipsychotics. Antipsychotic-induced tardive syndromes are difficult to treat and have a low tendency of remission. Therefore, prophylaxis is of utmost importance, with the responsible use of antipsychotics as a prime desideratum. With respect to managing tardive dyskinesia, discontinuing the antipsychotic, if possible, albeit not backed up by unequivocal evidence, is still the main recommendation. If this is not possible, the switch to an antipsychotic with a lower TD risk is the next-preferred option. Other symptomatic treatments have been explored, but clinical trials have provided inhomogeneous results and only very few compounds are approved for the treatment of tardive dyskinesia. This manuscript summarizes the current evidence with respect to the phenomenology, course, prevention and treatment of tardive syndromes.

Drug-Induced Extrapyramidal Syndromes: Implications for Contemporary Practice

The development of drugs to treat psychosis is a fascinating nexus for understanding mechanisms underlying disorders of mind and movement. Although the risk of drug-induced extrapyramidal syndromes has been mitigated by the acceptance of less potent dopamine antagonists, expansive marketing and off-label use has increased the number of susceptible people who may be at risk for these neurologic effects. Clinicians need to be familiar with advances in diagnosis and management, which are reviewed herein. A better understanding of drug-induced effects on the motor circuit may improve patient safety, enhance antipsychotic effectiveness, and provide insights into mechanisms underlying antipsychotic activity in parallel brain circuits.

New Models of Frontal-Subcortical Skeletomotor Circuit Pathology in Tardive Dyskinesia

Tardive dyskinesia (TD) is a hyperkinetic movement disorder that can occur as a side effect of treatment with antipsychotic medications. Because antipsychotics block the D2 family of dopamine receptors in the striatum, it has long been suspected this blockade contributes to the development of TD. Specifically, increased sensitivity of the dopamine receptors following chronic blockade has been thought to result in abnormal functioning of the frontal-subcortical (FSC) skeletomotor circuit and the symptoms of TD. However, this hypothesis remains unproven. In recent years, substantial research has focused on the basal ganglia and FSC circuits. This research has resulted in the development of the focused selection model of skeletomotor circuit function. This hypothesis provides a compelling model of neurocircuit abnormalities in TD. A greater understanding of the neuropathology of TD may lead to the development of better treatment and prevention strategies for this disorder. Furthermore, this information may contribute to a more complete understanding of normal skeletomotor circuit function and the role of circuit pathology in numerous neuropsychiatric conditions.

Tardive dyskinesia (syndrome): Current concept and modern approaches to its management

Tardive dyskinesia is a serious, disabling and potentially permanent, neurological hyperkinetic movement disorder that occurs after months or years of taking psychotropic drugs. The pathophysiology of tardive dyskinesia is complex, multifactorial and still not fully understood. A number of drugs were tried for the management of this motor disturbance, yet until now no effective and standard treatment has been found. It is very disappointing to realize that the introduction of antipsychotics from the second generation has not significantly decreased the prevalence and incidence of tardive dyskinesia. Therefore, the management of this motor disturbance remains an actual topic as well as a challenge for clinicians. This review summarizes recent relevant publications concerning the treatment of tardive dyskinesia.

Supersensitivity psychosis and its response to asenapine in a patient with delusional disorder

Supersensitivity psychosis is a recognized complication of long-term antipsychotic treatment, in which patients develop new or reemergent psychotic symptoms, generally accompanied by dyskinetic movements, due to prolonged dopamine receptor blockade and resultant supersensitivity. Though it is most closely associated with schizophrenia and the use of typical antipsychotic agents, it has also been documented in patients with other diagnoses, and in those receiving atypical antipsychotics. There is no established treatment for this condition. In this paper, we describe a patient with persistent delusional disorder, jealous type, who developed a supersensitivity psychosis characterized by persecutory delusions, auditory hallucinations, and thought insertion in association with mild tardive dyskinesia. These symptoms resolved completely following six weeks of treatment with the second-generation antipsychotic asenapine, 20 mg/day. The mechanisms and implications of the patient's symptomatology and response are discussed.

Is schizophrenia a dopamine supersensitivity psychotic reaction?

