Preface to The First Edition
This book grew out of my experience over the past few years of teaching trainee physicians, psychiatrists, and psychologists about cognitive function and its assessment. I had initially intended to write a very brief pocket guide dealing only with bedside testing. But it became apparent that there was little value in merely describing how to assess cognition, unless the reader had some conceptual knowledge about normal psychological function on which to base the assessment and, most importantly, to guide the interpretation of the examination’s findings. The book, therefore, expanded in scope and in size. It now attempts to provide a rational and theoretical basis for cognitive assessment at the bedside or in the clinic, as well as practical guidance on how to take an appropriate history and how to examine patients presenting with disorders of higher cerebral function. The approach advocated in the book is illustrated by twelve case histories of patients seen by me over the last two years. The final section consists of an appendix describing commonly used neuropsychological tests.
When writing the theoretical sections which underpin the assessment, I have drawn on two major strands of research—the traditional localizationalist approach, and the more recent cognitive neuropsychological approach. Most clinicians will be aware of the former; ever since the original observations of Broca, Wernicke, Pick, Dejerine and others in the last century, neurologists have been interested in the cerebral localization of higher mental functions. After a period of relative neglect, recent advances in static (CT and MRI) and functional (PET and SPECT) neuroimaging have reactivated this traditional approach, and considerable advances have been made in the localization of various cognitive functions, which I have attempted to summarize.
The other major strand, cognitive neuropsychology, will be less familiar to clinicians. Most medical curricula still contain only a rudimentary grounding in psychology, and virtually no cognitive neuropsychology. Even some psychology graduates have little experience of this area. Yet in the past two decades there has been an explosion of interest in this field which has produced unparalleled insights into the workings of the human mind. Much of this research originated in Britain, beginning with the pioneering work of John Marshall and Freda Newcombe, and of Elizabeth Warrington and her colleagues. Their experimentally based approach to dissecting the individual subprocesses underlying functions such as reading, object recognition, etc., paved the way for working out the detailed cognitive models that now exist and can be tested experimentally. These and kindred researchers have stressed the critical importance of single-case studies, and of designing tests which isolate specific and dissociable cognitive processes. I have attempted to introduce readers to this exciting area, and to provide a review of the clinically important advances that have been made in cognitive neuropsychology.
Unfortunately, the two major research traditions have, until recently, carried on independently, so that although we now know a great deal about the cognitive basis of many aspects of language, memory, and perception, the neural bases of these processes remain largely unknown. This creates problems when trying to unite these disparate approaches to neuropsychology. In places, the marriage that I have imposed between neurology and cognitive neuropsychology appears rather shaky. It is to be hoped that further advances in the next few years will consolidate our understanding in these areas.
The structure of the book is as follows. Chapters 1 and 2 deal with the theoretical aspects of cognitive function, divided into those which have a widely distributed neural basis (attention/concentration, memory, and highest-order ‘executive’ function), and those functions which are lateralized to one hemisphere, and often one region of one hemisphere (language, praxis, visuospatial and -perceptual abilities, etc.). Each section of these chapters deals with the neuropsychology, the basic applied anatomy, the clinical disorders, and appropriate tests. The tests mentioned are described in more detail in the Appendix. At the end of Chapter 1 there is also a brief section on delirium and dementia, which constitute the commonest presenting disorders in behavioural neurology and old age psychiatry.
Chapter 3 describes how to take a cognitive history, with a few tips on physical examination. Chapter 4 outlines my approach to assessment at the bedside or in the clinic, and follows the same format as the earlier introductory theoretical chapters. Chapter 5 contains twelve case histories, most of which are taken from our joint neurology–psychiatry cognitive disorders clinic and which illustrate the approach advocated in the earlier chapters. In Chapter 6, I describe the standardized mental test batteries in common use [for example the Mini Mental State Examination, the Blessed Information–Memory–Concentration (IMC) Test, the Hodkinson Brief Mental Test, the Dementia Rating Scale, and the Cambridge Cognitive Examination (CAMCOG)] with notes on their use and abuse. Finally, the Appendix contains details on a selection of neuropsychological tests, consisting of those widely used in neuropsychological practice, with which clinicians should be familiar, and tests which can be given fairly readily by clinicians without specialist training.
I should point out that this is not intended to be a textbook of neuropsychology, of which there are several excellent examples listed under ‘Selected Further Reading’ at the end of the book. Neither is it a compendium of neuropsychological tests. It is aimed at clinicians with a nascent, but underdeveloped, interest in cognitive function. The approach advocated forms no substitute for professional psychological evaluation. However, many neurologists and psychiatrists work without adequate neuropsychological provision. By becoming more conversant with bedside cognitive testing, clinicians should be able to use the services of their neuropsychologists more effectively. It is not necessary, for instance, to refer every patient with suspected dementia; many patients can be satisfactorily diagnosed by clinicians if the basic principles outlined in the book are followed. There are, however, patients in whom a thorough neuropsychological evaluation is mandatory, as is illustrated by several of the cases in Chapter 5.
If this book stimulates any trainee neurologist or psychiatrist to develop a special interest in neuropsychology, or to pursue a research career in this field, then it will have more than fulfilled its original aims.