Biomedical subjects

A Breier

Publications and source records attributed to A Breier.

At least 55 records · Page 3Linked to original sources

PubMed2000

Olanzapine versus risperidone. A prospective comparison of clinical and economic outcomes in schizophrenia.

OBJECTIVE: To compare the clinical and economic outcomes associated with olanzapine and risperidone treatment for schizophrenia. DESIGN AND SETTING: An international, multicentre, double-blind, prospective study. To facilitate economic comparisons, our sample was restricted to patients enrolled in US sites. 150 patients with a Diagnostic and Statistical Manual of mental disorders, 4th edition (DSM-IV) diagnosis of schizophrenia, schizoaffective disorder or schizophreniform disorder were randomised to therapy with either olanzapine 10 to 20 mg/day (n = 75) or risperidone 4 to 12 mg/day (n = 75) for a maximum of 28 weeks. In addition to tolerability and efficacy assessments, use of health services was assessed at baseline and prospectively, at 8-week intervals and at study completion. Clinically important response, defined as a 40% improvement in the Positive and Negative Syndrome Scale total score, maintenance of response and rates of treatment-emergent extrapyramidal symptoms were compared between groups. Direct medical costs were estimated by assigning standardised prices to resource units. Median total, inpatient/outpatient service and medication acquisition costs were compared between treatment groups. MAIN OUTCOME MEASURES AND RESULTS: The mean modal dosages for the olanzapine and risperidone treatment groups were 17.7 +/- 3.4 mg/day and 7.9 +/- 3.2 mg/day, respectively. Olanzapine-treated patients were more likely to maintain response compared with risperidone-treated patients (p = 0.048). In addition, a smaller proportion of olanzapine-treated patients required anticholinergic therapy compared with risperidone-treated patients (25.3 vs 45.3%; p = 0.016). Total per patient medical costs over the study interval were $US2843 (1997 values) [36%] lower in the olanzapine treatment group than in the risperidone treatment group (p = 0.342). Medication costs were significantly higher for olanzapine-treated patients ($US2513 vs $US1581; p < 0.001), but this difference was offset by a reduction of $US3774 (52%) in inpatient/outpatient service costs for olanzapine-treated patients in comparison with risperidone-treated patients ($US3516 vs $US7291, p = 0.083). Median cost findings were consistent with results observed using other robust measures of central tendency and provide conservative estimates of potential savings that may be obtained from olanzapine therapy. CONCLUSIONS: In this study, olanzapine-treated patients experienced clinical improvements that translated into savings in costs of care for both inpatient and outpatient services. These savings offset the difference in medication acquisition cost between olanzapine and risperidone.

Adult↗

PubMed2000

The safety of olanzapine compared with other antipsychotic drugs: results of an observational prospective study in patients with schizophrenia (EFESO Study). Pharmacoepidemiologic Study of Olanzapine in Schizophrenia.

INTRODUCTION: Results of controlled clinical trials should be confirmed through safety and effectiveness studies in nonselected patient cohorts treated according to routine clinical practice. METHOD: Outpatients with schizophrenia (ICD-10 criteria) entered this prospective, naturalistic study when they received a new prescription for an antipsychotic drug. Treatment assignment was based on purely clinical criteria, as the study did not include any experimental intervention. Safety was evaluated through the collection of spontaneous adverse events and a specific questionnaire for extrapyramidal symptoms. Global clinical status was measured through the Clinical Global Impressions-Severity (CGI-S) and the Global Assessment of Functioning (GAF) scales. RESULTS: From the 2967 patients included, 2128 patients were treated with olanzapine as monotherapy or combined with other drugs (olanzapine group), and 821 were treated with other antipsychotic drugs as monotherapy or combined with other drugs (control group). There were no statistical differences between treatment groups at baseline regarding age, gender, disease duration, or severity of symptoms. Olanzapine was well tolerated and effective in this study. Overall incidence of adverse events was significantly lower in the olanzapine group compared with the control group (p < .001). Somnolence and weight gain were significantly more frequent in the olanzapine group, and akathisia, dystonia, extrapyramidal syndrome, hypertonia, hypokinesia, and tremor were significantly higher in the control group. Clinical improvement at endpoint, measured through the mean change in the CGI-S and the GAF, was significantly higher in the olanzapine group compared with the control group (p = .004). CONCLUSION: These results show that olanzapine is safe and effective in nonselected schizophrenic outpatients and are consistent with the efficacy and safety profile that olanzapine has shown in previous controlled clinical trials.

