NMDA receptor antagonists for depression: Critical considerations

BACKGROUND

Research studies suggest that glutamate dysfunction, in particular N-methyl-D-aspartate receptors (NMDARs) abnormalities, may be involved in the pathophysiology of major neuropsychiatric conditions. Increased glutamatergic excitotoxic activity may be found in some brain circuits of patients with major depression. According to several published reports, NMDAR antagonists may exert antidepressant activity, but the molecular changes associated with abnormal glutamatergic neurotransmission remain unclear.

METHODS

We have critically reviewed the current literature in order to investigate the role of NMDAR antagonists in major depression.

RESULTS

NMDAR antagonists, such as ketamine, may be considered novel and promising pharmacological options for the rapid treatment of treatment-resistant depression patients. This is in contrast to the delayed action of the currently available antidepressant medications. Studies suggest that glutamatergic receptor modulation may enhance neuroplasticity mechanisms and neurogenesis together with the release of some neurotransmitters. Unfortunately, the use of ketamine is currently limited by some transient adverse events, including dissociative symptoms.

CONCLUSIONS

Targeting NMDARs using antagonists represents an important alternative antidepressant option in major depression. However, NMDAR antagonists may exert different actions based on the differential brain location of NMDAR.

A randomized, double-blind, placebo-controlled trial of aripiprazole lauroxil in acute exacerbation of schizophrenia

OBJECTIVE

This study evaluated the efficacy, safety, and tolerability of aripiprazole lauroxil, a novel long-acting injectable atypical antipsychotic, for the treatment of schizophrenia.

METHOD

An international multicenter, randomized, double-blind, placebo-controlled trial was conducted between December 2011 and March 2014. Patients (N = 623) aged 18 to 70 years with schizophrenia (DSM-IV-TR criteria), experiencing an acute exacerbation, were randomized in a 1:1:1 ratio to receive gluteal intramuscular injection of aripiprazole lauroxil 441 mg, aripiprazole lauroxil 882 mg, or matching placebo once monthly for 12 weeks. The primary efficacy outcome was change in Positive and Negative Syndrome Scale (PANSS) total score from baseline to day 85. The Clinical Global Impressions-Improvement scale (CGI-I) score at day 85 was the secondary efficacy outcome. Safety and tolerability were assessed.

RESULTS

The PANSS total score (mean ± standard error [SE]) improved significantly from baseline to day 85 in the aripiprazole lauroxil 441 mg and 882 mg groups, with placebo-adjusted differences of -10.9 ± 1.8 (P < .001) and -11.9 ± 1.8 (P < .001), respectively. Significant (P ≤ .004) improvements in both active treatment groups were demonstrated as early as day 8 and continued throughout the treatment period. The proportion of patients who were very much or much improved on the CGI-I was significantly greater with aripiprazole lauroxil 441 mg and 882 mg treatment versus placebo (P < .001). The most common treatment-emergent adverse events were insomnia, akathisia, headache, and anxiety. The incidence of injection site reactions was low, predominantly described as injection site pain, and was associated with the first injection.

CONCLUSIONS

Aripiprazole lauroxil demonstrated robust efficacy for treatment of patients experiencing acute exacerbation of schizophrenia. The improvement in psychotic symptoms was statistically significant and clinically meaningful. Symptom improvement occurred rapidly after initiation of aripiprazole lauroxil treatment and was maintained throughout the study. Both aripiprazole lauroxil 441 mg and 882 mg doses were well tolerated. These results support aripiprazole lauroxil as an important new treatment option for schizophrenia.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT01469039; Clinicaltrialsregister.eu identifier: 2012-003445-15.

The Management of Schizophrenia in Clinical Practice (MOSAIC) Registry: a focus on patients, caregivers, illness severity, functional status, disease burden and healthcare utilization

BACKGROUND

The Management of Schizophrenia in Clinical Practice (MOSAIC), a disease-based registry of schizophrenia, was initiated in December 2012 to address important gaps in our understanding of the impact and burden of schizophrenia and to provide insight into the current status of schizophrenia care in the US. Recruitment began in December 2012 with ongoing assessment continuing through May 2014.