Adolf Meyer (1866-1950) did not see schizophrenia as a discrete disorder with a specific etiology but, rather, as a reaction to a wide variety of biopsychosocial factors. He may have been right. Today, we have evidence that gene mutations, brain injury, drug use (cocaine, amphetamine, marijuana, phencyclidine, and steroids), prenatal infection and malnutrition, social isolation and marginalization, can all result in the signs and symptoms of schizophrenia. This clinical picture is generally associated with supersensitivity to dopamine, and activates dopamine neurotransmission that is usually alleviated or blocked by drugs that block dopamine D2 receptors. While the dopamine neural pathway may be a final common route to many of the clinical symptoms, the components of this pathway, such as dopamine release and number of D2 receptors, are approximately normal in schizophrenia patients who are in remission. Postmortem findings, however, reveal more dimers of D1D2 and D2D2 receptors in both human schizophrenia brains and in animal models of schizophrenia. Another finding in animal models is an elevation of high-affinity state D2High receptors, but no radioactive ligand is yet available to selectively label D2High receptors in humans. It is suggested that synaptic dopamine supersensitivity in schizophrenia is an attempt at compensation for the original damage by heightening dopamine neurotransmission pathways (preparing the organism for fight or flight). The dopamine overactivity is experienced subjectively as overstimulation, which accounts for some of the clinical symptoms, with attempts at dampening down the stimulation leading to still other symptoms. Reaction and counter-reaction may explain the symptoms of schizophrenia.

Clozapine and tardive movement disorders: a review

BACKGROUND

Tardive syndromes (TS) arise from long term exposure to dopamine receptor blocking agents. Clozapine has been considered to have low risk of causing new onset TS and is considered as a treatment option in patients with TS.

AIM

This review evaluates the usefulness of clozapine in patients with TS and occasional reports of clozapine causing TS.

METHODOLOGY

Electronic searches were carried out using the search engines of PUBMED, Science direct and Google Scholar databases. All reports describing use of clozapine in management of TS, monitoring of TS while on clozapine and onset of TS after initiation of clozapine were identified.

RESULTS

Fifteen trials and 28 case series/case reports describe the use of clozapine in TS. Most of these reports show that clozapine is useful in patients with TS, in the dose range of 200-300 mg/day and the beneficial effect is seen within 4-12 weeks of initiation. One case series and two case reports described clozapine withdrawal emergent dyskinesias suggesting a masking role of clozapine. One trial, three case series and two case reports describe beneficial effects of clozapine on long standing neurological syndromes. There is relatively less literature (2 trials and 15 case series/reports) describing the emergence of TS with clozapine.

CONCLUSION

Evidence of beneficial effects of clozapine in TS is greater than its role in causation/worsening of TS. Hence, clozapine should be considered in symptomatic patients who develop TS while receiving other antipsychotics. Further research on mechanism of TS and clozapine effect on TS is required.

Neuropathological changes in the nucleus basalis in schizophrenia

The nucleus basalis has not been examined in detail in severe mental illness. Several studies have demonstrated decreases in glia and glial markers in the cerebral cortex in schizophrenia, familial bipolar disorder and recurrent depression. Changes in neocortical neuron size and shape have also been reported. The nucleus basalis is a collection of large cholinergic neurons in the basal forebrain receiving information from the midbrain and limbic system, projecting to the cortex and involved with attention, learning and memory, and receives regulation from serotonergic inputs. Forty-one cases aged 41-60 years with schizophrenia or major depressive disorder with age-matched controls were collected. Formalin-fixed paraffin-embedded coronal nucleus basalis sections were histologically stained for oligodendrocyte identification with cresyl-haematoxylin counterstain, for neuroarchitecture with differentiated cresyl violet stain and astrocytes were detected by glial fibrillary acid protein immunohistochemistry. Cell density and neuroarchitecture were measured using Image Pro Plus. There were larger NB oval neuron soma in the combined schizophrenia and major depression disorder groups (p = 0.038), with no significant change between controls and schizophrenia and major depression disorder separately. There is a significant reduction in oligodendrocyte density (p = 0.038) in the nucleus basalis in schizophrenia. The ratio of gemistocytic to fibrillary astrocytes showed a greater proportion of the former in schizophrenia (18.1 %) and major depressive disorder (39.9 %) than in controls (7.9 %). These results suggest glial cell abnormalities in the nucleus basalis in schizophrenia possibly leading to cortical-limbic disturbance and subcortical dysfunction.

