Comparative placebo-controlled pharmacodynamic studies with zotepine and clozapine utilizing pharmaco-EEG and psychometry

Quantitative Resting State Electroencephalography in Patients with Schizophrenia Spectrum Disorders Treated with Strict Monotherapy Using Atypical Antipsychotics

OBJECTIVE

The effect of antipsychotic drugs on quantitative electroencephalography (EEG) has been mainly examined by the administration of a single test dose or among patients using combinations of other psychotropic drugs. We therefore investigated the effects of strict monotherapy with antipsychotic drugs on quantitative EEG among schizophrenia patients.

METHODS

Data from 2,364 medical reports with EEG results from psychiatric patients admitted to the Hokkaido University Hospital were used. We extracted EEG records of patients who were diagnosed with schizophrenia spectrum disorders and who were either undergoing strict antipsychotic monotherapy or were completely free of psychotropic drugs. The spectral power was compared between drug-free patients and patients using antipsychotic drugs. We also performed multiple regression analysis to evaluate the relationship between spectral power and the chlorpromazine equivalent daily dose of antipsychotics in all the patients.

RESULTS

We included 31 monotherapy and 20 drug-free patients. Compared with drug-free patients, patients receiving antipsychotic drugs demonstrated significant increases in theta, alpha and beta power. When patients taking different types of antipsychotics were compared with drug-free patients, we found no significant change in any spectrum power for the aripiprazole or blonanserin groups. Patients taking risperidone demonstrated significant increases in alpha and beta power. Patients taking clozapine and olanzapine demonstrated significant slow wave increases. Multiple regression analysis revealed that the chlorpromazine equivalent dose was positively associated with theta power.

CONCLUSION

Use of any antipsychotic drug by patients was associated with a dose-dependent increase in theta power. However, each type of antipsychotic demonstrated different spectral power changes.

Modulation of mGlu2 Receptors, but Not PDE10A Inhibition Normalizes Pharmacologically-Induced Deviance in Auditory Evoked Potentials and Oscillations in Conscious Rats

Improvement of cognitive impairments represents a high medical need in the development of new antipsychotics. Aberrant EEG gamma oscillations and reductions in the P1/N1 complex peak amplitude of the auditory evoked potential (AEP) are neurophysiological biomarkers for schizophrenia that indicate disruption in sensory information processing. Inhibition of phosphodiesterase (i.e. PDE10A) and activation of metabotropic glutamate receptor (mGluR2) signaling are believed to provide antipsychotic efficacy in schizophrenia, but it is unclear whether this occurs with cognition-enhancing potential. The present study used the auditory paired click paradigm in passive awake Sprague Dawley rats to 1) model disruption of AEP waveforms and oscillations as observed in schizophrenia by peripheral administration of amphetamine and the N-methyl-D-aspartate (NMDA) antagonist phencyclidine (PCP); 2) confirm the potential of the antipsychotics risperidone and olanzapine to attenuate these disruptions; 3) evaluate the potential of mGluR2 agonist LY404039 and PDE10 inhibitor PQ-10 to improve AEP deficits in both the amphetamine and PCP models. PCP and amphetamine disrupted auditory information processing to the first click, associated with suppression of the P1/N1 complex peak amplitude, and increased cortical gamma oscillations. Risperidone and olanzapine normalized PCP and amphetamine-induced abnormalities in AEP waveforms and aberrant gamma/alpha oscillations, respectively. LY404039 increased P1/N1 complex peak amplitudes and potently attenuated the disruptive effects of both PCP and amphetamine on AEPs amplitudes and oscillations. However, PQ-10 failed to show such effect in either models. These outcomes indicate that modulation of the mGluR2 results in effective restoration of abnormalities in AEP components in two widely used animal models of psychosis, whereas PDE10A inhibition does not.

The effects of combined caffeine and glucose drinks on attention in the human brain

The objective of this research was to measure the effects of energising drinks containing caffeine and glucose, upon mental activity during sustained selective attention. Non-invasive electrophysiological brain recordings were made during a behavioural study of selective attention in which participants received either energising or placebo drinks. We tested specifically whether energising drinks have significant effects upon behavioural measures of performance during a task requiring sustained visual selective attention, as well as on accompanying components of the event-related potential (ERPs) related to information processing in the brain. Forty healthy volunteers were blindly assigned to receive either the energising drink or a similar-tasting placebo drink. The behavioural task involved identifying predefined target stimulus among rapidly presented streams of peripheral visual stimuli, and making speeded motor responses to this stimulus. During task performance, accuracy, reaction times and ongoing brain activity were stored for analysis. The energising drink enhanced behavioural performance both in terms of accuracy and speed of reactions. The energising drink also had significant effects upon the event-related potentials. Effects started from the enhancement of the earliest components (Cl/P1), reflecting early visual cortical processing in the energising-drink group relative to the placebo group over the contralateral scalp. The later N1, N2 and P3 components related to decision-making and responses were also modulated by the energising drink. Energising drinks containing caffeine and glucose can enhance behavioural performance during demanding tasks requiring selective attention. The behavioural benefits are coupled to direct effects upon neural information processing.

