Cognition, schizophrenia, and the atypical antipsychotic drugs

Human iN neuronal model of schizophrenia displays dysregulation of chromogranin B and related neuropeptide transmitter signatures

Schizophrenia (SZ) is a serious mental illness and neuropsychiatric brain disorder with behavioral symptoms that include hallucinations, delusions, disorganized behavior, and cognitive impairment. Regulation of such behaviors requires utilization of neurotransmitters released to mediate cell-cell communication which are essential to brain functions in health and disease. We hypothesized that SZ may involve dysregulation of neurotransmitters secreted from neurons. To gain an understanding of human SZ, induced neurons (iNs) were derived from SZ patients and healthy control subjects to investigate peptide neurotransmitters, known as neuropeptides, which represent the major class of transmitters. The iNs were subjected to depolarization by high KCl in the culture medium and the secreted neuropeptides were identified and quantitated by nano-LC-MS/MS tandem mass spectrometry. Several neuropeptides were identified from schizophrenia patient-derived neurons, including chromogranin B (CHGB), neurotensin, and natriuretic peptide. Focusing on the main secreted CHGB neuropeptides, results revealed differences in SZ iNs compared to control iN neurons. Lower numbers of distinct CHGB peptides were found in the SZ secretion media compared to controls. Mapping of the peptides to the CHGB precursor revealed peptides unique to either SZ or control, and peptides common to both conditions. Also, the iNs secreted neuropeptides under both KCl and basal (no KCl) conditions. These findings are consistent with reports that chromogranin B levels are reduced in the cerebrospinal fluid and specific brain regions of SZ patients. These findings suggest that iNs derived from SZ patients can model the decreased CHGB neuropeptides observed in human SZ.

Valuable interaction with cognitive remediation and optimal antipsychotics for recovery in schizophrenia (VICTORY-S): study protocol for an interventional, open-label, randomized comparison of combined treatment with cognitive remediation and lurasidone or paliperidone

Background

Cognitive impairment, a core feature of schizophrenia, is associated with poor outcomes. Pharmacotherapy and psychosocial treatment, when used alone, have inadequate effect sizes for cognitive impairment, leading to recent interest in combination interventions. A previous study examined the additive effect of cognitive remediation on lurasidone in patients with schizophrenia, which was negative. Although improvement in cognitive function was suggested for lurasidone, it was inconclusive because there was no antipsychotic control in the study. To clarify whether lurasidone has a meaningful impact on cognitive function in combination with cognitive remediation, we use paliperidone as a control antipsychotic in this study. We hypothesize that combination with lurasidone will improve cognitive and social function to a greater extent than paliperidone.

Methods

The valuable interaction with cognitive remediation and optimal antipsychotics for recovery in schizophrenia study is a multicenter, interventional, open-label, rater-blind, randomized comparison study, comparing the effect of lurasidone plus cognitive remediation with that of paliperidone plus cognitive remediation in patients with schizophrenia. The Neuropsychological Educational Approach to Remediation (NEAR) is used for cognitive remediation. Eligible patients will be randomized 1:1 to receive lurasidone or paliperidone combined with NEAR (6 weeks antipsychotic alone followed by 24 weeks combination antipsychotic plus NEAR). The primary endpoint is the change from baseline in the tablet-based Brief Assessment of Cognition in Schizophrenia composite T-score at the end of the NEAR combination treatment period. Secondary endpoints will include change from baseline in social function, schizophrenia symptoms, and quality of life at the end of the NEAR combination treatment period. Furthermore, change from baseline to the end of the pharmacotherapy period and change from the end of the pharmacotherapy period to the end of the NEAR combination treatment period will be assessed for all endpoints. Safety will also be evaluated.

Discussion

Achievement of adequate cognitive function is central to supporting social function, which is a key treatment goal for patients with schizophrenia. We think this study will fill in the gaps of the previous study and provide useful information regarding treatment decisions for patients with schizophrenia.

Clinical trial registration

Japan Registry of Clinical Trials ID, jRCTs031200338.

Lipopolysaccharide Exacerbates Ketamine-Induced Psychotic-Like Behavior, Oxidative Stress, and Neuroinflammation in Mice: Ameliorative Effect of Diosmin

Schizophrenia, a neuropsychiatric disorder has been associated with aberrant neurotransmission affecting behaviors, social preference, and cognition. Limitations in understanding its pathogenesis via the dopamine hypothesis have engendered other hypotheses such as the glutamate hypothesis. That antagonism of the N-methyl-D-aspartate receptor (NMDAR) elicits schizophrenia-like behaviors indistinguishable from the disorder in animal and human models. There are growing concerns that redox imbalance and neuro-immuno dysfunction may play role in aggravating the symptomologies of this disorder. This 14-day treatment study was designed to investigate the effect of diosmin on lipopolysaccharide (LPS) plus ketamine (NMDAR antagonist). Mice were divided into 4 groups (n = 6). Group 1 was administered 5% DMSO (10 mL/kg, i.p) while group 2-4 received LPS (0.1 mg/kg, i.p) daily for 14 days. Diosmin (50 mg/kg, i.p) and risperidone (0.5 mg/kg, i.p) were given to groups 3 and 4 respectively. Groups 2-4 were given KET (20 mg/kg, i.p.) daily from days 8-14. Behavioral tests were done 30 min after the last dose, and oxidative stress and neuroinflammatory maker were assayed. LPS plus ketamine-induced hyperlocomotion, stereotypy, decreased social preference, and memory impairment. Furthermore, LPS plus-ketamine-induced oxidative stress (reduced GSH, CAT, SOD, and increased MDA and nitrite levels) and marked pro-inflammatory cytokines TNF-α and IL-6 suggesting neuroinflammation. However, diosmin attenuated behavioral deficits and improved memory. Additionally, diosmin potentiated antioxidant level via increased GSH, CAT, and SOD while reducing MDA and nitrite levels. Finally, diosmin reduced TNF-α and IL-6 suggesting anti-neuro-immuno activity. Conclusively, diosmin attenuated LPS plus ketamine-induced behavioral deficits, oxidative stress, neuroinflammation, and improved memory.

Effect of dopamine receptor-related compounds on naive common marmosets for auditory steady state response

Abnormalities of auditory steady state responses (ASSR) and the effects of antipsychotic drugs on ASSR have been investigated in patients with schizophrenia. It is presumed that effects of drugs do not directly reflect on ASSR, because of ASSR abnormalities associated with schizophrenia. Therefore, to investigate the direct effect of drugs on ASSR, we established an ASSR evaluation system for common marmosets in a naïve state. Dopamine D1 receptor stimulation (SKF-81297, 2 mg/kg, intraperitoneal) significantly increased evoked power (EP) at 40 Hz. The phase locking factor (PLF) was increased significantly at 20, 30, 40, and 80 Hz. However, the administration of a dopamine D1 receptor antagonist (SCH-39166, 0.3 mg/kg intraperitoneal) resulted in a significant decrease in EP and PLF at 30 Hz. Dopamine D2 receptor stimulation (quinpirole, 1 mg/kg, intramuscular) tended to increase EP and induced power (IP) at all frequencies, and a significant difference was observed at 30 Hz IP. There was no change in PLF at all frequencies. In addition, dopamine D2 receptor blockade (raclopride, 3 mg/kg, intraperitoneal) reduced EP and PLF at 30 Hz. Subcutaneous administration of the serotonin dopamine antagonist, risperidone (0.3 mg/kg), tended to increase IP and decrease PLF, but not significantly. Taken together, it is possible to compare the differences in the mode of action of drugs on ASSR using naïve non-human primates.

Involvement of anti-inflammatory, antioxidant, and BDNF up-regulating properties in the antipsychotic-like effect of the essential oil of Alpinia zerumbet in mice: a comparative study with olanzapine

The current drug therapy for schizophrenia effectively treats acute psychosis and its recurrence; however, this mental disorder's cognitive and negative symptoms are still poorly controlled. Antipsychotics present important side effects, such as weight gain and extrapyramidal effects. The essential oil of Alpinia zerumbet (EOAZ) leaves presents potential antipsychotic properties that need further preclinical investigation. Here, we determined EAOZ effects in preventing and reversing schizophrenia-like symptoms (positive, negative, and cognitive) induced by ketamine (KET) repeated administration in mice and putative neurobiological mechanisms related to this effect. We conducted the behavioral evaluations of prepulse inhibition of the startle reflex (PPI), social interaction, and working memory (Y-maze task), and verified antioxidant (GSH, nitrite levels), anti-inflammatory [interleukin (IL)-6], and neurotrophic [brain-derived neurotrophic factor (BDNF)] effects of this oil in hippocampal tissue. The atypical antipsychotic olanzapine (OLZ) was used as standard drug therapy. EOAZ, similarly to OLZ, prevented and reversed most KET-induced schizophrenia-like behavioral alterations, i.e., sensorimotor gating deficits and social impairment. EOAZ had a modest effect on the prevention of KET-associated working memory deficit. Compared to OLZ, EOAZ showed a more favorable side effects profile, inducing less cataleptic and weight gain changes. EOAZ efficiently protected the hippocampus against KET-induced oxidative imbalance, IL-6 increments, and BDNF impairment. In conclusion, our data add more mechanistic evidence for the anti-schizophrenia effects of EOAZ, based on its antioxidant, anti-inflammatory, and BDNF up-regulating actions. The absence of significant side effects observed in current antipsychotic drug therapy seems to be an essential benefit of the oil.