METHODS

Participants were recruited from a network of 15 centralized Patient Assessment Centers supporting proximal care sites. Broad entry criteria included patients diagnosed with schizophrenia, schizophreniform or schizoaffective disorder, presenting within the normal course of care, in usual treatment settings, aged ≥18years and able to read and speak English.

RESULTS

By May 2014, 550 participants (65.8% male, 59.8% White, 64.4% single, mean age 42.9years), were enrolled. The majority had a diagnosis of schizophrenia (62.0%). Mean illness duration at entry was 15.0years. Common comorbidities at entry were high lipid levels (26.9%), hypertension (23.1%) and type II diabetes (13%). Participants were categorized by baseline overall Clinical Global Impression-Schizophrenia Severity Score as minimally (9.1%), mildly (25.3%), moderately (39.9%), markedly (22.3%) and severely (3.4%) ill. Most commonly used second generation antipsychotics at entry were risperidone (17.8%), clozapine (16.5%), olanzapine (14.0%), aripiprazole (13.6%) and quetiapine (5.6%).

CONCLUSIONS

No large-scale patient registry has been conducted in the US to longitudinally follow patients with schizophrenia and describe symptom attributes, support network, care access and disease burden. These data provide important epidemiological, clinical and outcome insights into the burden of schizophrenia in the US.

Defining therapeutic benefit for people with schizophrenia: focus on negative symptoms

Schizophrenia is a complex, heterogeneous, multidimensional disorder within which negative symptoms are a significant and disabling feature. Whilst there is no established treatment for these symptoms, some pharmacological and psychosocial interventions have shown promise and this is an active area of research. Despite the effort to identify effective interventions, as yet there is no broadly accepted definition of therapeutic success. This article reviews concepts of clinical relevance and reports on a consensus conference whose goal was to apply these concepts to the treatment of negative symptoms. A number of key issues were identified and discussed including: assessment of specific negative symptom domains; defining response and remission for negative symptoms; assessment of functional outcomes; measurement of outcomes within clinical trials; and the assessment of duration/persistence of a response. The group reached a definition of therapeutic success using an achieved threshold of function that persisted over time. Recommendations were agreed upon with respect to: assessment of negative symptom domains of apathy-avolition and deficit of expression symptoms; thresholds for response and remission of negative symptoms based on level of symptomatology; assessing multiple domains of function including social occupation, activities of daily living, and socialization; the need for clinical trial data to include rate of change over time and converging sources of evidence; use of clinician, patient and caregiver perspectives to assess success; and the need for establishing criteria for the persistence of therapeutic benefit. A consensus statement and associated research criteria are offered as an initial step towards developing broad agreement regarding outcomes of negative symptoms treatment.

CYP450 pharmacogenetic treatment strategies for antipsychotics: a review of the evidence

Although a number of first- and second-generation antipsychotics are available, achieving optimal therapeutic response for patients with schizophrenia can be challenging. The presence of polymorphic alleles for cytochrome P (CYP) 450 may result in lack of expression, altered levels of expression, or altered function of CYP450 enzymes. CYP2D6, CYP1A2, and CYP3A4/5 are major enzymes in the metabolism of antipsychotics and polymorphisms of alleles for these proteins are associated with altered plasma levels. Consequently, standard dosing may result in drug plasma concentrations that are subtherapeutic or toxic in some patients. Patient CYP450 genotype testing can predict altered pharmacokinetics, and is currently available and relatively inexpensive. Evidence-based guidelines provide dose recommendations for some antipsychotics. To date few studies have demonstrated a significant association with genotype-guided antipsychotic use and clinical efficacy. However, many studies have been small, retrospective or cohort designs, and many have not been adequately powered. Numerous studies have shown a significant association between genotype and adverse effects, such as CYP2D6 polymorphisms and tardive dyskinesia. This review summarizes evidence for the role of CYP450 genetic variants in the response to antipsychotic medications and the clinical implications of pharmacogenetics in the management of patients with schizophrenia.

