Brain, Vol. 124, No. 9, 1877-1879,
September 2001
© 2001 Oxford University Press
Book reviews |
VASCULAR DEMENTIA
Edited by John Stirling Meyer, Gaiane M. Rauch, Helmut Lechner and Carlo Loeb. 2000. Armonk: Futura Publishing Company. Price US $88. Pp. 320. ISBN 0-87993-425-5.
Department of Neurology, University Medical Centre, Utrecht, The Netherlands
The prevalence of dementia dramatically increases in ageing populations, affecting 1% of 60–64 year olds, and up to 40% of those over age 85 years. This devastating disease poses a large burden on the patients and their families, but also on the health care system in general in terms of the enormous costs involved. Vascular dementia is the second most frequent type of dementia, just behind Alzheimer's disease, although the clinical distinction between these two forms of dementia is becoming more and more difficult as there is increasing evidence for the involvement of vascular risk factors, even for pathologically confirmed Alzheimer's disease. This book addresses topics on epidemiology (prevalence, incidence, risk factors, diagnosis and prognosis), treatment, neuroimaging and neuropathology of vascular dementia.
Chapter 1 is an original contribution that critically addresses the effect of classification criteria on the observed frequency of vascular dementia. The authors clearly point out that misclassification of dementia may mask true associations between a certain risk factor and dementia. In addition to this, the frequency of the several subtypes of vascular dementia that do exist is reviewed. In Chapter 11, eight different subtypes of vascular dementia are described: multi-infarct dementia, dementia due to strategic infarcts or multiple subcortical lacunar infarcts, `Binswanger's disease' or subcortical arteriosclerotic leucoencephalopathy, genetically determined arteriolopathies leading to subcortical dementias, a mixture of the first three types mentioned, a haemorrhagic lesion due to several causes and a combination of Alzheimer's disease and vascular dementia. They briefly describe the organic substrate of the lesion causing the dementia syndrome and clinical features; however, they do not clearly point out on which basis this subdivision has been based.
In several chapters the frequency of various risk factors for vascular dementia such as hypertension, heart disease, diabetes mellitus, smoking and other—in particular vascular risk factors—is described, as is the strength of the association between these risk factors and vascular dementia. Unfortunately, there is substantial overlap between various chapters dealing with this topic.
Chapters 13 and 17 describe the prognosis of individuals with vascular dementia. The course of several neuropsychological features and cause-specific mortality among vascular dementia and Alzheimer's disease patients are reviewed. Apparently, there are no major differences in the cause-specific mortality between vascular dementia and Alzheimer's disease patients. Surprisingly, there was no statistically significant difference in the median survival among individuals with vascular dementia and Alzheimer's disease, with or without vascular risk factors. This may reflect difficulties in the distinction between subjects with vascular dementia or Alzheimer's disease.
The book also includes a few chapters on possible treatment strategies for vascular dementia. Chapter 14, for example, summarizes again a number of vascular risk factors and potential treatments for vascular dementia. However, the authors illustrate any beneficial effect of treatment of these factors only with respect to those vascular outcomes that do not include vascular dementia. An interesting novel approach in the treatment of vascular dementia is described in Chapter 15, namely plasmapheresis. In an, albeit small, double blind randomized clinical trial, it was shown that plasmapheresis improved cognition of vascular dementia patients as compared with their baseline cognition, and compared with the control patients with vascular dementia who did not receive plasmapheresis. In addition, an interesting pathophysiological explanation is given. Other therapeutic strategies, such as oestrogen replacement therapy and the use of aspirin in patients with vascular dementia are reviewed in separate chapters. Aspirin, in a daily dose of 325 mg, was related to an increase in cognitive performance as compared with baseline cognition. Those who were not receiving aspirin showed a decrease in cognition.
Several chapters deal with the major problem of making the distinction between the diagnosis of vascular dementia or Alzheimer's disease. Chapter 8, in particular, provides a comprehensive review of neuropsychological testing among individuals with vascular dementia compared with those with other types of dementia. In addition, there is a good methodological section on several drawbacks of these kinds of neuropsychological tests.
In other chapters the problem of the differential dementia diagnosis by means of neuroimaging is covered. Several neuroimaging techniques such as SPECT (single photon emission computed tomography), PET and MRI are discussed. A promising technique, according to the authors, is the measurement of the so-called vascular reserve capacity by means of CO2-enhanced transcranial Doppler, which may be potentially powerful in discriminating between vascular dementia and Alzheimer's disease. Neuroimaging reveals a number of cerebral changes that occur during ageing, e.g. white matter lesions and both cortical and subcortical atrophy. In particular, when it comes to white matter lesions there is little agreement among the authors of the several chapters on the role of white matter lesions in the pathogenesis of vascular dementia or Alzheimer's disease. This is, of course, complicated by the fact that virtual everybody above the age of 60 years has white matter lesions, which does not help to elucidate their role in vascular dementia or Alzheimer's disease.
The authors point out that white matter lesions reflect some sort of chronic cerebral ischaemia and might therefore be pathognomonic for vascular dementia. However, by excluding white matter lesions from the diagnostic criteria for Alzheimer's disease (because they are a factor representing vascular disease), it will be, for obvious reasons, impossible to establish a relationship between vascular risk factors and Alzheimer's disease. This is an important topic, as is illustrated by the fact that neuroimaging of clinically diagnosed Alzheimer's disease patients quite often reveals white matter lesions. Apparently, the opinion on this issue also differs among the several authors of the chapters; some view white matter lesions as a non-specific entity without any cognitive consequence, while others dedicate entire paragraphs to pathophysiological explanations of the possible emergence of white matter lesions and their importance in cognitive decline.
Chapters 4 and 5 deal with neuropathological changes observed in the brains of individuals who have suffered from vascular dementia. Sometimes the authors mention the difficulties they have experienced in the distinction between vascular dementia and Alzheimer's disease, even at neuropathological examination. In these chapters, they describe several vascular changes seen at the microscopic level in vascular dementia and they elaborate on the causes of these changes. In this neuropathological chapter they state that `in general, it is advisable to treat each existing risk factor in a given patient'. However, literature indicating that this would indeed be beneficial to a patient with vascular dementia, as proven in double blind randomized clinical trials, does not support this notion. Nor is there mention of the enormous increase of costs that doing this would lead to.
As with most books, the authors have been seriously hampered by the fact that they were not able to include the latest references in their contributions. Especially in the last few years, results became available from large prospective population-based studies and double blind randomized clinical trials that have shed light on the role of vascular risk factors for white matter lesions and cerebral atrophy and their role in cognitive decline.
In conclusion, this book offers a comprehensive survey of the epidemiology and the neuropathology of vascular dementia and, to a lesser extent, of Alzheimer's disease. It sometimes touches the intriguing difficulties that do exist in the differential diagnosis of Alzheimer's disease and vascular dementia; however, this topic could possibly be a bit more critically reviewed. There is substantial overlap between the content of various chapters, some of which have more or less the structure of an original paper instead of a review of the literature. This book may be worthwhile reading for the general neurologist for whom ageing and dementia is not common practice, or for those who are relatively new to the field.
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