Does risperidone improve verbal working memory in treatment-resistant schizophrenia?

On the trail of a cognitive enhancer for the treatment of schizophrenia

The aim of this critical review is to address that the study of cognition and antipsychotics is not always driven by logic and that research into real pro-cognitive drug treatments must be guided by a better understanding of the biochemical mechanisms underlying cognitive processes and deficits. Many studies have established that typical neuroleptic drugs do not improve cognitive impairment. Atypical antipsychotics improve cognition, but the pattern of improvement differs from drug to drug. Diminished cholinergic activity has been associated with memory impairments. Why atypical drugs improve aspects of cognition might lie in their ability to increase dopamine and acetylcholine in the prefrontal cortex. An optimum amount of dopamine activity in the prefrontal cortex is critical for cognitive functioning. Another mechanism is related to procedural learning, and would explain the quality of the practice during repeated evaluations with atypical antipsychotics due to a more balanced blockage of D2 receptors. Laboratory studies have shown that clozapine, ziprasidone, olanzapine, and risperidone all selectively increase acetylcholine release in the prefrontal cortex, whereas this is not true for haloperidol and thioridazine. A few studies have suggested that cholinomimetics or AChE inhibitors can improve memory functions not only in Alzheimer's disease but also in other pathologies. Some studies support the role of decreased cholinergic activity in the cognitive deficits while others demonstrate that decreased choline acetyltransferase activity is related to deterioration in cognitive performance in schizophrenia. Overall, results suggest the hypothesis that the cholinergic system is involved in the cognitive dysfunctions observed in schizophrenia and that increased cholinergic activity may improve these impairments. Furthermore, a dysfunction of glutamatergic neurotransmission could play a key role in cognitive deficits associated with schizophrenia. Further meta-analysis of various clinical trials in this field is required to account for matters on the grounds of evidence-based medicine.

Working Memory Impairments in Schizophrenia: A Meta-Analysis

Working memory (WM) deficit is a cardinal cognitive symptom of schizophrenia, but the differences among the tasks and measures used to assess WM make it difficult to compare across studies. The authors conducted a meta-analytic review to address 3 major questions: (a) Do patients with schizophrenia show WM deficits across diverse methodology; (b) Is WM deficit supramodal; and (c) Does the WM deficit worsen with longer delays? The results indicate that significant WM deficit was present in schizophrenia patients in all modalities examined. Increasing delay beyond 1 s did not influence the performance difference between schizophrenia patients and healthy control participants in WM. These results suggest that WM deficit in schizophrenia is modality independent and that encoding and/or early part of maintenance may be problematic.

Effects of haloperidol and risperidone on psychomotor performance relevant to driving ability in schizophrenic patients compared to healthy controls

The effects of antipsychotic treatment on the psychomotor performance and driving ability of schizophrenic patients is subject of investigation. The present study was designed to evaluate the effects of an atypical neuroleptic (risperidone) in comparison to a conventional dopamine antagonist neuroleptic (haloperidol) on several dimensions of psychomotor performance (visual perception, attention, reaction time, and sensorimotor performance) considered to be of relevance in evaluating driving fitness. Psychomotor performance was assessed by means of the ART 90 (act-and-react test), a computerized test battery which is frequently used in diagnosis of psychomotor performance. The 40 participating patients were examined at discharge following psychopathological stabilisation; 20 received haloperidol medication, 20 received the atypical neuroleptic risperidone. Nineteen healthy individuals were studied as a control group. Our findings indicate a remarkably reduced psychomotor performance in both groups of schizophrenic patients compared to healthy controls. We did find a significant but low correlation between age and some items of the RST3 and between age and the tracking performance on the PVT. The younger patients showed a better test performance than older patients. The BPRS-score was significantly correlated with only two items of the RST3. However, patients under treatment with risperidone showed significantly better results compared to patients treated with haloperidol. Only one (5%) subject passed all subtests without major failures and could be regarded as competent to drive. Among patients with risperidone, seven patients (35%) passed all test parameters without major failures. Clinical implications of these findings are discussed.

Treatments for schizophrenia: a critical review of pharmacology and mechanisms of action of antipsychotic drugs

The treatment of schizophrenia has evolved over the past half century primarily in the context of antipsychotic drug development. Although there has been significant progress resulting in the availability and use of numerous medications, these reflect three basic classes of medications (conventional (typical), atypical and dopamine partial agonist antipsychotics) all of which, despite working by varying mechanisms of actions, act principally on dopamine systems. Many of the second-generation (atypical and dopamine partial agonist) antipsychotics are believed to offer advantages over first-generation agents in the treatment for schizophrenia. However, the pharmacological properties that confer the different therapeutic effects of the new generation of antipsychotic drugs have remained elusive, and certain side effects can still impact patient health and quality of life. Moreover, the efficacy of antipsychotic drugs is limited prompting the clinical use of adjunctive pharmacy to augment the effects of treatment. In addition, the search for novel and nondopaminergic antipsychotic drugs has not been successful to date, though numerous development strategies continue to be pursued, guided by various pathophysiologic hypotheses. This article provides a brief review and critique of the current therapeutic armamentarium for treating schizophrenia and drug development strategies and theories of mechanisms of action of antipsychotics, and focuses on novel targets for therapeutic agents for future drug development.

Clinical constructs and therapeutic discovery

Schizophrenia, as a single disease entity, has been the major paradigm during the past 100 years. Classification has increasingly emphasized diagnostically discriminating psychotic symptoms. This has made reality distortion and thought disorder the defining qualities of the disorder. One result is 50 years of developing dopamine antagonist antipsychotic drugs while neglecting novel therapeutic pathways related to nonpsychotic pathology. The domains of psychopathology provides an alternative paradigm. In this paradigm, the relative independence of reality distortion, disorganization, negative pathology, and impairments in cognition is stressed. Application of this paradigm has revealed that impaired cognition and negative symptoms are robustly associated with poor functional outcomes. Antipsychotic drugs fail to address these pathologies. These unmet treatment needs are clinical targets for drug discovery involving novel therapeutic pathways.

Nicotinic receptor mechanisms and cognition in normal states and neuropsychiatric disorders

Cigarette smoking rates in the American population are approximately 23%, whereas rates of smoking in clinical and population studies of individuals with neuropsychiatric disorders are typically two- to four-fold higher. Studies conducted in a variety of neuropsychiatric populations [e.g. attention-deficit hyperactivity disorder (ADHD), Alzheimer's disease, schizophrenia] have collectively suggested that nicotine may be efficacious in remediating selected cognitive deficits associated with these disorders, thus providing a framework for understanding the specific vulnerability of these patients to smoking initiation and maintenance. However, the specific gain in cognitive performance produced by nicotine administration in healthy subjects with normal cognitive function is less clear. This article reviews our current understanding of central nicotinic acetylcholine receptor (nAChRs) systems in normal and neuropsychiatric disease states and, specifically, their role with respect to cognitive dysfunction and clinical symptoms in several specific neuropsychiatric populations, including ADHD, Alzheimer's disease, Parkinson's disease, Tourette's Disorder, schizophrenia and affective disorders. The potential benefits of nicotinic agents for therapeutic use in neuropsychiatric disorders is discussed, as well as directions for further research in this area.