Lipidomics reveals early metabolic changes in subjects with schizophrenia: effects of atypical antipsychotics

There is a critical need for mapping early metabolic changes in schizophrenia to capture failures in regulation of biochemical pathways and networks. This information could provide valuable insights about disease mechanisms, trajectory of disease progression, and diagnostic biomarkers. We used a lipidomics platform to measure individual lipid species in 20 drug-naïve patients with a first episode of schizophrenia (FE group), 20 patients with chronic schizophrenia that had not adhered to prescribed medications (RE group), and 29 race-matched control subjects without schizophrenia. Lipid metabolic profiles were evaluated and compared between study groups and within groups before and after treatment with atypical antipsychotics, risperidone and aripiprazole. Finally, we mapped lipid profiles to n3 and n6 fatty acid synthesis pathways to elucidate which enzymes might be affected by disease and treatment. Compared to controls, the FE group showed significant down-regulation of several n3 polyunsaturated fatty acids (PUFAs), including 20:5n3, 22:5n3, and 22:6n3 within the phosphatidylcholine and phosphatidylethanolamine lipid classes. Differences between FE and controls were only observed in the n3 class PUFAs; no differences where noted in n6 class PUFAs. The RE group was not significantly different from controls, although some compositional differences within PUFAs were noted. Drug treatment was able to correct the aberrant PUFA levels noted in FE patients, but changes in re patients were not corrective. Treatment caused increases in both n3 and n6 class lipids. These results supported the hypothesis that phospholipid n3 fatty acid deficits are present early in the course of schizophrenia and tend not to persist throughout its course. These changes in lipid metabolism could indicate a metabolic vulnerability in patients with schizophrenia that occurs early in development of the disease.

Effects of switching from olanzapine, quetiapine, and risperidone to aripiprazole on 10-year coronary heart disease risk and metabolic syndrome status: results from a randomized controlled trial

PURPOSE

This study examined the clinical significance of switching from olanzapine, quetiapine, or risperidone to aripiprazole by examining changes in predicted risk of cardiovascular disease (CVD) according to the Framingham Risk Score (FRS) and metabolic syndrome status. FRS estimates 10-year risk of "hard" coronary heart disease (CHD) outcomes (myocardial infarction and coronary death) while metabolic syndrome is associated with increased risk of CVD, stroke, and diabetes mellitus.

METHOD

Changes in FRS and metabolic syndrome status were compared between patients with BMI ≥ 27 and non-HDL-C ≥ 130 mg/dL randomly assigned to stay on stable current treatment (olanzapine, quetiapine, or risperidone) or switch to treatment with aripiprazole with 24 weeks of follow-up. All study participants were enrolled in a behavioral program that promoted healthy diet and exercise.

RESULTS

The pre-specified analyses included 89 switchers and 98 stayers who had post-baseline measurements needed to assess changes. Least squares mean estimates of 10-year CHD risk decreased more for the switch (from 7.0% to 5.2%) than the stay group (from 7.4% to 6.4%) (p = 0.0429). The odds ratio for having metabolic syndrome (stay vs. switch) at the last observation was 1.748 (95% CI 0.919, 3.324, p = 0.0885).

CONCLUSION

Switching from olanzapine, quetiapine, or risperidone to aripiprazole was associated with larger reductions in predicted 10-year risk of CHD than the behavioral program alone. The advantage of switching on metabolic syndrome was not statistically significant. The benefits of switching must be balanced against its risks, which in this study included more discontinuations of the study treatment but no significant increase in symptoms or hospitalizations.