Anticholinergic Burden and Cognitive Performance in Patients With Schizophrenia: A Systematic Literature Review

Objective: Cognitive impairment in schizophrenia forms the key cause of the disease's disability, leading to serious functional, and socioeconomic implications. Dopaminergic-cholinergic balance is considered essential to cognitive performance in schizophrenia and patients are often treated with many drugs with anticholinergic properties. This study aims to examine the cognitive impact of anticholinergic burden in patients with schizophrenia. Methods: A systematic literature review was performed on English-language studies published on PubMed, Embase, and Web of Science, from inception to June 2021, to identify research studies that examined the effect of anticholinergic load on cognition in clinically stable patients with schizophrenia. No restrictions on study design, age of participants, or geographical distribution were applied. Two researchers performed independently the screening and shortlisting of the eligible articles. A narrative synthesis of the main characteristics and findings of studies included was reported. Results: In total, 17 articles of varying methodological design met the inclusion criteria. Three of them found statistically significant improvement in cognition after anticholinergic tapering without adverse effects. Thirteen studies found a statistically significant association between high anticholinergic burden and cognitive impairment (neurocognitive composite scores and individual cognitive domains such as learning and memory, executive function, processing speed), apart from a study, related to the specific characteristics of clozapine. Conclusions: Medication with increased anticholinergic load has been found in most of the studies to negatively affect neurocognitive performance of patients with schizophrenia. However, the clinical and methodological heterogeneity of studies included limit our interpretation and conclusions.

Subcortical Dopamine and Cognition in Schizophrenia: Looking Beyond Psychosis in Preclinical Models

Schizophrenia is characterized by positive, negative and cognitive symptoms. All current antipsychotic treatments feature dopamine-receptor antagonism that is relatively effective at addressing the psychotic (positive) symptoms of schizophrenia. However, there is no clear evidence that these medications improve the negative or cognitive symptoms, which are the greatest predictors of functional outcomes. One of the most robust pathophysiological observations in patients with schizophrenia is increased subcortical dopamine neurotransmission, primarily in the associative striatum. This brain area has an important role in a range of cognitive processes. Dopamine is also known to play a major part in regulating a number of cognitive functions impaired in schizophrenia but much of this research has been focused on cortical dopamine. Emerging research highlights the strong influence subcortical dopamine has on a range of cognitive domains, including attention, reward learning, goal-directed action and decision-making. Nonetheless, the precise role of the associative striatum in the cognitive impairments observed in schizophrenia remains poorly understood, presenting an opportunity to revisit its contribution to schizophrenia. Without a better understanding of the mechanisms underlying cognitive dysfunction, treatment development remains at a standstill. For this reason, improved preclinical animal models are needed if we are to understand the complex relationship between subcortical dopamine and cognition. A range of new techniques are facillitating the discrete manipulation of dopaminergic neurotransmission and measurements of cognitive performance, which can be investigated using a variety of sensitive translatable tasks. This has the potential to aid the successful incorporation of recent clinical research to address the lack of treatment strategies for cognitive symptoms in schizophrenia. This review will give an overview on the current state of research focused on subcortical dopamine and cognition in the context of schizophrenia research. We also discuss future strategies and approaches aimed at improving the translational outcomes for the treatment of cognitive deficits in schizophrenia.

Connectivity Analyses of Bioenergetic Changes in Schizophrenia: Identification of Novel Treatments

We utilized a cell-level approach to examine glycolytic pathways in the DLPFC of subjects with schizophrenia (n = 16) and control (n = 16) and found decreased mRNA expression of glycolytic enzymes in pyramidal neurons, but not astrocytes. To replicate these novel bioenergetic findings, we probed independent datasets for bioenergetic targets and found similar abnormalities. Next, we used a novel strategy to build a schizophrenia bioenergetic profile by a tailored application of the Library of Integrated Network-Based Cellular Signatures data portal (iLINCS) and investigated connected cellular pathways, kinases, and transcription factors using Enrichr. Finally, with the goal of identifying drugs capable of "reversing" the bioenergetic schizophrenia signature, we performed a connectivity analysis with iLINCS and identified peroxisome proliferator-activated receptor (PPAR) agonists as promising therapeutic targets. We administered a PPAR agonist to the GluN1 knockdown model of schizophrenia and found it improved long-term memory. Taken together, our findings suggest that tailored bioinformatics approaches, coupled with the LINCS library of transcriptional signatures of chemical and genetic perturbagens, may be employed to identify novel treatment strategies for schizophrenia and related diseases.

A comparative study of childhood/adolescent and adult onset schizophrenia: does the neurocognitive and psychosocial outcome differ?

AIMS & OBJECTIVES

The present study aimed to evaluate the neurocognitive functioning and psychosocial outcome (in terms of social functioning, disability and internalized stigma) in patients with schizophrenia with childhood/adolescent onset (age of onset ≤18 years) and adult onset (>18years) schizophrenia and to evaluate the effect of neurocognitive impairment on the outcome variables in patients with youth and adult onset schizophrenia.

METHODOLOGY

34 patients with youth onset schizophrenia (Group-I) and 56 patients with adult onset schizophrenia (Group-II), who were currently in clinical remission were assessed on a comprehensive neurocognitive battery,Positive and Negative syndrome Scale (PANSS), Global Assessment of Functioning Scale (GAF), Indian Disability Evaluation and Assessment Scale (IDEAS),Social and Occupational Functioning Assessment Scale (SOFS) and Internalised Stigma of Mental Illness Scale (ISMIS).

RESULTS

On neurocognitive domains (after adjusting for co-variates) significant differences were noted between the two groups in terms of processing speed (TMT-A; I > II; p-value -0.009), verbal fluency (COWA;I < II;p-value-0.001) and cognitive flexibility (TMT-B; I > II; p -0.031). Compared to patients with adult onset schizophrenia, patients with childhood & adolescent onset schizophrenia had significantly higher PANSS negative score, higher disability in all domains of IDEAS, poorer socio-occupational functioning, low global functioning and reported more stigma in the domains of alienation and discrimination.In patients with childhood & adolescent onset schizophrenia, higher deficits in the processing speed and verbal fluency were associated with significantly lower socio-occupational functioning and higher disability; higher executive dysfunction was associated with higher internalized stigma. Among patients with adult onset schizophrenia, higher disability was related to executive dysfunction only and higher stigma was associated with poor cognitive processing, selective attention and poor executive functioning.

CONCLUSIONS

The present study suggests that compared to adult onset schizophrenia, patients with childhood & adolescent onset schizophrenia have more deficits in neurocognition, have higher level of disability, poorer socio-occupational functioning and have higher level of self-stigma.

Cognitive function in schizophrenia: conflicting findings and future directions

INTRODUCTION

Schizophrenia is a severe mental disorder with multiple psychopathological domains being affected. Several lines of evidence indicate that cognitive impairment serves as the key component of schizophrenia psychopathology. Although there have been a multitude of cognitive studies in schizophrenia, there are many conflicting results. We reasoned that this could be due to individual differences among the patients (i.e. variation in the severity of positive vs. negative symptoms), different task designs, and/or the administration of different antipsychotics.

METHODS

We thus review existing data concentrating on these dimensions, specifically in relation to dopamine function. We focus on most commonly used cognitive domains: learning, working memory, and attention.

RESULTS

We found that the type of cognitive domain under investigation, medication state and type, and severity of positive and negative symptoms can explain the conflicting results in the literature.

CONCLUSIONS

This review points to future studies investigating individual differences among schizophrenia patients in order to reveal the exact relationship between cognitive function, clinical features, and antipsychotic treatment.

The preclinical discovery and development of quetiapine for the treatment of mania and depression

INTRODUCTION

Bipolar disorder is a chronic disabling condition characterized by alternating manic and depressive episodes. Bipolar disorder has been associated with functional impairment, poor quality of life, morbidity and mortality. Despite its significant clinical, social and economic burden, treatment options for bipolar disorder are still limited. Several clinical trials have shown efficacy of the atypical antipsychotic quetiapine (QTP) in the treatment of this condition. However, the mechanisms underlying the antidepressant and anti-manic effects of QTP remain poorly understood. Areas covered: The article provides the emerging evidence from pre-clinical studies regarding the antidepressant and anti-manic mechanisms of action of QTP. In combination with its primary active metabolite norquetiapine, QTP modulates several neurotransmitter systems, including serotonin, dopamine, noradrenaline and histamine. QTP also seems to influence mediators of the immune system. Expert opinion: Pre-clinical studies have provided valuable information on the potential antidepressant mechanisms of action of QTP, but pre-clinical studies on QTP's anti-manic effects are still scarce. A major problem refers to the lack of valid experimental models for bipolar disorder. Additionally, immune and genetic based studies are largely descriptive. The role of the QTP metabolite norquetiapine in modulating non-neurotransmitter systems also needs to be further addressed.

