Quetiapine has a direct effect on the negative symptoms of schizophrenia

Improving myelin/oligodendrocyte-related dysfunction: a new mechanism of antipsychotics in the treatment of schizophrenia?

Schizophrenia is a severe psychiatric disorder with complex clinical manifestations and its aetiological factors remain unclear. During the past decade, the oligodendrocyte-related myelin dysfunction was proposed as a hypothesis for schizophrenia, supported initially by a series of neuroimaging studies and genetic evidence. Recently, the effects of antipsychotics on myelination and oligodendroglial lineage development and their underlying molecular mechanisms were evaluated. Data from those studies suggest that the antipsychotics-resulting improvement in myelin/oligodendrocyte-related dysfunction may contribute, at least in part, to their therapeutic effect on schizophrenia. Importantly, these findings may provide the basis for a new insight into the therapeutic strategy by targeting the oligodendroglia lineage cells against schizophrenia.

Cognitive effects of six months of treatment with quetiapine in antipsychotic-naïve first-episode schizophrenia

Effects of quetiapine on cognition were assessed in a group of first-episode antipsychotic-naïve patients with schizophrenia (N=24). A comprehensive battery of neuropsychological tests was administered at baseline and after 6 months of treatment with quetiapine. In order to examine retest effects, a matched healthy control group (N=24) was also tested at baseline and after 6 months. Only few differential changes were observed between patients and healthy controls. Of 8 cognitive domains examined, only significant changes in executive function suggested possible ameliorating effects of quetiapine. Patients also improved on speed of processing; however, this was parallel to the retest effects found in healthy controls. When covaried for differences at baseline, patients showed smaller improvements in speed of processing than the retest effects found in controls, as well as a lack of retest effects on sustained attention and working memory that were found in healthy controls. The main result of the study is that there was very little evidence of efficacy of quetiapine on cognition. The study also indicated a lack of normal retest effects in patients compared to controls.

Paliperidone extended-release for schizophrenia: effects on symptoms and functioning in acutely ill patients with negative symptoms

BACKGROUND

Most patients with schizophrenia exhibit negative symptoms, even during acute episodes. These difficult-to-treat symptoms are often associated with poor functioning and outcomes.

METHODS

A post-hoc analysis of pooled data from three 6-week double-blind studies included patients in an acute episode of schizophrenia who received paliperidone extended-release (ER) (3, 6, 9, or 12 mg) or placebo. Based on criteria developed by the authors, patients were stratified by the presence or absence of predominant negative symptoms at baseline (>or=40% of the maximum negative factor score and <40% of the maximum positive factor score on the Positive and Negative Syndrome Scale [PANSS]).

RESULTS

Although these studies were not designed to examine patients with predominant negative symptoms, the criteria identified 23% of acutely ill patients (270/1193). The mean (SD) baseline PANSS negative symptoms factor score, 27.4 (3.3), was 49% of the maximum; the positive symptoms factor score, 23.7 (2.8), was 33% of the maximum. Completion rates with paliperidone ER (n=195) and placebo (n=75) were 64.6% and 44.0%, respectively. Greater improvements occurred with paliperidone ER vs placebo on PANSS (total, negative and other factors), Clinical Global Impressions-Severity and Personal and Social Performance scores at endpoint (all P values <0.05). Adverse events reported in >or=10% of patients were (paliperidone ER vs placebo): headache (14.4% vs 6.7%), insomnia (13.8% vs 21.3%) and sinus tachycardia (10.3% vs 1.3%). Paliperidone ER treatment was associated with a similar response profile in patients without predominant negative symptoms (paliperidone ER, n=647; placebo, n=276).

CONCLUSIONS

Schizophrenia patients with predominant negative symptoms were identified in a population of acutely ill patients. Findings of this post-hoc analysis suggest that acutely ill patients with or without predominant negative symptoms respond similarly to treatment with paliperidone ER. No unexpected tolerability findings were observed.