A case of paliperidone-palmitate-induced tardive dyskinesia

OBJECTIVES

This is one of the first cases reported in the literature of paliperidone-palmitate-induced prolonged dyskinesia.

METHOD

Case report.

RESULTS

We report the case of a 49-year-old woman with paranoid schizophrenia who developed orofacial dyskinesia some 4 months after the commencement of paliperidone long-acting injection.

CONCLUSION

This case serves as a clinical reminder that dyskinesia can occur with all antipsychotic medications.

Prevention of haloperidol-induced alterations in brain acetylcholinesterase activity by vitamins B co-administration in a rodent model of tardive dyskinesia

Tardive dyskinesia (TD) is an iatrogenic syndrome being a significant adverse outcome of typical and atypical antipsychotic therapy. Recently we demonstrated that vitamins B (B1, B6, B12 alone or in combination) were able to prevent haloperidol-induced orofacial dyskinesia (OD) possibly by their antioxidant activity in the striatum, using a well-established model of TD. Here, based on the fact that alterations in cholinergic neurotransmission are related to TD pathophysiology and that vitamins B seems to influence brain cholinergic neurotransmission, we decided to investigate the effects of vitamins B1, B6, B12 and their association, vitamin B cocktail in haloperidol-induced cholinergic alterations, evaluated by alterations in acetylcholinesterase (AChE) activity, in striatum, prefrontal cortex and hippocampus, as a way to determine the participation of cholinergic neurotransmission, in these vitamins antidyskinetic mechanism. Haloperidol 1 mg/kg i.p. daily administration during 21 days to Wistar rats caused OD while decreased AChE activity in all brain areas studied. Vitamins B administration (B1:B6:B12 at 60:60:0.6 mg/kg, s.c) alone and vitamin B cocktail co-administered with haloperidol prevented OD development and increased AChE activity in all brain areas studied, with the maximum activity increment observed in the hippocampus of the animals co-treated with vitamin B12 and vitamin B cocktail. The antidyskinetic drug, clozapine did not induce OD and increased AChE activity similarly to the groups coadministered with vitamin B and HAL. The present data suggest that vitamins B can prevent haloperidol-induced alterations in AChE activity what can be related to the mechanism underlying their antidyskinetic effect.

Treatment of neurolept-induced tardive dyskinesia

Tardive dyskinesia (TDK) includes orobuccolingual movements and "piano-playing" movements of the limbs. It is a movement disorder of delayed onset that can occur in the setting of neuroleptic treatment as well as in other diseases and following treatment with other drugs. The specific pathophysiology resulting in TDK is still not completely understood but possible mechanisms include postsynaptic dopamine receptor hypersensitivity, abnormalities of striatal gamma-aminobutyric acid (GABA) neurons, and degeneration of striatal cholinergic interneurons. More recently, the theory of synaptic plasticity has been proposed. Considering these proposed mechanisms of disease, therapeutic interventions have attempted to manipulate dopamine, GABA, acetylcholine, norepinephrine and serotonin pathways and receptors. The data for the effectiveness of each class of drugs and the side effects were considered in turn.

Adenosine A2A-receptor antagonism and pathophysiology of Parkinson's disease and drug-induced movement disorders

Parkinson's disease and drug-induced movement disorders (DIMDs) have commonalities in etiology based on impaired dopamine-based neurotransmission. Adenosine A(2A)-receptor antagonism may provide a new mechanism through which these disorders can be managed. In the motor circuit, tonic output from the globus pallidus and substantia nigra regulates movement via opposing excitatory and inhibitory inputs to the cerebral cortex through the direct and indirect pathways. Increased activity of the direct pathway increases movement via an inhibitory effect on thalamocortical projection neurons; increased activity of the indirect pathway has the opposite effect. Regulation of these pathways is mediated primarily by reciprocal inhibitory interactions between dopamine and adenosine receptors on neurons of these pathways. Adenosine A(2A) receptors are colocalized with dopamine D(2) receptors on the indirect pathway neurons, with A(2A) activation opposing the effect of D(2) activation. The A(2A) receptors' role in the pathophysiology of Parkinson's disease and DIMDs is evidenced by the upregulation of A(2A) receptors in patients with Parkinson's disease and patients receiving long-term administration of dopamine blockers. Further, A(2A)-receptor antagonists are effective in reversing parkinsonian motor deficits and extrapyramidal symptoms in animal models of Parkinson's disease and DIMDs. Understanding the role of A(2A)-receptor antagonism in the pathophysiology of Parkinson's disease and DIMD has therapeutic implications.