Clozapine administration ameliorates disrupted long-range synchrony in a neurodevelopmental animal model of schizophrenia

The abnormal synchronisation of neural networks may underlie some of the deficits observed in schizophrenia. Abnormal synchronisation can be induced in animal models. We investigated whether acute clozapine treatment might function therapeutically by ameliorating the deficit in theta frequency coherence between the prefrontal cortex and the hippocampus that is induced in rats exposed to maternal immune activation (MIA)--a risk-factor for schizophrenia. Clozapine treatment increased synchrony levels to that of control animals in a dose-dependent manner. Clozapine's effect on synchrony may in part be mediated through increases in local synchrony that occurred in prefrontal cortex but not hippocampus.

Clozapine versus other atypical antipsychotics for schizophrenia

BACKGROUND

Clozapine is an atypical antipsychotic demonstrated to be superior in the treatment of refractory schizophrenia which causes fewer movement disorders. Clozapine, however, entails a significant risk of serious blood disorders such as agranulocytosis which could be potentially fatal. Currently there are a number of newer antipsychotics which have been developed with the purpose to find both a better tolerability profile and a superior effectiveness.

OBJECTIVES

To compare the clinical effects of clozapine with other atypical antipsychotics (such as amisulpride, aripiprazole, olanzapine, quetiapine, risperidone, sertindole, ziprasidone and zotepine) in the treatment of schizophrenia and schizophrenia-like psychoses.

SEARCH STRATEGY

We searched the Cochrane Schizophrenia Groups Register (June 2007) and reference lists of all included randomised controlled trials. We also manually searched appropriate journals and conference proceedings relating to clozapine combination strategies and contacted relevant pharmaceutical companies.

SELECTION CRITERIA

All relevant randomised, at least single-blind trials, comparing clozapine with other atypical antipsychotics, any dose and oral formulations, for people with schizophrenia or related disorders.

DATA COLLECTION AND ANALYSIS

We selected trials and extracted data independently. For dichotomous data we calculated relative risks (RR) and their 95% confidence intervals (CI) based on a random-effects model. We calculated numbers needed to treat/harm (NNT/NNH) where appropriate. For continuous data, we calculated mean differences (MD) again based on a random-effects model.

MAIN RESULTS

The review currently includes 27 blinded randomised controlled trials, which involved 3099 participants. Twelve randomised control trials compared clozapine with olanzapine, five with quetiapine, nine with risperidone, one with ziprasidone and two with zotepine. Attrition from these studies was high (overall 30.1%), leaving the interpretation of results problematic. Clozapine had a higher attrition rate due to adverse effects than olanzapine (9 RCTs, n=1674, RR 1.60 CI 1.07 to 2.40, NNT 25 CI 15 to 73) and risperidone (6 RCTs, n=627, RR 1.88 CI 1.11 to 3.21, NNT 16 CI 9 to 59). Fewer participants in the clozapine groups left the trials early due to inefficacy than risperidone (6 RCTs, n=627, RR 0.40 CI 0.23 to 0.70, NNT 11 CI 7 to 21), suggesting a certain higher efficacy of clozapine.Clozapine was more efficacious than zotepine in improving the participants general mental state (BPRS total score: 1 RCT, n=59, MD -6.00 CI -9.83 to -2.17), but not consistently more than olanzapine, quetiapine, risperidone and ziprasidone. There was no significant difference between clozapine and olanzapine or risperidone in terms of positive or negative symptoms of schizophrenia. According to two studies from China quetiapine was more efficacious for negative symptoms than clozapine (2 RCTs, n=142, MD 2.23 CI 0.99 to 3.48).Clozapine produced somewhat fewer extrapyramidal side-effects than risperidone (use of antiparkinson medication: 6 RCTs, n=304, RR 0.39 CI 0.22 to 0.68, NNT 7 CI 5 to 18) and zotepine (n=59, RR 0.05 CI 0.00 to 0.86, NNT 3 CI 2 to 5). More participants in the clozapine group showed decreased white blood cells than those taking olanzapine, more hypersalivation and sedation than those on olanzapine, risperidone and quetiapine and more seizures than people on olanzapine and risperidone. Also clozapine produced an important weight gain not seen with risperidone.Other differences in adverse effects were less documented and should be replicated, for example, clozapine did not alter prolactin levels whereas olanzapine, risperidone and zotepine did; compared with quetiapine, clozapine produced a higher incidence of electrocardiogram (ECG) alterations; and compared with quetiapine and risperidone clozapine produced a higher increase of triglyceride levels. Other findings that should be replicated were: clozapine improved social functioning less than risperidone and fewer participants in the clozapine group had to be hospitalised to avoid suicide attempts compared to olanzapine.Other important outcomes such as service use, cognitive functioning, satisfaction with care or quality of life were rarely reported.

