Systematic review and meta-analysis

Background: The primary prevention of illness at the population level, the ultimate aim of medicine, seems out of reach for schizophrenia. Schizophrenia has a strong genetic component, and its pathogenesis begins long before the emergence of psychosis, as early as fetal brain development. Cholinergic neurotransmission at nicotinic receptors is a pathophysiological mechanism related to one aspect of this genetic risk. Choline activates these nicotinic receptors during fetal brain development. Dietary supplementation of maternal choline thus emerges as a possible intervention in pregnancy to alter the earliest developmental course of the illness. 

Background: Pharmacological treatment of geriatric depression is often ineffective because patients cannot tolerate adequate doses of antidepressant medications. 

Background: The organization of risk genes within signaling pathways may provide clues about the converging neurobiological effects of risk genes for alcohol dependence. 

Summary: The use of biomarkers in the diagnosis of Alzheimer’s disease (AD) has been increasingly emphasized, but the feasibility and value of using biomarkers in clinical practice remain limited. However,the use of biomarkers in clinical and pharmaceutical research about AD may prove quite useful in clarifying the pathology underlying AD and, thus, help in the early identification of effective preventive and therapeutic interventions. Moreover, wide adoption of the new diagnostic criteria will improve comparability of research results across studies, and, thus, allow for the combination and comparison of study results using meta-analytic techniques – the types of analyses needed to definitively answer fundamental questions about the etiology, course, prevention, and treatment of AD. 

Summary: Alzheimer’s Disease (AD) is a leading cause of disease burden among elderly individuals that is increasingly important in middle-income countries like China where improvements in overall health (which increase longevity) and other factors are leading to a rapidly aging population. The diagnostic criteria for AD have recently been revised to reflect advances in the understanding of the condition over the past three decades. Different international organizations have proposed algorithms for diagnosing AD that subdivide the AD spectrum into overlapping stages and, in some cases, require the concurrent presence of memory impairment and specific biomarkers. There are, however, several substantial limitations to these revised criteria: highly trained clinicians are needed to make the fine discriminations between the stages; the role of the proposed biomarkers in the onset and course of AD remain uncertain; and assessment of these biomarkers requires the use of expensive, high-tech equipment by well-trained technicians. These problems limit the clinical utility of these diagnostic criteria, particularly in low-resource settings where the clinicians responsible for identifying and treating individuals with AD have limited training and where the equipment needed to identify the biomarkers are either non-existent or in short supply. 

Commentary

Summary: The transition from a dichotomous diagnostic classification system to the more holistic approach to understanding mental disorders engendered by the so-called biopsychosocial model has definite advantages, but it runs the risk of sacrificing methodological rigor to achieve all-inclusiveness. The Special Article by Bebbington on understanding psychosis in this issue attempts to show that high-quality psychosocial epidemiological research on the development of psychosis can, at least partially, overcome these limitations. Bebbington’s emphasis on the importance of non-psychotic symptoms such as disturbance in sleep and mood in the development of psychosis provides a new perspective on the conceptualization of psychosis, but I remain unconvinced about the usefulness of such symptoms in the differentiation of valid sub-categories of schizophrenia or other psychoses. 

Summary: If psychosis is a transdiagnostic dimension, the expression of which is governed by a dynamic set of contextual and emotional factors that are amenable to treatment, current approaches in psychiatric nosology and therapeutic research may need to be revised. The dominant approach to date is to clinically and conceptually situate psychotic symptoms in the construct of schizophrenia. However, schizophrenia,which has a lifetime prevalence of 1%, only represents the poor outcome fraction of a much broader spectrum of psychotic disorders which have a lifetime prevalence of 3.5%. Therefore, research findings in schizophrenia may reflect mechanisms of prognosis rather than fundamental associations with psychosis and other symptom domains per se. Similarly, the discovery that up to 30% of individuals with non-psychotic common mental disorders have subthreshold psychotic symptoms that situate them on the transdiagnostic dimension of psychosis – and which impact clinical severity and treatment response – indicates that the rigid separation between ‘psychotic’ and ‘non-psychotic’ hampers both clinical practice and research.Diagnostic manuals in psychiatry would benefit from a system of transdiagnostic dimensions, including a transdiagnostic dimension of psychosis. Introduction of transdiagnostic dimensions allows for a system combining a nomothetic (i.e., group-specific) categorical diagnosis with an idiographic (i.e., person-specific)combination of dimensional scores. The advantage of such a system is that it encourages consideration of how symptoms dynamically interact with each other in a network of psychopathology, and of how this network is impacted by the social world. 

Summary: Hallucinations rarely occur in individuals with anxiety disorders. This case report describes a 36-year-old male with Social Phobia and Agoraphobia with Panic Attacks who had prominent visual hallucinations that were both distressing and incapacitating. Treatment with sertraline 200 mg/d,clonazepam 1 mg/d, and propranolol 20 mg/day for one month completely resolved both his anxiety and the hallucinations, after which he was able to return to his social and occupational life. The report underscores the fact that visual hallucinations are not always indicators of a psychotic disorder, they may be present across a spectrum of mental disorders. In cases where hallucinations occur in nonpsychotic disorders, treatment of the underlying condition usually simultaneously resolves the associated hallucinations without the need to resort to the use of antipsychotic medication. Detailed analyses of such unusual cases can help improve our understanding of the pathogenesis of psychotic-like symptoms. 

Biostatistics in psychiatry

Summary: Decision tree methodology is a commonly used data mining method for establishing classification systems based on multiple covariates or for developing prediction algorithms for a target variable. This method classifies a population into branch-like segments that construct an inverted tree with a root node, internal nodes, and leaf nodes. The algorithm is non-parametric and can efficiently deal with large,complicated datasets without imposing a complicated parametric structure. When the sample size is large enough, study data can be divided into training and validation datasets. Using the training dataset to build a decision tree model and a validation dataset to decide on the appropriate tree size needed to achieve the optimal final model. This paper introduces frequently used algorithms used to develop decision trees(including CART, C4.5, CHAID, and QUEST) and describes the SPSS and SAS programs that can be used to visualize tree structure.