New Frontiers in Cognitive AgingEdited by:
- Roger A. Dixon,
- Lars Bäckman &
- Lars-Göran Nilsson
John Morley, the retiring editor of a leading journal of medical gerontology, wrote a farewell editorial entitled “The Top 10 Hot Topics In Aging” (J. Gerontol. A Biol. Sci. Med. Sci. 59, 24–33; 2004). Not surprisingly, perhaps, cognitive decline was the first topic on his list. It is probably the single most feared aspect of growing old. It may also be among the most complex and least understood features of a host of age-related changes that can be summarized as senescent phenotypes.
Fortunately for those of us on the verge of entering the ‘fourth age’ (defined by Paul Baltes and Jacqui Smith as the age at which 50% of those who are alive at ages 50–60 years subsequently die), help may be on its way. There are, for example, efforts to define more accurately ‘minimal cognitive impairment’ and its transition, in many instances, to dementias of the Alzheimer type. In developed countries, the fourth age comes at about 80–85 years; this is when various behavioural and physiological compensatory mechanisms — what I have called ‘sageing’ — no longer work very well. But events that modulate the age of onset and rate of progression of senescent phenotypes can have their origins much earlier. A fuller understanding of cognitive ageing therefore requires a lifespan approach, as first appreciated by my colleagues in social gerontology.
New Frontiers in Cognitive Aging has its origins in a conference held in an exceptionally pleasant ski resort in British Columbia, Canada. The contributors include Swedish, Canadian, US and Australian scientists. According to the editors, both the conference and the book were designed to bring together workers from different disciplines to consider three ‘new frontiers’ in cognitive ageing: new theoretical directions; integrations of findings from cognitive neuroscience with cognitive ageing; and the effects of biology and health on cognitive ageing.
The book will be of most interest to cognitive psychologists who specialize in memory research and want an update on some of the major findings from such methods as functional magnetic resonance imaging and positron emission tomography (PET). Those new to the field will have to go elsewhere for basic definitions of such terms as episodic and semantic memory. There is a little genetics thrown in, too — notably some brief discussions of the influence of polymorphic alleles at the apolipoprotein E locus on cognitive functioning and susceptibility to dementias of the Alzheimer type. We still do not know the mechanistic details of how specific alleles at this locus affect cognitive functioning even in middle age, or why these polymorphic alleles evolved and are maintained at such variable frequencies in many human populations.
We can certainly be grateful for the achievements of cognitive psychologists, epitomized by the pioneering work of Timothy Salthouse on processing speed, which is well discussed in this volume. The findings derived from joint efforts of cognitive psychologists and neuroimaging experts are also nicely documented here. A striking example from a Swedish PET study is illustrated in a chapter by Lars Nyberg and Lars Bäckman, showing the altered prefrontal lateralization associated with the retrieval of certain forms of memory in normal aged human subjects compared with younger people.
What surprised me, however, was the paucity of information about recent studies on the cellular and molecular aspects of cognition and their significance for our understanding of cognitive ageing. The efforts of Ancino Silva are particularly notable: he has set up the Molecular and Cellular Cognition Society (http://www.molcellcog.org), which meets in connection with the annual meeting of the Society for Neuroscience, a cosy little gathering of almost 30,000 neurobiologists.
The cover image of this book, a painting by Zbigniew Pronaszko shown on the previous page, reminded me that depressive illness is very common in older people and may sometimes be misdiagnosed as an early form of dementia.
More on ageing
Forever Young: A Cultural History of Longevity by Lucian Boia Reaktion, 224pp. £16.95, $25
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