This video is part of a series. To see the complete list of videos in this series, click here.
This video introduces what it means to be a neuropsychologist, outlining and highlighting the important contributions that the discipline of neuropsychology can make to patient care. It also shows how clinical neuropsychology benefits those who practise it (for example, its being scientifically and intellectually fascinating, and the fact that the human condition can be seen in a unique way through the wonders of neuropathology). The point is strongly made that one’s training as a clinical neuropsychologist is a life-long process; one is always learning as there is an infinite amount to know, and knowledge in this field is constantly growing.
The central part of this video encompasses a detailed introduction to the key principles that underpin how one carries out neuropsychological work. These key principles explain how to go about examining neurological patients’ mental functions. The key steps that constitute a thorough clinical assessment are then also outlined. Up front, the teaching covers the important distinction between two differing approaches to patient assessment within the field of neuropsychology, which underlie the key principles: the psychometric approach and the hypothetico-deductive approach. Both of these approaches are outlined in detail. A persuasive argument is provided for why the hypothetico-deductive approach is considered to be the vastly superior of these two approaches. Here, it is emphasised that the hypothetico-deductive approach is synonymous with theory-driven assessment.
The psychometric approach is outlined as follows. It is the “easy” approach that focuses on the measurement of the mind (primarily using fixed assessment batteries), and it is quantitative in nature (a standardised approach), involving doing exactly the same thing for every patient. It is norm-referenced and norm based. This approach is about measuring a patient’s mental performances and comparing his/her scores, his/her measurement to what the average person (the norm), would achieve. In other words, it is all about the measurement of deficits: how far below the expected performance the patient is, based on the average adult performance, or the average performance of whichever group one is comparing it to. The key point is made that this is a weak approach because it: (i) does not utilise clinical skills and reasoning to address clinical problems; (ii) does not consider the underlying multiple determinants of failure of a test performance; (iii) renders patients ‘unassessable’ if they do not fit in with the rules and protocol of the tests; and (iv) it is slow. This video, however, also explains where the psychometric approach is valuable: for benchmarking impairments over time, in medico-legal situations, and for research purposes.
The hypothetico-deductive approach is outlined in this video as follows. It is a clinical, qualitative approach, which is flexible, not standardised, and involves hypothesis testing. It is about interpreting symptoms and signs. This approach brings the mind into clinical medicine, and uses the same language, and the same flexible techniques, where patients’ problems are the starting point and the job is to understand what is going on so that you know what to do. It rests upon very long traditions in medicine and involves examining the mind of the patient just like any internal physician of any organ system of the body would examine that system.
This video outlines, with examples, the four key steps to the hypothetico-deductive clinical examination, namely: (i) identifying the question that is being asked; (ii) formulising hypotheses as to what the answers to the question might be; (iii) testing these hypotheses; and (iv) communicating the answer back to the referring party with one’s reasons, once the various hypotheses have been disconfirmed and confirmed.
The three guiding principles outlined, which form the cornerstone of the hypothetico-deductive approach, are nosology, mechanism and pathology. All three of these coordinates are required to link together in order to tie up a clinical examination. Each is described in this video as follows, and examples of each are provided. Firstly, nosology is the classification of the different clinical pictures one can encounter; the symptoms and signs that are differentiated from each other. Here, the neuropsychologist has to identify and name the symptoms and the signs (of a non-fluent aphasia, for example). Secondly, one has to identify the pathology that has caused, that underlies, the symptom/s. Thirdly, the mechanism is the explanation of how/why the pathology/disease caused the symptoms/syndrome. The mechanism is the whole theory of how mental functions relate to brain functions.
A key lesson from this video is that clinical neuropsychology is about recognising meaningful constellations of symptoms and signs that are of pathonomic significance.