Changes in neuronal activation in patients with bipolar disorder during performance of a working memory task

OBJECTIVES

Several lines of evidence suggest that deficits in cognition persist in bipolar patients during periods of euthymia. Working memory impairment has been observed in euthymic bipolar patients and noted to be a significant source of functional deficits in psychiatric disorders. Functional changes associated with these cognitive deficits however, remain poorly understood. We hypothesized that patients with bipolar disorder would demonstrate changes in neuronal activation in specific regions forming part of the working memory network.

METHODS

Fifteen euthymic bipolar patients and fifteen age- and gender-matched healthy controls were recruited. Subjects participated in fMRI scans during which a two-back working memory task alternated with a zero-back control/attention task using a block-design paradigm. Groups were analyzed separately, and intergroup comparisons were made using an exploratory, voxel-by-voxel analysis.

RESULTS

Bipolar patients performed more poorly on the cognitive tasks than did healthy controls (F = 3.77, p = 0.04). After covarying for task performance and reaction time, bipolar patients demonstrated significantly greater activation than healthy subjects in several regions including the fronto-polar prefrontal cortex, temporal cortex, basal ganglia, thalamus, and posterior parietal cortex. No areas showed a significant decrease in activation, compared with healthy controls.

CONCLUSIONS

Our findings suggest that decreased working memory performance in bipolar patients reflects specific neurofunctional deficits. These deficits may represent primary areas of neuropathology or be secondary to neuropathology elsewhere in the working memory network. Continued research utilizing other imaging modalities may further clarify the underlying neuropathology involved in these cognitive deficits.

Effect of switching to atypical antipsychotics on memory in patients with chronic schizophrenia

While the usefulness of atypical antipsychotics for improving cognitive function has been proven, the specific effects of these drugs are still unknown. The objective of this study was to investigate changes of the immediate memory and verbal working memory in patients with chronic schizophrenia after switching to one of four atypical antipsychotic agents and cessation of anticholinergic therapy. The subjects included 77 schizophrenic patients who were treated primarily with typical antipsychotics. Treatment was randomly switched to one of four atypical antipsychotics (olanzapine, perospirone, quetiapine, or risperidone) over a 4-week period, and then the drug was continued for another 4 weeks while the patient was taken off anticholinergics. The immediate memory, verbal working memory, and symptoms were evaluated. Significant improvement of immediate memory was only seen with olanzapine and risperidone. Improvement was also seen after switching to perospirone, but immediate memory worsened after treatment with this anticholinergic drug was discontinued. Deterioration was seen after switching to quetiapine, but immediate memory improved and reached the previous level after treatment with anticholinergic drugs was discontinued. Significant improvement of the verbal working memory was only seen during risperidone administration. The findings suggested that switching chronic schizophrenic patients to atypical antipsychotics can improve both the immediate memory and the verbal working memory when risperidone is used, while improvement of immediate memory can be expected with olanzapine. From the viewpoint of improving the memory, quetiapine should not be administered concomitantly with anticholinergic drugs, and caution should be exercised when discontinuing anticholinergic drugs during treatment with perospirone.

Effects of amisulpride, risperidone and chlorpromazine on auditory and visual latent inhibition, prepulse inhibition, executive function and eye movements in healthy volunteers

In view of the evidence that cognitive deficits in schizophrenia are critically important for long-term outcome, it is essential to establish the effects that the various antipsychotic compounds have on cognition, particularly second-generation drugs. This parallel group, placebo-controlled study aimed to compare the effects in healthy volunteers (n = 128) of acute doses of the atypical antipsychotics amisulpride (300 mg) and risperidone (3 mg) to those of chlorpromazine (100 mg) on tests thought relevant to the schizophrenic process: auditory and visual latent inhibition, prepulse inhibition of the acoustic startle response, executive function and eye movements. The drugs tested were not found to affect auditory latent inhibition, prepulse inhibition or executive functioning as measured by the Cambridge Neuropsychological Test Battery and the FAS test of verbal fluency. However, risperidone disrupted and amisulpride showed a trend to disrupt visual latent inhibition. Although amisulpride did not affect eye movements, both risperidone and chlorpromazine decreased peak saccadic velocity and increased antisaccade error rates, which, in the risperidone group, correlated with drug-induced akathisia. It was concluded that single doses of these drugs appear to have little effect on cognition, but may affect eye movement parameters in accordance with the amount of sedation and akathisia they produce. The effect risperidone had on latent inhibition is likely to relate to its serotonergic properties. Furthermore, as the trend for disrupted visual latent inhibition following amisulpride was similar in nature to that which would be expected with amphetamine, it was concluded that its behaviour in this model is consistent with its preferential presynaptic dopamine antagonistic activity in low dose and its efficacy in the negative symptoms of schizophrenia.

A meta-analysis and critical review of the effects of conventional neuroleptic treatment on cognition in schizophrenia: opening a closed book

BACKGROUND

In recent years, numerous studies have examined whether new-generation antipsychotic agents impact cognitive impairment in patients with schizophrenia when compared with conventional antipsychotic treatment. The working assumption of such studies, supported by narrative reviews, is that the conventional antipsychotic medications have little or no effect on cognition. The studies concerning the effects of conventional neuroleptics on cognition, however, have never been analyzed quantitatively. In this meta-analysis, we revisit the question of whether typical agents might have enhancing effects on cognition.

METHODS

The meta-analysis included studies that 1) compared the effects of typical neuroleptic agents with those of placebo or no medication on cognition; 2) examined adult patients identified as having schizophrenia; and 3) produced adequate data to estimate an effect size. Studies were identified by searches of computerized literature databases and by cross-referencing included studies. The effect size calculated was d, the difference between the means in cognitive measures of patients with schizophrenia taking and not taking conventional neuroleptic medication, divided by the pooled SD. Critically, when multiple measures were reported in a single article, effect sizes were combined so as to minimize the possibility that one study had undue weight simply because of the number of cognitive outcome variables that it contained. These results were corrected for bias due to sample size, with each of the effect sizes weighted by the reciprocal of its variance. The final sample after exclusion of outliers comprised 208 effect sizes from 34 studies.

RESULTS

With a random-effects model, effect sizes from the primary studies were weighted according to sample size and averaged. The resulting mean effect size was.22 (95% confidence interval =.10,.34). The result is positive, in that the range did not include zero and was of low moderate size. No moderating effects of study design or patient qualities were found to be significant. With the same procedures, effect sizes for individual neurocognitive domains were computed. Effect sizes were generally in the.13-.29 range for the majority of cognitive functions, whereas motor function was impacted negatively (-.11). Unexpectedly, medication dose did not correlate with effect size.

CONCLUSIONS

Typical antipsychotic medication provides modest-to-moderate gains in multiple cognitive domains. Given unavoidable methodologic limitations of the primary studies, current findings suggest that the impact of conventional medication on cognitive function should be re-evaluated.

Improvement in cognitive function following a switch to ziprasidone from conventional antipsychotics, olanzapine, or risperidone in outpatients with schizophrenia

OBJECTIVE

To assess changes in cognitive function in stable outpatients with schizophrenia switched to ziprasidone from conventional antipsychotics (n = 108), olanzapine (n = 104), or risperidone (n = 58) because of suboptimal efficacy or poor tolerability.