All roads to schizophrenia lead to dopamine supersensitivity and elevated dopamine D2(high) receptors

BACKGROUND

The dopamine D2 receptor is the common target for antipsychotics, and the antipsychotic clinical doses correlate with their affinities for this receptor. Antipsychotics quickly enter the brain to occupy 60-80% of brain D2 receptors in patients (the agonist aripiprazole occupies up to 90%), with most clinical improvement occurring within a few days. The D2 receptor can exist in a state of high-affinity (D2(High) ) or in a state of low-affinity for dopamine (D2Low).

AIM

The present aim is to review why individuals with schizophrenia are generally supersensitive to dopamine-like drugs such as amphetamine or methyphenidate, and whether the D2(High) state is a common basis for dopamine supersensitivity in the animal models of schizophrenia.

RESULTS

All animal models of schizophrenia reveal elevations in D2(High) receptors. These models include brain lesions, sensitization by drugs (amphetamine, phencyclidine, cocaine, corticosterone), birth injury, social isolation, and gene deletions in pathways for NMDA, dopamine, GABA, acetylcholine, and norepinephrine.

CONCLUSIONS

These multiple abnormal pathways converge to a final common pathway of dopamine supersensitivity and elevated D2(High) receptors, presumably responsible for psychotic symptoms. Although antipsychotics alleviate psychosis and reverse the elevation of D2(High) receptors, long-term antipsychotics can further enhance dopamine supersensitivity in patients. Therefore, switching from a traditional antipsychotic to an agonist antipsychotic (aripiprazole) can result in psychotic signs and symptoms. Clozapine and quetiapine do not elicit parkinsonism or tardive dyskinesia because they are released from D2 within 12 to 24 h. Traditional antipsychotics remain attached to D2 receptors for days, preventing relapse, but allowing accumulation that can lead to tardive dyskinesia. Future goals include imaging D2(High) receptors and desensitizing them in early-stage psychosis.

Mechanisms of action of antipsychotic drugs of different classes, refractoriness to therapeutic effects of classical neuroleptics, and individual variation in sensitivity to their actions: Part II

Rapid-onset psychotic rebound is uncommon on discontinuation of most antipsychotic drugs, as might be expected for antipsychotic drugs with (hypothetically) indirect actions at their final target receptors. Rapid-onset psychosis is more common on withdrawal of clozapine, which might be expected if its action is direct. Drugs other than clozapine (notably thioridazine) may have hitherto unrecognised similarities to clozapine (but without danger of agranulocytosis), and may be useful in treatment of refractory psychosis. Quetiapine fulfils only some criteria for a clozapine-like drug. Clinical response to neuroleptics varies widely at any given plasma level. Haase's "neuroleptic threshold" concept suggests that the dose producing the slightest motor side effects produces most or all of the therapeutic benefit, but analyses presented here suggest that antipsychotic actions are not subject to a sharp "all-or-none" threshold but increase over a small dose range. This concept could provide a method for quantitative determination of individualized optimal doses.

Mechanisms of action of antipsychotic drugs of different classes, refractoriness to therapeutic effects of classical neuroleptics, and individual variation in sensitivity to their actions: Part I

Many issues remain unresolved about antipsychotic drugs. Their therapeutic potency scales with affinity for dopamine D2 receptors, but there are indications that they act indirectly, with dopamine D1 receptors (and others) as possible ultimate targets. Classical neuroleptic drugs disinhibit striatal cholinergic interneurones and increase acetyl choline release. Their effects may then depend on stimulation of muscarinic receptors on principle striatal neurones (M4 receptors, with reduction of cAMP formation, for therapeutic effects; M1 receptors for motor side effects). Many psychotic patients do not benefit from neuroleptic drugs, or develop resistance to them during prolonged treatment, but respond well to clozapine. For patients who do respond, there is a wide (>ten-fold) range in optimal doses. Refractoriness or low sensitivity to antipsychotic effects (and other pathologies) could then arise from low density of cholinergic interneurones. Clozapine probably owes its special actions to direct stimulation of M4 receptors, a mechanism available when indirect action is lost.