Direct and indirect effects of paliperidone extended-release tablets on negative symptoms of schizophrenia

Direct and indirect effects of the new psychotropic paliperidone extended-release (paliperidone ER) tablets on negative symptom improvement in schizophrenia were investigated using path analysis. A post hoc analysis of pooled data from three 6-week, double-blind, placebo-controlled studies of paliperidone ER in patients experiencing acute exacerbation was conducted. Regression analysis explored relationships between baseline/study characteristics and negative symptoms. Change in Positive and Negative Syndrome Scale (PANSS) negative factor score at endpoint was the dependent variable; explanatory variables included demographic and clinical characteristics. Path analysis determined direct and indirect effects of treatment on negative symptom change. Indirect mediators of negative symptom change in the model included changes in positive symptoms, anxiety/depression symptoms and movement disorders. Path analysis indicated that up to 33% of negative symptom improvement was a direct treatment effect. Indirect effects on negative symptoms were mediated through changes in positive symptoms (51%) and anxiety/depression symptoms (18%), whereas changes in movement disorders had a 2.1% inverse effect. Path analysis indicated that paliperidone ER has a direct effect on negative symptoms. Negative symptom improvement also was indirectly mediated via changes in positive and depressive symptoms.

Quetiapine facilitates oligodendrocyte development and prevents mice from myelin breakdown and behavioral changes

Recent neuroimaging and postmortem studies have reported abnormalities in white matter of schizophrenic brains, suggesting the involvement of oligodendrocytes in the etiopathology of schizophrenia. This view is being supported by gene microarray studies showing the downregulation of genes related to oligodendrocyte function and myelination in schizophrenic brain compared to control subjects. However, there is currently little information available on the response of oligodendrocytes to antipsychotic drugs (APDs), which could be invaluable for corroborating the oligodendrocyte hypothesis. In this study we found: (1) quetiapine (QUE, an atypical APD) treatment in conjunction with addition of growth factors increased the proliferation of neural progenitors isolated from the cerebral cortex of embryonic rats; (2) QUE directed the differentiation of neural progenitors to oligodendrocyte lineage through extracellular signal-related kinases; (3) addition of QUE increased the synthesis of myelin basic protein and facilitated myelination in rat embryonic cortical aggregate cultures; (4) chronic administration of QUE to C57BL/6 mice prevented cortical demyelination and concomitant spatial working memory impairment induced by cuprizone, a neurotoxin. These findings suggest a new neural mechanism of antipsychotic action of QUE, and help to establish a role for oligodendrocytes in the etiopathology and treatment of schizophrenia.

Long-acting risperidone improves negative symptoms in stable psychotic patients

The aim of this paper was to evaluate the efficacy of risperidone long-acting injectable (RLAI) for reducing negative symptoms of schizophrenia in patients with predominantly negative symptoms at baseline. A subanalysis was performed on data from the 6-month, open-label Switch to Risperidone Microspheres trial. Patients with Positive and Negative Syndrome Scale (PANSS) negative subscale score > or = 21, which was higher than their PANSS positive subscale score, were included in this subanalysis. Improvement in negative symptoms was measured by assessing change in the PANSS negative subscale and a negative factor score. Additional outcome variables included measures in general functioning, quality of life and patient satisfaction. A total of 842 patients were eligible for inclusion in this subanalysis. Six months of treatment was completed by 631 (74.9%) patients. Forty-three (5.1%) patients discontinued treatment due to an adverse event. Negative symptoms were significantly reduced by 6.1 +/- 6.3 points for the PANSS negative score and 6.1 +/- 6.4 points for the negative factor score (P < 0.0001 for both). Significant improvements were also noted for total PANSS and other PANSS subscale scores, general functioning, quality of life and patient satisfaction (P < 0.0001). The most common treatment-emergent adverse events (>5%) were: anxiety (6.8% of patients), exacerbation of disease (6.2%) and insomnia (5.7%). Overall, RLAI was well tolerated and associated with significant reductions in movement disorder severity. The treatment resulted in a significant improvement in negative symptom severity and was well tolerated in patients with predominantly negative symptoms, who switched from a stable antipsychotic regimen

Randomized controlled pilot study of quetiapine in the treatment of adolescent conduct disorder

OBJECTIVE

The aim of this study was to examine whether quetiapine is superior to placebo in the treatment of adolescents with conduct disorder.