METHODS

In three separate 6-week trials, patients received ziprasidone 40 mg b.i.d. for 2 days, followed by 20-80 mg b.i.d. for the next 40 days. Before switching, and at endpoint, patients were evaluated with tests of working and secondary verbal memory, vigilance, visuomotor speed, verbal fluency, and executive functioning. Principal components factor analysis was performed to test for clustering of cognitive variables.

RESULTS

Significant improvements were seen at endpoint in secondary verbal memory (in all three groups), vigilance (in patients switched from conventional antipsychotics or risperidone), executive function (in patients switched from conventional antipsychotics or risperidone), and verbal fluency. Factor analysis on baseline scores suggested reduction of the cognitive variables to three factors: verbal skills, attention and short-term memory, and executive functioning. Analysis of z-transformed mean change in factor scores showed significant improvement in verbal skills and global score following the switch from conventional antipsychotics, olanzapine, or risperidone.

CONCLUSIONS

Patients requiring a change in antipsychotic therapy may exhibit cognitive improvement following a switch to ziprasidone.

Cognitive effects of atypical antipsychotics: focus on bipolar spectrum disorders

Studies examining cognitive dysfunction in bipolar disorder have documented neuropsychologic impairment in some patients. Recollection memory, attention, and visual information processing may be particularly impaired in patients with bipolar illness. Cognitive impairment appears to worsen with illness progression, and may have a significant impact on function. Pharmacotherapy to treat bipolar disorder including lithium, anticonvulsants, antidepressants, and atypical antipsychotics may have varying effects on cognitive functioning. Treatment with atypical antipsychotics has been associated with improvement in various cognitive measures in patients with schizophrenia, and the little data available in patients with bipolar disorder suggest the potential for similar benefits. Studies to determine if current treatments for bipolar disorder can prevent, delay, or even improve cognitive dysfunction are needed.

Risperidone in acute and long-term therapy of schizophrenia--a clinical profile

Data from a range of well-controlled clinical trials, observational studies, and clinical use support the efficacy of risperidone for both acute and long-term therapy of schizophrenic psychoses. With regard to positive symptoms, the efficacy of risperidone was shown to be at least comparable with that of haloperidol. However, risperidone differs from conventional antipsychotics because it is more effective against the negative symptoms, has beneficial effects on affective and cognitive symptoms, and carries less risk of extrapyramidal side effects (EPS). To date, risperidone is the only atypical antipsychotic to have shown a significantly lower relapse rate compared with haloperidol in a long-term double-blind trial. This review describes comprehensive trial data and therapeutic observations gained with risperidone in the treatment of schizophrenia since its approval.

Effect of second-generation antipsychotics on employment and productivity in individuals with schizophrenia: an economic perspective

Schizophrenia is a serious mental illness that imposes a considerable burden not only on those who are ill, but also on their families, neighbours and the wider society. Costs associated with treating people with schizophrenia are those derived from the use of a wide range of services provided by public psychiatric facilities and/or by voluntary and private agencies. In addition, a large part of the economic impact of schizophrenia is related to the difficulties that patients encounter in finding and keeping paid employment. The introduction of second-generation antipsychotics (SGAs), also defined as atypicals, has increased the therapeutic options available for individuals with schizophrenia. Potential benefits of these agents include a more favourable profile in terms of positive and negative symptoms, less adverse effects and better cognitive functioning than first-generation antipsychotics (FGAs). As a consequence, SGAs might favourably affect the capacity, seriously impaired in schizophrenia, of finding and keeping paid employment. To date, only 13 published studies have investigated the effect of SGA agents on employment and work productivity. Clozapine was studied in eight studies, while both olanzapine and risperidone were studied in three. Clozapine emerged as the SGA with at least some effect on work status. However, all but one clozapine study enrolled only a few individuals and did not adopt an experimental design, making it very difficult to judge the validity and generalisability of findings. Taken together, studies found little benefit, in terms of employment and work productivity, for the use of SGAs compared with FGAs. The evidence available suggests that until data demonstrate a robust effect of newer agents on employment, it remains mandatory for mental health professionals to use the most effective drug treatment together with non-pharmacological interventions, such as vocational rehabilitative programmes nested into models of community psychiatric care, which have proven effect on the capacity of finding and keeping paid employment. This will ensure that the economic impact of schizophrenia is most effectively contained.

Automatic activation of the semantic network in schizophrenia: evidence from event-related brain potentials

BACKGROUND

Language disorder associated with schizophrenia might be due to disturbances in both automatic activation and mechanisms of controlled attention. The contribution of each process to semantic memory dysfunction has not been determined for schizophrenia, and the semantic priming paradigm is well-suited for addressing this question. In the present report, event-related potentials (ERPs) elicited under conditions assumed to reveal automatic activation (short prime-target interval and low proportion of related words) are compared directly with ERPs elicited under conditions associated with controlled processing (long prime-target interval and high proportion of related words).

METHODS

Visual ERPs were recorded during a lexical decision task, in which semantic relationship (associated and unassociated words), expectancy (relatedness proportions), and prime-target interval (250- and 850-msec inter-stimulus intervals [ISIs]) were varied. Diagnosis and expectancy were between-subjects factors; semantic relationship and ISI were repeated measures. The N400 priming effect (enhanced negativity to unassociated words) was compared between 34 male normal control subjects tested once and 37 male schizophrenia inpatients evaluated during their participation in a double-blind haloperidol maintenance therapy and placebo replacement protocol.

RESULTS

The N400 priming effect for patients was significantly reduced during both pharmacologic phases, compared with controls. During haloperidol treatment, however, patients showed a significant N400 priming effect over the anterior scalp region and additionally under the automatic activation condition. The N400 priming effect was enhanced under the controlled processing condition for control subjects; this effect was not observed for patients. N400 amplitude elicited under the rapid presentation rate (250-msec ISI) differed between medicated patients and controls; groups did not differ for the 850-msec ISI.

CONCLUSIONS

Findings suggest that automatic activation and mechanisms of controlled attention are both disrupted during semantic memory access for schizophrenia patients. Pharmacologic agents, such as haloperidol, might enhance automatic activation of the semantic network in this patient population, as indexed by the N400 component of the ERP.

The relationship between membrane pathology and language disorder in schizophrenia

Receptive language disorder in schizophrenia has been hypothesized to involve a fundamental deficit in the temporal (time-based) dynamics of brain function that includes disruptions to patterns of activation and synchronization. In this paper, candidate mechanisms and pathways that could account for this basic deficit are discussed. Parallels are identified between the patterns of language dysfunction observed for schizophrenia and dyslexia, two separate clinical disorders that may share a common abnormality in cell membrane phospholipids. A heuristic is proposed which details a trajectory involving an interaction of brain fatty acids and second-messenger function that modulates synaptic efficacy, and, in turn, influences language processing in schizophrenia patients. It is additionally hypothesized that a primary deficit of functional excitation originating in the cerebellum, in combination with a compensatory decrease of functional inhibition in the prefrontal cortex, influences receptive language dysfunction in schizophrenia.