Oxazolidinone-based allosteric modulators of mGluR5: Defining molecular switches to create a pharmacological tool box

Herein we describe the structure activity relationships uncovered in the pursuit of an mGluR5 positive allosteric modulator (PAM) for the treatment of schizophrenia. It was discovered that certain modifications of an oxazolidinone-based chemotype afforded predictable changes in the pharmacological profile to give analogs with a wide range of functional activities. The discovery of potent silent allosteric modulators (SAMs) allowed interrogation of the mechanism-based liabilities associated with mGluR5 activation and drove our medicinal chemistry effort toward the discovery of low efficacy (fold shift) PAMs devoid of agonist activity. This work resulted in the identification of dipyridyl 22 (BMS-952048), a compound with a favorable free fraction, efficacy in a rodent-based cognition model, and low potential for convulsions in mouse.

Hippocampal place cell and inhibitory neuron activity in disrupted-in-schizophrenia-1 mutant mice: implications for working memory deficits

Background:

Despite the prevalence of working memory deficits in schizophrenia, the neuronal mechanisms mediating these deficits are not fully understood. Importantly, deficits in spatial working memory are identified in numerous mouse models that exhibit schizophrenia-like endophenotypes. The hippocampus is one of the major brain regions that actively encodes spatial location, possessing pyramidal neurons, commonly referred to as ‘place cells’, that fire in a location-specific manner. This study tests the hypothesis that mice with a schizophrenia-like endophenotype exhibit impaired encoding of spatial location in the hippocampus.

Aims:

To characterize hippocampal place cell activity in mice that exhibit a schizophrenia-like endophenotype.

Methods:

We recorded CA1 place cell activity in six control mice and six mice that carry a point mutation in the disrupted-in-schizophrenia-1 gene (Disc1-L100P) and have previously been shown to exhibit deficits in spatial working memory.

Results:

The spatial specificity and stability of Disc1-L100P place cells were similar to wild-type place cells. Importantly, however, Disc1-L100P place cells exhibited a higher propensity to increase their firing rate in a single, large location of the environment, rather than multiple smaller locations, indicating a generalization in their spatial selectivity. Alterations in the signaling and numbers of CA1 putative inhibitory interneurons and decreased hippocampal theta (5–12 Hz) power were also identified in the Disc1-L100P mice.

Conclusions:

The generalized spatial selectivity of Disc1-L100P place cells suggests a simplification of the ensemble place codes that encode individual locations and subserve spatial working memory. Moreover, these results suggest that deficient working memory in schizophrenia results from an impaired ability to uniquely code the individual components of a memory sequence.

Supplementary information

The online version of this article (doi:10.1038/npjschz.2015.11) contains supplementary material, which is available to authorized users.

Place cells that encode spatial information in the hippocampus in the brain have abnormal activity in a mouse model of schizophrenia. Researchers led by Lia Mesbah-Oskui at the University of Toronto, Canada, measured the activity of place cells in healthy mice and in mice that have a mutation in the Disrupted-in-schizophrenia-1 gene; this gene has previously been associated with schizophrenia, and the mutant mice exhibit similar cognitive impairments to those observed in patients with schizophrenia. Although place cells showed normal, location-specific increases in activity in mutant mice, each cell was less selective about the locations to which it responded. Consequently, the ensembles of place cells that normally encode specific locations were simpler and less unique. This impairment might underlie spatial memory deficits that are observed in people with schizophrenia.

Placebo response in antipsychotic clinical trials: a meta-analysis

IMPORTANCE

Because increasing placebo response rates decrease drug-placebo differences and increase the number of failed trials, it is imperative to determine what is causing this trend.

OBJECTIVES

To investigate the relationship between antipsychotic medication and placebo response by publication year, and to identify associated study design and implementation variables.

DATA SOURCES

MEDLINE, PsycINFO, and PubMed were searched to identify randomized clinical trials of antipsychotic medications published from 1960 to July 2013.

STUDY SELECTION

Included were randomized clinical trials lasting 4 to 24 weeks, contrasting antipsychotic medication with placebo or an active comparator, and enrolling patients 18 years of age or older with schizophrenia or schizoaffective disorder.

DATA EXTRACTION AND SYNTHESIS

Standardized mean change scores were calculated for each treatment arm, plotted against publication year, and tested with Spearman rank correlation coefficients. Hierarchical linear modeling identified factors associated with the standardized mean change across medication and placebo treatment arms.

MAIN OUTCOMES AND MEASURES

We hypothesized that the mean change in placebo-treated patients would significantly increase from 1960 to the present, that a greater change would be observed in active comparator vs placebo-controlled trials, and that more protocol visits would increase the symptom change observed.

RESULTS

In the 105 trials examined, the mean change observed in placebo arms increased significantly with year of publication (n=39, r=0.52, P=.001), while the mean change in effective dose medication arms decreased significantly (n=208, r=-0.26, P<.001). Significant interactions were found between assignment to effective dose medication and publication year (t260=-5.55, P<.001), baseline severity (t260=5.08, P<.001), and study duration (t260=-3.76, P<.001), indicating that the average drug-placebo difference significantly decreased over time, with decreasing baseline severity and with increasing study duration. Medication treatment in comparator studies was associated with significantly more improvement than medication treatment in placebo-controlled trials (t93=2.73, P=.008).

CONCLUSIONS AND RELEVANCE

The average treatment change associated with placebo treatment in antipsychotic trials increased since 1960, while the change associated with medication treatment decreased. Changes in randomized clinical trials leading to inflation of baseline scores, enrollment of less severely ill participants, and higher expectations of patients may all be responsible.

Potential enhancing effects of histamine H₁ agonism/H₃ antagonism on working memory assessed by performance and bold response in healthy volunteers

BACKGROUND AND PURPOSE

Schizophrenia is a highly debilitating disorder characterized by hallucinations and delusions, but also impaired cognition such as memory. While hallucinations and delusions are the main target for pharmacological treatment, cognitive impairments are rarely treated. Evidence exists that histamine has a role in the cognitive deficits in schizophrenia, which could be the basis of the development of a histamine-type treatment. Histamine H₃ antagonists have been shown to improve memory performance in experimental animals, but these effects have been little investigated in humans within the context of impaired cognition in schizophrenia and using sensitive measures of brain activity. In the present study, the effects of betahistine (H₃ antagonist/H₁ agonist) on learning and memory, and associated brain activity were assessed.

EXPERIMENTAL APPROACH

Sixteen healthy volunteers (eight female) aged between 18 and 50 years received two p.o. doses of betahistine (48 mg) or placebo separated by 30 min, on separate days according to a two-way, double-blind, crossover design. Volunteers performed an N-back working memory task and a spatial paired associates learning task while being scanned using a MRI scanner.

KEY RESULTS

Task-related activity changes in well-defined networks and performance were observed. No betahistine-induced changes in brain activity were found in these networks. Alternatively, liberal whole-brain analyses showed activity changes in areas outside task networks, like the lateral geniculate nucleus.

CONCLUSIONS AND IMPLICATIONS

Clear effects of betahistine on working memory could not be established. Future studies should use higher doses and explore the role of histamine in visual information processing.

Benefits and limits of anticholinergic use in schizophrenia: focusing on its effect on cognitive function

All currently available antipsychotic drugs are the dopamine D2 receptor antagonists and are capable of producing extrapyramidal side-effects (EPS). Anticholinergic drugs are primarily used to treat EPS or prevent EPS induced by antipsychotics in the treatment of psychosis and schizophrenia. However, they can cause a variety of distressing peripheral side-effects (e.g. dry mouth, urinary disturbances, and constipation) and central adverse effects (e.g. cognitive impairment, worsening of tardive dyskinesia, and delirium). Disturbances in cognitive abilities are cardinal features of schizophrenia from its earliest phases and account for much of the functional disability associated with the illness. It is likely that long-term concomitant administration of anticholinergics exacerbates the underlying cognitive impairment in patients with schizophrenia and subsequently affects patients' quality of life. Thus, current treatment guidelines for schizophrenia generally do not recommend the prophylactic and long-term use of anticholinergics. However, the high use of long-term anticholinergic drugs with antipsychotics has been identified as an important issue in the treatment of schizophrenia in several countries. To assess the benefits and limits of anticholinergic use in psychosis and schizophrenia, this article will provide a brief review of the pharmacology and clinical profiles of anticholinergic drugs and will focus on their effects on cognitive function in schizophrenia, particularly during the course of the early phase of the illness. In addition, we will address the effects of discontinuation of anticholinergics on cognitive function in patients with schizophrenia and provide a strategy for adjunctive anticholinergic use in patients treated with long-acting injectable antipsychotics.

Antipsychotic treatments; focus on lurasidone

The introduction of atypical antipsychotic drugs (AAPDs), or second-generation antipsychotics, with clozapine as the prototype, has largely changed the clinicians' attitudes toward the treatment of mental illnesses including, but not limited to schizophrenia. Initially, there was optimism that AAPDs would be superior over typical antipsychotic drugs (TAPDs), or first-generation antipsychotic drugs, in terms of efficacy in various phenomenological aspects, including cognitive impairment, and less likelihood of causing adverse events. However, these views have been partly challenged by results from recent meta-analysis studies. Specifically, cardio-metabolic side effects of AAPDs, in spite of a relative paucity of extrapyramidal symptoms, may sometimes limit the use of these agents. Accordingly, attempts have been made to develop newer compounds, e.g., lurasidone, with the aim of increasing efficacy and tolerability. Further investigations are warranted to determine if a larger proportion of patients will be benefitted by treatment with AAPDs compared to TAPDs in terms of remission and recovery.

