Latent structure of cognitive tests is invariant in men and women with schizophrenia

Studies comparing the cognitive functioning of men and women with schizophrenia have produced conflicting results which could arise from sex-based differences in the latent structure of cognitive abilities. The current study used multigroup confirmatory factor analysis to examine invariance in latent structure of cognitive abilities to between men and women with schizophrenia. Confirmatory factor analysis of an initial neurocognitive assessment (men n = 612, women n = 201) and cross-validation using second assessment (men n = 549, women n = 198) demonstrated that a bifactor seven-factor model fit the data best for both men and women. Invariance analyses further indicated this model was invariant across men and women at both assessments. Group comparisons indicated women had significantly higher scores for Semantic Memory, Verbal Memory, and General Cognitive factors, whereas men exhibited better performance on the Vigilance factor. Results indicate that cognition in SZ is characterized by both a general cognitive factor and specific domains for both men and women. Invariance analysis provides evidence that cognitive differences between men and women do not result from sex-based differences in the latent structure of cognitive abilities. Current results also indicate small but statistically significant neurocognitive differences between men and women with schizophrenia.

An innovative technique towards personalized antipsychotic drug therapy in schizophrenia treatment

The CATIE schizophrenia trial was a very influential randomized controlled trial in patients with chronic schizophrenia. Patients were followed for up to 18 months under treatment with a randomly assigned antipsychotic. The primary endpoint, time to discontinuation of treatment for any reason, is influenced by individual patient characteristics, external factors as well as effects of drug treatment. New insight is obtained by applying an innovative survival analysis based on constrained confidence partitioning (SA-C²P). Through this data-driven approach we identify homogeneous collectives of patients with similar patient characteristics differing from the study population in the primary endpoint, enabling us to predict patient individual outcome more precisely. A subgroup of patients treated with olanzapine featuring neither an anxiety disorder in the past month, drug abuse in the past five years nor hospitalizations in the past year discontinued drug therapy substantially later compared to patients meeting at least one of the named parameters. Moreover, differences in the primary outcome between second-generation antipsychotics increased compared to the original CATIE analysis when looking into this subgroup in the entire study sample. Our findings suggest that SA-C²P may assist in identifying relevant responder subgroups, probably missed by conventional statistical methods, making it a potential tool for personalized medicine.

Bifactor model of cognition in schizophrenia: Evidence for general and specific abilities

BACKGROUND

Despite extensive study of cognition in schizophrenia, it remains unclear as to whether cognitive deficits and their latent structure are best characterized as reflecting a generalized deficit, specific deficits, or some combination of general and specific constructs.

METHOD

To clarify latent structure of cognitive abilities, confirmatory factor analysis was used to examine the latent structure of cognitive data collected for the Clinical Antipsychotic Trials of Intervention Effectiveness (CATIE) for Schizophrenia study. Baseline assessment data (n = 813) were randomly divided into calibration (n = 413) and cross-validation samples (n = 400). To examine whether generalized or specific deficit models provided better explanation of the data, we estimated first-order, hierarchical, and bifactor models.

RESULTS

A bifactor model with seven specific factors and one general factor provided the best fit to the data for both the calibration and cross-validation samples.

CONCLUSIONS

These findings lend support for a replicable bifactor model of cognition in schizophrenia, characterized by both a general cognitive factor and specific domains. This suggests that cognitive deficits in schizophrenia might be best understood by separate general and specific contributions.

Assessing hidden parentage and genetic integrity of the "United Fruit Clones" of cacao (Theobroma cacao) from Costa Rica using SNP markers

The international cacao collection in CATIE, Costa Rica contains nearly 1200 accessions of cacao, mainly from the center of genetic diversity of this species. Among these accessions, the United Fruit clones (UF clones) were developed by the United Fruit Company in Costa Rica, and they represent one of the earliest groups of improved cacao germplasm in the world. Some of these UF clones have been used as key progenitors for breeding resistance/tolerance to Frosty Pod and Black Pod diseases in the Americas. Accurate information on the identity and background of these clones is important for their effective use in breeding. Using Single Nucleotide Polymorphism (SNP) markers, we genotyped 273 cacao germplasm accessions including 44 UF clones and 229 reference accessions. We verified the true-to-type identity of UF clones in the CATIE cacao collection and analyzed their population memberships using maximum-likelihood-based approaches. Three duplicate groups, representing approximately 30% of the UF clones, were identified. Both distance- and model-based clustering methods showed that the UF clones were mainly composed of Trinitario, ancient Nacional and hybrids between ancient Nacional and Amelonado. This result filled the information gap about the UF clones thus will improve their utilization for cacao breeding.

