Effects of davunetide on N-acetylaspartate and choline in dorsolateral prefrontal cortex in patients with schizophrenia.

Schizophrenia is associated with extensive neurocognitive and behavioral impairments. Studies indicate that N-acetylaspartate (NAA), a marker of neuronal integrity, and choline, a marker of cell membrane turnover and white matter integrity, may be altered in schizophrenia. Davunetide is a neurotrophic peptide that can enhance cognitive function in animal models of neurodegeneration. Davunetide has recently demonstrated modest functional improvement in a study of people with schizophrenia. In a subset of these subjects, proton magnetic resonance spectroscopy ((1)H-MRS) was conducted to explore the effects of davunetide on change in NAA/creatine (NAA/Cr) and choline/creatine (choline/Cr) over 12 weeks of treatment. Of 63 outpatients with schizophrenia who received randomized davunetide (5 and 30 mg/day) or placebo in the parent clinical trial, 18 successfully completed (1)H-MRS in dorsolateral prefrontal cortex (DLPFC) at baseline and at 12 weeks. Cognition was assessed using the MATRICS Consensus Cognitive Battery (MCCB). NAA/Cr was unchanged for combined high- and low-dose davunetide groups (N=11). NAA/Cr in the high-dose davunetide group (N=8) suggested a trend increase of 8.0% (P=0.072) over placebo (N=7). Choline/Cr for combined high- and low-dose davunetide groups suggested a 6.4% increase (P=0.069), while the high-dose group showed a 7.9% increase (P=0.040) over placebo. Baseline NAA/Cr correlated with the composite MCCB score (R=0.52, P=0.033), as did individual cognitive domains of attention/vigilance, verbal learning, and social cognition; however, neither metabolite correlated with functional capacity. In this exploratory study, 12 weeks of adjunctive davunetide appeared to produce modest increases in NAA/Cr and choline/Cr in DLPFC in people with schizophrenia. This is consistent with a potential neuroprotective mechanism for davunetide. The data also support use of MRS as a useful biomarker of baseline cognitive function in schizophrenia. Future clinical and preclinical studies are needed to fully define the mechanism of action and cognitive effects of davunetide in schizophrenia.

A review of anti-inflammatory agents for symptoms of schizophrenia.

Schizophrenia is a chronic debilitating mental disorder that affects about 1% of the US population. The pathophysiology and etiology remain unknown, thus new treatment targets have been challenging and few novel treatments with new mechanisms of action have come to market in the past few decades. Increasing attention has been paid to the role of inflammation in schizophrenia and new data suggests that decreasing inflammation and inflammatory biomarkers may play some role in schizophrenia treatment. This review summarizes the clinical trial literature regarding medications that possess anti-inflammatory properties that have been tested for schizophrenia symptoms and covers such medications as non-steroidal anti-inflammatory agents, such as the cyclo-oxygenase-2 (COX-2) inhibitors and aspirin, omega-3 fatty acids, neurosteroids and minocycline. Overall, there is accumulating evidence, albeit mostly adjunctive treatments, that agents working on inflammatory pathways have some benefits in people with schizophrenia. In the next few years the field will begin to see data on many treatments with anti-inflammatory properties that are currently under study. Hopefully advancements in understanding inflammation and effective treatments having anti-inflammatory properties may help revolutionize our understanding and provide new targets for prevention and treatment in schizophrenia.

Effects of the cannabinoid-1 receptor antagonist rimonabant on psychiatric symptoms in overweight people with schizophrenia: a randomized, double-blind, pilot study.

Weight gain is a major adverse effect of several second-generation antipsychotic medications. Rimonabant is a cannabinoid-1 receptor antagonist that promotes weight loss in the general population. We conducted a 16-week, double-blind, placebo-controlled study of rimonabant (20 mg/d) in people with schizophrenia or schizoaffective disorder, based on the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition criteria, who were clinically stable on second-generation antipsychotics. Participants had a body mass index of 27 kg/m or higher with hyperlipidemia or body mass index of 30 kg/m or higher, and no current substance abuse/dependence (except nicotine), more than weekly cannabis use, or recent depressive symptoms/suicidality. An exercise and dietary counseling group was offered weekly. Target enrollment was 60; the trial was terminated early because of withdrawal of rimonabant from the European market. Fifteen participants were randomized (7 rimonabant, 8 placebo); 5 completed in each group. Rimonabant was associated with a greater reduction in Brief Psychiatric Rating Scale total score versus placebo (mean ± SE difference, -1.9 ± 0.8, P = 0.02), driven by differences in the Brief Psychiatric Rating Scale anxiety/depression (-1.4 ± 0.35, P = 0.0004) and hostility (-0.7 ± 0.3, P = 0.02) factors. Group differences were not significant for the Calgary Depression Scale total score (P = 0.24), Scale for the Assessment of Negative Symptoms total score (P = 0.13), weight, blood pressure, or fasting lipids or glucose. Rimonabant was well tolerated with no significant adverse events. No significant weight loss, metabolic effects, or adverse psychiatric effects were associated with the cannabinoid-1 receptor antagonist rimonabant in this small sample of people with schizophrenia. The endocannabinoid system remains a promising target for pharmacotherapy of schizophrenia and obesity.

Independent domains of inhibitory gating in schizophrenia and the effect of stimulus interval.