Reduction of cortical GABAergic inhibition correlates with working memory impairment in recent onset schizophrenia

BACKGROUND

Cognitive impairments are present during the early course of schizophrenia, and the contribution of GABAergic dysfunction to these cognitive impairments has received increasing attention. Cortical GABAergic inhibition can be assessed using short-interval intracortical inhibition (SICI) in a paired-pulse transcranial magnetic stimulation (ppTMS). The aim of this study was to examine the relationship between cortical GABAergic inhibition and cognitive function in recent onset schizophrenia patients using ppTMS and a neuropsychological battery.

METHODS

The subjects were 20 healthy controls (HC group) and 20 patients with schizophrenia whose duration of illness was less than three years (SZ group). All subjects underwent ppTMS measurements of SICI and intracortical facilitation (ICF), and cognitive performance of the SZ group was assessed using the Brief Assessment of Cognition in Schizophrenia Japanese-language version. We examined group differences in ppTMS measurements (resting motor threshold, SICI, and ICF). In the SZ group, we assessed the relationship between SICI and cognitive performance, and the relationships between SICI and age, duration of illness, medications, and psychopathology.

RESULTS

The SZ group showed a significant reduction of SICI compared to the HC group, and demonstrated a significant correlation between the reduction of SICI and impaired performance of a working memory task. The HC and the SZ groups did not differ significantly in resting motor threshold and ICF. The SZ group did not show any significant correlations between SICI and age, duration of illness, medications, or psychopathology.

CONCLUSIONS

Our results suggest that the reduction of cortical GABAergic inhibition is related to impairment of working memory in patients with recent onset schizophrenia.

Serotonergic hallucinogens differentially modify gamma and high frequency oscillations in the rat nucleus accumbens

RATIONALE

The nucleus accumbens (NAc) is a site critical for the actions of many drugs of abuse. Psychoactive compounds, such as N-methyl-D-aspartate receptor (NMDAR) antagonists, modify gamma (40-90) and high frequency oscillations (HFO, 130-180 Hz) in local field potentials (LFPs) recorded in the NAc. Lysergic acid diethylamide (LSD) and 2,5-dimethoxy-4-iodoamphetamine (DOI) are serotonergic hallucinogens and activation of 5HT2A receptors likely underlies their hallucinogenic effects. Whether these compounds can also modulate LFP oscillations in the NAc is unclear.

OBJECTIVE

This study aims to examine the effect of serotonergic hallucinogens on gamma and HFO recorded in the NAc and to test whether 5HT2A receptors mediate the effects observed.

METHODS

LFPs were recorded from the NAc of freely moving rats. Drugs were administered intraperitoneally.

RESULTS

LSD (0.03-0.3 mg/kg) and DOI (0.5-2.0 mg/kg) increased the power and reduced the frequency of HFO. In contrast, the hallucinogens produced a robust reduction in the power of low (40-60 Hz), but not high gamma oscillations (70-90 Hz). MDL 11939 (1.0 mg/kg), a 5HT2A receptor antagonist, fully reversed the changes induced by DOI on HFO but only partially for the low gamma band. Equivalent increases in HFO power were observed after TCB-2 (5HT2A receptor agonist, 0.1-1.5 mg/kg), but not CP 809101 (5H2C receptor agonist, 0.1-3 mg/kg). Notably, hallucinogen-induced increases in HFO power were smaller than those produced by ketamine (25 mg/kg).

CONCLUSIONS

Serotonergic hallucinogen-induced changes in HFO and gamma are mediated, at least in part, by stimulation of 5HT2A receptors. Comparison of the oscillatory changes produced by serotonergic hallucinogens and NMDAR antagonists are also discussed.

Effects of antipsychotics on dentate gyrus stem cell proliferation and survival in animal models: a critical update

Schizophrenia is a complex psychiatric disorder. Although a number of different hypotheses have been developed to explain its aetiopathogenesis, we are far from understanding it. There is clinical and experimental evidence indicating that neurodevelopmental factors play a major role. Disturbances in neurodevelopment might result in alterations of neuroanatomy and neurochemistry, leading to the typical symptoms observed in schizophrenia. The present paper will critically address the neurodevelopmental models underlying schizophrenia by discussing the effects of typical and atypical antipsychotics in animal models. We will specifically discuss the vitamin D deficiency model, the poly I:C model, the ketamine model, and the postnatal ventral hippocampal lesion model, all of which reflect core neurodevelopmental issues underlying schizophrenia onset.

Novel allosteric agonists of M1 muscarinic acetylcholine receptors induce brain region-specific responses that correspond with behavioral effects in animal models

M(1) muscarinic acetylcholine receptors (mAChRs) represent a viable target for treatment of multiple disorders of the central nervous system (CNS) including Alzheimer's disease and schizophrenia. The recent discovery of highly selective allosteric agonists of M(1) receptors has provided a major breakthrough in developing a viable approach for the discovery of novel therapeutic agents that target these receptors. Here we describe the characterization of two novel M(1) allosteric agonists, VU0357017 and VU0364572, that display profound differences in their efficacy in activating M(1) coupling to different signaling pathways including Ca(2+) and β-arrestin responses. Interestingly, the ability of these agents to differentially activate coupling of M(1) to specific signaling pathways leads to selective actions on some but not all M(1)-mediated responses in brain circuits. These novel M(1) allosteric agonists induced robust electrophysiological effects in rat hippocampal slices, but showed lower efficacy in striatum and no measureable effects on M(1)-mediated responses in medial prefrontal cortical pyramidal cells in mice. Consistent with these actions, both M(1) agonists enhanced acquisition of hippocampal-dependent cognitive function but did not reverse amphetamine-induced hyperlocomotion in rats. Together, these data reveal that M(1) allosteric agonists can differentially regulate coupling of M(1) to different signaling pathways, and this can dramatically alter the actions of these compounds on specific brain circuits important for learning and memory and psychosis.

Hippocampal shape and volume changes with antipsychotics in early stage psychotic illness

Progression of hippocampal shape and volume abnormalities has been described in psychotic disorders such as schizophrenia. However it is unclear how specific antipsychotic medications influence the development of hippocampal structure. We conducted a longitudinal, randomized, controlled, multisite, double-blind study involving 14 academic medical centers (United States 11, Canada 1, Netherlands 1, and England 1). One hundred thirty-four first-episode psychosis patients (receiving either haloperidol [HAL] or olanzapine [OLZ]) and 51 healthy controls were followed for up to 104 weeks using magnetic resonance imaging and large-deformation high-dimensional brain mapping of the hippocampus. Changes in hippocampal volume and shape metrics (i.e., percentage of negative surface vertex slopes, and surface deformation) were evaluated. Mixed-models analysis did not show a significant group-by-time interaction for hippocampal volume. However, the cumulative distribution function of hippocampal surface vertex slopes showed a notable left shift with HAL treatment compared to OLZ treatment and to controls. OLZ treatment was associated with a significantly lower percentage of "large magnitude" negative surface vertex slopes compared to HAL treatment (p = 0.004). Surface deformation maps however did not localize any hippocampal regions that differentially contracted over time with OLZ treatment, after FDR correction. These results indicate that surface analysis provides supplementary information to volumetry in detecting differential treatment effects of the hippocampus. Our results suggest that OLZ is associated with less longitudinal hippocampal surface deformation than HAL, however the hippocampal regions affected appear to be variable across patients.

Comparative pharmacology of antipsychotics possessing combined dopamine D2 and serotonin 5-HT1A receptor properties

RATIONALE

There is increasing interest in antipsychotics intended to manage positive symptoms via D(2) receptor blockade and improve negative symptoms and cognitive deficits via 5-HT(1A) activation. Such a strategy reduces side-effects such as the extrapyramidal syndrome (EPS), weight gain, and autonomic disturbance liability.

OBJECTIVE

This study aims to review pharmacological literature on compounds interacting at both 5-HT(1A) and D(2) receptors (as well as at other receptors), including aripiprazole, perospirone, ziprasidone, bifeprunox, lurasidone and cariprazine, PF-217830, adoprazine, SSR181507, and F15063.

METHODS

We examine data on in vitro binding and agonism and in vivo tests related to (1) positive symptoms (e.g., psychostimulant-induced hyperactivity or prepulse inhibition deficit), (2) negative symptoms (e.g., phencyclidine-induced social interaction deficits and cortical dopamine release), and (3) cognitive deficits (e.g., phencyclidine or scopolamine-induced memory deficits). EPS liability is assessed by measuring catalepsy and neuroendocrine impact by determining plasma prolactin, glucose, and corticosterone levels.

RESULTS

Compounds possessing "balanced" 5-HT(1A) receptor agonism and D(2) antagonism (or weak partial agonism) and, in some cases, combined with other beneficial properties, such as 5-HT(2A) receptor antagonism, are efficacious in a broad range of rodent pharmacological models yet have a lower propensity to elicit EPS or metabolic dysfunction.

CONCLUSIONS

Recent compounds exhibiting combined 5-HT(1A)/D(2) properties may be effective in treating a broader range of symptoms of schizophrenia and be better tolerated than existing antipsychotics. Nevertheless, further investigations are necessary to evaluate recent compounds, notably in view of their differing levels of 5-HT(1A) affinity and efficacy, which can markedly influence activity and side-effect profiles.