Movement disorders induced by antipsychotic drugs: implications of the CATIE schizophrenia trial

Drug-induced movement disorders have dramatically declined with the widespread use of second-generation antipsychotics, but remain important in clinical practice and for understanding antipsychotic pharmacology. The diagnosis and management of dystonia, parkinsonism, akathisia, catatonia, neuroleptic malignant syndrome, and tardive dyskinesia are reviewed in relation to the decreased liability of the second-generation antipsychotics contrasted with evidence from the Clinical Antipsychotic Trials of Intervention Effectiveness (CATIE) Schizophrenia Trial. Data from the CATIE trial imply that advantages of second-generation antipsychotics in significantly reducing extrapyramidal side effects compared with haloperidol may be diminished when compared with modest doses of lower-potency first-generation drugs.

Role of the central cholinergic system in the therapeutics of schizophrenia

The therapeutic agents currently used to treat schizophrenia effectively improve psychotic symptoms; however, they are limited by adverse effects and poor efficacy when negative symptoms of the illness and cognitive dysfunction are considered. While optimal pharmacotherapy would directly target the neuropathology of schizophrenia neither the underlying neurobiological substrates of the behavioral symptoms nor the cognitive deficits have been clearly established. Abnormalities in the neurotransmitters dopamine, serotonin, glutamate, and GABA are commonly implicated in schizophrenia; however, it is not uncommon for alterations in the brain cholinergic system (e.g., choline acetyltransferase, nicotinic and muscarinic acetylcholine receptors) to also be reported. Further, there is now considerable evidence in the animal literature to suggest that both first and second generation antipsychotics (when administered chronically) can alter the levels of several cholinergic markers in the brain as well as impair memory-related task performance. Given the well-established importance of central cholinergic neurons to information processing and cognition, it is important that cholinergic function in schizophrenia be further elucidated and that the mechanisms of the chronic effects of antipsychotic drugs on this important neurotransmitter system be identified. A better understanding of these mechanisms would be expected to facilitate optimal treatment strategies for schizophrenia as well as the identification of novel therapeutic targets. In this review, the following topics are discussed: 1) the central cholinergic system in schizophrenia 2) effects of antipsychotic drugs on central cholinergic neurons 3) important neurotrophins in schizophrenia, especially those that support central cholinergic neurons; 4) novel strategies to optimize the therapeutics of schizophrenia via the use of cholinergic compounds as primary (i.e., antipsychotic) treatments as well as adjunctive, pro-cognitive agents.

[Iatrogenic psychiatric-like symptoms recognition]

INTRODUCTION

This article proposes a review of atypical multicentre studies for drug-induced movement disorders (and related psychiatric symptoms) and supersensitivity psychosis. A well-conducted antipsychotic treatment consists of regular attempts to reduce the dose by finding the minimal therapeutic dose. To achieve optimal antipsychotic treatment, it is important to distinguish psychiatric symptoms associated with drug-induced movement disorder(s) (DIMD) or supersensitivity psychosis from true relapse.

LITERATURE FINDINGS

Persistent DIMD have been found to be a predictor of supersensitivity psychosis or tardive dyskinesia (DT). DIMD-associated psychiatric symptoms can be classified into three types: directly induced by DIMD; resulting from confounding DIMD with psychiatric symptoms; and supersensitivity symptoms associated with DIMD. Without this distinction, the beneficial effects of antipsychotics are masked by emergent DIMD psychiatric symptoms (as was confounded in the CATIE study).

DISCUSSION

A constant decline in the prevalence of TD (hyperkinetic, involuntary and purposeless movement disorder) has been observed since the introduction of atypical antipsychotics. The neurotoxic effects of classical antipsychotics are well documented and their discontinuation is required. However, the risk of TD still exits with atypical antipsychotics and continued surveillance of emerging cases is very important for clinicians. Moreover, a regular evaluation of DIMD and associated psychiatric symptoms is crucial. It is important to underline the fact that DIMD persists with antipsychotics, with significantly higher total PANSS scores than in patients without DIMD.