AUTHORS' CONCLUSIONS

Clozapine may be a little more efficacious than zotepine and risperidone but further trials are required to confirm this finding. Clozapine differs more clearly in adverse effects from other second generation antipsychotics and the side-effect profile could be key in the selection of treatment depending on the clinical situation and a patient's preferences. Data on other important outcomes such as cognitive functioning, quality of life, death or service use are currently largely missing, making further large and well-designed trials necessary. It is also important to take into account that the large number of people leaving the studies early limits the validity and interpretation of our findings.

Zotepine versus other atypical antipsychotics for schizophrenia

BACKGROUND

In many parts of the world, particularly in industrialised countries, second generation (atypical) antipsychotic drugs have become first line treatment for people suffering from schizophrenia. The question as to whether the effects of various second generation antipsychotic drugs differ is a matter of debate.

OBJECTIVES

To evaluate the effects of zotepine compared with other second generation antipsychotic drugs for people suffering from schizophrenia and schizophrenia-like psychoses.

SEARCH STRATEGY

We searched the Cochrane Schizophrenia Group Trials Register (November 2009), inspected references of all identified studies for further trials and contacted authors of trials for additional information.

SELECTION CRITERIA

We included only randomised clinical controlled trials that compared zotepine with any forms of amisulpride, aripiprazole, clozapine, olanzapine, risperidone, sertindole or ziprasidone in people suffering from only schizophrenia or schizophrenia-like psychoses.

DATA COLLECTION AND ANALYSIS

SS and KK extracted data independently. For dichotomous data we calculated relative risks (RR) and their 95% confidence intervals (CI) on an intention-to-treat basis based on a random-effects model. For continuous data, we calculated weighted mean differences (MD) again based on a random-effects model.

MAIN RESULTS

We included three studies (total n=289; 2 RCTs zotepine vs clozapine; 1 RCT zotepine vs clozapine vs risperidone (at 4 mg, 8 mg doses) vs remoxipride. All studies were of limited methodological quality. When zotepine was compared with clozapine, it was clozapine that was found to be more effective in terms of global state (n=59, 1 RCT, RR No clinically significant response 8.23 CI 1.14 to 59.17). Mental state scores also favoured clozapine (n=59, 1 RCT, MD average score (BPRS total, high = poor) 6.00 CI 2.17 to 9.83) and there was less use of antiparkinson medication in the clozapine group (n=116, 2 RCTs, RR 20.96 CI 2.89 to 151.90). In the comparison of zotepine and risperidone, mental state scoring found no significant difference between the groups (vs 4 mg: n=40, 1 RCT, MD average endpoint score (BPRS total, high=poor) 1.40 CI -9.82 to 12.62; vs 8 mg: n=40, 1 RCT, MD -1.30 CI -12.95 to 10.35) and use of antiparkinson medication was equivocal (vs 4 mg: n=40, 1 RCT, MD 1.80 CI -0.64 to 4.24; vs 8 mg: n=40, 1 RCT, MD 2.50 CI -0.05 to 5.05). Finally, when zotepine was compared with remoxipride, again no effect was found for mental state (n=58, 1 RCT, MD average endpoint score (BPRS total, high=poor) 5.70 CI -4.13 to 15.53) and there was no significant difference between the two groups in terms of use of antiparkinson medication (n=49, 1 RCT, RR 0.97 CI 0.41 to 2.29).Data on important other outcomes such as other adverse events, service use or satisfaction with care, quality of life were not available.

AUTHORS' CONCLUSIONS

The evidence base around zotepine is insufficient to provide firm conclusions on its absolute or relative effects. This is despite it being in use in Austria, France, Germany, Japan and the UK.