Evidence-based treatment for schizophrenia

Taken together, the research on what treatments help people with schizophrenia point to the value of treatment programs that combine medications with a range of psychosocial services. Provision of such packages of services likely reduces the need for crisis-oriented care hospitalizations and emergency room visits and enables greater recovery. For most people with schizophrenia, the combination of psychopharmacological and psychosocial interventions improves outcomes. Several psychosocial treatments have demonstrated efficacy. These include family intervention, supported employment, assertive community treatment, skills training, and CBT. In the same way that psychopharmacologic management must be tailored individually to the needs and preferences of the patient, so too should the selection of psychosocial treatments. At the very least, all people with schizophrenia should be provided with education about their illness. Beyond illness education, all of the recommended psychosocial interventions would be used rarely during any one phase of illness for an individual. Some psychosocial treatments share treatment components, and patients have different clinical and social needs at different points in their illness course. Knowledge regarding how best to combine treatments to optimize outcomes is scarce.

Neurocognitive performance and clinical changes in olanzapine-treated patients with schizophrenia

Diffuse cognitive impairment characterizes patients with schizophrenia throughout the course of illness. The deficits persist despite clinical improvement associated with neuroleptic intervention and are related to outcome. It is unclear whether treatment with atypical agents is associated with improved cognition that relates to symptoms and outcome. Using a set of computerized neurocognitive measures, we evaluated whether the effects of olanzapine are greater than practice effects for specific neurocognitive domains that could provide targets for large-scale randomized studies. We enrolled 19 patients with schizophrenia before initiation of treatment with olanzapine and 16 of them were examined at 6 weeks and 6 months of follow-up. They were compared to 34 healthy participants who enrolled, 24 of whom were evaluated longitudinally. Improvement exceeding practice effects was observed in patients for abstraction and spatial memory and the latter correlated with clinical improvement in negative symptoms. These results suggest that some effects of olanzapine may impact both symptoms and cognitive performance.

Refining pharmacogenetic research in schizophrenia: Control for patient‐related variables

There is strong evidence to suggest that genetic variation plays an important role in inter‐individual differences in medication response and toxicity. Most of the previous pharmacogenetic studies, however, cannot be reconfirmed. Of note, drug efficacy or side effects depend not only on genetic factors but also on nongenetic factors, such as illness duration, past treatment history, and drug dosage or blood concentration. However, most pharmacogeneticists did not consider or control the possible impact of the nongenetic factors. Schizophrenia is a severe neuropsychiatric disorder with a polygenic mode of inheritance that is also governed by nongenetic factors. Schizophrenia's symptoms are principally subdivided into two subtypes, positive and negative. The positive symptoms include delusions and hallucinations; the negative symptoms, blunted affect and social withdrawal. Atypical antipsychotics are usually superior in the treatment of negative symptoms than typical agents. Although atypical agents are becoming the mainstay for schizophrenia treatment, what makes an antipsychotic “atypical” remains unclear. One of our recent studies have simultaneously evaluated the effects of genetic and nongenetic determinants on the efficacy of risperidone (a widely used atypical antipsychotic agent). We found that 5‐HT2A receptor 102‐T/C polymorphism could predict clinical response (mainly for negative symptoms rather than positive symptoms) in schizophrenia. Among nongenetic factors, fewer previous hospitalizations and higher risperidone dosage also predicted better treatment response after control for the 102‐T/C polymorphism and other confounders. It is hoped that this novel study model could revolutionize future research in pharmacogenetics or other fields of genetics. Drug Dev. Res. 60:164–171, 2003. © 2003 Wiley‐Liss, Inc.

Serotonin receptors: their key role in drugs to treat schizophrenia

Serotonin (5-HT)-receptor-based mechanisms have been postulated to play a critical role in the action of the new generation of antipsychotic drugs (APDs) that are usually referred to as atypical APDs because of their ability to achieve an antipsychotic effect with lower rates of extrapyramidal side effects (EPS) compared to first-generation APDs such as haloperidol. Specifically, it has been proposed by Meltzer et al. [J. Pharmacol. Exp. Ther. 251 (1989) 238] that potent 5-HT2A receptor antagonism together with weak dopamine (DA) D2 receptor antagonism are the principal pharmacologic features that differentiate clozapine and other apparent atypical APDs from first-generation typical APD. This hypothesis is consistent with the atypical features of quetiapine, olanzapine, risperidone, and ziprasidone, which are the most common treatments for schizophrenia in the United States and many other countries, as well as a large number of compounds in various stages of development. Subsequent research showed that 5-HT1A agonism may be an important consequence of 5-HT2A antagonism and that substitution of 5-HT1A agonism for 5-HT2A antagonism may also produce an atypical APD drug when coupled with weak D2 antagonism. Aripiprazole, the most recently introduced atypical APD, and a D2 receptor partial agonist, may also owe some of its atypical properties to its net effect of weak D2 antagonism, 5-HT2A antagonism and 5-HT1A agonism [Eur. J. Pharmacol. 441 (2002) 137]. By contrast, the alternative "fast-off" hypothesis of Kapur and Seeman [Am. J. Psychiatry 158 (2001) 360] applies only to clozapine and quetiapine and is inconsistent with the "slow" off rate of most atypical APDs, including olanzapine, risperidone and ziprasidone. 5-HT2A and 5-HT1A receptors located on glutamatergic pyramidal neurons in the cortex and hippocampus, 5-HT2A receptors on the cell bodies of DA neurons in the ventral tegmentum and substantia nigra and GABAergic interneurons in the cortex and hippocampus, and 5-HT1A receptors in the raphe nuclei are likely to be important sites of action of the atypical APDs. At the same time, evidence has accumulated for the important modulatory role of 5-HT2C and 5-HT6 receptors for some of the effects of some of the current APDs. Thus, 5-HT has joined DA as a critical target for developing effective APDs and led to the search for novel drugs with complex pharmacology, ending the exclusive search for single-receptor targets, e.g., the D3 or D4 receptor, and drugs that are selective for them.

Comparative effects of risperidone and olanzapine on cognition in elderly patients with schizophrenia or schizoaffective disorder

OBJECTIVE

To examine the effects of risperidone and olanzapine on cognitive functioning in elderly patients with schizophrenia or schizoaffective disorder.

METHOD

One hundred seventy-six elderly inpatients and outpatients with schizophrenia or schizoaffective disorder were enrolled in this multicenter, double-blind trial. After their antipsychotic medications were tapered for 1 week, patients were randomly assigned to receive either risperidone 1 to 3 mg/day or olanzapine 5 to 20 mg/day for 8 weeks. Performance on the Continuous Performance Test (CPT), Serial Verbal Learning Test (SVLT), TMT (Trail Making Test) Parts A and B, Wisconsin Card Sorting Test (WCST), and Verbal Fluency Examinations (VFE) was assessed at baseline and at end point.

RESULTS

Patients in the risperidone group had improved scores on at least one test of attention, memory, executive function, and verbal fluency, and those in the olanzapine group had improved scores on at least one test of attention and memory function. Scores on the TMT Part B, WCST total errors (executive function domain), and the VFE improved significantly from baseline in the risperidone group but not in the olanzapine group. No significant differences in change scores between the two groups were found. Higher baseline scores on each test predicted more improvement at endpoint.

CONCLUSIONS

Low doses of risperidone and olanzapine improve cognitive function in elderly patients with schizophrenia or schizoaffective disorder. Consistent with research in younger populations, these improvements occur in aspects of cognitive functioning related to functional outcome.