METHODS

This was a 7-week, randomized, double-blind, placebo-controlled pilot study with two parallel arms. Nine youths were randomly assigned to receive quetiapine, and 10 youths were randomly assigned to receive placebo. Patients were assessed weekly throughout the trial. Quetiapine was dosed twice daily, and medications could be titrated flexibly through the end of study week 5. The dose was fixed for the final 2 weeks of the study. The primary outcome measures were the clinician-assessed Clinical Global Impressions-Severity (CGI-S) and-Improvement (CGI-I) scales. Secondary outcome measures included parent-assessed quality of life, the overt aggression scale (OAS), and the conduct problems subscale of the Conners' Parent Rating Scale (CPRS-CP).

RESULTS

The final mean dose of quetiapine was 294 +/- 78 mg/day (range 200-600 mg/day). Quetiapine was superior to placebo on all clinician-assessed measures and on the parent-assessed quality of life rating scale. No differences were found on the parent-completed OAS and CPRS-CP. Quetiapine was well tolerated. One patient randomized to quetiapine developed akathisia, requiring medication discontinuation. No other extrapyramidal side effects occurred in patients receiving active drug.

CONCLUSIONS

This methodologically controlled pilot study provides data that quetiapine may have efficacy in the treatment of adolescents with conduct disorder. Because of the preliminary nature of the study, further research with larger samples is needed to confirm these findings.

Modulation of human motor cortex excitability by quetiapine

RATIONALE

Quetiapine is increasingly used for the treatment of patients with psychosis and bipolar disorder. However, the neurobiological mechanisms, which may account for the favourable risk/benefit profile of this drug, are not entirely understood.

OBJECTIVES

Transcranial magnetic stimulation was used to investigate the effects of acute and repeated administration of quetiapine on cortical excitability in healthy volunteers.

MATERIALS AND METHODS

Within a double-blind, placebo-controlled, randomized cross-over design motor threshold, intracortical inhibition, intracortical facilitation and cortical silent period were studied in 15 healthy volunteers before and after a single dose of placebo and 100 mg quetiapine. Additional measurements were performed after 5 days of daily intake of 100 mg quetiapine.

RESULTS

We observed a significant prolongation of the cortical silent period after a single dose of quetiapine, whereas the placebo had no effects. After repeated administration, there was a trend towards CSP prolongation, which did not reach significance. However, plasma concentrations at this time point were relatively low, as measurements were performed 15 h after the last drug intake. Other parameters of cortical excitability remained unaffected.

CONCLUSIONS

By lengthening CSP without affecting MT, ICI and ICF, quetiapine demonstrates a unique neurophysiological profile which differs distinctively from brain excitability profiles of typical antipsychotics such as haloperidol. Provided that the CSP prolongation reflects the antipsychotic potential of quetiapine, TMS may be developed as a tool to monitor neurobiological effects of quetiapine treatment in schizophrenic patients and to explore the efficacy of other antipsychotic drugs with a similar mode of action.