Persistent infection with neurotropic herpes viruses and cognitive impairment

BACKGROUND

Herpes virus infections can cause cognitive impairment during and after acute encephalitis. Although chronic, latent/persistent infection is considered to be relatively benign, some studies have documented cognitive impairment in exposed persons that is untraceable to encephalitis. These studies were conducted among schizophrenia (SZ) patients or older community dwellers, among whom it is difficult to control for the effects of co-morbid illness and medications. To determine whether the associations can be generalized to other groups, we examined a large sample of younger control individuals, SZ patients and their non-psychotic relatives (n=1852). Method Using multivariate models, cognitive performance was evaluated in relation to exposures to herpes simplex virus type 1 (HSV-1), herpes simplex virus type 2 (HSV-2) and cytomegalovirus (CMV), controlling for familial and diagnostic status and sociodemographic variables, including occupation and educational status. Composite cognitive measures were derived from nine cognitive domains using principal components of heritability (PCH). Exposure was indexed by antibodies to viral antigens.

RESULTS

PCH1, the most heritable component of cognitive performance, declines with exposure to CMV or HSV-1 regardless of case/relative/control group status (p = 1.09 × 10-5 and 0.01 respectively), with stronger association with exposure to multiple herpes viruses (β = -0.25, p = 7.28 × 10-10). There were no significant interactions between exposure and group status.

CONCLUSIONS

Latent/persistent herpes virus infections can be associated with cognitive impairments regardless of other health status.

Lurasidone for the treatment of acutely psychotic patients with schizophrenia: a 6-week, randomized, placebo-controlled study

Despite the availability of established antipsychotic agents for the treatment of schizophrenia, continued unmet needs exist for effective medications with lower adverse-effect burden. The present study evaluated the efficacy, safety, and tolerability of treatment with the atypical antipsychotic lurasidone for patients with an acute exacerbation of schizophrenia. Patients were randomized to 6 weeks of double-blind treatment with lurasidone 40 mg/day, 80 mg/day, or 120 mg/day, or placebo. Changes in Positive and Negative Syndrome Scale (PANSS) scores were evaluated using mixed-model repeated-measures (MMRM) analysis. Vital signs, laboratory parameters, extrapyramidal symptoms, and electrocardiogram were assessed. Treatment with lurasidone 80 mg/day resulted in significantly greater improvement in PANSS total score compared with placebo (-23.4 versus -17.0; p < 0.05) at study endpoint (MMRM); lurasidone 40 mg/day and 120 mg/day achieved clinically meaningful overall PANSS score reductions from baseline (-19.2 and -20.5), but not significant separation from placebo. Differences between all lurasidone groups and placebo for changes in laboratory parameters and electrocardiographic measures were minimal. Weight gain ≥ 7% occurred in 8.2% of patients receiving lurasidone and 3.2% receiving placebo. Modest increases in prolactin (median increase, 0.7 ng/mL) and extrapyramidal symptoms were observed following treatment with lurasidone compared with placebo. Akathisia was the most commonly reported adverse event with lurasidone (17.6%, versus 3.1% with placebo). In this study, in which a large placebo response was observed, lurasidone 80 mg/day, but not 40 mg/day or 120 mg/day, was statistically superior to placebo in treating acute exacerbation of chronic schizophrenia. All lurasidone doses were generally well tolerated.

Evaluation of HLA polymorphisms in relation to schizophrenia risk and infectious exposure

BACKGROUND

Genome-wide association studies (GWAS) implicate single nucleotide polymorphisms (SNPs) on chromosome 6p21.3-22.1, the human leukocyte antigen (HLA) region, as common risk factors for schizophrenia (SZ). Other studies implicate viral and protozoan exposure. Our study tests chromosome 6p SNPs for effects on SZ risk with and without exposure.

METHOD

GWAS-significant SNPs and ancestry-informative marker SNPs were analyzed among African American patients with SZ (n = 604) and controls (n = 404). Exposure to herpes simplex virus, type 1 (HSV-1), cytomegalovirus (CMV), and Toxoplasma gondii (TOX) was assayed using specific antibody assays.