Revisiting the canons of psychiatry: Teaching the fundamentals of CATIE, STAR*D, and STEP-BD to family medicine residents

Family medicine physicians are often the first providers to encounter and identify mental illness in their patients. Having a solid understanding of three landmark studies-Clinical Antipsychotic Trials of Intervention Effectiveness (CATIE), Sequenced Treatment Alternatives to Relieve Depression (STAR*D), and Systemic Treatment Enhancement Program for Bipolar Disorder (STEP-BD)-can significantly improve a family medicine physician's approach to mental illness and treatment choices, ultimately improving patient outcomes. Each of these studies has generated dozens of publications and consolidating the fundamentals of each one is essential for a resident to retain and implement findings in a real-world setting when treating patients with schizophrenia, depression, and bipolar disorder. When presented at the 38th Forum for Behavioral Science in Family Medicine in Chicago, IL, in September 2017, learners answered pre- and post-presentation questions about the treatment and guidelines pertaining to the three studies. Discussion leaders-physicians double-boarded in family medicine and psychiatry-presented key findings, clinical guidelines generated from each study, and updates since their respective publications. At the conclusion of the talk, participants received access to a slide deck and one-page summary for use in teaching at their home residency programs. Here, we present a framework for teaching family medicine residents three important canons of psychiatry with the goal of better management of three commonly encountered mental illnesses in the primary care setting.

Internal, External, and Ecological Validity in Research Design, Conduct, and Evaluation

Reliability and validity describe desirable psychometric characteristics of research instruments. The concept of validity is also applied to research studies and their findings. Internal validity examines whether the study design, conduct, and analysis answer the research questions without bias. External validity examines whether the study findings can be generalized to other contexts. Ecological validity examines, specifically, whether the study findings can be generalized to real-life settings; thus ecological validity is a subtype of external validity. These concepts are explained using examples so that readers may understand why the consideration of internal, external, and ecological validity is important for designing and conducting studies, and for understanding the merits of published research.

Symptoms of Depression, Positive Symptoms of Psychosis, and Suicidal Ideation Among Adults Diagnosed With Schizophrenia Within the Clinical Antipsychotic Trials of Intervention Effectiveness

Suicide is among leading causes of death for adults diagnosed with schizophrenia. While symptoms of depression are consistently supported factors involved in suicidal ideation, findings on the role of positive symptoms of psychosis have been mixed with limited understandings of risk. Accordingly, this study aimed to identify the pathways of influence between symptoms of depression, positive symptoms of psychosis (i.e. hallucinations and delusions), and suicidal ideation. Data were obtained from the Clinical Antipsychotic Trials of Intervention Effectiveness (CATIE; n = 1,460). Suicidal ideation and symptoms of depression were measured by the Calgary Depression Scale (CDRS) and hallucinations and delusions by the Positive and Negative Syndrome Scale (PANSS). The data were analyzed using Structural Equation Modeling (SEM). As symptoms of depression and positive symptoms of psychosis independently increased, on average there were associated increases in suicidal ideation. The present study provides support for the relationship between positive symptoms of psychosis, specifically hallucinations and delusions, and suicidal ideation. Future prospective longitudinal study designs are needed to further increase understandings of the roles that hallucinations, delusions, and additional symptoms of schizophrenia play in both suicidal ideation and attempt to ultimately inform evidence-based interventions aiming to reduce suicidal death.

Comparative efficacy between clozapine and other atypical antipsychotics on depressive symptoms in patients with schizophrenia: analysis of the CATIE phase 2E data

BACKGROUND

The comparative antidepressant effects of clozapine and other atypical antipsychotics for schizophrenia remain elusive, leading us to examine this question using the data from the Clinical Antipsychotic Trials of Intervention Effectiveness phase 2E.