Quetiapine in the treatment of schizophrenia and related disorders

Quetiapine was developed in 1985 by scientists at AstraZeneca (formerly Zeneca) Pharmaceuticals. It received official US Food and Drug Administration approval in September 1997 and approval in Germany in 2000. Since then, quetiapine has been used in the treatment of severe mental illness in approximately 70 countries including Canada, most Western European countries, and Japan. Quetiapine is a dibenzothiazepine derivative with a relatively broad receptor binding profile. It has major affinity to cerebral serotonergic (5HT(2A)), histaminergic (H1), and dopaminergic D(1) and D(2) receptors, moderate affinity to alpha(1)- und alpha(2)-adrenergic receptors, and minor affinity to muscarinergic M1 receptors; it demonstrates a substantial selectivity for the limbic system. This receptor occupancy profile with relatively higher affinity for the 5HT(2A) receptor compared with the D(2) receptor is in part responsible for the antipsychotic characteristics and low incidence of extrapyramidal side-effects of quetiapine. The efficacy of quetiapine in reducing positive and negative symptoms of schizophrenia has been proven in several clinical trials with placebo-controlled comparators. Quetiapine has also demonstrated robust efficacy for treatment of cognitive, anxious-depressive, and aggressive symptoms in schizophrenia. Long-term trials show sustained tolerability for a broad spectrum of symptoms. Quetiapine has also proven efficacy and tolerability in the treatment of moderate to severe manic episodes, and in the treatment of juveniles with oppositional-defiant or conduct disorders, and in the geriatric dementia population. Recent data indicate that quetiapine may also be effective in the treatment of bipolar depressive symptoms without increasing the risk of triggering manic episodes, and in borderline personality disorder. In comparison with other antipsychotics, quetiapine has a favorable side-effect profile. In clinical trials only small insignificant prolongations of the QT interval were observed. Weight-gain liabilities and new-onset metabolic side-effects occupy a middle-ground among newer antipsychotics. As a result of its good efficacy and tolerability profile quetiapine has become well established in the treatment of schizophrenia and manic episodes.

Symptom domains of schizophrenia: the role of atypical antipsychotic agents

Given their more obvious presentation, the reduction of positive symptoms and their associated behavioural problems have been considered the most important treatment outcome parameter in patients with schizophrenia. However, the development of the atypical antipsychotic agents in the early 1990s resulted in the adoption of more wide-reaching measures of therapeutic outcome. The aim of this review was to evaluate the efficacy of currently available atypical agents across multiple symptom domains of schizophrenia with a specific focus on negative symptoms, neurocognition, social functioning, quality of life and insight. As such, studies published between January 1990 and December 2005 that evaluated the clinical efficacy and tolerability of atypical antipsychotics in different symptom domains of schizophrenia were reviewed as identified from literature researches using MEDLINE and Embase. Abstracts and posters presented at key psychiatry and schizophrenia congresses during this period were also reviewed where available in the public domain. Results from the studies identified have consistently demonstrated that atypical antipsychotics have substantial advantages over conventional antipsychotics with a broader spectrum of efficacy across symptomatic domains of schizophrenia as proven by greater improvements in negative symptoms and cognitive function and a beneficial effect on affective symptoms and quality of life. However, their clinical advantages have often been limited by patients' partial compliance with therapy. As such, the development of a long-acting atypical antipsychotic agent may provide a new and valuable treatment option for patients with schizophrenia.

Randomized, double-blind 6-month comparison of olanzapine and quetiapine in patients with schizophrenia or schizoaffective disorder with prominent negative symptoms and poor functioning

This study compared the effects of olanzapine (OLZ) with those of quetiapine (QUE) for improving negative symptoms in patients diagnosed with schizophrenia or schizoaffective disorder who had prominent negative symptoms and marked deficits in social or occupational functioning. In this 6-month, multicenter, double-blind clinical trial, patients were randomized to treatment with OLZ (n = 171, 10-20 mg/d) or QUE (n = 175, 300-700 mg/d). Patients were treated at community mental health centers and assigned case managers who developed individualized psychosocial treatment plans. The primary efficacy measure was the reduction in negative symptoms using the Scale for the Assessment of Negative Symptoms. Secondary measures assessed changes in functioning, psychopathology, and treatment tolerability. Treatment with OLZ or QUE led to a significant reduction in negative symptoms, with no between-group difference (P = 0.09). Both treatment groups also showed significant improvement on most efficacy measures. Olanzapine-treated patients showed significantly greater improvement on positive symptoms and on several measures of functioning including Global Assessment of Functioning Scale, Quality of Life Instrumental Role domain, and level of effort in psychosocial or occupational rehabilitation programs. Significantly more OLZ-treated patients completed the study (52.6% OLZ, 37.7% QUE, P = 0.007). Treatment differences in safety were relatively small and not thought to be clinically relevant. Patients with schizophrenia who manifest prominent negative symptoms and marked functional deficits demonstrated significant improvement in negative symptoms after treatment with OLZ or QUE. Greater improvement in positive symptoms and a greater study completion rate may hold relevance to enhanced functional outcomes observed after OLZ therapy.