Adolescent↗

PubMed2000

The relation between dopamine D2 receptor density and personality: preliminary evidence from the NEO personality inventory-revised.

OBJECTIVE: To examine the relation between dopamine (DA) D2 receptor-specific binding and personality, we assessed the relation between DA D2 binding and the NEO Personality Inventory-Revised (NEO PI-R). BACKGROUND: Previous studies have demonstrated a relation between DA D2 receptor-specific binding and a personality trait involving personal detachment as defined by the Karolinska Scales of Personality: A subsequent study using a different measure of personal detachment failed to replicate this finding, suggesting that metric properties of the personality scale may be important. To further examine this issue, we assessed the relation between DA D2 binding and a third personality measure, the NEO PI-R. METHODS: Eighteen adult subjects completed the NEO PI-R and participated in an 11C-raclopride positron emission tomography study to quantify striatal DA D2 receptor binding. RESULTS: We did not find a significant relation between binding and detachment-like traits on the NEO PI-R; however, we found a significant relation between DA D2 receptor binding and the NEO PI-R personality facet of Depression (r = 0.75, p <0.0001). CONCLUSIONS: The results fail to replicate the findings of previous studies reporting an association between DA D2 receptor density and personal detachment, suggesting that the relation is relatively specific to the trait defined by the Karolinska Scales of Personality. The relation between a nonclinical personality trait of depression and DA D2 binding, if replicated, may help to elucidate the role of dopamine in depression.

Adult↗

PubMed2000

Measurement of dopamine release with continuous infusion of [11C]raclopride: optimization and signal-to-noise considerations.

UNLABELLED: PET studies with [11C]raclopride provide an indirect measure of changes in synaptic dopamine. Previously, we used the bolus-plus-infusion (B/I) method to assess dopamine response from the percentage change in binding potential (deltaBP) before and after administration of amphetamine. The goal of this work is to optimize the measurement of changes in neurotransmitter with the B/I method by choosing the optimal timing for pre- and poststimulus scanning. METHODS: Two sources of variability in deltaBP were considered: within-subject and between-subject noise. A noise model based on a phantom study and human data was used to evaluate the within-subject noise. For between-subject noise, simulated time--activity curves were generated from measured [11C]raclopride input functions. Optimal timing to measure deltaBP was determined and applied to human data. RESULTS: According to the simulation study, the optimal scan times for pre-and poststimulus scans were 39-50 and 58-100 min, respectively. The optimal timing resulted in a 28% noise reduction compared with the original timing. By applying the optimal timing to human studies, the statistical significance of the difference in deltaBP between patients with schizophrenia and healthy volunteers increased from P = 0.038 to 0.012. CONCLUSION: Careful assessment of the sources of noise in receptor imaging studies can increase the sensitivity of the B/I method for the detection of biologic signals.

Adult↗

PubMed2000

Na,K-ATPase in the myocardium: molecular principles, functional and clinical aspects.

The role that Na,K-ATPase plays in Na+ and K+ antiport through the sarcolemma, in cation-homeostasis in cardiomyocytes as well as in excitation-contraction coupling and cell signalling in the myocardium is now widely recognized. It was its key importance for the cell membrane function that kept this enzyme intensively studied during the last three decades and finally brought to its discoverer the deserved Nobel Prize. Almost weekly are appearing new data concerning structure, function, regulation and role of the Na,K-ATPase in different physiological and pathological conditions. The special importance of the enzyme for heart function as well as the great amount of data that is concerned specifically with the heart Na,K-ATPase and accumulated since yet, started to call for setting them in order. The present paper updates basically important data on the cardiac Na,K-ATPase in relation to its specific properties, molecular mechanisms of function, mode of action, humoral and pharmacological modulation, adaptability, physiological role and clinical aspects.

Animals↗

PubMed2000

Cytotoxic activity of several unrelated drugs on L1210 mouse leukemic cell sublines with P-glycoprotein (PGP) mediated multidrug resistance (MDR) phenotype. A QSAR study.