METHODS

Ninety-nine patients who discontinued treatment with olanzapine, quetiapine, risperidone, or ziprasidone because of inadequate efficacy were randomly assigned to open-label treatment with clozapine (n=49) or double-blind treatment with another atypical antipsychotic not previously received in the trial (olanzapine [n=19], quetiapine [n=15], or risperidone [n=16]). The primary outcome was the Calgary Depression Scale for Schizophrenia (CDSS) total score. Antidepressant effects of clozapine and the other atypical antipsychotics were compared in patients with chronic schizophrenia and those with a major depressive episode (MDE) at baseline (i.e. ≥6 on the CDSS), using mixed models.

RESULTS

No differences in the baseline CDSS total scores were found between the treatment groups regardless of presence of an MDE. Clozapine was more effective than quetiapine in antidepressant effects for chronic schizophrenia (p<.01 for the whole sample and p=.01 for those with an MDE), and comparable to olanzapine and risperidone.

CONCLUSION

The present findings suggest that clozapine demonstrates superior antidepressant effects to quetiapine and comparable effects to olanzapine and risperidone in chronic schizophrenia regardless of presence of MDE. Given the indication of clozapine for treatment-resistant schizophrenia (TRS) and the negative impacts of depressive symptoms on clinical outcomes in schizophrenia, further research is warranted to investigate antidepressant effects of clozapine in TRS with an MDE.

Cost-effectiveness of second-generation antipsychotics for the treatment of schizophrenia

OBJECTIVE

To compare the cost-effectiveness of alternate treatment strategies using second-generation antipsychotics (SGAs) for patients with schizophrenia.

METHODS

We developed a Markov model to estimate the costs and quality-adjusted life-years (QALYs) for different sequences of treatments for 40-year-old patients with schizophrenia. We considered first-line treatment with one of the four SGAs: olanzapine (OLZ), risperidone (RSP), quetiapine (QTP), and ziprasidone (ZSD). Patients could switch to another of these antipsychotics as second-line therapy, and only clozapine (CLZ) was allowed as third-line treatment. We derived parameter estimates from the Clinical Antipsychotic Trial of Intervention Effectiveness (CATIE) study and published sources.

RESULTS

The ZSD-QTP strategy (first-line treatment with ZSD, change to QTP if ZSD is discontinued, and switch to CLZ if QTP is discontinued) was most costly while yielding the greatest QALYs, with an incremental cost-effective ratio (ICER) of $542,500 per QALY gained compared with the ZSD-RSP strategy. However, the ZSD-RSP strategy had an ICER of $5,200/QALY gained versus the RSP-ZSD strategy and had the greatest probability of being cost-effective given a willingness-to-pay threshold between $50,000 and $100,000 per QALY. All other treatment strategies were more costly and less effective than another strategy or combination of other strategies. Results varied by different time horizons adopted.

CONCLUSIONS

The ZSD-RSP strategy was most cost-effective at a willingness-to-pay threshold between $5,200 and $542,500 per QALY. Our results should be interpreted with caution because they are based largely on the CATIE trial with potentially limited generalizability to all patient populations and doses of SGAs used in practice.

Tardive dyskinesia in relation to estimated dopamine D2 receptor occupancy in patients with schizophrenia: analysis of the CATIE data

OBJECTIVE

The objective of this study was to evaluate the relationship between antipsychotic-induced tardive dyskinesia (TD) and estimated dopamine D2 receptor occupancy levels in patients with schizophrenia, using the dataset from the Clinical Antipsychotic Trials in Intervention Effectiveness (CATIE).

METHODS

The dataset from 218 subjects (risperidone, N=78; olanzapine, N=100; ziprasidone, N=40) who presented with a score of zero on the Abnormal Involuntary Movement Scale (AIMS) at baseline in Phase 1 of the CATIE study, and remained for ≥6months, was used. Peak and trough dopamine D2 receptor occupancy levels on the day of the AIMS assessment at the endpoint were estimated from plasma antipsychotic concentrations, using population pharmacokinetic analysis and our D2 prediction model. The estimated dopamine D2 receptor occupancy levels were compared between patients who presented an AIMS score of ≥2 at endpoint and those with a score of zero, using the Mann-Whitney U test.

RESULTS

Estimated dopamine D2 receptor occupancy levels at trough were significantly higher in subjects who developed involuntary movements (N=23) than those who did not (N=195) (71.7±14.4% vs. 64.3±19.3%, p<0.05) while no significant difference was found in the estimated peak D2 receptor occupancy between them (75.4±8.7% vs. 72.1±9.9%, p=0.07). When the analyses were separately conducted for the three drugs, there were no significant differences in estimated peak or trough D2 occupancy although the values were consistently numerically higher among those developing involuntary movements.

