Posted in Book Reviews on 13th Mar 2017
The Neuroethics of Biomarkers
What the development of bioprediction means for moral responsibility, justice, and the nature of mental disorder
Author: Matthew l Baum
Published by: Oxford University Press
Price: £38.99, 206 pages
Reviewed by: AJ Larner, Cognitive Function Clinic, WCNN, Liverpool, UK.
Published online: 13/3/17
Biomarkers have become an integral part of clinical practice in some spheres of neurology, such as dementia where they are enshrined in diagnostic criteria for Alzheimer’s disease as part of a clinico-biological (as opposed to an older clinico-pathological) definition of disease. The hope is that identification of disease in preclinical phases using predictive biomarkers may facilitate preventative treatment. But objections may be raised, for example to medicalising those who are currently well. The ethics of biomarker use in neurological and psychiatric disorders is explored in this volume by Matthew Baum, a Harvard MD-PhD trainee.
Addressing the bioprediction of brain disorder, the author argues for a reorientation of the medical concept of “disorder”, rejecting the old binary or categorical formulation (disorder/normalcy) in favour of a probabilistic model based on present and future risks of harm. This is justified in part by the belief, undoubtedly true, that “There is no a priori justification for believing that biomarkers will map cleanly onto diagnostic categories arrived at by historical accident” (p. 46). The result is a proposal for a “probability dysfunction” model in which disorders are conceptualised as graphs of probability over time, the area under which would help to separate out self-limiting disorders from those with low probabilities of harm over longer time periods.
“Risk banding”, based on the shape of the probability function, is the strategy advocated to determine the necessity or otherwise for response. This is illustrated with respect to bioprediction of future psychotic episodes and dementia (Chapter 5). This “risk of harm” approach is not seen as a fracture with past practice, since “Diagnosis is application of heuristic categories that capture a risk of harm associated with biological variation” (p. 125). The probabilistic claims of biomarkers may be used as a form of Bayesian updating. But will patients accept this reformulation?
This thought-provoking book will particularly appeal to those of a philosophical bent, rather than those who just want to know about biomarkers. It is not a book for dipping into during the interstices of the outpatient clinic, although the author must be commended for making the material accessible, his text is highly readable (and sometimes funny). Some clinicians will perhaps have little interest in the ramifications of predictive biomarkers for legal practice and societal distributive justice (when is biopredicted risk morally significant?), although even here there are interesting learning points: the discus- sion of prediction of seizures and driving is particularly pertinent. Furthermore, I was amazed to learn that in law the appeal to the “reasonable man” is regarded as an “objective” test, although the author rightly points out that this is almost always subjective in that it relies “almost exclusively on common sense and the persuasion of skilled law professionals to do this Bayesian updating” (p. 138). Whatever deficiencies there may be in medical (neurological) practice, at least we are attempting to put it on a research-based evidential footing.
The Brain: A Student’s Self-test Colour Book
Consultant Editors: Dr Joshua Gowin and Dr Wade Kothman
Published by: Quad Books
Price: £14.99 Pages: 192
Reviewed by: Rhys Davies, Consultant Neurologist, Liverpool, UK.
Published online: 13/3/17
I had two motives for reviewing ‘The Brain: A Student’s Self-test Colouring Book’.
Firstly, seeing well-learnt knowledge presented in a new way is useful preparation for teaching and it so happens that I have recently had to take responsibility for pre-clinical Neuroscience teaching. And secondly, I have always taken (childish) pleasure in reading encyclopaedias designed for children. The latter
is generally manifested as taking a few minutes longer than strictly necessary in leafing through such volumes in book-
shops when deciding on a purchase to offer as a gift to some unsuspecting young relative.
For the mature clinician or scientist of the nervous system, this book may be the literary equivalent of Lucozade. But few of us have such stamina or such sophistication of the palate that we can’t get some refreshment, or even pleasure, from an occasional sip of fizzy pop.
Unsurprisingly, there were moments when the need for a more sophisticated beverage was felt. In discussing the conduction of the action potential, the term ‘saltatory’ was said to derive from the Latin for ‘to dance’, which got me ‘jumping’. At one point, the dorsal root was mislabelled as the dorsal horn. The medial lemniscus was omitted from the section of text concerning somatosensory pathways.
For me, the biggest missed trick in terms of providing depth to the reader’s learning was the failure to distinguish either in the drawings or accompanying texts those areas that are juxtaposed largely for reasons of parallel development, from neighbouring regions that are intimately linked in function. The basal ganglia provide a good example: the caudate and putamen are both functionally part of the neostriatum but separated by the anterior limb of the internal capsule, whose constituent fibres must traverse the deep grey matter of the forebrain from the origin in the cortex to their destination in the pons and elsewhere. I understand that one has to draw a line on descriptions of function in a book about structure; I just think they drew it too soon.
For the medical neurologist, coronal and axial sections through the diencephalon and basal ganglia are perhaps less like the backs of our hands than for surgeons and radiologists. I found those pages the most useful.
All in all, this is a modest book – modestly priced and quick to leaf through. I can recommend it to my peers, especially those wishing to consolidate their Anatomy before teaching.
ACNR 2017;16(4):20. Published online 13/3/17