OBJECTIVE: Patients with schizophrenia are known to have inhibitory gating deficits in the suppression of evoked potential P50 response to repeated stimuli and the prepulse inhibition of the startle response. In the current study, the authors aimed to determine whether these two inhibitory gating measures are related in schizophrenia patients or whether abnormal P50 suppression and abnormal prepulse inhibition are independent neurophysiological characteristics of schizophrenia. The authors hypothesized that the relationship of the two measures may vary as a function of interstimulus intervals of stimulus presentations. METHOD: Fifty-nine schizophrenia patients and 17 healthy comparison subjects were tested on both P50 suppression and prepulse inhibition. P50 suppression was measured using paired clicks with 500-msec interstimulus intervals. Prepulse inhibition was measured by using a series of prepulse-pulse pairs with interstimulus intervals ranging from 30 to 500 msec. RESULTS: Patients showed reduced P50 suppression and prepulse inhibition in relation to healthy comparison subjects. Concordance analysis showed that abnormal P50 suppression and abnormal prepulse inhibition do not necessarily occur together. Prepulse inhibition was most prominent at the 120-msec interstimulus interval, which was not correlated to P50 suppression. At the 500-msec interstimulus interval, prepulse inhibition was significantly but negatively correlated to P50 suppression. Prepulse inhibition at the other interstimulus intervals was not correlated with P50 suppression. CONCLUSIONS: These neurophysiological measures lack robust and direct relationships and likely mark independent aspects of abnormal brain inhibitory functions in schizophrenia.

Review of clinical correlates of P50 sensory gating abnormalities in patients with schizophrenia.

A large percentage of patients with schizophrenia are characterized by an abnormality in P50 sensory gating. This abnormality has been shown to be genetically linked to the alpha-7 nicotinic receptor and is transiently reversed by acute nicotine administration. These observations have led to the development of pharmacological treatments designed to improve sensory gating. However, if normalization of P50 gating abnormalities is to guide drug development, then it becomes important to delineate the clinical correlates of enhanced P50 gating. We conducted a review of all available articles through March 2005 that have examined this issue. We found that, despite the prominent role that P50 abnormalities have played in our understanding of schizophrenia, there is a relative dearth of data examining P50 clinical correlates. There is evidence suggestive of an association between P50 and measures of attention, and multiple studies have failed to document a cross-sectional or longitudinal relationship between P50 and positive, negative, or other symptoms. These results suggest that considerably more work needs to be done to understand and validate the clinical significance of this impairment.

Gamma/beta oscillation and sensory gating deficit in schizophrenia.

Sensory gating can be measured by the suppression of auditory evoked potentials in a paired-click paradigm. The normal gating of the P50 response to the second stimulus (S2) is impaired in many schizophrenic patients. Various in vitro and in vivo evoked potential paradigms have shown that a stimulus evokes early gamma frequency oscillation, which is followed by beta frequency oscillation. The gamma-to-beta shift in response to the first stimulus (SI) in the paired-click paradigm may contain critical electrophysiological signals that modulate the S2 suppression. The results of the present study showed that post-SI beta frequency response was inversely correlated to the S2 P50 response in patients with schizophrenia.

Olanzapine effects on auditory sensory gating in schizophrenia.

OBJECTIVE: New-generation antipsychotics have been proposed to normalize the P50 sensory gating index in patients with schizophrenia. In the context of a double-blind comparison of olanzapine and haloperidol, the authors examined the effect of olanzapine on P50 suppression. METHOD: P50 measurements were obtained at baseline while patients were being treated with fluphenazine and after 12 weeks of double-blind treatment with either olanzapine (N=12) or haloperidol (N=12). RESULTS: There were no treatment group differences in P50 amplitude, latency, or sensory gating ratio. CONCLUSIONS: These results suggest that there is not a significant differential effect of olanzapine and haloperidol on the P50 sensory gating index in schizophrenia.

The Mount Sinai conference on the pharmacotherapy of schizophrenia.

This report summarizes the recommendations from a consensus meeting that focused on specific questions regarding the pharmacotherapy of schizophrenia. The issues were selected because there was evidence that experts had recently disagreed about the evidence supporting a particular practice or when there were substantial variations in a clinical practice indicating that there was disagreement among clinicians. The group of experts was able to reach a consensus regarding the evidence base pertaining to the following issues: First generation (FGAs) and second generation (SGAs) antipsychotics as first line agents; the duration of antipsychotic trials; the effectiveness of clozapine and other agents for treatment refractory schizophrenia; risk of tardive dyskinesia on FGAs and SGAs; differences among antipsychotics for different dimensions of psychopathology; and side effect monitoring for various antipsychotics.

The schizophrenia PORT pharmacological treatment recommendations: conformance and implications for symptoms and functional outcome.

This cross-sectional study examines conformance to four of the Schizophrenia Patient Outcomes Research Team (PORT) antipsychotic treatment recommendations, patient and treatment setting characteristics assocated with conformance, and the relationship of conformance with outcome. Two hundred twenty-four inpatients and 358 outpatients with schizophrenia underwent an interview and review of their medical records. Demographic, clinical, and role function data were collected. Almost all inpatients and outpatients with schizophrenia or schizoaffective disorder were prescribed an antipsychotic. The majority of inpatients were prescribed an antipsychotic within the recommended dose range, whereas the majority of outpatients were prescribed an antipsychotic either below or above the recommended dose range. There were no consistent relationships between patient, geographic, and treatment characteristics and antipsychotic dose. Patients treated with conventional antipsychotic doses below the recommended dose range had significantly better role function. Prospective longitudinal studies are required to delineate the factors that may underlie this relationship.