CONCLUSION

Supersensitivity psychosis is a drug-induced psychotic relapse (6 weeks following the decrease or withdrawal of an antipsychotic). Discontinuation syndromes can produce psychiatric symptoms (and be confounded with true relapse), but can be improved more quickly after reintroduction of treatment. Interestingly, various data suggest that lower doses of antipsychotics could prevent such symptoms. Anticonvulsants can be efficient adjuvants in the treatment of psychosis. In the United States, many patients received valproate or gabapentin treatment. These adjuvants, by antikindling effect, can facilitate minimal maintenance drug treatment and be efficient for anxiety. Resistant schizophrenia can be related to supersensitivity psychosis; gabapentin and lamotrigine are effective in this case.

Anticholinergic agents can induce oromandibular dyskinesia

Background and Purpose:

Oromandibular dyskinesia (OMD) can occur spontaneously or they can be induced by the conventional dopamine receptor antagonists. Anticholinergic medications have rarely been reported to cause OMD in parkinsonian or non-parkinsonian patients.

Methods:

We analyzed the clinical features of two parkinsonian and one non-parkinsonian patients who experienced OMD after anticholinergic medication.

Results:

Each patient of our cases developed oromandibular symptoms in the temporal regions that were related to the addition of anticholinergic agents, and the symptoms were relieved following the discontinuation of the causative anticholinergic drugs. In one of our case, levodopa alone did not cause dyskinesia but augmented dyskinesia associated with anticholinergics.

Conclusions:

Here we report two parkinsonian and one non-parkinsonian patients with OMD induced by the use of anticholinergic agents. In our cases, we could not find any other precipitating or actual secondary causes for the OMD symptoms in our patients. Furthermore, the fact that the OMD in our cases were ameliorated with cessation of anticholinergics suggests that it may be anticholinergic-induced.

Effects of vitamin E supplementation on plasma membrane permeabilization and fluidization induced by chlorpromazine in the rat brain

Neurotransmitter receptors play a key role in most research on antipsychotic drugs, but little is known about the effects of these drugs on the plasma membrane in the central nervous system. Therefore, we investigated whether chlorpromazine (CPZ), a typical phenothiazine antipsychotic drug, affects the plasma membrane integrity in the rat brain, and if so, whether these membrane alterations can be prevented by dietary supplementation with vitamin E, which has been shown to be an antioxidant and also a membrane-stabilizer. Leakage of [(18)F]2-fluoro-2-deoxy-D-glucose ([(18)F]FDG)-6-phosphate from rat striatal slices and decrease in 1,6-diphenyl-1,3,5-hexatriene fluorescence anisotropy were used as indexes for plasma membrane permeabilization and fluidization, respectively. CPZ induced leakage of [(18)F]FDG-6-phosphate from striatal slices, and the leakage was delayed in the vitamin E-supplemented group compared to that in the normal diet group. The decrease in plasma membrane anisotropy induced by CPZ was significantly attenuated by vitamin E supplementation. Chronic treatment with alpha-phenyl-N-tert-butyl nitrone, a free radical scavenger, had no effect on CPZ-induced plasma membrane permeabilization, and the treatment with CPZ did not induce lipid peroxidation. CPZ can reduce plasma membrane integrity in the brain, and this reduction can be prevented by vitamin E via its membrane-stabilizing properties, not via its antioxidant activity.

Relations between movement disorders and psychopathology under predominantly atypical antipsychotic treatment in adolescent patients with schizophrenia

OBJECTIVE

To examine relations between movement disorders (MD) and psychopathological symptoms in an adolescent population with schizophrenia under treatment with predominantly atypical antipsychotics.

METHOD

MD symptoms and psychopathology were cross-sectionally assessed in 93 patients (aged 19.6 +/- 2.2 years) using Tardive Dyskinesia Rating Scale (TDRS), Abnormal Involuntary Movement Scale (AIMS), Extrapyramidal Symptom Scale (EPS), Barnes Akathisia Scale (BAS), Brief Psychiatric Rating Scale (BPRS) and the Schedule for Assessment of Negative/Positive Symptoms (SANS/SAPS).

RESULTS

All patients with MD symptoms (n = 37; 39.8 %) showed pronounced global psychpathological signs (SANS/SAPS, BPRS: p = 0.026, p = 0.033, p = 0.001) with predominant anergia symptoms (p = 0.005) and inclinations toward higher anxiety- and depression-related symptoms (p = 0.051) as well as increased thought disturbance (p = 0.066). Both negative symptoms and anergia showed trends for positive correlations with tardive dyskinesia (p = 0.068; p = 0.065) as well as significant correlations with parkinsonism symptoms (p = 0.036; p = 0.023). Akathisia symptoms correlated significantly with hostile and suspicious symptoms (p = 0.013). A superfactor-analysis revealed four factors supporting the aforementioned results.

