Focus on psychosis

The concept of psychosis has been shaped by traditions in the concepts of mental disorders during the last 170 years. The term “psychosis” still lacks a unified definition, but denotes a clinical construct composed of several symptoms. Delusions, hallucinations, and thought disorders are the core clinical features. The search for a common denominator of psychotic symptoms points toward combinations of neuropsychological mechanisms resulting in reality distortion. To advance the elucidation of the causes and the pathophysiology of the symptoms of psychosis, a deconstruction of the term into its component symptoms is therefore warranted. Current research is dealing with the delineation from “normality”, the genetic underpinnings, and the causes and pathophysiology of the symptoms of psychosis.     

Pharmacologic treatment of schizophrenia

Despite pharmacologic advances, the treatment of schizophrenia remains a challenge, and suboptimal outcomes are still all too frequent. Although treatment goals of response, remission, and recovery have been defined more uniformly, a good "effectiveness" measure mapping onto functional outcomes is still lacking. Moreover, the field has to advance in transferring measurement-based approaches from research to clinical practice. There is an ongoing debate whether, and which, first- or second-generation antipsychotics should be used. However an individualized treatment approach needs to consider current symptoms, comorbid conditions, past therapeutic response, and adverse effects, as well as patient choice and expectations. Moreover acute and long-term goals and effects of medication treatment need to be balanced. While the acute response to appropriately dosed first-generation antipsychotics may not differ much from second-generation antipsychotics, advantages of lower rates of extrapyramidal side effects, tardive dyskinesia, and, possibly, relapse may favor second-generation antipsychotics. However when considering individual adverse effect profiles, the differentiation into first- and second-generation antipsychotics as unified classes can not be upheld, and a more differentiated view and treatment selection is required. To date, clozapine is the only evidence-based treatment for refractory patients, and the role of antipsychotic polypharmacy and other augmentation strategies remains unclear, at best. To improve the treatment outcomes in schizophrenia, research efforts are needed that elucidate biomarkers of the illness and of treatment response (both therapeutic and adverse effects). Moreover, new treatment options are needed that affect nondopaminergic targets with relevance for symptom reduction, relapse prevention, enhanced efficacy for nonresponders, and reduced key adverse effects.     

Environmental risk factors for psychosis

Genetic factors are clearly important in the etiology of schizophrenia, but the environment in which an individual's genes find expression is also crucial to the development of the illness. In this review of environmental risk factors for schizophrenia, we consider risks operating prenatally and perinatally, during childhood, and then later in life prior to illness onset Some of these risk factors have been well documented, for example, early hazards causing fetal growth retardation or hypoxia, and hazards nearer the onset of illness like drug abuse and migration. Others are much less certain. The importance of interaction between genetic and environmental risk is, however, undoubtedly important and there is emerging evidence for this from a range of sources. As the etiology of schizophrenia is unraveled, the picture becomes more complex, but also more obviously relevant to the plight of the individual patient.     

Conceptualization of the liability for schizophrenia: clinical implications

Historically, the Diagnostic and Statistical Manual of Mental Disorders (DSM) diagnostic criteria for schizophrenia have emphasized several features, including symptoms of psychosis, a dissociation of symptoms from their etiology, a reliance on clinical symptoms, and a categorical approach to classifying the disorder. Although these emphases are quite useful, they have limitations. We review these here, and stress the importance of incorporating recent data on the genetic /biological and neurodevelopmental origins of schizophrenia into current conceptions of the disorder. We also review "schizotaxia, " which is a concept thai embodies this point of view, occurs before the onset of psychosis, and is hypothesized to represent the liability for schizophrenia. If our hypothesis on this point is correct, the identification of schizotaxic individuals will eventually facilitate the development of prevention strategies by identifying a premorbid (but clinically significant) condition for schizophrenia. Moreover, the identification of biological or neuropsychological components of schizotaxia will provide more specific bases for developing novel treatment interventions. Our initial attempts to develop protocols for the assessment and treatment of schizotaxia are encouraging, and will be reviewed.     

The treatment of schizophrenia: from premorbid manifestations to the first episode of psychosis

To achieve the best therapeutic results in schizophrenia--like most other disorders--primary prevention is preferable to early and prompt treatment, which, in turn, is preferable to treatment of chronically established illness. Unfortunately, there currently exist no accurate markers that can provide information regarding the future course of illness and guide treatment in asymptomatic or mildly symptomatic individuals. Therefore, most treatment efforts are currently focused on patients who have already experienced their first psychotic episode. This paper reviews the efforts to identify accurate markers heralding psychotic illness, as well as treatment considerations in the early phase of the disease.     

