Search Results

This chapter proposes some uniform algorithmic methodology for finding interpolants in various logic. It operates with translations of non-classical logics into classical first-order theories and introduces so-called expansion interpolation. This leads us to find interpolants in the classical theories using the existing algorithms, which can then be translated back into non-classical theories. Two examples from modal logic are considered: quantified S5 and propositional S4.3. These logic lack ordinary interpolation but have expansion interpolation.

This chapter describes some of the neurological processes that influence behavior. Genetic processes encode proteins that ultimately inspire neurochemical releases as individuals respond to the stimuli they confront. One method to capture differences in neuroanatomy comes from neuroimaging. The chapter provides an overview of how we go from genes to brains, and how this process can be investigated using functional magnetic resonance imaging (fMRI) technology.

This chapter reviews the most important devices for assessing the prevalence of mental disorders, as well as assessing levels of distress, impairment, and need. A brief discussion of the history of methods in psychiatric epidemiologic studies of prevalence is included. The assessment devices include those for screening, such as the K-6 scale, the CESD-r, and the World Health Organization Disability Assessment Schedule (WHODAS). Also included are assessment instruments designed for use by clinicians, such as the Structured Clinical Interview for Diagnosis (SCID) and Structured Clinical Assessment in Neuropsychiatry (SCAN). A brief section includes guidance for conducting field surveys of mental disorders in the general population. Methods of evaluating the measurement properties are discussed, and a review of studies of agreement between survey interviewers and clinicians is presented.

Depression is an everyday term, but if clinical management is to be empirically based, there needs to be a valid and reliable definition of the disorder that is distinct from normal sadness. The validity of the concept and all studies of screening for depression are hampered by the absence of a gold standard. Nevertheless, various thorough methods of assessment may help to improve the clinical utility of our concept of depression. This book is built around the premise that major depressive disorder (MDD) exists in a way that is recognizable time and again by clinicians around the world. Considerable effort has been expended in developing and refining methods to measure depression. This chapter takes a step back and asks whether this effort is built upon a solid foundation. This begins with an important question: What is the purpose of making a meaningful diagnosis in any field of medicine? We suggest it is primarily to gain consensus and knowledge that may help individuals and populations who have healthrelated ‘‘meetable unmet needs.’’ A medical diagnosis (spurious or not) has several other benefits (Textbox 1.1). It facilitates agreement with colleagues, it lends confidence to patients, it adds legitimacy to treatments, and it may allow the development of targeted interventions. Because many conditions can be successfully treated without knowing the true etiology or the precise diagnosis, the lack of gold standard should not be a cause of therapeutic nihilism. Consider neurologists attempting to treat a midlife inherited chorea in 1862. Meticulous clinical method could bring some success despite the absence of a name and a description for another 10 years and the absence of a known etiology for another 110 years. Although many early treatments were based largely on placebo effects or environmental manipulation, once a definitive cause is found and the pathophysiologic mechanism is revealed, the potential for treatment becomes vast, whereas once it was small. Yet there is an even more fundamental issue. Kraepelin believed the major psychiatric disorders were ‘‘natural disease entities’’ simply awaiting a discovery of a specific medical cause. After intensive effort the search for fundamental causes was resigned and nosology underwritten by internal cohesion of symptoms and signs.

Many scales and tools have been developed by expert opinion. Several methods are available by which tools can be field tested in order to more accurately gauge their diagnostic potential. Promising new methods including item banks and computer-adaptive tests are under development to maximize the efficiency of screening tools for depression. Various methods are available to diagnose psychiatric disorders (see Chapter 2), but in the absence of a formal semi-structured psychiatric assessment, which remains impractical, the most commonly used method for assessing and screening levels of emotional distress remains by self-completed questionnaire. There have been many hundreds of validation attempts, comparing the severity questions against clinical judgment, semi-structured interviews, DSM and ICD criteria, and of course each other. Almost universally in primary care, community, and specialist settings, their accuracy is imperfect and further refinement is required. When tested according to their ability to enhance the detection and quality of care for depression, the efficacy of these instruments remains modest. A recent review from Gilbody and colleagues found that screening and case-finding instruments were associated with a modest increase in the recognition of depression by clinicians (relative risk [RR] 1.27, 95% confidence interval [CI] 1.02 to 1.59) and only a borderline significant effect on the overall management of depression (RR 1.30, 95% CI 0.97 to 1.76). Seven studies provided data on the impact of screening on depression outcomes, but there was no evidence of an effect (standardized mean difference –0.02, 95% CI –0.25 to 0.20). No doubt some of the problem lies with the organizational elements that may (or may not) accompany screening and some lies with clinicians’ willingness to treat a probable case. However, some blame also lies with the instruments themselves, as most were developed by expert opinion rather than by a scientific process. The quantitative methods that enable evaluation of the diagnostic accuracy of severity scales are discussed in Chapter 5. However, the evaluation of scales should be viewed in a wider context of tool development (Table 4.1). In the preclinical phase a tool is developed, often in the case of depression borrowing from existing scales and usually by consensus rather than by scientific testing. In phases I and II preliminary testing occurs, ideally in the clinically representative sample with several competing comparison groups.