CONCLUSION

MD symptoms and psychopathology are in some respects related to each other. Motor symptoms representing on the one hand trait characteristics of schizophrenia might additionally be triggered by antipsychotics and finally co-occur with more residual symptoms within a long-term treatment.

Time dependent decreases in central alpha7 nicotinic acetylcholine receptors associated with haloperidol and risperidone treatment in rats

Alpha(7) nicotinic acetylcholine receptor deficits may contribute to cognitive dysfunction in schizophrenia; however, the contribution of antipsychotic drug exposure to these deficits is unknown. In this study, rats were treated orally with haloperidol (2.0 mg/kg/day) or risperidone (2.5 mg/kg/day) for 15 or 90 days. Subsequent immunoassays indicated that both antipsychotics were associated with alpha(7) nicotinic receptor decreases in the basal forebrain and prefrontal cortex when administered for 90 (but not 15) days, a result that was confirmed in autoradiographic experiments. These data suggest that haloperidol and risperidone may be associated with time dependent decreases in an important neurobiological substrate of memory.

Oral haloperidol or risperidone treatment in rats: temporal effects on nerve growth factor receptors, cholinergic neurons, and memory performance

First and second generation antipsychotics (FGAs and SGAs) ameliorate psychotic symptoms of schizophrenia, however, their chronic effects on information processing and memory function (i.e. key determinants of long term functional outcome) are largely unknown. In this rodent study the effects of different time periods (ranging from 2 weeks to 6 months) of oral treatment with the FGA, haloperidol (2.0 mg/kg/day), or the SGA, risperidone (2.5 mg/kg/day) on a water maze repeated acquisition procedure, the levels of nerve growth factor receptors, and two important cholinergic proteins, the vesicular acetylcholine transporter and the high affinity choline transporter were evaluated. The effects of the antipsychotics on a spontaneous novel object recognition procedure were also assessed during days 8-14 and 31-38 of treatment. Haloperidol (but not risperidone) was associated with impairments in water maze hidden platform trial performance at each of the time periods evaluated up to 45 days, but not when tested during days 83-90. In contrast, risperidone did not impair water maze task performance at the early time periods and it was actually associated with improved performance during the 83-90 day period. Both antipsychotics, however, were associated with significant water maze impairments during the 174-180 day period. Further, haloperidol was associated with decrements in short delay performance in the spontaneous novel object recognition task during both the 8-14 and 31-38 day periods of treatment, while risperidone was associated with short delay impairment during the 31-38 day time period. Both antipsychotics were also associated with time dependent alterations in the vesicular acetylcholine transporter, the high affinity choline transporter, as well as tyrosine kinase A, and p75 neurotrophin receptors in specific brain regions. These data from rats support the notion that while risperidone may hold some advantages over haloperidol, both antipsychotics can produce time-dependent alterations in neurotrophin receptors and cholinergic proteins as well as impairments in the performance of tasks designed to assess spatial learning and episodic memory.

Relating with professionals

This paper addresses my difficulties as a carer in engaging with many professionals in mental health, both locally associated with my son's acute inpatient care, and nationally where policies are being developed and their implementation is pursued. All of us are affected by The Department of Health (DoH) Mental Health policies and their implementation by professionals has formed the way in which professionals relate with my son and myself. The way in which my son is impacted inextricably affects the way I relate to professionals. I think my difficulty in engaging lies in the relationships we all have with each another. In focusing on the process within our relationships, I attempt to raise professionals' awareness of what constitutes a relationship when we dialogue. As it takes two to engage in a dialogue, I perceive my difficulty is also the difficulty of the professionals. Carers are becoming increasingly involved in the training of mental health professionals and our combined difficulty needs to be resolved, so that we all benefit. In order to achieve positive progression, there needs to be a radical change within our relationship to provide ease of engagement from all parties. In this paper I tentatively suggest how this process can be achieved.