Procedural learning in schizophrenia after 6 months of double-blind treatment with olanzapine, risperidone, and haloperidol

RATIONALE

First generation antipsychotics induce extrapyramidal motor symptoms (EPS), presumably through dopamine D(2) receptor blockade at the dorsal striatum. This may also produce impairment of cognitive processes, such as procedural learning, that are dependent on this region. Haloperidol and, to a lesser extent, risperidone, are active in the dorsal striatum and may induce EPS and impairment of procedural learning. In contrast, the prototypical second-generation antipsychotic, clozapine, is less active in the dorsal striatum and does not induce EPS or impair procedural learning. Olanzapine is pharmacologically similar to clozapine and has a low incidence of EPS induction.

OBJECTIVES

To assess the hypothesis that olanzapine would not have a deleterious effect on procedural learning.

METHODS

Thirty-nine subjects with early phase schizophrenia were randomly assigned to double blind treatment with haloperidol, risperidone, or olanzapine. They were administered the Tower of Toronto test at an unmedicated baseline and again following 6 weeks and 6 months of treatment.

RESULTS

Procedural learning, defined as the improvement observed between two blocks of five trials of the Tower of Toronto, was preserved after 6 weeks of all three treatments but showed a substantial decline after 6 months of treatment with haloperidol or risperidone.

CONCLUSIONS

These data are consistent with the differential activity of the three medications in dorsal striatum structures and suggest that the advantages of olanzapine over haloperidol and risperidone in relation to extrapyramidal syndromes may also generalize to procedural learning. The results also suggest that the procedural learning disadvantages of haloperidol and risperidone accrue slowly but are apparent after 6 months of treatment.

Effect of L-tryptophan on memory in patients with schizophrenia

ABSTRACT It has been well established that patients with schizophrenia have impaired cognitive abilities on neuropsychological tasks related to memory. Previous studies also suggest a central role for serotonin in memory. This double-blind crossover study aimed to explore the effect of l-tryptophan, a serotonin precursor, on a variety of memory tasks in schizophrenic patients. Antipsychotic-treated schizophrenic patients in remission (N = 21) were randomly treated with l-tryptophan or placebo and then evaluated at three consecutive points on clinical measures (including Positive and Negative Syndrome Scale for Schizophrenia, Clinical Global Impression, and Extrapyramidal Symptoms Rating Scale) and by neuropsychological tests (including Digit-Span, Paired Association, Rey-Osterich Complex Figure Test, Digit Symbol, Number Facility Test, and the Rivermead Behavioral Memory Tests. Compared with placebo, l-tryptophan had a beneficial effect on memory functions but not on the patients' psychotic state or on the side effects of medications. These preliminary results suggest the possibility of using serotonin precursor to enhance memory function in schizophrenia.

NMDA receptor antagonist effects, cortical glutamatergic function, and schizophrenia: toward a paradigm shift in medication development

There is an urgent need to improve the pharmacotherapy of schizophrenia despite the introduction of important new medications. New treatment insights may come from appreciating the therapeutic implications of model psychoses. In particular, basic and clinical studies have employed the N-methyl-D-aspartate (NMDA) glutamate receptor antagonist, ketamine, as a probe of NMDA receptor contributions to cognition and behavior. These studies illustrate a translational neuroscience approach for probing mechanistic hypotheses related to the neurobiology and treatment of schizophrenia and other disorders. Two particular pathophysiologic themes associated with schizophrenia, the disturbance of cortical connectivity and the disinhibition of glutamatergic activity may be modeled by the administration of NMDA receptor antagonists. The purpose of this review is to consider the possibility that agents that attenuate these two components of NMDA receptor antagonist response may play complementary roles in the treatment of schizophrenia.

Emotion perception in schizophrenia: an eye movement study comparing the effectiveness of risperidone vs. haloperidol

We used a psychophysiological marker of visual attention (the visual scanpath) to investigate the effects of atypical (risperidone) vs. typical (haloperidol) antipsychotic medication on facial emotion perception in schizophrenia (n=28) and healthy control (n=28) groups. Of the schizophrenia subjects, 15 were prescribed risperidone. Visual scanpaths to 'happy', 'sad' and 'neutral' faces were recorded using video-oculography, and concurrent emotion-recognition accuracy was assessed using multiple-option tasks. Compared to control subjects, both schizophrenia subgroups showed a restriction in visual scanning (reduced total fixation number and decreased scanpath length). Haloperidol-treated schizophrenia subjects exhibited an additional and consistent pattern of reduced attention (fixation) to salient features for neutral and happy. By contrast, risperidone-treated subjects showed a relatively greater attention to salient features for these expressions, in which they did not differ from controls. Recognition accuracy for happy and neutral showed a similar lack of impairment. These findings suggest that risperidone may play a specific role in schizophrenia in the ability to attend to salient features, and to integrate this information into an accurate percept for neutral and positive expressions in particular.

Comparison of cognitive performances during a placebo period and an atypical antipsychotic treatment period in schizophrenia: critical examination of confounds

Although previous studies report cognitive improvement following atypical antipsychotic administration in schizophrenia (SC), few placebo-controlled within-subject studies with examination of confounds (symptom reduction, cooperation, learning, and outliers) have been reported. The present study examines the effects of atypicals and confounds upon cognition in SC. The hypothesis tested was that relative to placebo, atypicals as a general class of medication would elicit cognitive improvement in SC. In all, 19 patients with SC (15 males) completed the double-blind, counterbalanced, randomized within-subject study of the effects of atypical antipsychotics (risperidone, clozapine, olanzapine, or quetiapine) vs placebo administration upon cognitive performance in the domains of executive function, attention, memory, language, visual perception, and general intellect. Significant cognitive improvement during atypical antipsychotic administration relative to placebo withdrawal occurred in most cognitive domains with robust improvements in intelligence (p=0.001), memory (p=0.0009), and fluency (p <0.002) even after outliers and unmotivated performances were excluded. These findings suggest that relative to placebo withdrawal, atypicals improve cognitive performance in SC. However, this finding may not be specific to atypicals, since analogous studies of typicals have not been performed.

Altered effective connectivity during working memory performance in schizophrenia: a study with fMRI and structural equation modeling

The present study aimed to explore altered effective connectivity in schizophrenic patients while performing a 2-back working memory task. Twelve right-handed, schizophrenic patients treated with typical or atypical antipsychotics and 6 healthy control subjects were studied with fMRI while performing a "2-back" working memory task. Effective connectivity within a cortical-subcortical-cerebellar network for mnemonic information processing was assessed and compared between both groups. The path model included cortico-cortical connections comprising the parietal association cortex, ventrolateral prefrontal cortex (VLPFC), and the dorsolateral prefrontal cortex (DLPFC) as well as a cortico-cerebellar feedback loop comprising prefrontal cortex, contralateral cerebellum, and thalamus. Group differences were analyzed with a stacked models approach. Relative to normal controls, both patient groups revealed a pattern of reduced connectivity within the prefrontal-cerebellar and the cerebellar-thalamic limbs but enhanced connectivity in the thalamo-cortical limb of the cortical-cerebellar circuit. Moreover, a direct comparison of both treatment groups revealed enhanced connectivity in the interhemispheric connections between the cortical association areas in patients treated with atypical antipsychotics. However, right prefrontal and left parieto-frontal path coefficients were lower in the patient group receiving atypical antispychotic drugs. The findings suggest that the relationship between pathology in cortical-subcortical cerebellar networks and associated functional connectivity is complex and may include aspects of increased and decreased levels of connectivity consistent with the notion of "cognitive dysmetria" in schizophrenia. The observed pronounced connectivity within thalamo-cortical projections could be attributed to a compensatory increase of thalamic input in the presence of disrupted effective connectivity within the preceding limb of the cortical-cerebellar circuitry. The study demonstrated the feasibility of structural equation modeling for the investigation of group and treatment-related differences in effective connectivity and provides a promising approach to further disentangle the relationship between altered functional capacity and associated fMRI signal changes.

