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Light and biological rhythms in man
Neuropsycholo,qla,Vol 33. No 3, pp 391 392, 1995 ElsevierScienceLid Printed in Great Britain
l-'ergamon
BOOK REVIEWS Dementia and Normal Brain Aging. Edited by FELICIA A. H U P P E R T , CAROL BRAYNE and DANIEL O ' C O N N O R . 573 pp. Cambridge University Press, 1994. Preparing a book on the topic "Dementia and normal aging" is always a risk and a challenge, for two reasons. First, at least some of the theories and experimental data selected for presentation may become obsolete already during the preparation of the book. Second, an enormous amount of information must be squeezed into relatively few pages, possibly neglecting several relevant articles and even excluding the work of brilliant scientists from the reference list. The Editors of this multi-authored book seem to have coped successfully with these difficulties by focusing on a specific problem, i.e. the relationship between normal aging and dementia, seen as a continuum by some authors and a dichotomy by others. Indeed most of the book is devoted to an analysis of this relationship and an evaluation-perhaps even a validation--of the hypothesis that dementia may be on a continuum with age-dependent changes. The first parts of the book offers useful historical surveys of the problem including old references, generally ignored in previous recent publications on the subject. Other chapters deal with present diagnostic and clinical problems and with brain imaging in demented patients. Yet others give a comprehensive and clear overview of the neuropathologic, neurochemical and genetic literature on dementia. The final part of the book deals with practical health-care and social policy issues. The main question as to whether changes seen in dementm relate to changes found m normal aging, and to what extent there is a continuum from normal aging to severe dementia through intermediate stages, ~s addressed in depth with clear and detailed contributions from a wide range of disciplines. In my opinion the only weak point of the book appears to be the lack of a chapter on electrophysiology and the neglect of the results of many extensive investigations on normal aging and dementia using EEG and evoked-potentials. Event-related responses are useful mdexes of information processing by the brain. Electrophysiological signs of normal aging can be minimal or absent, and a minority of demented patients may present a normal E EG. This could be an argument in favour of the continuum hypothesis. Moreover, the P300 response has been used by several authors for discriminating truedementia from pseudodementia. In the book, the EEG is discussed only in relation to sleep disturbances IP 282), and evoked potentials are only mentioned in passing (p. 356). The statement on p. 375 that the right hemisphere ages more rapidly than the left, based on performance on visuospatlal tasks, is contradicted by EEG studies. There are a few Inconsistencies in the use of Latin terms (e.g. locus caeruleus on pp. 49 and 51 becomes locus coeruleus on p. 65) and surely the correct Italian expression for "hurriedly baptized" is not "fretta battezzate" (p. 34), a mutilated sentence which should read "'troppo m fretta battezzate". However these minor imperfections do not detract from the generally good quality of the text. In summary, because of its many excellent chapters, updated references and cogent discussions the book should constitute a very informative and instructive reading for neurologists, psychiatrists, gerontologists and psychologists. It can also be of interest to geneticists and sociologists, and be recommended as a comprehensive reference on aging and dementia to nurses, medical students and general practitioners SALVATORE GIAQUINTO
Light and Biological Rhythms in Man. Edited by L. WETTERBERG. 448 pp. Pergamon Press, 1993 The interest in endogenous biological rhythms has exploded in the last decades, and m particular m the last years, due to a number of discoveries about their physiological regulation and pathological correlates An increasingly large number of studies in this field has been devoted to the suprachiasmatic nuclei (SCN) of the mammalian hypothalamus, which have been found to play a major role as a biological clock in the entrainment of endogenous rhythms. The SCN act as circadian pacemakers, synchronizing endogenous biological rhythms to environmental cues, among which the light/dark cycle plays a crucial role. Direct retinal afferents are conveyed to the SCN through the retlnohypothalamic pathway. The volume includes 32 chapters, and summarizes the trends ranging (as indicated by the clear and respiring introductory lecture) "from gcne expression to behavior", including behaworal disturbances. The rationale of the volume is to provide an ample multidisciplinary view on the effects of light not only on the normal control of endogenous rhythms, but also on neurohormonal regulation, mood disturbances and affective disorders. The chapters span from the basic sciences to clinical and therapeutical approaches. 391
392
Book Reviews
The first section is devoted to light in the entrainment of biological rhythms in a variety of experimental animals and in humans. This is followed by chapters dealing with the organization of neural pathways underlying the photic regulation of endogenous oscillators and their physiological control. All of the chapters of this section (as many others throughout the book) are focused on the regulatory mechanisms exerted by the pineal hormone melatonin. The other parts of the volume are devoted to the infuence of light on circadian rhythms, with particular reference to sleep and the sleep/wake cycle, and the relationships between light and neuroendocrine regulation. Finally, a large section is devoted to the discussion of phototherapy in different kinds of depressive states. Altogether the volume is stimulating and provides an exhaustive view of the problem. Although there are a number of repetitions (for example, the basic knowledge about the SCN and related circuitry, and the involvement of melatonin, is dealt with in many of the chapters and illustrated in more than one figure), the book offers a clear overview of the beneficial effect of light as a regulator in health and disease. The book certainly has the merit of making comprehensible to neuroscientists, neurologists and psychiatrists many of the issues related to the rather complex field of chronobiology and its pathophysiology. The reader is accompanied from the anatomy and physiology of endogenous oscillators, and the importance of external cues, the intrinsic properties of the circadian oscillators, to the clinical disturbances in which these mechanisms are disrupted. The debates about the therapeutical effect of light treatment are presented honestly and in a critical perspective. The scientific route conducting from neural pacemakers and oscillators into mood changes is intriguing and fascinating. This volume clearly demonstrates how an itinerary can develop from basic sciences into the clinical perspective of not uncommon psychiatric disorders. MARINA BENTIVOGLIO