Receptor screening technologies in the evaluation of Amazonian ethnomedicines with potential applications to cognitive deficits

ETHNOPHARMACOLOGICAL RELEVANCE

Amazonian peoples utilize a variety of psychoactive plants that may contain novel biologically active compounds. Efforts to investigate such remedies in terms of neuropharmacology have been limited.

AIM OF THIS STUDY

This study identified Amazonian ethnomedicines with potential for the treatment of cognitive deficits in schizophrenia and dementias, and characterized their interactions with CNS neurotransmitter receptors in vitro.

MATERIALS AND METHODS

Approximately 300 Amazonian species with folk uses or constituents indicative of central nervous system activity were incorporated into a database constructed from literature searches, herbarium surveys, and interviews with traditional practitioners. Approximately 130 of these targeted species were collected in Loreto province, Peru, and 228 fractions derived from them were screened in 31 radioreceptor assays via the resources of the NIMH Psychoactive Drug Screening Program. A subset was also screened in functional assays at selected serotonin, muscarinic, and adrenergic receptors.

RESULTS

Ninety-one samples displayed ≥60% inhibition of radioligand binding activity in receptor assays; 135 samples displayed agonist or antagonist activity (or both) in functional assays.

CONCLUSIONS

Potential CNS activity was detected in about 40% of the samples screened, with some correlations to both folk uses and phytochemical constituents. These results may point to novel and potentially therapeutic CNS active compounds.

An unblinded comparison of the clinical and cognitive effects of switching from first-generation antipsychotics to aripiprazole, perospirone or olanzapine in patients with chronic schizophrenia

The objective of this study, the effect of aripiprazole on clinical symptoms and cognitive function in patients with chronic schizophrenia was compared to that of perospirone and olanzapine. The subjects were 31 patients, they were diagnosed with schizophrenia on the basis of the criteria of the DSM-IV. Clinical symptoms were assessed using Brief Psychiatric Rating Scale (BPRS), and cognitive function was assessed using the Wisconsin Card Sorting Test (Keio Version: KWCST) and the St. Marianna University School of Medicine's Computerized Memory Test (STM-COMET) as executive function and memory/attention function tests at baseline and 8 weeks after switching. As a result, comparison of the BPRS mean total score revealed no significant difference between aripiprazole and the other medications. Aripiprazole resulted in significant changes in the number of categories achieved (CA) and difficulty maintaining set (DMS) compared to olanzapine at the second level of the KWCST. Comparison thus revealed no difference in clinical effect between aripiprazole and the other medications, but might suggest possible differences between aripiprazole and olanzapine in the profiles of the improvement effects on executive function, memory, and attention function.

Auditory and visual P300 reflecting cognitive improvement in patients with schizophrenia with quetiapine: a pilot study

We recorded event-related potentials (ERPs) in patients with schizophrenia before and after treatment with quetiapine, to investigate this drug's effects on cognitive function. Auditory and visual oddball stimulus discrimination paradigms were presented to patients with schizophrenia (N=20) before and after 3months' treatment with quetiapine. The 2-stimulus auditory oddball paradigm used a standard tone (1000Hz, 75dB, 80%) and a target tone (2000Hz, 75dB, 20%). The 2-stimulus visual oddball paradigm used a standard stimulus (small circle, 80%) and a target stimulus (large circle, 20%). Patients' severity of psychopathology was initially evaluated with the Positive and Negative Syndrome Scale (PANSS) and was likewise re-evaluated after treatment. After treatment with quetiapine, patients' P300 amplitudes increased over baseline for both tasks (auditory stimuli, P<0.01; visual stimuli, P<0.01) and their P300 latencies for both target stimuli decreased significantly (auditory stimuli, P<0.001; visual stimuli, P<0.01). Visual P300 amplitude was negatively correlated with the severity of positive symptoms at the Fz electrode before the treatment (r=-0.45, P<0.05). After treatment with quetiapine, there were no significant correlations between severity of positive or negative symptoms and visual P300 amplitudes for midline electrodes. These findings suggest that the reduced and delayed P300 may be a state marker for schizophrenia, which may in turn be modulated by positive symptoms, and also suggest that the amplitude and latency for both auditory and visual tasks may be decreased by quetiapine treatment. Based on these results, we suggest that the atypical antipsychotic quetiapine may improve some aspects of cognitive domains in patients with schizophrenia.

The relationship between prepulse inhibition and general psychopathology in patients with schizophrenia treated with long-acting risperidone

Patients with schizophrenia exhibit impairments in prepulse inhibition (PPI) of the startle response. Available data suggest that atypical antipsychotics may be more effective than typical antipsychotics in improving PPI deficits in schizophrenia. However, previous studies have used between-subjects rather than longitudinal within-subjects designs to demonstrate superiority of particular atypical antipsychotics over typical antipsychotics in improving PPI in patients with schizophrenia. This longitudinal within-subjects test-retest study was designed to evaluate changes in PPI and clinical symptoms in patients with schizophrenia after switching from the conventional antipsychotic zuclopenthixol to long-acting injectable risperidone. PPI was measured in 45 chronic male patients with schizophrenia treated with zuclophentixol depot (session T1), and 12 weeks after switching to long-acting injectable risperidone (session T2). Thirty-six healthy control subjects were also evaluated. Patients with schizophrenia showed a significant improvement in PPI after changing to long-acting risperidone. Improvement of PPI deficits between T1 and T2 assessments correlated significantly with improvements in PANSS general psychopathology subscale scores. Our findings indicate that long-acting risperidone improves PPI deficits in subjects with chronic schizophrenia. These results also suggest that the PPI-restoring effect of risperidone may be related to improvement in symptoms other than positive and negative symptoms.

Repeated low dose of phencyclidine administration impairs spatial learning in mice: blockade by clozapine but not by haloperidol

The effect of phencyclidine (PCP), a non-competitive N-methyl-d-aspartate (NMDA) receptor antagonist, was examined in the water maze, a spatial learning and memory task dependent on hippocampal functions. Male adult C57Bl/6J mice received daily (s.c.) injections of either saline or PCP (0.25-4.0 mg/kg) for 12 days. During the last 5 days, the injections were followed by water maze training. Repeated PCP treatments disrupted spatial learning and memory in the 0.5-4.0 mg/kg dose range. Severe sensorimotor disturbances, observed at the 2.0 and 4.0 mg/kg doses of PCP, precluded further swim maze testing. The 0.5 mg/kg but not the 1.0 mg/kg dose of PCP impaired spatial learning and memory without any apparent sensorimotor deficits. PCP, at 1.0 mg/kg, produced impairment in non-spatial learning in the swim maze task and motor disturbances in the rotarod test. Repeated daily treatment with either the "atypical" antipsychotic drug clozapine (0.5 mg/kg i.p.) or the "typical" antipsychotic drug haloperidol (0.05 mg/kg i.p.) failed to influence spatial performances. The spatial impairment caused by the 0.5 mg/kg dose of PCP was blocked by concomitant treatment with clozapine (0.5 mg/kg), but not with haloperidol (0.05 mg/kg). The results suggest that it is possible, at low doses of PCP, to dissociate the spatial learning impairment in the water maze from the adverse behavioral effects of NMDA receptor blockade. This model may provide a basis for the analysis of the mechanisms underlying declarative memory disturbances in schizophrenia and the differences in mechanisms between typical and atypical antipsychotic drugs.

Agonist and antagonist properties of antipsychotics at human dopamine D4.4 receptors: G-protein activation and K+ channel modulation in transfected cells

Interaction at dopamine D4 receptors may improve cognitive function, which is highly impaired in individuals with schizophrenia, but comparative studies of recent antipsychotics in cellular models of D4 receptor activation are lacking. Here, we report the in-vitro profile of over 30 ligands at recombinant hD4.4 receptors. In [35S]GTPgammaS binding experiments using membranes of CHO-hD4.4 cells, apomorphine, preclamol and the selective D4 agonists, ABT724, CP226269, Ro-10-5824 and PD168077, behaved as partial agonists (Emax 20-60% vs. dopamine), whereas L745870 and RBI257, displayed antagonist properties. The 'conventional' antipsychotic, haloperidol and the 'atypicals', clozapine and risperidone, exhibited antagonist properties, while 'third generation' compounds bifeprunox, SLV313 and F15063, acted as partial agonists (10-30%). Aripiprazole and SSR181507 slightly stimulated [35S]GTPgammaS binding at micromolar concentrations. In Xenopus laevis oocytes co-expressing hD4.4 receptors with G-protein-coupled inwardly rectifying potassium (GIRK) channels, apomorphine, preclamol, ABT724, CP226269, and PD168077 stimulated GIRK currents (Emax 70-80%). The 5-HT1A receptor ligands, WAY100635 and flibanserin, also exhibited partial agonist activity (30% and 15%, respectively). Haloperidol, clozapine, olanzapine and nemonapride did not stimulate GIRK currents, whereas aripiprazole, bifeprunox, SLV313 and F15063, but not SSR181507, exhibited partial agonism (Emax 20-35%). In-vitro responses depended on experimental conditions: increasing NaCl concentration (30 mm to 100 mm) reduced agonist efficacy in [35S]GTPgammaS binding, whereas decreasing the amount of hD4.4 cRNA injected into oocytes (from 2.0 to 0.5 ng/oocyte) reduced agonist efficacy of several compounds. These data indicate that, unlike conventional or 'atypical' antipsychotics, several 'third generation' agents display D4 receptor partial agonism that may be sufficient to influence physiological D4 receptor activity in vivo.