Patterns of spontaneous magnetoencephalographic activity in patients with schizophrenia

Magnetoencephalography noninvasively measures the magnetic fields produced by the brain. Pertinent research articles from 1993 to 2009 that measured spontaneous, whole-head magnetoencephalography activity in patients with schizophrenia were reviewed. Data on localization of oscillatory activity and correlation of these findings with psychotic symptoms are summarized. Although the variety of measures used by different research groups makes a quantitative meta-analysis difficult, it appears that magnetoencephalography activity in patients may exhibit identifiable patterns, defined by topographic organization and frequency band. Specifically, 11 of the 12 studies showed increased theta (4-8 Hz) and delta (1-4 Hz) band oscillations in the temporal lobes of patients; of the 10 studies that examined the relationship between oscillatory activity and symptomatology, 8 found a positive correlation between temporal lobe theta activity and positive schizophrenic symptoms. Abnormally high frontal delta activity was not seen. These findings are analyzed in comparison with the electroencephalogram literature on schizophrenics, and possible confounds (e.g., medication effects) are discussed. In the future, magnetoencephalography might be used to assist in diagnosis or might be fruitfully used in conjunction with new neuroscience research approaches such as computational modeling, which may be able to link oscillatory activity and cellular-level pathology.

Psychomotor and cognitive effects of a single oral dose of talnetant (SB223412) in healthy volunteers compared with placebo or haloperidol

Central Nervous System (CNS) effects of talnetant, an NK-3 antagonist in development for schizophrenia, were compared to those of haloperidol and placebo. The study was randomised, double-blind, three-way crossover of talnetant 200 mg, haloperidol 3 mg or placebo. Twelve healthy males participated and EEG, saccadic and smooth pursuit eye movements, adaptive tracking, body sway, finger tapping, hormones, visual analogue scales (VAS) for alertness, mood and calmness and psychedelic effects, left/right distraction task, Tower of London and Visual and Verbal Learning Task were assessed. Haloperidol showed (difference to placebo; 95% CI; p-value) decreases in EEG alpha power (-0.87microV; -1.51/-0.22; p = 0.0110), saccadic inaccuracy (2.0%; 0.5/3.6; p = 0.0133), smooth pursuit eye movements (-7.5%; -12.0/-3.0; p = 0.0026), adaptive tracking (-3.5%; -5.4/-1.7; p = 0.0009), alertness (-6.8 mm; -11.1/-2.4; p = 0.0039), negative mood (-4.6 mm; -8.6/-0.6; p = 0.0266), the ability to control thoughts (1.2 mm; 0.2/2.3; p = 0.0214), and an increase of serum prolactin (ratio 4.1; 3.0/5.6; p < 0.0001). Talnetant showed decreased alpha power (-0.69 muV; -1.34/-0.04; p = 0.0390), improved adaptive tracking (1.9%; 0.1/3.7; p = 0.0370) and reduced calmness on VAS Bond and Lader (-4.5 mm; -8.0/-1.0; p = 0.0151). Haloperidol effects were predominantly CNS-depressant, while those of talnetant were slightly stimulatory. The results suggest that talnetant penetrates the brain, but it remains to be established whether this dose is sufficient and whether the observed effect profile is class-specific for NK3-antagonists.

Zotepine for schizophrenia

BACKGROUND

Zotepine is a relatively new antipsychotic often used for the treatment of people with schizophrenia. It is claimed to be particularly effective for negative symptoms.

OBJECTIVES

To determine the effects of zotepine compared with placebo, typical and other atypical antipsychotic drugs for schizophrenia and related psychoses.

SEARCH STRATEGY

For the 2006 update we searched the Cochrane Schizophrenia Group's register of trials.

SELECTION CRITERIA

We included all randomised clinical trials comparing zotepine with other treatments for people with schizophrenia or other psychoses.

DATA COLLECTION AND ANALYSIS

We independently inspected citations and abstracts, ordered papers, re-inspected these and assessed their quality. For homogenous dichotomous data we calculated the relative risk (RR), 95% confidence intervals (CI) and, where appropriate, numbers needed to treat/harm (NNT/H) on an intention-to-treat basis. For continuous data, we calculated weighted mean differences (WMD). We inspected all data for heterogeneity.