RESULTS

Five SNPs were nominally associated with SZ, adjusted for population admixture (P < .05, uncorrected for multiple comparisons). These SNPs were next analyzed in relation to infectious exposure. Multivariate analysis indicated significant association between rs3130297 genotype and HSV-1 exposure; the associated allele was different from the SZ risk allele.

CONCLUSIONS

We propose a model for the genesis of SZ incorporating genomic variation in the HLA region and neurotropic viral exposure for testing in additional, independent African American samples.

Clinical pharmacology of paliperidone palmitate a parenteral long-acting formulation for the treatment of schizophrenia

Paliperidone Palmitate is a long-acting intramuscular atypical antipsychotic drug indicated for the acute maintenance treatment of schizophrenia in adults. Its mechanism of action, like all other atypical agents, is attributed to the antagonism of brain dopamine D2 and serotonin 5-HT2A receptors. The pharmacodynamics, pharmacokinetics, and metabolism of paliperidone palmitate are reviewed. Current studies for clinical efficacy of paliperidone palmitate for both acute and maintenance treatment and adherence in adults with schizophrenia are discussed. Studies for safety and tolerability are also reviewed.

Impaired plasmalogens in patients with schizophrenia

Plasmalogens are a subclass of glycerophospholipids and ubiquitous constituents of cellular membranes and serum lipoproteins. Several neurological disorders show decreased level of plasmogens. An earlier study found differences in plasma phospholipids between unmedicated patients with schizophrenia and matched healthy control subjects. We here report a comparison of plasma plasmalogen levels across 20 drug-naïve patients experiencing first psychotic episodes, 20 recently unmedicated patients experiencing psychotic relapses after failing to comply with prescribed medications, and 17 matched healthy control subjects. Multiple plasma phosphatidylcholine and phosphatidylethanolamine plasmalogen levels were significantly lower in first episode patients and patients with recurrent disease compared to healthy controls. Reduced plasmalogen levels appear to be a trait evident at the onset of psychotic illness and after multiple psychotic relapses. It is implied that reductions in plasmalogen levels are not related to antipsychotic treatment but due to the illness itself. Reduced plasmalogen levels suggest impairments in membrane structure and function in patients with schizophrenia that might happen early in development. This may serve as a clue to the neurobiology of schizophrenia and should be studied as a potential biomarker for individuals at risk for schizophrenia.

Recent advances in understanding and mitigating adipogenic and metabolic effects of antipsychotic drugs

Although offering many benefits for several psychiatric disorders, antipsychotic drugs (APDs) as a class have a major liability in their tendency to promote adiposity, obesity, and metabolic dysregulation in an already metabolically vulnerable population. The past decade has witnessed substantial research aimed at investigating the mechanisms of these adverse effects and mitigating them. On July 11 and 12, 2011, with support from 2 NIH institutes, leading experts convened to discuss current research findings and to consider future research strategies. Five areas where significant advances are being made emerged from the conference: (1) methodological issues in the study of APD effects; (2) unique characteristics and needs of pediatric patients; (3) genetic components underlying susceptibility to APD-induced metabolic effects; (4) APD effects on weight gain and adiposity in relation to their acute effects on glucose regulation and diabetes risk; and (5) the utility of behavioral, dietary, and pharmacological interventions in mitigating APD-induced metabolic side effects. This paper summarizes the major conclusions and important supporting data from the meeting.

On-label on the table: what the package insert informs us about the tolerability profile of oral atypical antipsychotics, and what it does not

INTRODUCTION

The product label is commonly used as an authoritative source for drug information, especially for new medications that have a limited published evidence base. Key elements of the product label are descriptions of safety and tolerability.

AREAS COVERED

The package inserts of oral atypical antipsychotics approved by the US Food and Drug Administration are reviewed with regard to product safety and tolerability.