Time-Dependent Cognitive Deficits Associated with First and Second Generation Antipsychotics: Cholinergic Dysregulation as a Potential Mechanism

Although cognitive dysfunction is considered one of the more debilitating symptoms of schizophrenia, there is a fundamental gap in our knowledge of how the primary pharmacologic treatments of this disease, first- and second-generation antipsychotics (FGAs and SGAs, respectively), affect cognition, particularly over extended periods of time. Moreover, it has been known for decades that chronic treatment with FGAs can lead to imbalances in cholinergic function in the striatum that result in movement disorders; however, there is a growing body of evidence to suggest that both FGAs and SGAs can lead to cholinergic alterations in brain areas more traditionally considered as memory-related, such as cortical and hippocampal regions. Data from our laboratories in rodents indicate that some SGAs (if administered for sufficient periods of time) can be associated with impairments in memory-related task performance as well as alterations in the cholinergic enzyme choline acetyltransferase, the vesicular acetylcholine transporter, and nicotinic (alpha(7)) and muscarinic (M(2)) acetylcholine receptors. Given the well documented importance of central cholinergic function to information processing and cognitive function, it is important that the mechanisms for such chronic antipsychotic effects be identified. In this review, two potential mechanisms for long-term antipsychotic-related cholinergic alterations in the central nervous system are discussed: 1) antipsychotic antagonist activity at dopaminergic-D(2) receptors on cholinergic neurons and 2) antipsychotic effects on neurotrophins that support cholinergic neurons, such as nerve growth factor and brain derived growth factor. Novel strategies to optimize the therapeutics of schizophrenia and maintain cognitive function via adjunctive cholinergic compounds and antipsychotic crossover approaches are also discussed.

Schizophrenia as an inflammation-mediated dysbalance of glutamatergic neurotransmission

This overview tries to bridge the gap between psychoneuroimmunological findings and recent results from pharmacological, neurochemical and genetic studies in schizophrenia. Schizophrenia is a disorder of dopaminergic neurotransmission, but modulation of the dopaminergic system by glutamatergic neurotransmission seems to play a key role. This view is supported by genetic findings of the neuregulin- and dysbindin genes, which have functional impact on the glutamatergic system. Glutamatergic hypofunction, however, is mediated by the N-methyl-D-aspartate (NMDA)-receptor antagonism. The only endogenous NMDA receptor antagonist identified up to now is kynurenic acid (KYNA). Despite the NMDA receptor antagonism, KYNA also blocks, in lower doses, the nicotinergic acetycholine receptor, i.e., increased KYNA levels can explain psychotic symptoms and cognitive deterioration. KYNA levels are described to be higher in the cerebrospinal fluid (CSF) and in critical central nervous system (CNS) regions of schizophrenics as compared to controls. Another line of evidence suggests that a (prenatal) infection is involved in the pathogenesis of schizophrenia. Due to an early sensitization process of the immune system or to a (chronic) infection, which is not cleared through the immune response, an immune imbalance between the type-1 and the type-2 immune responses takes place in schizophrenia. The type-1 response is partially inhibited, while the type-2 response is over-activated. This immune constellation is associated with inhibition of the enzyme indoleamine dioxygenase (IDO), because IDO - located in astrocytes and microglial cells - is inhibited by type-2 cytokines. IDO catalyzes the first step in tryptophan metabolism, the degradation from tryptophan to kynurenine, as does tryptophan 2,3-dioxygenase (TDO). Due to the inhibition of IDO, tryptophan-kynurenine is predominantly metabolized by TDO, which is located in astrocytes, not in microglial or other CNS cells. In schizophrenia, astrocytes in particular are activated, as increased levels of S100B appear. Additionally, they do not have the enzymatic equipment for the normal metabolism-route of tryptophan. Due to the lack of kynurenine hydroxylase (KYN-OHase) in astrocytes, KYNA accumulates in the CNS, while the metabolic pathway in microglial cells is blocked. Accordingly, an increase of TDO activity has been observed in critical CNS regions of schizophrenics. These mechanisms result in an accumulation of KYNA in critical CNS regions. Thus, the immune-mediated glutamatergic-dopaminergic dysregulation may lead to the clinical symptoms of schizophrenia. Therapeutic consequences, e.g., the use of anti-inflammatory cyclo-oxygenase-2 inhibitors, which can also decrease KYNA directly, are discussed.