Cognitive impairment as a risk factor for psychosis

Since the time of Kraepelin and Bleuler, it has been recognized that schizophrenia is associated with a profound and persistent cognitive impairment. This paper reviews the major clinical and epidemiological studies of cognitive functioning in schizophrenia and other psychotic disorders, and presents several possible models to explain the association between cognitive impairment and psychosis. Cognitive impairment is present in the majority of patients with schizophrenia, and, in some, it is already evident in the premorbid stages of the disorder. This cognitive impairment is not secondary to psychotic symptoms, negative symptoms, or socioeconomic status. Cognitive impairment can also be observed in nonpsychotic family members of psychotic patients. On the basis of this evidence, it has been proposed that abnormal cognitive functioning can be considered as a possible causal risk factor for psychosis. Recent studies assessing the relationship between genetic background, cognition, brain function, and schizophrenia are presented here as an outline for future research.     

The impact of subjective well-being under neuroleptic treatment on compliance and remission

The patients' perspective of antipsychotic treatment was largely neglected for a long period. It has only been during the last 10 years, with the development of atypical antipsychotics, that scientific interest in this issue has markedly increased. Numerous studies have shown that the majority of schizophrenic patients are able to fill out a self-rating scale in a meaningful way, and several self-report scales with sufficient internal consistency and good construct validity have been developed. The effects of antipsychotic treatment on psychopathology and on subjective well-being (SW) are not strongly related; the perspectives of the patient and his/her psychiatrist markedly differ. Recent research indicates that SW/quality of life, much more improved by atypical than by typical antipsychotics, has a strong impact on compliance, as well as on the chance of achieving remission. The data strongly suggest that a systematic evaluation of the patient's perspective of antipsychotic treatment is meaningful and necessary to increase compliance, functional outcome, and long-term prognosis.     

New directions for drug discovery in psychiatric disease

Although many new potential drug targets have been discovered subsequent to the cloning of the human genome and the discovery of most of the relevant receptors, the role of these receptors in psychiatric disease is still not clear. We argue that research into the disease process leading to new animal models that can be transposed to man is critical to drug discovery, and present an example of an animal model for schizophrenia using electroencephalography.     

Early biomarkers of psychosis

Biological traits that are predictive of the later development of psychosis have not yet been identified. The complex, multidetermined nature of schizophrenia and other psychoses makes it unlikely that any single biomarker will be both sensitive and specific enough to unambiguously identify individuals who will later become psychotic. However, current genetic research has begun to identify genes associated with schizophrenia, some of which have phenotypes that appear early in life. While these phenotypes have low predictive power for identifying individuals who will become psychotic, they do serve as biomarkers for pathophysiological processes that can become the targets of prevention strategies. Examples are given from work on the role of the alpha(T)nicotinic receptor and its gene CHRNA7 on chromosome 15 in the neurobiology and genetic transmission of schizophrenia.     

The NIMH-MATRICS project for developing cognition-enhancing agents for schizophrenia

The US National Institute of Mental Health supported an initiative to facilitate the development of pharmacological agents for enhancing neurocognition in patients with schizophrenia. This has been accomplished through a consensus-building process that has included representatives from academia, the pharmaceutical industry, and government. The group has addressed obstacles to drug development that include (i) the lack of a well-accepted instrument for measuring neurocognition in clinical trials; (ii) the lack of a consensus on the best molecular target or targets for drug development; (iii) the lack of a consensus regarding the optimal trial design for either comedication that improves cognition when added to an antipsychotic or a broad spectrum agent that improves cognition and treats psychosis; and (iv) the approaches of regulatory agencies such as the US Food and Drug Administration to approving and labeling a new agent.     

Neuroimaging biomarkers to predict treatment response in schizophrenia: the end of 30 years of solitude?