EXPERT OPINION

Product labels of oral second-generation antipsychotics provide an opportunity to indirectly compare the safety and tolerability profiles of each agent. Some warnings and precautions are found across the entire class; other warnings and precautions may be worded somewhat differently from agent to agent and some may be unique to a particular medication. Guidance is provided in the product label regarding use in specific populations, drug-drug interactions and other issues relating to dosing. Common adverse reactions are tabulated but the reader is left to calculate the risk differences from placebo and number needed to harm. The latter can be helpful in appraising potential differences in discontinuation rates because of adverse reactions, the proportion gaining at least 7% in body weight from baseline in short-term studies, the proportion experiencing somnolence and the proportion experiencing akathisia. The product label, although limited in terms of being product-specific, is often the most authoritative and accessible source of information about new agents in the marketplace. However, clinicians will need to mind the gap between the efficacy and preliminary safety and tolerability data provided by registration trials and the real-world effectiveness of medications when used in the clinic.

Executive function impairment in first-degree relatives of persons with schizophrenia: A meta-analysis of controlled studies

A meta-analysis of past research evaluated the relationship between deficits in executive functioning among unaffected first-degree relatives of schizophrenia patients and healthy controls. The Wisconsin Cart Sorting Test (WCST), a reliable measurement of cognition and abstract thinking, was examined as the dependent variable. Unaffected first-degree relatives perform worse than controls on two important dimensions of the WCST. They achieve significantly less categories and significantly more perseverative errors.

Schizophrenia, "Just the Facts" 6. Moving ahead with the schizophrenia concept: from the elephant to the mouse

The current construct of schizophrenia as a unitary disease is far from satisfactory, and is in need of reconceptualization. The first five papers in our "facts" series reviewed what is known about schizophrenia to date, and a limited number of key facts appear to stand out. Schizophrenia is characterized by persistent cognitive deficits, positive and negative symptoms typically beginning in youth, substantive heritability, and brain structural, functional and neurochemical alterations including dopaminergic dysregulation. Several pathophysiological models have been proposed with differing interpretations of the illness, like the fabled six blind Indian men groping different parts of an elephant coming up with different conclusions. However, accumulating knowledge is integrating the several extant models of schizophrenia etiopathogenesis into unifying constructs; we discuss an example, involving a neurodevelopmental imbalance in excitatory/inhibitory neural systems leading to impaired neural plasticity. This imbalance, which may be proximal to clinical manifestations, could result from a variety of genetic, epigenetic and environmental causes, as well as pathophysiological processes such as inflammation and oxidative stress. Such efforts to "connect the dots" (and visualizing the elephant) are still limited by the substantial clinical, pathological, and etiological heterogeneity of schizophrenia and its blurred boundaries with several other psychiatric disorders leading to a "fuzzy cluster" of overlapping syndromes, thereby reducing the content, discriminant and predictive validity of a unitary construct of this illness. The way ahead involves several key directions: a) choosing valid phenotype definitions increasingly derived from translational neuroscience; b) addressing clinical heterogeneity by a cross-diagnostic dimensional and a staging approach to psychopathology; c) addressing pathophysiological heterogeneity by elucidating independent families of "extended" intermediate phenotypes and pathophysiological processes (e.g. altered excitatory/inhibitory, salience or executive circuitries, oxidative stress systems) that traverse structural, functional, neurochemical and molecular domains; d) resolving etiologic heterogeneity by mapping genomic and environmental factors and their interactions to syndromal and specific pathophysiological signatures; e) separating causal factors from consequences and compensatory phenomena; and f) formulating or reformulating hypotheses that can be refuted/tested, perhaps in the mouse or other experimental models. These steps will likely lead to the current entity of schizophrenia being usefully deconstructed and reconfigured into phenotypically overlapping, but etiopathologically unique and empirically testable component entities (similar to mental retardation, epilepsy or cancer syndromes). The mouse may be the way to rescue the trapped elephant!