Dopamine depletion of the prefrontal cortex induces dendritic spine loss: reversal by atypical antipsychotic drug treatment

Dystrophic changes in dendrites of cortical neurons are present in several neuro-psychiatric disorders, including schizophrenia. The mechanisms that account for dendritic changes in the prefrontal cortex (PFC) in schizophrenia are unclear. Cognitive deficits in schizophrenia have been linked to compromised cortical dopamine function, and the density of the PFC dopamine innervation is decreased in schizophrenia. We determined if 6-hydroxydopamine lesions of the ventral tegmental area that disrupt the PFC dopamine innervation cause dystrophic changes in cortical neurons. Three weeks post-operatively we observed a marked decrease in basal dendritic length and spine density of layer V pyramidal cells in the prelimbic cortex; no change was seen in neurons of the motor cortex. We then examined rats in which the PFC dopamine innervation was lesioned and 3 weeks later were started on chronic treatment with an atypical (olanzapine) or typical (haloperidol) antipsychotic drug. Olanzapine but not haloperidol reversed lesion-induced changes in PFC pyramidal cell dendrites. These data suggest that dopamine regulates dendritic structure in PFC neurons. Moreover, the findings are consistent with a decrease in cortical dopaminergic tone contributing to the pathological changes in the cortex of schizophrenia, and suggest that the progressive cortical loss in schizophrenia may be slowed or reversed by treatment with atypical antipsychotic drugs.

Electrophysiological basis for the ability of olanzapine to improve verbal memory and functional outcome in patients with schizophrenia: a LORETA analysis of P300

Abnormality of P300 waveforms of event-related potentials (ERPs) has been suggested to represent an aspect of the pathophysiology of schizophrenia. Previous work points to the contribution of altered neural function in discrete brain regions in the left hemisphere to psychotic symptoms and cognitive deficits of schizophrenia. In this study, we sought to determine: 1) if patients with schizophrenia elicit a decreased P300 current source density in brain areas, such as the superior temporal gyrus (STG); 2) if decreased P300 generator density in the left STG is recovered by treatment with the most widely-used antipsychotic drug olanzapine; and 3) if the recovery of P300 source density is associated with improvements of cognitive and functional status. P300 in response to an auditory oddball task, as well as verbal learning memory, psychopathology, and quality of life were evaluated in 16 right-handed patients with schizophrenia before and after treatment with olanzapine for 6 months. ERP data were also obtained from 16 right-handed age and gender-matched normal volunteers. Low resolution electromagnetic tomography (LORETA) analysis was used to obtain current density images of P300. Patients with schizophrenia showed significantly smaller LORETA values in several brain regions in the left side, particularly STG, middle frontal gyrus, and precentral gyrus, compared with control subjects. Six-month treatment with olanzapine significantly increased P300 source density only in the left STG. Positive symptoms, negative symptoms, verbal learning memory, and quality of life were also improved during treatment. Significant correlations were found between the increase in LORETA values of left STG vs. improvements of negative symptoms, as measured by Scale for the Assessment of the Negative Symptoms, and verbal learning memory, as measured by the Japanese Verbal Learning Test. Improvement of quality of life, as evaluated by the Quality of Life Scale, were significantly associated with an increase in LORETA values of middle frontal gyrus, and tended to correlate with that of precentral gyrus. The results of this study suggest that changes in cortical activity, as measured by ERPs, are responsible for the ability of some antipsychotic drugs to improve cognition and functional outcome in patients with schizophrenia.

Olanzapine-induced weight gain: chronic infusion using osmotic minipumps does not result in stable plasma levels due to degradation of olanzapine in solution

The mechanisms underlying olanzapine-induced weight gain have not yet been fully elucidated. To examine the effects of long-term treatment with olanzapine on different aspects of energy balance, we administered olanzapine to male rats. Osmotic minipumps were chosen as preferred mode of administration because the half-life of olanzapine is only 2(1/2) h in rats compared to 30 h in humans. We discovered that, within one week, degradation of olanzapine occurred in the solution used to fill the minipump reservoir. This resulted in a decrease in delivered olanzapine and declining plasma levels over the course of the experiment. Therefore, we caution other researchers for the limitations of using osmotic minipumps to administer olanzapine for longer periods of time.

F15063, a potential antipsychotic with D2/D3 antagonist, 5-HT 1A agonist and D4 partial agonist properties. I. In vitro receptor affinity and efficacy profile

BACKGROUND AND PURPOSE

Combining 5-HT(1A) receptor activation with dopamine D(2)/D(3) receptor blockade should improve negative symptoms and cognitive deficits in schizophrenia. We describe the in vitro profile of F15063 (N-[(2,2-dimethyl-2,3-dihydro-benzofuran-7-yloxy)ethyl]-3-(cyclopent-1-enyl)-benzylamine).

EXPERIMENTAL APPROACH

F15063 was characterised in tests of binding affinity and in cellular models of signal transduction at monoamine receptors.

KEY RESULTS

Affinities (receptor and pK(i) values) of F15063 were: rD(2) 9.38; hD(2L) 9.44; hD(2S) 9.25; hD(3) 8.95; hD(4) 8.81; h5-HT(1A) 8.37. F15063 had little affinity (40-fold lower than D(2)) at other targets. F15063 antagonised dopamine-activated G-protein activation at hD(2), rD(2) and hD(3) receptors with potency (pK (b) values 9.19, 8.29 and 8.74 in [(35)S]GTP gamma S binding experiments) similar to haloperidol. F15063 did not exhibit any hD(2) receptor agonism, even in tests of ERK1/2 phosphorylation and G-protein activation in cells with high receptor expression. In contrast, like (+/-)8-OH-DPAT, F15063 efficaciously activated h5-HT(1A) (E(max) 70%, pEC(50) 7.57) and r5-HT(1A) receptors (52%, 7.95) in tests of [(35)S]GTP gamma S binding, cAMP accumulation (90%, 7.12) and ERK1/2 phosphorylation (93%, 7.13). F15063 acted as a partial agonist for [(35)S]GTP gamma S binding at hD(4) (29%, 8.15) and h5-HT(1D) receptors (35%, 7.68). In [(35)S]GTP gamma S autoradiography, F15063 activated G-proteins in hippocampus, cortex and septum (regions enriched in 5-HT(1A) receptors), but antagonised quinelorane-induced activation of D(2)/D(3) receptors in striatum.

CONCLUSIONS AND IMPLICATIONS

F15063 antagonised dopamine D(2)/D(3) receptors, a property underlying its antipsychotic-like activity, whereas activation of 5-HT(1A) and D(4) receptors mediated its actions in models of negative symptoms and cognitive deficits of schizophrenia (see companion papers).

Olanzapine increases RGS7 protein expression via stimulation of the Janus tyrosine kinase-signal transducer and activator of transcription signaling cascade

Atypical antipsychotics such as olanzapine have high affinity for multiple monoamine neurotransmitter receptors and are the mainstay of pharmacological therapy for treatment of schizophrenia. In addition to blocking monoamine receptors, these drugs also affect intracellular signaling cascades. We now report that 24-h treatment with 300 nM olanzapine causes desensitization of serotonin (5-HT)(2A) receptors in A1A1v cells, a rat cortical cell line, as indicated by a reduction in inositol phosphate accumulation following stimulation with a 5-HT(2A/2C) receptor agonist (-)-1-(2,5-dimethoxy-4-lodophenyl)-2-aminopropane HCl. Olanzapine treatment for 24 h increased the levels of 5-HT(2A) receptors in both cytosol (234 +/- 34% of control level) and membrane fractions (206 +/- 14% of control levels) and RGS7 proteins in both cytosol (193 +/- 32% of control levels) and membrane fractions (160 +/- 18% of control levels) as measured on Western blots. Increased phosphorylation of Janus tyrosine kinase (JAK) 2 and increased phosphorylation and nuclear translocation of signal transducer and activator of transcription (STAT) 3 with 24-h olanzapine treatment demonstrate activation of the JAK-STAT signaling cascade. Pretreatment with a JAK inhibitor, AG490 [alpha-cyano-(3,4-dihydroxy)-N-benzylcinnamide], prevented the olanzapine-induced increase in membrane RGS7 protein levels; AG490 alone had no effect on RGS7 protein levels. We verified that treatment with AG490 reduced phosphorylation of JAK2 and inhibited the nuclear localization of phospho-STAT3. Interestingly, treatment with the JAK inhibitor had no effect on 5-HT(2A) receptor protein levels. These data suggest that olanzapine-induced activation of the JAK-STAT signaling cascade causes increased expression of RGS7 protein, which in turn could mediate desensitization of 5-HT(2A) receptor signaling caused by olanzapine because RGS7 binds to Galpha(q) protein and accelerates GTP hydrolysis.

