Posted in Book Reviews on 6th Dec 2012
Epilepsy and Memory
Editors: Zeman A, Kapur N, Jones-Gotman M
Published by: Oxford University Press, 2012
Reviewed by: AJ Larner, Cognitive Function Clinic, WCNN, Liverpool, UK.
Hearing complaints of memory problems is a familiar experience for most if not all clinicians having any dealings with epilepsy patients. It is well recognised that such memory difficulties are heterogeneous, ranging from subjective to objective, and multifactorial in origin – related to underlying brain lesions causing the epilepsy, frequency of seizures, antiepileptic drug therapy, concurrent mood disorder, or any combination thereof. This fascinating volume seeks to review what is known about the interrelationships of memory and epilepsy, summarising both clinical and laboratory studies.
That research on patients with epilepsy has contributed to knowledge of the neural basis of memory and temporolimbic models of memory function cannot be denied. The critical importance of epileptic patient HM (Henry Gustav Molaison, 1926-2008) and the studies of Brenda Milner (summarised in Chapter 2) cannot be overstated.
Considering brain lesions, the loss of hippocampal functional integrity in medial temporal lobe epilepsy may account for the retention deficits found in this condition (Chapter 4) but findings of lateralized material-specificity (verbal-dominant, nonverbal-nondominant) have proven inconsistent, perhaps in part because ‘nonverbal tests’ may not be entirely nonverbal (Chapter 10).
The role of seizures per se is addressed by the study of transient epileptic amnesia (Chapter 8) which, despite its rarity (vis-a-vis transient global amnesia) has afforded some insights, including the phenomenon of accelerated long-term forgetting (surely, intuited by anybody who has ever crammed for an exam). Whether epileptiform EEG changes are also detrimental to memory function (‘transient cognitive impairments’) remains uncertain, in part because of the difficulty of distinguishing such events from subtle nonconvulsive seizures (Chapter 9).
Antiepileptic drugs (AEDs) are often blamed for memory problems, with justification in the case of older, sedating, medications. The newer AEDs largely escape culpability, with the exception of topiramate and possibly zonisamide, although not all new drugs have been submitted to rigorous study (Chapter 23).
Psychiatric factors, particularly co-morbid psychosis or depression may play a role in epilepsy-related memory problems and impact on performance in neuropsychological test performance (Chapter 15).
The editors have achieved their aims with this book (as perhaps might be expected considering a gestation period of some six years): it is well-produced, and handsomely illustrated with paintings and drawings by artists who have epilepsy. My only criticism is the absence of any extended analysis of epileptic seizures in Alzheimer’s disease, a subject of current interest and possible relevance in understanding mechanisms of concurrent memory impairment and epilepsy.
The Paradoxical Brain
Editors: Narinder Kapur, with Alvaro Pascual-Leone, Vilayanur Ramachandran, Jonathan Cole, Sergio Della Sala, Tom Manly and Andrew Mayes
Published by: Cambridge University Press, 2011
Reviewed by: Paresh Malhotra, Senior Lecturer in Neurology, Imperial College London, UK.
Thomas Browne, physician and author, coined the term paradoxology, the use of paradoxes, in his Pseudotoxia Epidemica or, Enquiries into Very many Received Tenets, and commonly Presumed Truths. Now Narinder Kapur has assembled a crack team of eminent scientists and clinicians to use paradoxology to illuminate various facets of how we understand (but very often don’t understand) the brain today. In this extremely interesting and ambitious book, with a foreword from Oliver Sacks (surely the foremost exponent of popular neuroparadoxology), the experts candidly discuss counterintuitive phenomena observed while studying the brain. Most relate to patient groups and treatment effects, but there are also chapters on topics such as comparative cognition between different species (it is humbling to know that my visuospatial performance on certain tasks is likely to be worse than a well-trained chimp’s) and the nature of human expertise.
The book is refreshingly targeted at people who are interested in the brain regardless of particular career path or level of seniority, and I very much doubt that there is anyone who is well-versed with all of the paradoxes, from the creativity of those with psychiatric conditions to the relationship between allergies and gliomas, described here. Moreover, many of the chapter authors, who are leaders in their fields, seem to relish being able to be discursive without the need to be as forcefully directed as is sometimes necessary for a journal article or specialist review. In addition, most of them cite across the breadth of the topic, rather than concentrating on their own contributions. Personally, I found the chapters on paradoxes in Parkinson’s Disease (Ashwani Jha and Peter Brown) and Learning and Memory (Henry L Roediger, III and Andrew C Butler) especially interesting. A number of the authors begin with historical introductions to each subject and I particularly enjoyed the backgrounds in the chapters on ECT (Angela Merkl and Malek Bajbouj) and psychosurgery (Perminder Sachdev) showing us just how far we haven’t come.
One drawback to the book is the occasional feeling that it is trying too hard to contrive a paradox, where the underlying issue is one of biological complexity (‘non-linear’ effects etc) rather than apparent contradiction.
In the final chapter, ten ‘principles of brain function’ are proposed in order successfully and sensibly to disentangle the paradoxes of brain research. Whether or not the ten principles catch on remains to be seen but Professor Kapur and colleagues have succeeded in producing a book that will stimulate thought on phenomena encountered during the course of our neuroscientific work and in our daily lives, which is a great achievement. I would recommend it to anyone (presumably all the people reading this) genuinely interested in the workings of the brain and how we go about trying to understand them. Thomas Browne, whose own brain has been commemorated in stone in his hometown of Norwich, would have approved.