L1210/VCR-1 and L1210/VCR-2 cell lines are multidrug resistant (MDR) sublines obtained by adaptation of mouse leukemic cell line L1210 to vincristine and, the development of MDR in these cell lines has been found to be associated with an overexpression of P-glycoprotein (PGP). In the present work we studied the relationship between the structure of 15 cytotoxic active substances (drugs) and their cytotoxicities on L1210/VCR-1 and L1210/VCR-2 resistant cell lines. The resistance of these MDR cells to the respective drugs was expressed as the ratio of IC50 values obtained for resistant and sensitive cells. These values of resistance were correlated with the following physico-chemical constants of the test substances: binding energy, Ebind; total energy of the molecule, Esum; aromaticity, Kpi; molecular weight, Mw; acidobasic constant, pKa; partition coefficient in water/octanol two phase system, log(p). It has been found that according to the cytotoxic effects the tested drugs may be divided into three groups: (i) drugs with higher cytotoxicity to the resistant cell lines as to sensitive cells (collateral hypersensitivity); (ii) drugs exhibiting approximately similar effects on sensitive and resistant cell lines; (iii) drugs with weaker cytotoxicity to resistant cells than to sensitive cells. No direct correlations with any physico-chemical constant described above could be established for cell resistance to the drug studied. However, resistance values could be fitted by multiple exponential regression with all described physico-chemical constants implied as six independent variables. The latter procedure made us to conclude that the ability of a drug to be a substrate for PGP is connected with its fulfilling the following criteria: (i) flexible structure of its molecule; (ii) molecular weight lower than approximately 1,300 g/mol; (iii) nonprotonized character at pH 7.0.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2000

Glutathione S-transferase does not play a role in multidrug resistance of L1210/VCR cell line.

Multidrug resistance of cancer cells is often accompanied by the (over)expression of integral plasma membrane P-glycoprotein, an ATP-dependent transport pump for diverse unrelated compounds. The glutathione detoxification system represents another mechanism that may be involved in multidrug resistance. In the multidrug-resistant L1210/VCR cell line obtained by long-term adaptation of parental L1210 cells to vincristine, an increased expression of P-glycoprotein has previously been established. In this paper, we investigated if the glutathione detoxification system is also involved in the multidrug resistance of these cells. L1210/VCR cells with resistance induced by adaptation to vincristine were also found to be cross-resistant to vinblastine, actinomycin D, mitomycin C, doxorubicin and cyclophosphamide. The resistance of the above cells to vincristine and doxorubicin was accompanied by a depression of drug accumulation (which has not yet been established for other drug). L1210/VCR cells are able to survive better than sensitive cells under conditions when glutathione was depleted by L-buthionine sulfoximine. Nevertheless, L-buthionine sulfoximine did not influence the resistance of L1210/VCR cells to vincristine. Moreover, the presence of sublethal concentrations of cytostatics neither changed the IC50 value of resistant cells to L-buthionine sulfoximine nor the cytoplasmic activity of glutathione S-transferase, the crucial enzyme of glutathione detoxification system. All the above findings indicate that the glutathione detoxification system is not involved in the mechanisms that ensure the multidrug resistance phenotype of L1210/VCR cells.

Antibiotics, Antineoplastic↗

PubMed2000

"Lysine is the Lord", thought some scientists in regard to the group interacting with fluorescein isothiocyanate in ATP-binding sites of P-type ATPases but, is it not cysteine?

Isothiocyanates are recognized inhibitors acting on ATP-binding sites of P-type ATPases. Detailed studies with modification of proteins in molecules of purified ATPases by fluorescein isothiocyanate (FITC) and consequent tryptic hydrolysis followed by isolation and sequencing of the respective peptide fragments revealed FITC bound to a lysine residue. This residue was then indicated to be essential for the interaction of ATP with the P-type ATPases. Nevertheless, upon an exchange by site directed mutagenesis of lysine, believed to be essential, the expected total inhibition of ATPase activity was missing. In addition, in the case of the plasma membrane Ca2+-ATPase, the residual activity still remained sensitive to FITC. It was attempted to explain the latter finding by hypothetical existence of some other lysine residue essential for the ATPase activity. On the contrary, in our previous studies we have shown that, based on the reactivity of isothiocyanates, the primary target of FITC in P-type ATPases has to be the SH group of a cysteine residue. However, later on, in altered conditions during trypsinolysis and sequencing, FITC may become transferred from its original site of interaction to a lysine residue and this may lead to final identification of the label on a false place. The present study represents all attempt of elucidating the controversy whether it is lysine or cysteine that represents the FITC-sensitive group truly responsible for the recognition by the active site of P-type ATPases of ATP and its binding.