Antipsychotic clozapine inhibits the function of alpha7-nicotinic acetylcholine receptors

The effects of the antipsychotic clozapine on the function of the cloned alpha(7) subunit of the nicotinic acetylcholine (nACh) receptor expressed in Xenopus oocytes was investigated by using the two-electrode voltage-clamp technique. Clozapine reversibly inhibited nicotine (10 microM)-induced currents in a concentration-dependent manner (300 nM to 90 microM), with an IC(50) value of 3.2+/-0.4 microM. The effect of clozapine was not dependent on the membrane potential. Clozapine did not affect the activity of endogenous Ca(2+)-dependent Cl(-) channels since the inhibition by clozapine was unaltered by the intracellularly injected Ca(2+) chelator BAPTA and perfusion with Ca(2+)-free bathing solution containing 2mM Ba(2+). Clozapine decreased the maximal nicotine-induced responses without significantly affecting its potency, indicating that it acts as a noncompetitive antagonist on alpha(7)-nACh receptors. In hippocampal slices, the whole-cell recordings from CA1 pyramidal neurons indicated that the increases in the frequency and amplitudes of the GABA-mediated spontaneous inhibitory postsynaptic currents induced by bath application of 2 mM choline, a specific agonist for alpha(7)-nACh receptors, were abolished after 10 min application of 5 microM clozapine. In conclusion, these results demonstrate that clozapine inhibits the function of alpha(7)-nACh receptors expressed in Xenopus oocytes and in hippocampal neurons.

Measuring changes in functional status among patients with schizophrenia: the link with cognitive impairment

Cognitive impairment associated with schizophrenia (CIAS) includes neuropsychological deficits in attention, working memory, verbal learning, and problem solving. These deficits have been shown to be linked to impairment in functional status (eg, social behavior, work performance, and activities of daily living) among patients with schizophrenia in cross-sectional studies. Less is known about the relationship between cognitive and functional change over time, such as potential functional implications of treatment-related improvement in CIAS. The purpose of this review is to summarize research on the association between change in CIAS and change in functional status, to discuss responsiveness of functional outcomes measures, and to provide recommendations for future research and measure development. Nine longitudinal studies were located on the link between CIAS and functional status, and 8 functional outcomes measures were used across these studies. The 9 studies offer initial support for a link between change in cognitive function and change in functional status. However, inconsistent findings across studies indicate that available research is preliminary, and substantial questions remain unanswered. Shortcomings of functional status measures are noted: most instruments were not developed for the target population, and none have demonstrated responsiveness to cognitive change among schizophrenic patients. It is recommended that new functional outcome measures be developed that are specifically designed to be responsive to change in cognition, with domains previously shown to be related to cognitive ability. When creating new functional outcomes measures for assessment of patients with schizophrenia, responsiveness to change in CIAS should be evaluated as part of the development and validation process.

Analysis of sensitivity to MK-801 treatment in a novel active allothetic place avoidance task and in the working memory version of the Morris water maze reveals differences between Long-Evans and Wistar rats

The aims of the present study were to compare the effect of subchronic administration of MK-801 on performance in the active allothetic place avoidance (AAPA) task and in the working version of Morris water maze (MWM) in Long-Evans and Wistar rats. Animals were trained for four daily sessions either in the AAPA or in the working memory version of the MWM. Wistar rats treated by MK-801 (0.1 mg/kg) showed a cognitive deficit in the AAPA task without a significant hyperlocomotion, whereas they were not impaired in the working memory version of the MWM compared to controls. Long-Evans rats treated by MK-801 (0.1 mg/kg) were not impaired either in the AAPA task or in the MWM task. Higher doses of MK-801 (0.2 and 0.3 mg/kg) produced hyperlocomotion in both strains which corresponded to an inability to solve both spatial tasks. Long-Evans rats were superior in the MWM to the Wistar rats in the groups treated with the low dose of MK-801. In conclusion, intact Wistar rats can efficiently solve both spatial tasks; however, they are more sensitive to MK-801-induced behavioural deficit. This has relevance for modeling of the schizophrenia-related deficits and for screening substances for their therapeutic potential.

Self-initiated encoding facilitates object working memory in schizophrenia: implications for the etiology of working memory deficit

BACKGROUND

Working memory (WM) deficit is present in a majority of patients with schizophrenia but it is unclear which components of WM are impaired. Past studies suggest that encoding may be compromised. One important determinant of encoding is the deployment of selective attention to the target stimulus. In addition, attention and encoding are modulated by motivational factors. In this study, we investigated the effects of self-initiated encoding (i.e., voluntary attention) on WM.

METHODS

19 patients with schizophrenia and 19 matched control subjects participated in visual WM and control tasks. Encoding was manipulated by asking subjects to select from two face targets and memorize 1) one of the two identical faces (Non-preference condition), 2) one that is marked (Non-choice condition), and 3) one they prefer (Preference condition). WM accuracy for both location (spatial) and identity (object) was measured.

RESULTS

Overall, patients with schizophrenia were less accurate and slower than the control subjects but the deficit was greater for object WM. However, patients were more accurate in object WM when they selected a preferred face as their target during encoding (preference condition) compared with the other two conditions. This effect was not significant for spatial WM.

CONCLUSIONS

These results suggest that voluntary, self-initiated attention may facilitate object encoding especially if the selection of the target involves affective choice, and that attention may play different roles in encoding 'what' versus 'where' in WM. Since encoding affects all forms of memory, these results may have a more general implication for memory.

Pharmacological treatment to augment hole board habituation in prenatal Vitamin D-deficient rats

Neurocognitive impairment has consistently been considered a central and stable feature of schizophrenia. There is much controversy about the effects of neuroleptics on neurocognitive deficits. Thus, further investigations are needed to clarify the pathological substrate of cognitive deficits in schizophrenia as well as to identify pharmacological tools for treatment. Transient prenatal Vitamin D deficiency is considered a developmental model in schizophrenia research. Recently, it was reported that prenatal Vitamin D-depleted rats showed a habituation deficit in the hole board. Here, we tested the effect on hole board habituation of haloperidol (Hal, 0.075 mg/kg, i.p.), risperidone (Ris, 0.2 mg/kg, i.p.) and the mGluR5 agonist CHPG (0.1 mg, i.c.v.) after subchronic treatment. Hal was found to impair habituation in control animals, Ris restored hole board habituation, whereas Hal and CHPG normalised hole board habituation in the deplete animals completely. The results of the study demonstrate that (i) the Vitamin D model might be a valuable tool in the study of neurodevelopmental aspects of schizophrenia, (ii) the model is sensitive in detecting the effect of antipsychotic drugs and (iii) the model appears to be sensitive in differentiating between typical and atypical antipsychotic drug.

Executive function assessment of patients with schizophrenic disorder residual type in olanzapine treatment: an open study

Cognitive deficits are a fundamental feature of the schizophrenic disorder, but the effect of antipsychotic treatment is still debated. The study assesses the effect of olanzapine on neurocognitive functioning and symptomatology of patients with schizophrenic disorder residual type. Executive function evaluation by the Wisconsin card sorting test (WCST) was performed on 39 patients treated with olanzapine (5-20 mg/day); the efficacy of drug in improving symptomatology, safety and quality of life was also evaluated. After 7 months of treatment, the mean number of WCST categories tended to increase. Correct responses increased with a statistically significant change from the baseline. The total and unique errors decreased significantly. At all post-baseline visits a decrease from baseline in the PANSS total, positive and negative scores was seen. The proportion of patients with less severe illness (CGI), increased over the course of the study with a corresponding decrease of patients with more severe illness. The quality of life scores also tended to improve during treatment. The Simpson Angus scale, Barnes-akathisia and abnormal involuntary movement scale scores decreased consistently. The most common treatment emergent drug related adverse events were weight gain, insomnia, agitation and anxiety. Neurocognitive functioning in terms of executive performance and symptomatology improved in people with schizophrenia residual type.

Different effects of typical and atypical antipsychotics on grey matter in first episode psychosis: the AESOP study

Typical antipsychotic drugs act on the dopaminergic system, blocking the dopamine type 2 (D2) receptors. Atypical antipsychotics have lower affinity and occupancy for the dopaminergic receptors, and a high degree of occupancy of the serotoninergic receptors 5-HT2A. Whether these different pharmacological actions produce different effects on brain structure remains unclear. We explored the effects of different types of antipsychotic treatment on brain structure in an epidemiologically based, nonrandomized sample of patients at the first psychotic episode. Subjects were recruited as part of a large epidemiological study (AESOP: aetiology and ethnicity in schizophrenia and other psychoses). We evaluated 22 drug-free patients, 32 on treatment with typical antipsychotics and 30 with atypical antipsychotics. We used high-resolution MRI and voxel-based methods of image analysis. The MRI analysis suggested that both typical and atypical antipsychotics are associated with brain changes. However, typicals seem to affect more extensively the basal ganglia (enlargement of the putamen) and cortical areas (reductions of lobulus paracentralis, anterior cingulate gyrus, superior and medial frontal gyri, superior and middle temporal gyri, insula, and precuneus), while atypical antipsychotics seem particularly associated with enlargement of the thalami. These changes are likely to reflect the effect of antipsychotics on the brain, as there were no differences in duration of illness, total symptoms scores, and length of treatment among the groups. In conclusion, we would like to suggest that even after short-term treatment, typical and atypical antipsychotics may affect brain structure differently.