MAIN RESULTS

The review currently includes 11 studies with 966 participants. Most outcomes were short term (4-12 weeks). We found no data for outcomes such as relapse, time in hospital, satisfaction with care and day-to-day functioning. Compared with placebo, mental state ratings favoured zotepine (n=106, 1 RCT, RR No 20% decrease in BPRS 0.44 CI 0.3 to 0.7, NNT 3 CI 2 to 6) using the last observation carried forward method. For the comparison with typical drugs, limited data suggest that zotepine may be as effective as these older medications. Mental state measures of 'no clinically important improvement' favour zotepine when compared with other active drugs (n=356, 4 RCTs, RR 0.77 CI 0.7 to 0.9, NNT 7 CI 4 to 22). About one third of people in both the zotepine and control groups left the studies before trial completion. Zotepine may result in less movement disorder adverse effects than typical antipsychotic drugs. Trials have not highlighted clear differences between zotepine and other atypical drugs.

AUTHORS' CONCLUSIONS

Zotepine may be a valuable addition to the class of atypical antipsychotic drugs. However, more data from existing studies is urgently needed to increase confidence in the findings of this review. In addition to this, new data from well planned, conducted and reported long term pragmatic randomised trials are needed. Otherwise clinical use of zotepine will be based upon speculation of short explanatory trials for everyday practice.

Quantitative EEG in schizophrenia and in response to acute and chronic clozapine treatment

Topographic quantitative electroencephalographic (EEG) power and frequency indices were collected in 17 treatment refractory, DSM-III diagnosed schizophrenic patients, before and after acute (single dose) and chronic (six weeks) clozapine treatment, as well as in 17 healthy volunteers. Prior to treatment, patients exhibited greater overall absolute theta power, slower mean alpha frequency and elevated absolute delta and total power in anterior regions. Acute dosing increased total spectrum power globally, slow wave power posteriorally, mean alpha frequency and beta power anteriorally and decreased alpha power posteriorally. Six weeks of clozapine treatment significantly reduced clinical ratings of positive and negative symptoms as well as symptoms of global psychopathology. Chronic treatment resulted in EEG slowing as shown by decreases in relative alpha power, mean beta/total spectrum frequency and by widespread increases in absolute total and delta/theta power. The preliminary findings suggest that brain electric profiling may be a promising tool for assessing and understanding the central impact of pharmacotherapeutic interventions in schizophrenia.

Biomarkers for the effects of antipsychotic drugs in healthy volunteers

Studies of novel antipsychotics in healthy volunteers are traditionally concerned with kinetics and tolerability, but useful information may also be obtained from biomarkers of clinical endpoints. A useful biomarker should meet the following requirements: a consistent response across studies and antipsychotics; a clear response of the biomarker to a therapeutic dose; a dose-response relationship; a plausible relationship between biomarker, pharmacology and pathogenesis. In the current review, all individual tests found in studies of neuroleptics in healthy volunteers since 1966 were progressively evaluated for compliance with these requirements. A MedLine search yielded 65 different studies, investigating the effects of 23 different neuroleptics on 101 different (variants of) neuropsychological tests, which could be clustered into seven neuropsychological domains. Subjective and objective measures of alertness, and of visual-visuomotor-auditory and motor skills were most sensitive to antipsychotics, although over half of all the studies failed to show statistically significant differences from placebo. The most consistent effects were observed using prolactin response and saccadic eye movements, where 96% and 83% of all studies resp. showed statistically significant effects. The prolactin inducing dose equivalencies relative to haloperidol of 19 different antipsychotic agents correlated with the lowest recommended daily maintenance dose (r(2) = 0.52). This relationship could reflect the clinical practice of aiming for maximum tolerated levels, or it could represent a common basis behind prolactin release and antipsychotic activity (probably D2-receptor antagonism). The number of tests used in human psychopharmacology appears to be excessive. Future studies should look for the most specific and sensitive test within each of the domains that are most susceptible to neuroleptics.

Zotepine for schizophrenia

BACKGROUND

Typical antipsychotic drugs are widely used as first line treatment for people with schizophrenia. The atypical class of antipsychotic drugs, however, is making important inroads into this approach and zotepine is one such compound. It is a dopamine antagonist and claimed to be to be particularly effective for negative symptoms

OBJECTIVES

To determine the effects of zotepine compared with placebo, typical and other atypical antipsychotic drugs for schizophrenia and related psychoses.

SEARCH STRATEGY

Electronic searches of Biological Abstracts (1980-1999), CINAHL (1982-1999), The Cochrane Library (Issue 1, 1999), The Cochrane Schizophrenia Group's Register (January 1999), EMBASE (1980-1999), Dialog Corporation Datastar service (1999), MEDLINE (1966-1999), and PsycLIT (1974-1999) were undertaken. References of all identified studies were searched for further trials. Knoll Pharmaceuticals and authors of trials were contacted.