Adenosine Triphosphatases↗

PubMed1999

The psychosis of schizophrenia: prevalence, response to atypical antipsychotics, and prediction of outcome.

BACKGROUND: Psychosis is a defining feature of schizophrenia consisting of formal thought disorder, delusions, and hallucinations. Although psychosis is present in the majority of patients with schizophrenia, the prevalence, responsiveness to atypical antipsychotic drug therapy, and prediction of outcome of individual psychotic symptoms in a population of well-diagnosed patients with schizophrenia have not been conclusively established. METHODS: This paper examined the prevalence, responsiveness to the atypical antipsychotic olanzapine, and relationship to outcome of individual psychotic symptoms using data from a previously reported large multicenter, double-blind clinical trial of olanzapine (mean daily dose at endpoint = 13.6 +/- 6.9 mg/day). RESULTS: The most frequently reported psychotic symptoms at baseline were delusions (65%), conceptual disorganization (50%), and hallucinations (52%), and the majority of patients (68%) experienced from one to three symptoms. Additionally, with olanzapine treatment there were significant improvements (p < .001) in baseline to endpoint Positive and Negative Symptom Scale (PANSS) psychotic item scores, with the largest effect sizes observed for hallucinatory behavior, unusual thought content, suspiciousness/persecution, and delusions. During the acute phase of the trial, quality of life was correlated significantly with baseline conceptual disorganization (p = .038) and unusual thought content (p = .023), and time spent in the hospital was correlated with unusual thought content (p = .005). CONCLUSIONS: The implications of these for the clinical management of schizophrenia are discussed.

Adult↗

PubMed1999

Avoidance learning in schizophrenia: a dissociation between the effects of aversive and non-aversive stimuli.

Patients with schizophrenia did not take significantly more trials than normal controls to learn to use a visual warning signal to avoid a non-aversive stimulus on a simple computer-administered avoidance learning task. When the stimulus to be avoided was aversive (i.e., a loud buzzer), however, the schizophrenic group could be divided into two subgroups based upon their performance; almost one half of the schizophrenic group failed to learn how to avoid this task successfully. The other half, like the normal controls and the closed head injury group in our previous studies, benefited from the aversiveness of the stimulus to be avoided, and learned to avoid more quickly than in the non-aversive condition. A post-hoc analysis of the differences between these two subgroups of the patients suggested that the discrepancy in learning was related to the age of onset of illness.

Adult↗

PubMed1999

Comparative efficacy of olanzapine and haloperidol for patients with treatment-resistant schizophrenia.

BACKGROUND: There is relatively little information regarding the efficacy of newer atypical antipsychotic drugs for patients with schizophrenia who are treatment-resistant to neuroleptic agents. Several lines of evidence suggest that a clinical trial of olanzapine in this population is warranted. METHODS: A subpopulation of patients (n = 526) meeting treatment-resistant criteria selected from a large, prospective, double-blind, 6-week study assessing the efficacy and safety of olanzapine and haloperidol were examined. Both last-observation-carried-forward (LOCF) and completers (observed cases) analyses were conducted. RESULTS: Olanzapine demonstrated significantly greater mean improvement from baseline in Positive and Negative Syndrome Scale (PANSS) negative symptoms, comorbid depressive symptoms assessed by the Montgomery-Asberg Depression Rating Scale, akathisia as measured by Barnes Akathisia Scale, and extrapyramidal symptoms as measured by Simpson-Angus Extrapyramidal Rating Scale with both LOCF and completers analyses. In addition, olanzapine was significantly superior to haloperidol for Brief Psychiatric Rating Scale total (p = .006), PANSS total (p = .005), and PANSS positive symptoms (p = .017) in completers of the 6-week study. Significantly greater response rates were observed in olanzapine-treated (47%) than haloperidol-treated (35%) patients in the LOCF analysis (p = .008), but significance was not reached in the completers analysis (p = .093). Mean doses (+/- SD) of olanzapine and haloperidol were 11.1 +/- 3.4 mg/day and 10.0 +/- 3.6 mg/day, respectively. CONCLUSIONS: Olanzapine was superior to haloperidol for key symptom domains and parkinsonian side effects. Implications of these data for the therapeutics of this severely ill subgroup are discussed.