CONCLUSION

Greater dopamine D2 receptor blockade with antipsychotics at trough might increase the risk of tardive involuntary movements although this finding needs to be replicated in larger trials.

The role of pro-inflammatory cytokines in the neuroinflammation and neurogenesis of schizophrenia

Schizophrenia is a serious mental illness with chronic symptoms and significant impairment in psychosocial functioning. Although novel antipsychotics have been developed, the negative and cognitive symptoms of schizophrenia are still unresponsive to pharmacotherapy. The high level of social impairment and a chronic deteriorating course suggest that schizophrenia likely has neurodegenerative characteristics. Inflammatory markers such as pro-inflammatory cytokines are well-known etiological factors for psychiatric disorders, including schizophrenia. Inflammation in the central nervous system is closely related to neurodegeneration. In addition to pro-inflammatory cytokines, microglia also play an important role in the inflammatory process in the CNS. Uncontrolled activity of pro-inflammatory cytokines and microglia can induce schizophrenia in tandem with genetic vulnerability and glutamatergic neurotransmitters. Several studies have investigated the possible effects of antipsychotics on inflammation and neurogenesis. Additionally, anti-inflammatory adjuvant therapy has been under investigation as a treatment option for schizophrenia. Further studies should consider the confounding effects of systemic factors such as metabolic syndrome and smoking. In addition, the unique mechanisms by which pro-inflammatory cytokines are involved in the etiopathology of schizophrenia should be investigated. In this article, we aimed to review (1) major findings regarding neuroinflammation and pro-inflammatory cytokine alterations in schizophrenia, (2) interactions between neuroinflammation and neurogenesis as possible neural substrates for schizophrenia, and (3) novel pharmacological approaches.

Hyperprolactinemia and estimated dopamine D2 receptor occupancy in patients with schizophrenia: analysis of the CATIE data

BACKGROUND

Large-scale data are still lacking on the relationship between serum prolactin concentration and dopamine D2 receptor occupancy in patients with schizophrenia treated with antipsychotics.

METHODS

The dataset from 481 subjects (risperidone, N = 172, olanzapine, N = 211, and ziprasidone, N = 98) who participated in Phase 1 of the Clinical Antipsychotic Trials in Intervention Effectiveness (CATIE) was used in the present analysis. Dopamine D2 receptor occupancy levels on the day of the measurement of serum prolactin level were estimated from plasma antipsychotic concentrations. A multivariate general linear model was used to examine effects of clinical and demographic characteristics, including estimated D2 occupancy levels, on serum prolactin concentrations. Individual subjects were divided into two groups, stratified by the presence of hyperprolactinemia. To evaluate the performance of this binary classification, sensitivity, specificity, and accuracy of consecutive cut-off points in the D2 occupancy were calculated.

RESULTS

The multivariate general linear model revealed that estimated D2 occupancy levels had significant effects on serum prolactin concentrations while any other variables failed to show significant effects. The cut-off point associated with 0.5 or greater, in both sensitivity and specificity with the greatest accuracy, was 73% (sensitivity, 0.58; specificity, 0.68; accuracy = 0.64) (68-70% for risperidone, 77% for olanzapine, and 55% for ziprasidone.).

CONCLUSION

The threshold for hyperprolactinemia in D2 occupancy may lie somewhat on a lower side of the established therapeutic window with antipsychotics (i.e. 65-80%). This finding highlights the need for the use of the lowest possible dose to avoid this hormonal side effect in the treatment of schizophrenia.

Use of Antipsychotics Pre- and Post-Dissemination of CATIE Data

We investigated the share of branded and generic antipsychotics before and after the publication of the CATIE results in September, 2005. According to our data, the publication of the CATIE results has had very little impact on new patient starts. To determine the impact of CATIE on use of olanzapine (Zyprexa((R))) subsequent to first line therapy, we also examined product share for switch/add patients. We found that since the publication of the CATIE results, the use of olanzapine has stabilized, following a decline subsequent to first line therapy, and may potentially be growing very slowly. An expert commentary is provided on the data.