SELECTION CRITERIA

All randomised clinical trials that compared zotepine to other treatments for people with schizophrenia or other psychoses were included.

DATA COLLECTION AND ANALYSIS

Citations and, where possible, abstracts were independently inspected by reviewers, papers ordered, re-inspected and quality assessed. Data were independently extracted. Data were excluded if loss to follow up was greater than 50%. For homogeneous dichotomous data the relative risk (RR), 95% confidence interval (CI) and, where appropriate, the number needed to treat (NNT) and numbers needed to harm (NNH), were calculated on an intention-to-treat basis. For continuous data, weighted mean differences were calculated (WMD). All data were inspected for heterogeneity.

MAIN RESULTS

All outcomes were short term (4-12 weeks). Limited data suggest that zotepine is an antipsychotic, at least as effective as typical drugs. Mental state measures of 'no clinically important improvement' favour zotepine when compared to other active drugs (n=356, RR 0.8 CI 0.7-0.9, NNT 7 CI 4-22). About one third of people in both zotepine and control groups left the studies before trial completion. Zotepine may result in less movement disorder adverse effects than typical antipsychotic drugs. Trials have not highlighted clear differences between zotepine and other atypical drugs.

REVIEWER'S CONCLUSIONS

Zotepine may be a valuable addition to the increasing ranks of atypical antipsychotic drugs. More data from already existing studies is urgently needed to increase the confidence in the findings of this review. New data from well planned, conducted and reported long term pragmatic randomised trials are necessary. Otherwise clinical use of zotepine will be based on speculation on the meaning of the findings of short explanatory trials for everyday practice.

Topographic analysis of EEG photic driving in patients with schizophrenia following clozapine treatment

Reduced EEG photic driving has been found to be diagnostically sensitive and specific for schizophrenia. Thirty-one patients with schizophrenia were tested in this study to identify the typical and atypical neuroleptic effects on the photic driving. Compared with the placebo, clozapine significantly enhanced the photically driven EEG in theta and low alpha frequency band, while haloperidol did not have the same effect. These changes with clozapine appeared to be symmetrical and located primarily in the frontal, central and mid-parietal areas but not in the lateral parietal, temporal and occipital regions. Results were consistent with previous findings and suggested that the atypical EEG profile of clozapine might be associated with 5-HT2 antagonistic property.

Cognitive performance, mood and experimental pain before and during morphine-induced analgesia in patients with chronic non-malignant pain

This paper investigates subjective, behavioral and neurophysiological changes due to treatment with oral sustained-release morphine in six patients with severe non-malignant pain. Patients rated their mood and clinical pain on visual analog scales (VAS). Experimental pain reactions were quantified by ratings on categorical scales and evoked cerebral potentials (LEP) in response to standardized laser stimuli. A standard auditory oddball task provided reaction time (RT), errors, N1 and P2 of late auditory evoked potentials (AEP), and a P300 component. It was used to measure vigilance and cognitive performance. In parallel with clinical pain reduction, laser pain ratings and LEP amplitudes were significantly reduced. In contrast, auditory P2 and P300 amplitude were found to be even enlarged under morphine. RT and mood also failed to indicate any sedation. It is concluded that LEP indicated the analgesic morphine effects whereas late potentials and P300 from auditory stimuli reflected the perceptual-cognitive status which, instead of being deteriorated by morphine-induced sedation, improved probably due to the removal of pain as a mental stressor.

Guidelines for the use of antipsychotic drug studies in healthy volunteers. The BAP Consensus Group

The following article summarizes the background to a British Association for Psychopharmacology Workshop held at the Royal Society, London, on 15 March 1996. It includes abstracts of the papers presented at that meeting and concludes with a list of agreed guidelines for future studies with antipsychotic drugs in healthy volunteer subjects.

Enduring cognitive deficits and cortical dopamine dysfunction in monkeys after long-term administration of phencyclidine

The effects of the psychotomimetic drug phencyclidine on the neurochemistry and function of the prefrontal cortex in vervet monkeys were investigated. Monkeys treated with phencyclidine twice a day for 14 days displayed performance deficits on a task that was sensitive to prefrontal cortex function; the deficits were ameliorated by the atypical antipsychotic drug clozapine. Repeated exposure to phencyclidine caused a reduction in both basal and evoked dopamine utilization in the dorsolateral prefrontal cortex, a brain region that has long been associated with cognitive function. Behavioral deficits and decreased dopamine utilization remained after phencyclidine treatment was stopped, an indication that these effects were not simply due to direct drug effects. The data suggest that repeated administration of phencyclidine in monkeys may be useful for studying psychiatric disorders associated with cognitive dysfunction and dopamine hypofunction in the prefrontal cortex, particularly schizophrenia.