Adult↗

PubMed1999

The effects of pharmacological doses of 2-deoxyglucose on cerebral blood flow in healthy volunteers.

The effects of glucose deprivation on cerebral blood flow (CBF) have been extensively investigated during insulin-induced hypoglycemia in laboratory animals. Pharmacological doses of glucose analog, 2-deoxyglucose (2DG), is an alternative glucoprivic agent that in contrast to insulin, directly inhibits glycolysis and glucose utilization. Both glucoprivic conditions markedly increase CBF in laboratory animals. How 2DG affects CBF in humans is still undetermined. In the present study we have employed H215O positron emission tomography (PET) to examine the effects of pharmacological doses of 2DG (40 mg/kg) on regional and global cerebral blood flow in 10 brain areas in 13 healthy volunteers. 2DG administration significantly raised regional CBF (rCBF) in the cingulate gyrus, sensorimotor cortex, superior temporal cortex, occipital cortex, basal ganglia, limbic system and hypothalamus. 2DG produced a trend towards elevated CBF in whole brain and frontal cortex, while no changes were observed in the corpus callosum and thalamus. In addition, 2DG significantly decreased body temperature and mean arterial pressure (MAP). Maximal percent changes in hypothalamic rCBF were significantly correlated with maximal changes in body temperature but not with MAP. These results indicate that cerebral glucoprivation produced by pharmacological doses of 2DG is accompanied by widespread activation of cortical and subcortical blood flow and that the blood flow changes in the hypothalamus may be related to 2DG-induced hypothermia.

Adult↗

PubMed1999

Mechanism of peripheral noradrenergic stimulation by clozapine.

Elevated plasma norepinephrine (NE) levels is a relatively consistent clinical effect of clozapine. Plasma NE levels reflect an interplay of release, reuptake, metabolism, and excretion. To explore the mechanism of clozapine-induced plasma NE elevation, we measured arterial plasma levels of NE and other catechols during intravenous infusion of tritium-labeled NE (3H-NE) in schizophrenic patients treated with clozapine, fluphenazine, or placebo. Clozapine-treated patients had markedly higher levels of NE than did the patients treated with fluphenazine or placebo. NE spillover averaged more than three times higher in clozapine-treated patients; whereas NE clearance did not differ among the groups. Production of 3H-dihydroxyphenylglycol (3H-DHPG), a purely intraneuronal metabolite of 3H-NE in clozapine-treated patients was normal, indicating that clozapine did not affect neuronal uptake of NE. Because plasma levels of DHPG and dihydroxyphenylacetic acid (DOPAC), deaminated metabolites of catecholamines, in clozapine-treated patients were normal, clozapine also did not seem to inhibit intraneuronal monoamine oxidase (MAO). High plasma NE levels in clozapine-treated patients, therefore, resulted from increased NE spillover rather than decreased reuptake, metabolism, or clearance.

Adult↗

PubMed1999

Effects of atypical antipsychotic drug treatment on amphetamine-induced striatal dopamine release in patients with psychotic disorders.

Clozapine, risperidone, and other new "atypical" antipsychotic agents are distinguished from traditional neuroleptic drugs by having clinical efficacy with either no or low levels of extrapyramidal symptoms (EPS). Preclinical models have focused on striatal dopamine systems to account for their atypical profile. In this study, we examined the effects of clozapine and risperidone on amphetamine-induced striatal dopamine release in patients with psychotic disorders. A novel 11C-raclopride/PET paradigm was used to derive estimates of amphetamine-induced changes in striatal synaptic dopamine concentrations and patients were scanned while antipsychotic drug-free and during chronic treatment with either clozapine or risperidone. We found that amphetamine produced significant reductions in striatal 11C-raclopride binding during the drug-free and antipsychotic drug treatment phases of the study which reflects enhanced dopamine release in both conditions. There were no significant differences in % 11C-raclopride changes between the two conditions indicating that these atypical agents do not effect amphetamine-related striatal dopamine release. The implications for these data for antipsychotic drug action are discussed.

Adult↗

PubMed1999

Microvascular endothelial cells remodel cultured adult cardiomyocytes and increase their survival.