Amphetamine sensitization impairs cognition and reduces dopamine turnover in primate prefrontal cortex

BACKGROUND

Amphetamine (AMPH) sensitization in monkeys produces long-lasting behavioral changes that model positive (hallucinatory-like behaviors) and negative (psychomotor depression) symptoms of schizophrenia. The extent to which this model produces the core deficit in schizophrenia--working memory impairment--is unknown.

METHODS

Two groups of rhesus monkeys were sensitized to AMPH over 6 weeks. In one group, acquisition of cognitive tasks (delayed response, visual discrimination, delayed nonmatch-to-sample) was examined beginning 6+ months postsensitization. The second group was pretrained to stability on delayed response before sensitization. Regional postmortem concentrations of dopamine and its metabolites were examined in tissue from age-matched AMPH-naive and AMPH-sensitized monkeys using high-performance liquid chromatography with electrochemical detection (HPLC-ECD).

RESULTS

The AMPH-sensitized monkeys were profoundly impaired in their ability to acquire cognitive tasks compared with AMPH-naïve monkeys. Pretrained monkeys showed impaired delayed response performance for several months following sensitization. Analysis by HPLC revealed that AMPH sensitization significantly reduced dopamine turnover in prefrontal cortex and striatum.

CONCLUSIONS

Impairments in the acquisition and performance of spatial delayed response in association with reduced dopamine turnover in prefrontal cortex following AMPH sensitization provide further support for the relevance of this model to both the etiology and the treatment of cognitive dysfunction in schizophrenia.

Dopamine D3 receptor Ser9Gly polymorphism and risperidone response

Risperidone is an atypical antipsychotic agent with efficacy for both positive and negative symptoms of schizophrenia. Risperidone is a potent dopamine D3 antagonist and agonism at D3 sites induces behavioral suppression in rodents. We thus hypothesized that D3 antagonism may contribute to response to risperidone in negative symptoms. This study aimed to explore the influence of the Ser9Gly polymorphism of the dopamine D3 receptor (DRD3) gene on response to risperidone after controlling for nongenetic factors. One hundred twenty-three Han Chinese patients with acutely exacerbated schizophrenia were given risperidone monotherapy for up to 42 days. Clinical manifestations were measured biweekly with Positive and Negative Syndrome Scale and Nurses' Observation Scale for Inpatients Evaluation (for assessment of social functioning). For adjusting the within-subject dependence over repeated assessments, multiple linear regression with generalized estimating equation methods was used to analyze the effects of Ser9Gly polymorphism and other covariates on clinical performance. Compared with patients with the Gly9Gly genotype, those with either Ser9Ser or Ser9Gly had better performance on negative symptoms after control for other prognostic factors (P = 0.0002 and 0.0092, respectively). Patients with the Ser9Ser genotype had better social functioning than those with Gly9Gly (P = 0.0029). The Ser9Gly polymorphism, however, did not significantly affect positive symptoms. Male gender, fewer previous hospitalizations, and higher risperidone dose also predicted better treatment response. These data suggest that the DRD3 Ser9Gly polymorphism or, alternatively, another genetic variation that is in linkage disequilibrium, may influence response to risperidone in negative symptoms and social functioning.

Do new prescription drugs pay for themselves? The case of second-generation antipsychotics

During the last several years, spending on prescription drugs in the U.S. increased at a 15% annual rate, with the US 178 billion dollars spent in 2002 accounting for more than 11% of health care expenditures in the U.S. This growth has been largely driven by a shift to new drugs, which are typically more expensive than earlier drugs within the same therapeutic category. Recent research has suggested that the shift to new drugs may lower health care spending by reducing the demand for hospitalizations and other health care services. Using a 20% sample of Medicaid recipients from the state of California for the 1993-2001 period, I investigate this hypothesis for antipsychotic drugs--the therapeutic category that has accounted for more government spending than any other during the past decade. Using three different identification strategies, my findings demonstrate that the 610% increase in Medicaid spending on antipsychotic drugs during the study period caused by the shift to three new treatments has not reduced spending on other types of medical care, thus undermining the hypothesis that the drugs have "paid for themselves." Because of data limitations, the findings for health outcomes are necessarily more speculative but suggest that the new medications have increased the prevalence of diabetes while reducing the prevalence of extrapyramidal symptoms among the mentally ill.

Changes in extracellular dopamine in the rat globus pallidus induced by typical and atypical antipsychotic drugs

Typical antipsychotic drugs with a high extrapyramidal motor side-effects liability markedly increase extracellular dopamine in the caudate-putamen, while atypical antipsychotic drugs with a low incidence of extrapyramidal motor side-effects have less pronounced stimulating actions on striatal dopamine. Therefore, it has been suggested that the extrapyramidal motor side-effects liability of antipsychotic drugs (APD) is correlated with their ability to increase extracellular dopamine in the caudate-putamen. The globus pallidus (GP) is another basal ganglia structure probably mediating extrapyramidal motor side-effects of typical antipsychotic drugs. Therefore, the present study sought to determine whether extracellular dopamine in the globus pallidus might be a further indicator to differentiate neurochemical actions of typical and atypical antipsychotic drugs. Using in vivo microdialysis we compared effects on pallidal dopamine induced by typical and atypical antipsychotic drugs in rats. Experiment I demonstrated that systemic administration of haloperidol (1 mg/kg; i.p.) and clozapine (20 mg/kg; i.p.) induced a significant pallidal dopamine release to about 160 and 180% of baseline, respectively. Experiment II revealed that reverse microdialysis of raclopride and clozapine using a cumulative dosing regimen did not stimulate extracellular dopamine in the globus pallidus if low (1microM) or intermediate (10 and 100 microM) concentrations were used. Only at a high concentration (1,000 microM), raclopride and clozapine induced a significant pallidal dopamine release to about 130 and 300% of baseline values, respectively. Thus, effects of typical and atypical antipsychotic drugs on pallidal dopamine were similar and thus, may not be related to their differential extrapyramidal motor side-effects liability. Furthermore, the finding that reverse microdialysis of raclopride over a wide range of concentrations did not stimulate pallidal dopamine concentrations tentatively suggests that pallidal dopamine release under basal conditions is not regulated by D2 autoreceptors.

Synergistic dopamine increase in the rat prefrontal cortex with the combination of quetiapine and fluvoxamine

RATIONALE

The combination of atypical antipsychotic drugs in addition to serotonin reuptake inhibitors has recently proven to be beneficial in a number of neuropsychiatric disorders, such as major depression, schizophrenia, and obsessive-compulsive disorder.

OBJECTIVES

To investigate the effects of an atypical antipsychotic drug in combination with a serotonin reuptake inhibitor on extracellular serotonin [5-HT]ex, and dopamine levels [DA]ex in different brain areas.

METHODS

The effects of quetiapine (10 mg/kg) with fluvoxamine (10 mg/kg) on [5-HT]ex and [DA]ex were compared in the rat dorsal striatum, prefrontal cortex, nucleus accumbens (core and shell), and thalamus by means of microdialysis coupled to HPLC with electrochemical detection.

RESULTS

Quetiapine had no significant effect on [DA]ex and [5-HT]ex levels in the prefrontal cortex and thalamus, but increased [DA]ex and [5-HT]ex levels in the dorsal striatum. In the accumbens, quetiapine increased [DA]ex levels and decreased [5-HT]ex levels. Fluvoxamine increased [5-HT]ex levels in all brain areas, and also increased [DA]ex levels in the striatum. The combination of quetiapine with fluvoxamine increased [DA]ex and [5-HT]ex levels in all brain areas compared with baseline. Although neither quetiapine nor fluvoxamine in monotherapy affected [DA]ex levels in the prefrontal cortex and thalamus, the combination produced a significant increase of [DA]ex levels in these two brain areas.

CONCLUSIONS

The combination of quetiapine with fluvoxamine causes a synergistic dopamine increase in the prefrontal cortex and the thalamus.

Targeting the dopamine D1 receptor in schizophrenia: insights for cognitive dysfunction

BACKGROUND AND RATIONALE

Reinstatement of the function of working memory, the cardinal cognitive process essential for human reasoning and judgment, is potentially the most intractable problem for the treatment of schizophrenia. Since deficits in working memory are associated with dopamine dysregulation and altered D(1) receptor signaling within prefrontal cortex, we present the case for targeting novel drug therapies towards enhancing prefrontal D(1) stimulation for the amelioration of the debilitating cognitive deficits in schizophrenia.

OBJECTIVES

This review examines the role of dopamine in regulating cellular and circuit function within prefrontal cortex in order to understand the significance of the dopamine dysregulation found in schizophrenia and related non-human primate models. By revealing the associations among prefrontal neuronal function, dopamine and D(1) signaling, and cognition, we seek to pinpoint the mechanisms by which dopamine modulates working memory processes and how these mechanisms may be exploited to improve cognitive function.

RESULTS AND CONCLUSIONS

Dopamine deficiency within dorsolateral prefrontal cortex leads to abnormal recruitment of this region by cognitive tasks. Both preclinical and clinical studies have demonstrated a direct relationship between prefrontal dopamine function and the integrity of working memory, suggesting that insufficient D(1) receptor signaling in this region results in cognitive deficits. Moreover, working memory deficits can be ameliorated by treatments that augment D(1) receptor stimulation, indicating that this target presents a unique opportunity for the restoration of cognitive function in schizophrenia.