Four facets of a single brain: behaviour, cerebral blood flow/metabolism, neuronal activity and neurotransmitter dynamics

Is functional neuroimaging a royal way to understand brain function or is it a new phrenology without an exact understanding what we measure? After two decades of imaging revolution, more and more authors ask this question. Brain functions are multidimensional, which can be approached from the point of (1) behavioural measures, (2) brain activation as reflected by blood flow and metabolic changes, (3) electrical activity of cells and cell-populations, and (4) neurotransmitter dynamics (release, receptor binding and reuptake). Using imaging techniques, we must take into consideration that even during the simplest task all of these processes operate in a closely interacting manner. Therefore, before drawing final conclusions about brain functions on the basis of a single aspect of these mechanisms, we must clarify the exact relationship among them. In this paper, we address this issue in order to draw attention to a number of uncertainties and controversies in the relationship of the four facets of brain functions.

Prefrontal cortex dysfunction during working memory performance in schizophrenia: reconciling discrepant findings

Working memory (WM) deficits are a persistent, disabling and relatively treatment-resistant feature of schizophrenia that may underlie many cognitive deficits and symptoms. They are associated with prefrontal cortex dysfunction. While most neuroimaging studies of WM demonstrate "task-related hypofrontality" in schizophrenic relative to healthy subjects, several recent studies have reported equal or increased prefrontal activity. These findings challenge central assumptions regarding cognitive deficits and prefrontal cortex dysfunction in schizophrenia. The goal of this review is to reconcile these seemingly discrepant findings. Methodological factors addressed include the use of intersubject averaging, WM task parameters and the reliability of the measures. Factors intrinsic to schizophrenia and their relevance to the selection of experimental methods and the interpretation of group data are also discussed. Both hypo- and hyperfrontality are hypothesized to be valid and informative reflections of prefrontal cortex dysfunction in schizophrenia. Due to the heterogeneity and variability of both performance and regional recruitment in schizophrenia, whether individual data is considered, the level and type of WM demands and the composition of the sample with regard to performance deficits all influence study outcome and contribute to discrepancies. Although the prefrontal cortex is consistently implicated in WM deficits, the basis of its dysfunction and its exact contribution remain unclear. Future work might focus on delineating the exact WM processes, domains and components that are deficient. In addition, variability in behavior and activation might best be regarded as intrinsic to schizophrenia and having a neural basis that requires explanation. In combination with other techniques, neuroimaging can identify the neural circuitry responsible for WM deficits and elucidate the contribution of each anatomical component.

The new and evolving pharmacotherapy of schizophrenia

Based on the evidence presented here, the following tentative conclusions can be drawn. Atypical antipsychotics (except amisulpride) have shown superiority over placebo in acute schizophrenia. Compared with conventional antipsychotics, they are at least as effective. Generally, analyses employing conservative criteria (e.g., Cochrane reviews) report few efficacy differences between atypical and conventional agents. There are now many well-controlled studies indicating modest advantages for the atypical antipsychotics, however, particularly in specific symptom domains. For the treatment of negative symptoms, olanzapine and to a lesser extent amisulpride seem most promising. Risperidone, olanzapine, and quetiapine display advantages in improving cognitive and depressive symptoms. There are indications that the atypical antipsychotics are associated with decreased likelihood of rehospitalization and improved quality of life. In head-to-head comparisons of atypical antipsychotics, none have shown consistent efficacy advantages. In severely refractory samples, no atypical antipsychotics have consistently been shown to be as effective as clozapine or superior to conventional agents. There are indications, however, that risperidone, olanzapine, and quetiapine have advantages over conventional agents in less severely refractory patients. Few maintenance RCTs have been published, and efficacy advantages for atypical antipsychotics in prospective RCTs in first-episode schizophrenia have not been reported.

The use of atypical antipsychotics in traumatic brain injury

The use of antipsychotic medication in treating individuals with traumatic brain injury (TBI) has been controversial. Much of the caution derives from animal studies (and limited human data) with regard to typical antipsychotics. Of note, however, is that similar assumptions have been made about the newer generation of atypical antipsychotics as well. Because these agents have different mechanisms of action as well as different neurotransmitter targets, this may very well be unwarranted. In this article, mechanisms of action of typical and atypical antipsychotics are discussed, with particular attention paid to their use in TBI. Indications and contraindications are presented, and recommendations are made for the responsible prescribing of antipsychotic medications after TBI.

Cross-national cognitive assessment in schizophrenia clinical trials: a feasibility study

Clinical trials for the treatment of schizophrenia now often include cognitive assessments in addition to clinical ratings of symptoms. Recently, these trials have included cross-national assessments. It is not clear if translated psychological tests produce consistent results across different languages. This paper presents the results of a study of the comparability of the results of cognitive assessments in different English-speaking countries and a number of countries where tests were translated into other languages. Performance on tests of executive functioning, verbal and visuo-spatial learning and memory, language skills, psychomotor speed, and vigilance was compared across the first episode patients with schizophrenia (n = 301) assessed in six different languages (English, French, Finnish, German, Hebrew, and Afrikaans), including two different countries where patients were assessed in English and other languages: Canada (French) and South Africa (Afrikaans). The variance in performance across the sites tested in English was as large as the variance between English and non-English speakers when all tests were considered. Performance differences across English and other languages were found only for executive functions, vigilance, and psychomotor speed, with executive functioning differences nonsignificant when education was considered. No differences were found between English and non-English speakers in Canada. These results suggest that the translation of tests of memory and verbal skills can lead to consistent results across translated versions of the tests. Differences between countries were greater than differences between languages, suggesting the need to consider representativeness of patient samples in terms of local educational attainment. In general, these data support the validity of cross-national neuropsychological assessments.

Effects of the 5-HT2A agonist psilocybin on mismatch negativity generation and AX-continuous performance task: implications for the neuropharmacology of cognitive deficits in schizophrenia

Previously the NMDA (N-methyl-D-aspartate) receptor (NMDAR) antagonist ketamine was shown to disrupt generation of the auditory event-related potential (ERP) mismatch negativity (MMN) and the performance of an 'AX'-type continuous performance test (AX-CPT)--measures of auditory and visual context-dependent information processing--in a similar manner as observed in schizophrenia. This placebo-controlled study investigated effects of the 5-HT(2A) receptor agonist psilocybin on the same measures in 18 healthy volunteers. Psilocybin administration induced significant performance deficits in the AX-CPT, but failed to reduce MMN generation significantly. These results indirectly support evidence that deficient MMN generation in schizophrenia may be a relatively distinct manifestation of deficient NMDAR functioning. In contrast, secondary pharmacological effects shared by NMDAR antagonists and the 5-HT(2A) agonist (ie disruption of glutamatergic neurotransmission) may be the mechanism underlying impairments in AX-CPT performance observed during both psilocybin and ketamine administration. Comparable deficits in schizophrenia may result from independent dysfunctions of 5-HT(2A) and NMDAR-related neurotransmission.