We investigated the paracrine effect of cardiac microvascular endothelial cells (MVEC) on cultured adult rat cardiomyocytes (ARC). ARC were exposed for 8 days to serum-free medium (CM) conditioned by MVEC. Controls were grown in FCS or FCS-free medium. Protein synthesis of CM-stimulated ARC increased twofold versus 5% FCS-stimulated cells until day 8. Seventy-nine percent of CM-treated myocytes survived, whereas only twenty-four percent of FCS-free ARC retained viability. The phenotype of myocytes exposed to CM was different from control. Analysis by confocal laser microscopy of CM-stimulated myocytes showed actin staining throughout the whole cell body up to the peripheral extensions, with concomitant appearance of myomesin in a cross-striated pattern. The reexpression of fetal alpha-smooth muscle actin determined immunohistochemically and by Western blot increased from day 6 in CM-treated cells, whereas ARC grown in up to 20% serum were negative. These effects could not be mimicked by any of the other cardioactive substances tested here, indicating a novel trophic factor in CM.

Actins↗

PubMed1999

Comparison of ketamine-induced thought disorder in healthy volunteers and thought disorder in schizophrenia.

OBJECTIVE: This study sought to determine whether thought disorder induced in healthy volunteers by the N-methyl-D-aspartic acid (NMDA) receptor antagonist ketamine resembles the thought disorder found in patients with schizophrenia. METHOD: The Scale for the Assessment of Thought, Language, and Communication was used to assess thought disorder in healthy volunteers (N = 10) who received subanesthetic doses of ketamine and in a group of clinically stable inpatients with schizophrenia (N = 15) who did not receive ketamine. RESULTS: Mean scores on the Scale for the Assessment of Thought, Language, and Communication for patients with schizophrenia and healthy volunteers receiving ketamine did not differ significantly. Moreover, three of the four highest rated test items in both groups were the same. CONCLUSIONS: These data suggest that ketamine-induced thought disorder in healthy volunteers is not dissimilar to the thought disorder in patients with schizophrenia and provide support for the involvement of the NMDA receptor in a cardinal symptom of schizophrenia.

Adult↗

PubMed1999

Gender differences in temporal lobe structures of patients with schizophrenia: a volumetric MRI study.

OBJECTIVE: The temporal lobe and associated structures have been previously implicated in the neuroanatomy of schizophrenia. This study was designed to assess the potential influence of gender on the morphology of temporal lobe structures, including the superior temporal gyrus and the amygdala/hippocampal complex, in patients with schizophrenia and to examine whether schizophrenic patients differ morphologically in these structures from comparison subjects. METHOD: Magnetic resonance imaging was used to measure the volume of temporal lobe structures, including the superior temporal gyrus, the amygdala/hippocampal complex, and the temporal lobe (excluding the volumes of the superior temporal gyrus and amygdala/hippocampal complex), and two comparison areas--the prefrontal cortex and caudate--in 36 male and 23 female patients with schizophrenia and 19 male and 18 female comparison subjects. RESULTS: There was a significant main effect of diagnosis in the superior temporal gyrus and the amygdala/hippocampal complex, with smaller volumes in patients than in comparison subjects. There was a significant gender-by-diagnosis-by-hemisphere interaction for temporal lobe volume. Temporal lobe volume on the left was significantly smaller in male patients than in male comparison subjects. Female patients and female comparison subjects demonstrated no significant difference in temporal lobe volume. There were no statistically significant gender interactions for the superior temporal gyrus, the amygdala/hippocampal complex, or the comparison regions. CONCLUSIONS: These findings suggest that there may be a unique interaction between gender and the pathophysiologic processes that lead to altered temporal lobe volume in patients with schizophrenia.

Adult↗

PubMed1999

Cognitive deficit in schizophrenia and its neurochemical basis.

Cognitive impairment is a central feature of schizophrenia and has been correlated with negative symptoms and impaired social functioning. There is a growing body of data suggesting that the so-called atypical antipsychotic drugs (e.g. clozapine, risperidone, and olanzapine) are better at enhancing cognitive function than traditional neuroleptics. Preclinical studies of information processing using a pre-pulse inhibition model show that the mechanism of action of both olanzapine and clozapine for cognitive enhancement may involve glutamatergic/N-methyl-D-aspartate (NMDA) antagonism. Using positron emission tomography, we have described the metabolic and neurochemical correlates of cognitive impairment induced by glutamatergic/NMDA antagonism. A better understanding of the underlying causes of cognitive impairment may contribute to elucidating the pathophysiology of schizophrenia and the development of more efficacious treatments for this disorder.

Antipsychotic Agents↗