Studies that have used structural magnetic resonance imaging (MRI) suggest that individuals with psychoses have brain alterations, particularly in frontal and temporal cortices, and in the white matter tracts that connect them. Furthermore, these studies suggest that brain alterations may be particularly prominent, already at illness onset, in those individuals more likely to have poorer outcomes (eg, higher number of hospital admissions, and poorer symptom remission, level of functioning, and response to the first treatment with antipsychotic drugs). The fact that, even when present, these brain alterations are subtle and distributed in nature, has limited, until now, the utility of MRI in the clinical management of these disorders. More recently, MRI approaches, such as machine learning, have suggested that these neuroanatomical biomarkers can be used for direct clinical benefits. For example, using support vector machine, MRI data obtained at illness onset have been used to predict, with significant accuracy, whether a specific individual is likely to experience a remission of symptoms later on in the course of the illness. Taken together, this evidence suggests that validated, strong neuroanatomical markers could be used not only to inform tailored intervention strategies in a single individual, but also to allow patient stratification in clinical trials for new treatments.     

Treatment of the special patient with schizophrenia

Special patient populations with schizophrenia have received little attention. These populations include adolescents, the elderly, substance abusers, and patients who are considered treatment-resistant. Interest in these populations is rapidly growing, especially with regard to their treatment with second-generation antipsychotics. This article describes the treatment of special patient populations and summarizes the research that has been done in this field.     

Effectiveness studies: advantages and disadvantages

In recent years, so-called "effectiveness studies," also called "real-world studies" or "pragmatic trials," have gained increasing importance in the context of evidence-based medicine. These studies follow less restrictive methodological standards than phase III studies in terms of patient selection, comedication, and other design issues, and their results should therefore be better generalizable than those of phase III trials. Effectiveness studies, like other types of phase IV studies, can therefore contribute to knowledge about medications and supply relevant information in addition to that gained from phase III trials. However, the less restrictive design and inherent methodological problems of phase IV studies have to be carefully considered. For example, the greater variance caused by the different kinds of confounders as well as problematic design issues, such as insensitive primary outcome criteria, unblinded treatment conditions, inclusion of chronic refractory patients, etc, can lead to wrong conclusions. Due to these methodological problems, effectiveness studies are on a principally lower level of evidence, adding only a complementary view to the results of phase III trials without falsifying their results.     

Differing response to antipsychotic therapy in schizophrenia: pharmacogenomic aspects

Treatment-resistance in schizophrenia remains a public health problem: about 20% to 30% of patients do not respond to antipsychotic therapy. Clozapine has been shown to be effective in about one-third of patients, but the medical risks and weekly blood tests limit its broad application. While the heterogeneity of the disease and the duration of untreated psychosis are important, pharmacogenomic aspects must also be considered. Pharmacogenomic investigations offer the opportunity to individualize antipsychotic therapy according to the growing knowledge of the function and effect of the genetic polymorphisms that affect the pharmacokinetics and pharmacodynamics of antipsychotics. On the pharmacokinetic level, polymorphic phase I and II drug-metabolizing enzymes and transport proteins affect drug concentration at the target structure. The cytochrome P450 enzymes, N-acetyltransferase, and multidrug resistance protein (MDR1) particularly influence this parameter. Genetic alterations affecting drug pharmacodynamic properties have an impact on therapeutic outcome that is generally independent of the applied dosage regimen. A combined analysis of genetic polymorphisms in the dopaminergic and serotonergic receptors, neurotransmitter transporters, and other target structures involved in psychiatric disorders is already a powerful predictor of therapeutic outcome. An understanding of other factors influencing gene expression and protein production will facilitate individualized therapy in the future.     

Pharmacogenetics of antipsychotic therapy: pivotal research issues and the prospects for clinical implementation

The core hypothesis underlying pharmacogenetics is that genetic factors play a significant role in the well-recognized differences between individuals in response to medication and susceptibility to adverse effects. If these genetic factors can be identified and understood, they may serve as predictors to guide clinicians in tailoring medication to the individual patient. Recent developments in the field of antipsychotic drug treatment suggest that pharmacogenetics could play an important role, permitting the use of first-generation antipsychotics (FGAs) for patients in whom the use of second-generation antipsychotics (SGAs) is limited by efficacy considerations or adverse effects. In this paper, key issues that need to be taken into consideration in designing and interpreting pharmacogenetic studies of antipsychotic drugs are discussed against the background of data emanating from studies on the genetics of tardive dyskinesia (TD), an important adverse effect of FGAs. The issues considered include the advantages and potential pitfalls of case-control association studies of pharmacogenetic traits, the role of demographic factors such as age and gender, additive effects of genes, and gene-gene and gene-environment interaction. The prospects for implementation of pharmacogenetic testing in the clinic are considered in the context of a preliminary model that has been tested for prediction of susceptibility to TD.     