l-'ergamon
BOOK REVIEWS Dementia and Normal Brain Aging. Edited by FELICIA A. H U P P E R T , CAROL BRAYNE and DANIEL O ' C O N N O R . 573 pp. Cambridge University Press, 1994. Preparing a book on the topic "Dementia and normal aging" is always a risk and a challenge, for two reasons. First, at least some of the theories and experimental data selected for presentation may become obsolete already during the preparation of the book. Second, an enormous amount of information must be squeezed into relatively few pages, possibly neglecting several relevant articles and even excluding the work of brilliant scientists from the reference list. The Editors of this multi-authored book seem to have coped successfully with these difficulties by focusing on a specific problem, i.e. the relationship between normal aging and dementia, seen as a continuum by some authors and a dichotomy by others. Indeed most of the book is devoted to an analysis of this relationship and an evaluation-perhaps even a validation--of the hypothesis that dementia may be on a continuum with age-dependent changes. The first parts of the book offers useful historical surveys of the problem including old references, generally ignored in previous recent publications on the subject. Other chapters deal with present diagnostic and clinical problems and with brain imaging in demented patients. Yet others give a comprehensive and clear overview of the neuropathologic, neurochemical and genetic literature on dementia. The final part of the book deals with practical health-care and social policy issues. The main question as to whether changes seen in dementm relate to changes found m normal aging, and to what extent there is a continuum from normal aging to severe dementia through intermediate stages, ~s addressed in depth with clear and detailed contributions from a wide range of disciplines. In my opinion the only weak point of the book appears to be the lack of a chapter on electrophysiology and the neglect of the results of many extensive investigations on normal aging and dementia using EEG and evoked-potentials. Event-related responses are useful mdexes of information processing by the brain. Electrophysiological signs of normal aging can be minimal or absent, and a minority of demented patients may present a normal E EG. This could be an argument in favour of the continuum hypothesis. Moreover, the P300 response has been used by several authors for discriminating truedementia from pseudodementia. In the book, the EEG is discussed only in relation to sleep disturbances IP 282), and evoked potentials are only mentioned in passing (p. 356). The statement on p. 375 that the right hemisphere ages more rapidly than the left, based on performance on visuospatlal tasks, is contradicted by EEG studies. There are a few Inconsistencies in the use of Latin terms (e.g. locus caeruleus on pp. 49 and 51 becomes locus coeruleus on p. 65) and surely the correct Italian expression for "hurriedly baptized" is not "fretta battezzate" (p. 34), a mutilated sentence which should read "'troppo m fretta battezzate". However these minor imperfections do not detract from the generally good quality of the text. In summary, because of its many excellent chapters, updated references and cogent discussions the book should constitute a very informative and instructive reading for neurologists, psychiatrists, gerontologists and psychologists. It can also be of interest to geneticists and sociologists, and be recommended as a comprehensive reference on aging and dementia to nurses, medical students and general practitioners SALVATORE GIAQUINTO
Light and Biological Rhythms in Man. Edited by L. WETTERBERG. 448 pp. Pergamon Press, 1993 The interest in endogenous biological rhythms has exploded in the last decades, and m particular m the last years, due to a number of discoveries about their physiological regulation and pathological correlates An increasingly large number of studies in this field has been devoted to the suprachiasmatic nuclei (SCN) of the mammalian hypothalamus, which have been found to play a major role as a biological clock in the entrainment of endogenous rhythms. The SCN act as circadian pacemakers, synchronizing endogenous biological rhythms to environmental cues, among which the light/dark cycle plays a crucial role. Direct retinal afferents are conveyed to the SCN through the retlnohypothalamic pathway. The volume includes 32 chapters, and summarizes the trends ranging (as indicated by the clear and respiring introductory lecture) "from gcne expression to behavior", including behaworal disturbances. The rationale of the volume is to provide an ample multidisciplinary view on the effects of light not only on the normal control of endogenous rhythms, but also on neurohormonal regulation, mood disturbances and affective disorders. The chapters span from the basic sciences to clinical and therapeutical approaches. 391
392
Book Reviews
The first section is devoted to light in the entrainment of biological rhythms in a variety of experimental animals and in humans. This is followed by chapters dealing with the organization of neural pathways underlying the photic regulation of endogenous oscillators and their physiological control. All of the chapters of this section (as many others throughout the book) are focused on the regulatory mechanisms exerted by the pineal hormone melatonin. The other parts of the volume are devoted to the infuence of light on circadian rhythms, with particular reference to sleep and the sleep/wake cycle, and the relationships between light and neuroendocrine regulation. Finally, a large section is devoted to the discussion of phototherapy in different kinds of depressive states. Altogether the volume is stimulating and provides an exhaustive view of the problem. Although there are a number of repetitions (for example, the basic knowledge about the SCN and related circuitry, and the involvement of melatonin, is dealt with in many of the chapters and illustrated in more than one figure), the book offers a clear overview of the beneficial effect of light as a regulator in health and disease. The book certainly has the merit of making comprehensible to neuroscientists, neurologists and psychiatrists many of the issues related to the rather complex field of chronobiology and its pathophysiology. The reader is accompanied from the anatomy and physiology of endogenous oscillators, and the importance of external cues, the intrinsic properties of the circadian oscillators, to the clinical disturbances in which these mechanisms are disrupted. The debates about the therapeutical effect of light treatment are presented honestly and in a critical perspective. The scientific route conducting from neural pacemakers and oscillators into mood changes is intriguing and fascinating. This volume clearly demonstrates how an itinerary can develop from basic sciences into the clinical perspective of not uncommon psychiatric disorders. MARINA BENTIVOGLIO