The effect of melperone, an atypical antipsychotic drug, on cognitive function in schizophrenia

Melperone, a butyrophenone, has been shown to possess atypical antipsychotic properties, i.e. ability to produce an antipsychotic effect in man at doses that cause minimal extrapyramidal side effects. In addition, melperone shares the following with other atypical antipsychotic drugs: (1) effectiveness for ameliorating negative symptoms; (2) no prolactin elevation; and (3) effectiveness in the treatment of some patients with neuroleptic-resistant schizophrenia. Other atypical antipsychotic drugs have been reported to improve cognitive function. This study was performed to investigate the effect of melperone on cognitive function. Nineteen patients with schizophrenia or schizoaffective disorder, including 11 neuroleptic-resistant patients, were treated with melperone for 6 weeks. A comprehensive neurocognitive test battery and psychopathological ratings (Brief Psychiatric Rating Scale, BPRS) were administered at baseline and after 6 weeks of melperone treatment. Treatment with melperone was associated with improvement in executive function, as measured by the Wisconsin Card Sorting Test (WCST)-Categories and WCST-Percent Perseveration. On the other hand, visuospatial manipulation, as measured by the Wechsler Intelligent Scale for Children-Revised (WISC-R) Maze, worsened during melperone treatment. There were no significant changes in other domains of cognition, i.e. verbal learning and memory, verbal working memory, verbal fluency and sustained attention. Scores of WCST-Categories and Perseveration at 6 weeks were predicted from the relevant cognitive test scores at baseline and the change in BPRS Total and Positive scores. These results suggest the usefulness of melperone for facilitating work and social function in patients with schizophrenia. The differences in the cognition-enhancing abilities between melperone and clozapine are discussed.

Cognitive effects and antipsychotic treatment

Cognitive impairment has long been recognized as central to the abnormalities that occur in schizophrenia, since neurocognitive deficits are predictive of a number of outcome indices, and they pose a significant obstacle to any attempts at social rehabilitation. This raises the possibility that treatments producing improvements in cognitive function might, in turn, prove to have synergistic effects with psychosocial interventions. Rather than improving cognitive deficits, conventional antipsychotics may instead contribute to the impairment seen in many patients with schizophrenia. These damaging effects on cognition might be expected not only when antipsychotic drugs with intrinsic anticholinergic properties are used but also when anticholinergic drugs are prescribed for the relief of treatment-emergent extrapyramidal symptoms. The atypical antipsychotic drugs may be effective in this area, either in amelioration of the cognitive impairments that occur in schizophrenia or in arresting any continuing decline. New-generation atypical agents, such as quetiapine and risperidone, have minimal intrinsic anticholinergic effects, which suggest that some of the additional negative effects on cognition can be avoided. A number of large-scale, long-term follow-up studies of atypical antipsychotics are currently underway, in 'real world' settings, to assess not only control of symptoms of schizophrenia but also improvement in social, occupational, and inter-personal functioning.

Does risperidone act better in schizophrenic patients who have a family or obstetric history?

PURPOSE

The aim of the study was to assess the effect of treatment with risperidone on psychopathological symptoms and cognitive deficits in schizophrenic patients, in relation to family history, obstetric complications and duration of the illness.

METHODS

Fifty schizophrenic inpatients (29 males, 21 females), aged 16-50 (mean 28 years), with duration of the illness 1-15 (mean 4 years) who successfully completed a 3-month risperidone treatment were included into the study. Family history of psychiatric illness and the presence of obstetric complications were estimated by a semistructured questionnaire. Schizophrenic symptoms were assessed using the Positive and Negative Symptoms Scale (PANSS). Cognitive abilities were measured by neuropsychological "frontal lobe" tests: Trail Making Test (TMT), part B, Stroop Color Word Interference Test, part B, and Wisconsin Card Sorting Test (WCST). The clinical and neuropsychological evaluation was performed before and after 3 months of risperidone treatment, in doses 2-6 mg (mean 4.2 mg/day).

RESULTS

Before treatment, patients with family history had significantly higher intensity of negative symptoms, and obtained worse results on WCST perseverative errors (PE) and correct categories (CC). These measures were also impaired in subjects with obstetric complications. Additionally, in patients with obstetric complications, total and general PANSS psychopathology was higher and the results of Stroop B were worse. After a 3-month treatment with risperidone, no difference between respective groups was observed both in psychopathology and in neuropsychological tests. Patients with obstetric complications had higher degree of improvement on positive and negative symptoms and on TMT-B than the remaining ones. Patients with longer duration of the illness had less improvement on positive symptoms with risperidone treatment.

CONCLUSIONS

The results of this study show that treatment with risperidone results in better compensation of psychopathological (negative symptoms) and neuropsychological (working memory) deficits in patients who have a family history and/or obstetric complications. This may be due to a favourable effect of risperidone on the prefrontal cortex dysfunction mediating these deficits.

Impact of risperidone versus haloperidol on activities of daily living in the treatment of refractory schizophrenia

Risperidone has been shown to improve verbal working memory, executive functioning, attention, reaction time, and verbal learning, which, in turn, have been associated with improved functional outcomes. We tested whether risperidone was associated with greater improvements than haloperidol in activities of daily living (ADLs) among persons having treatment-refractory schizophrenia. In a double-blind, controlled trial of fixed and flexible doses of haloperidol and risperidone, changes in ADLs were operationally monitored on a behavior therapy unit of a state hospital. While no differential effects were noted between risperidone and haloperidol in ADLS, these self-care skills significantly improved as subjects spent longer times on the behavior therapy unit. Working memory and verbal learning did correlate with improvements in ADLs, independent of drug condition. The contingencies of reinforcement and specific training programs on the behavior therapy unit may have been prepotent for the learning of ADLs, obscuring any differential impact of risperidone. Moreover, ADLs may be governed more by "procedural" learning than by working memory or verbal learning, with the former not differentially influenced by typical verus atypical antipsychotics.

Spatial working memory span, delayed response and executive function in schizophrenia

This study investigated the spatial working memory span (SWMS) as well as the immediate memory span of schizophrenic patients, and examined the contribution of each span to the patients' executive function deficit in the visuospatial domain. SWMS measured the visuospatial working memory capacity that simultaneously processes and stores visuospatial information. Immediate memory span was measured with the spatial span (SS), a variant of Corsi's block-tapping test. A total of 16 patients diagnosed with schizophrenia and 16 normal control subjects participated in the study. SWMS, as well as the forward and backward SS, was significantly reduced in schizophrenia. The SWMS deficit observed in this study and previous findings of deficit in verbal working memory spans suggest that impairment in working memory capacity in schizophrenia is general, and not limited to the verbal domain. Executive function as assessed with the self-ordered pointing task (SOPT) was also impaired in the patients, which is consistent with clinical observations of self-monitoring impairment in schizophrenia. SWMS was able to account for the performance on the SOPT, but its contribution in the patients' impairment did not reach statistical significance. Backward span deficit explained this executive function impairment. SWMS was effective in explaining schizophrenic patients' impaired performance on the spatial delayed response, a prefrontal function task. Implications of the relations observed between the spans and the prefrontal function tasks are discussed.