Quality of life in schizophrenic patients

In the last decades, there has been increased interest in the field of quality of life in mental disorders in general, and particularly in schizophrenia. In addition, the appearance of the atypical antipsychotic drugs (amisulpride, aripiprazole, clozapine, olanzapine, quetiapine, risperidone, and ziprasidone) with different therapeutic and side-effect profiles, has promoted a greater interest in assessing the quality of life of schizophrenic patients. In this paper we will briefly summarize the difficulties in assessing quality of life in schizophrenic patients, as well as the results concerning their quality of life and the influence of psychopathology, especially negative and depressive symptoms, on it. We will also review data from recent clinical trials showing the impact ofantipsychotic treatments and their side effects upon quality of life.     

The epidemiology of schizophrenia: replacing dogma with knowledge

Major advances have been made in our understanding of the epidemiology of schizophrenia. We now know that the disorder is more common and severe in young men, and that the incidence varies geographically and temporally. Risk factors have been elucidated; biological risks include a family history of the disorder, advanced paternal age, obstetric complications, and abuse of drugs such as stimulants and cannabis. In addition, recent research has also identified social risk factors such as being born and brought up in a city, migration, and certain types of childhood adversity such as physical abuse and bullying, as well as social isolation and adverse events in adult life. Current research is focussing on the significance of minor psychotic symptoms in the general population, gene-environmental interaction, and how risk factors impact on pathogenesis; perhaps all risk factors ultimately impact on striatal dopamine as the final common pathway.     

Childhood trauma and psychosis - what is the evidence?

In the last decade, a substantial number of population-based studies have suggested that childhood trauma is a risk factor for psychosis. In several studies, the effects held after adjusting for a wide range of potentially confounding variables, including genetic liability for psychosis. Less is known about the mechanisms underlying the association between childhood trauma and psychosis. Possible pathways include relationships between negative perceptions of the self, negative affect, and psychotic symptoms, as well as biological mechanisms such as dysregulated cortisol and increased sensitivity to stress. Psychotic patients with a history of childhood trauma tend to present with a variety of additional problems, including post-traumatic stress disorder, greater substance abuse, higher levels of depression and anxiety, and more frequent suicide attempts. Initial studies suggest that trauma-specific treatments are as beneficial for these patients as for other diagnostic groups.     

DNA methylation and demethylation as targets for antipsychotic therapy

Schizophrenia (SZ) and bipolar disorder (BPD) patients show a downregulation of GAD67, reelin (RELN), brain-derived neurotrophic factor (BDNF), and other genes expressed in telencephalic GABAergic and glutamatergic neurons. This downregulation is associated with the enrichment of 5-methylcytosine and 5-hydroxymethylcytosine proximally at gene regulatory domains at the respective genes. A pharmacological strategy to reduce promoter hypermethylation and to induce a more permissive chromatin conformation is to administer drugs, such as the histone deacetylase (HDAC) inhibitor valproate (VPA), that facilitate chromatin remodeling. Studies in mouse models of SZ indicate that clozapine induces DNA demethylation at relevant promoters, and that this action is potentiated by VPA. By activating DNA demethylation, clozapine or its derivatives with VPA or other more potent and selective HDAC inhibitors may be a promising treatment strategy to correct the gene expression deficits detected in postmortem brain of SZ and BPD patients.     

Treating early psychosis: who,what, and when?

Early intervention and prevention in schizophrenia is just over 10 years old. The assumption guiding this field is that intervention is likely to be most effective if it begins before psychosis sets in, ie, during the prodromal phase. Although a substantial number of prodromal treatment programs have been initiated around the world, three early programs have generated most of the intervention findings to date: Personal Assessment and Crisis Evaluation (PACE) in Australia, and the Prevention through Risk Identification, Management, and Education (PRIME) and Recognition and Prevention (RAP) programs in the USA. The data suggest that early intervention leads to a reduction in prodromal symptoms and clinical distress. However, prevention of psychosis remains an unresolved question. Other issues include defining who should be treated, with what, and when. In addition, treatment targets associated with functional disability, such as early prodromal negative symptoms and risk factors, continue to emerge. Newly identified targets, in turn, suggest the need for a variety of novel interventions and treatment strategies.