Cognitive function in schizophrenia--do neuroleptics make a difference?

Valid cognitive deficits in schizophrenia are now well characterised: general poor performance with disproportionate deficits in aspects of memory and executive function. Symptomatology, motivation, institutionalization, etc. cannot explain these deficits, which are of considerable importance for both the testing of theoretical models of schizophrenia and the determination of patients' functional outcome. The receptor blocking properties of neuroleptic treatments afford them the potential for interacting with monoaminergic, indoleaminergic, and cholinergic arousal systems in the brain and, hence, for modifying cognitive processes. However, the effects of conventional neuroleptics on cognition in schizophrenia are minor according to numerous studies. Atypical neuroleptics may, owing to their novel mechanisms of action, have the capacity to remediate cognitive impairment in schizophrenia: there is some evidence that clozapine has a "cognitive sparing" effect, but further research is needed in this area, particularly with other new drugs. Future studies should employ more appropriate methodology, particularly in terms of psychological/neurophysiological sophistication, patient evaluation, and applicability to real life, and should be hypothesis driven rather than purely empirical.

Risperidone, negative symptoms and cognitive deficit in schizophrenia: an open study

The aim of this study was to evaluate the effects of a new antipsychotic compound on negative symptoms and cognitive deficit in schizophrenia. Psychiatric symptoms and cognition were assessed in 25 patients with schizophrenia, at baseline and after they had taken risperidone for 4 weeks. The Positive and Negative Symptoms Scale (PANSS), the Wisconsin Card Sorting Test (WCST) and two WAIS sub-tests were used to assess the patients. After the study period, both negative and positive symptoms and also measures of cognitive performance improved significantly. The WCST results correlated with negative symptom scores before and after treatment. This suggests that negative symptoms and cognitive deficit have a common underlying substrate which is the target of the risperidone treatment. Our data show that risperidone may have a substantial effect on complex cognitive functions in schizophrenia, and they suggest that certain cognitive deficits are relatively dependent on the negative symptoms of this disorder.

Multilead quantitative EEG profile of clozapine in resting and vigilance-controlled conditions

Clozapine is the prototype of a new class of drugs, referred to as 'atypical antipsychotics'. As a matter of fact, the antipsychotic activity of the drug was not predicted by the first studies with quantitative electroencephalography (QEEG), which actually reported an antidepressant pattern. All previous QEEG studies carried out in healthy subjects used a maximum of four leads, exploring only the posterior quadrants of the scalp. The present article reports findings of a multilead QEEG study carried out in 16 healthy men under resting and vigilance-controlled conditions. Increases in slow (delta, theta, and alpha1) and decreases in fast (alpha2 and beta) activities were found, corresponding to changes described for chlorpromazine-type antipsychotics. These results are compared with those of earlier studies. It is suggested that changes in the beta frequency range vary across subjects, whereas changes in slow and alpha activity are more consistent and critical for defining the QEEG profile of the drug.

Quantified EEG changes associated with a positive clinical response to clozapine in schizophrenia

1. The authors conducted a retrospective exploratory computerized EEG study on the effect of clozapine in treatment-refractory schizophrenics, 10 high-responders (HRs) and 10 low-responders (LRs), in an attempt to correlate amplitude but especially coherence changes with a positive clinical response to clozapine. 2. EEGs with eyes closed were obtained before and during a clozapine treatment. Both groups had a similar drug profile with regards to non-clozapine medication. Probability maps were computed to illustrate changes of amplitude and coherence (for all combinations of paired electrodes) for 4 frequency bands (theta, alpha, beta 1 and 2). 3. The effect on AMPLITUDE was a generalized increase in lower bands and a decrease in anterior regions in higher bands of both HRs and LRs. Considerable changes of COHERENCE were observed on a wide set of paired electrodes in most frequency bands with some electrodes involved in HRs but uninvolved or differently involved in LRs suggesting differences in selected brain regions. 4. Changes of coherence but not amplitude were correlated with changes on the BPRS, thus to clinical improvement, and concerned mostly the right anterior-medial temporal (T4) and central (C4) electrodes paired with prefrontal electrodes, left central (C3), temporal (T3) and parietal (P3) electrodes in the theta band. 5. Clozapine has both generalized and regional effects as can be suspected considering its effect on many subtypes of brain receptors. A brain dysfunction centralized on the right anterior-medial temporal region may characterize treatment-refractory schizophrenics.