Costs and outcomes of risperidone treatment in schizophrenia in the Czech Republic

The increasing cost of pharmaceuticals in the Czech Republic has led to restrictions on the prescription of more expensive atypical antipsychotics. The aim of the study was to compare the costs and outcomes of using risperidone versus classical neuroleptics in treatment of schizophrenia in order to see if there was any cost advantage in restricting use of more recent antipsychotics. Sixty-seven patients (39 women) with a mean age of 34.6 years (S.D. = 9.74) suffering from schizophrenia or schizoaffective disorder were treated with risperidone while 67 patients (39 women) with the same diagnoses with a mean age of 35.7 years (S.D. = 9.91) received standard neuroleptics. Yearly direct medical costs and outcomes (indicated by the average Global Assessment of Functioning score) were assessed retrospectively in an open, intent-to-treat study by abstracting psychiatric outpatient charts. The outcomes were not significantly different between the treatment groups while the risperidone treatment was significantly more expensive than the therapy with standard neuroleptics. This result which appears to be inconsistent with the literature was caused by the cheap labor force in the Czech Republic. The difference between the followed treatments in the direct costs will probably become insignificant in the future when the country's economy will be more developed.

Substance misuse in patients with schizophrenia: epidemiology and management

Substance misuse in individuals with schizophrenia is very common, especially in young men, in communities where use is frequent and in people receiving inpatient treatment. Problematic use occurs at very low intake levels, so that most affected people are not physically dependent (with the exception of nicotine). People with schizophrenia and substance misuse have poorer symptomatic and functional outcomes than those with schizophrenia alone. Unless there is routine screening, substance misuse is often missed in assessments. Service systems tend to be separated, with poor inter-communication, and affected patients are often excluded from services because of their comorbidity. However, effective management of these disorders requires a fully integrated approach because of the close inter-relationship of the disorders. Use of atypical antipsychotics may be especially important in this population because of growing evidence (especially on clozapine and risperidone) that nicotine smoking, alcohol misuse and possibly some other substance misuse is reduced. Several pharmacotherapies for substance misuse can be used safely in people with schizophrenia, but the evidence base is small and guidelines for their use are necessarily derived from experience in the general population.

The psychopathology, medical management and dental implications of schizophrenia

BACKGROUND

Schizophrenia is a psychiatric illness characterized by thought disturbances, bizarre behaviors and cognitive impairments that may diminish a person's abilities in the areas of social relations, school or work and self-care. The onset of the disorder typically occurs between the late teens and mid-30s. Advanced dental disease is seen frequently in patients with schizophrenia for several reasons: the disease impairs these patients' ability to plan and perform oral hygiene procedures; some of the antipsychotic medications they take have adverse orofacial effects such as xerostomia; and these patients sometimes have limited access to treatment because of a paucity of financial resources and adequate number of dentists comfortable in providing care. The recent introduction of more effective medications has permitted the majority of patients to receive their psychiatric care from community-based providers rather than in the hospital. Consequently, dentists in the private sector also are being called on more frequently to care for these people.

CONCLUSIONS

Dentists cognizant of the signs and symptoms of schizophrenia are likely to feel more secure in treating patients with schizophrenia and more confident when obtaining consultative advice from the patients' psychiatrists. Dentists usually can provide a full range of services to such patients, can enhance these patients' self-esteem and can contribute to the psychotherapeutic aspect of management.

CLINICAL IMPLICATIONS

To effectively provide treatment to patients with schizophrenia, dentists must be familiar with the disease process so that they can communicate effectively with the patient, the treating psychiatrist and family members who serve as caregivers. In addition, dental treatment may need to be modified because of the patient's impaired ability to think logically, the local and systemic effects of psychiatric medications, and adverse interactions between these drugs and medications used in dentistry.

Improved antisaccade performance with risperidone in schizophrenia

OBJECTIVE

Antisaccade errors are consistently increased in schizophrenia. As they have been demonstrated only in cross sectional studies, it is unclear how they vary longitudinally or with different medications. In a previous cross sectional study, we reported a trend towards a reduction in error rates in a patient group treated with risperidone, compared with clozapine and sulpiride treated groups.

METHODS

Gap random and antisaccade paradigms were performed on two occasions in the same sample of DSM-IV schizophrenic patients (n=12) in transition between conventional antipsychotic drugs and risperidone. A cross over design was used with six patients switching from risperidone to conventional (group I) and six in the opposite direction (group II). A control sample (n=12) was also tested on two occasions and their performance compared. The effects of practice between first and second testing and of switching between conventional antipsychotic drugs and risperidone and vice versa was also evaluated.

RESULTS

A significant reduction in error rate was demonstrated during risperidone treatment (n=12), compared with conventional APD treatment. Switching from conventional to risperidone produced a reduction in errors, and vice versa.

CONCLUSIONS

Treatment with risperidone was associated with improvement in antisaccade errors.

A double blind placebo controlled trial of donepezil adjunctive treatment to risperidone for the cognitive impairment of schizophrenia

BACKGROUND

Despite the beneficial effects of atypical antipsychotics on cognition, these improvements will not return most schizophrenic patients to normative standards of cognitive functioning. Therefore, other treatments need to be considered. Subtle changes in cholinergic function in schizophrenic patients provide the rationale to test the effectiveness of cholinesterase inhibitors in treating cognitive impairment in schizophrenia.

METHODS

Given this, a 12-week, double-blind, placebo-controlled trial of donepezil (5 mg and 10 mg) as adjunctive treatment to risperidone was conducted in a total of 36 schizophrenic patients.

RESULTS

Neither the 5-mg nor 10-mg dose of donepezil produced significant improvements in any cognitive measure compared with placebo.

CONCLUSIONS

It is possible that nicotinic receptor desensitization produced by chronic tobacco use in these patients rendered their nicotinic receptors refractory to the effects of increased agonist activity produced by donepezil. An alternative treatment is the allosterically potentiating ligands, which enhance the activity of (sensitize) nicotinic receptors in the presence of acetylcholine.

Does cognitive function improve with quetiapine in comparison to haloperidol?

Recent evidence suggests that schizophrenia patients taking atypical antipsychotic medications may perform better on some tests of cognitive function than those treated with older antipsychotics. The current study compared the effects of quetiapine and haloperidol on measures of executive function, memory and attention. Subjects were 58 stable outpatients with schizophrenia (DSM III-R) who received a battery of cognitive tests as part of a randomized, double-blind, multi-site clinical efficacy study conducted by AstraZeneca Pharmaceuticals. Cognitive assessments were conducted prior to randomization when patients were receiving < or =30 mg haloperidol or equivalent (mean: 9.2mg/day haloperidol equivalents), and again after 24 weeks of fixed-dose treatment with either quetiapine 600 or 300 mg/day or haloperidol 12 mg/day. Analyses of covariance with planned comparisons were used to compare scores on cognitive measures at the end of 24 weeks by treatment group with baseline cognitive function scores used as covariates. Patients receiving quetiapine 600 mg/day improved to a greater extent than patients receiving haloperidol on overall cognitive function (p<0.02). Specific differences were found for executive function (Verbal Fluency Test, p<0.04), attention (Stroop Color Word Test, p<.03) and verbal memory (Paragraph Recall Test, p<0.02). Treatment group differences were not solely due to benztropine use, medication side effects, or changes in symptomatology. Treatment with quetiapine at higher doses (600 mg/day) relative to haloperidol appears to have a positive impact on important domains of cognitive performance that have been found to predict role function and community outcomes in patients with schizophrenia.