The effect of clozapine on cognition and psychiatric symptoms in patients with schizophrenia

Psychiatric symptoms and cognition were assessed in 13 patients with schizophrenia, one patient with schizoaffective disorder, and one patient with psychosis not otherwise specified while they received a conventional neuroleptic and again after an average of 15 months on clozapine. Despite improvements in psychiatric symptoms, attention, memory, and higher-level problem-solving were essentially unchanged. This suggests that certain cognitive deficits are relatively independent of psychotic symptoms in schizophrenia, and are probably central and enduring features of the disorder. Cognitive disability appeared to have been rate-limiting in the sample's rehabilitation, as patients' social and vocational adjustment remained marginal during the study. We also observed that treatment with clozapine was associated with a decline in some memory functions; the potent anticholinergic properties of the drug may have been responsible for this.

The effect of neuroleptics on cognitive and psychomotor function

There has been great variability and inconsistency in the reported effects of neuroleptic drugs on cognitive and psychomotor function in both patients and normal controls. Experimental design rather than any particular cognitive or psychomotor test appears to have determined the sensitivity of detection of neuroleptic drug effects. In general, sedative phenothiazines have been found to depress psychomotor function and sustained attention, but higher cognitive functions are relatively unaffected. In the majority of studies of schizophrenic patients, both cognitive function and attention improve with neuroleptic treatment, in parallel with clinical recovery. Negative symptoms are not increased and usually show slight improvement with neuroleptic treatment. Controls are more sensitive than schizophrenic patients to neuroleptic drug-induced impairments. Tolerance has been seen in patients but has not been demonstrated in normal volunteers. The way in which neuroleptics produce their beneficial effects in patients remains unknown. Three main hypotheses to replace early arousal theories are proposed: normalisation of attention, facilitated indirectly by suppression of 'released' limbic dopamine hyperactivity; normalisation of asymmetrical temporohippocampal function; or direct improvement of attentional processing. Studies of the effects of new antipsychotic drugs with selective actions and the development of more reliable and selective tests of psychomotor and cognitive functions are required.

Clozapine: a novel antipsychotic agent

Clozapine is an antipsychotic without the extra-pyramidal adverse effects associated with currently marketed antipsychotics. In animals, this drug has not been shown to induce catalepsy and only weakly antagonizes the stereotypic movements induced by apomorphine and the amphetamines. Clozapine is rapidly absorbed after both single and repeated oral doses, with steady-state concentrations attained within eight to ten days after beginning therapy. It is metabolized to N-oxideclozapine and N-desmethylclozapine, which have less pharmacological activity than the parent compound and are excreted in the urine and, to a lesser extent, in the feces. Clozapine has overall therapeutic efficacy and/or superiority to currently marketed antipsychotics in the treatment of refractory schizophrenia. Usual doses (25-900 mg/d) of clozapine cause fewer extrapyramidal adverse reactions than available antipsychotics. Hypotension, dizziness, salivation, and sedation are the most frequently reported adverse effects and tend to subside over time. Agranulocytosis is the most serious adverse reaction, and those receiving clozapine should undergo weekly white blood cell count determinations. Clozapine is useful for those treatment-resistant patients who have not responded to adequate trials of other antipsychotics.

Clinical experience with clozapine in Germany

The so-far successful development of the atypical neuroleptic clozapine had been interrupted by the Finnish epidemic of agranulocytosis in 1975. However, though the strong regulatory control of prescribing clozapine, since then its clinical use has increased steadily, particularly recently. This may be due mainly to the considerable number of patients whose psychotic states or at least whose negative symptoms do not respond to other neuroleptics, or who have problems with extrapyramidal side effects. Due to its significant antipsychotic, and to its probable even if mild antidepressive efficacy as well as to its possible efficacy against some negative symptoms of schizophrenia, clozapine is currently a real and indispensable alternative to other existing neuroleptics. Further research should be directed both to the clinical validation of the latter mentioned therapeutically desired effects and to the causes and predictability of agranulocytosis, as yet the main risk of clozapine therapy. Theoretically profitable would be the clarification of the causes of hyperthermia and particularly of those of the mutual independency of extrapyramidal motor disturbances and antipsychotic efficacy.