Now is a time of great promise for learning more about the aging mind and turning that knowledge to the advantage of older people. Neuroscientists are making rapid progress in understanding the neural basis of sensation, memory, language, and other cognitive functions and are poised to understand, at the molecular and cellular levels, neural changes that affect the life course of cognitive capabilities. Behavioral researchers are classifying types of cognitive functioning, measuring them, tracking changes in particular functions over the life cycle, and documenting declines, maintenance, and improvement in these functions over the life span. Researchers in cognitive science are developing detailed models and theories of cognitive processes that can help make sense of observed patterns of change in functioning and link them to observed changes in neural systems. Social scientists are demonstrating the significance of cultural supports and life experiences in shaping cognitive content and processes over the life span. All these scientific developments are making possible new understandings of how normal processes of aging affect cognitive functioning and new interventions to maintain cognitive performance in older people.
In 1999, the National Institute on Aging (NIA) asked the National Research Council to identify areas of opportunity in which additional research support would substantially improve understanding of cognitive functioning in aging. The Committee on Future Directions for Cognitive Research on Aging was formed to identify highly promising opportunities in behavioral science, cognitive science, and neuroscience and at the conjunctions of these fields.
We worked from a conceptual framework that describes the aging mind in terms of three interacting systems that support the performance of cognitive tasks: cognitive structures and processes, neural health, and behavioral context, including task structure and social, cultural, and technological factors. We use the term ''the aging mind" to signal a broad conception of cognitive aging that includes not only changes that can be directly observed in the brain or by standard laboratory tests of cognitive function, but also complex and knowledge-based aspects of intelligence, as well as cognitive aspects of the self, personality, and interpersonal functioning. In this conception, people adapt to changes in the body and in the social, cultural, and technological context of behavior in order to perform the tasks of living. Adequate cognitive functioning depends both on the integrity of neural systems and on these contextual factors.
This framework takes seriously recent understandings of plasticity. Neural decline in aging may not be as uniform or as profound as once believed, and various adaptive processes at the neural, behavioral, and social levels may mitigate the behavioral effects of the neural changes that do occur. To understand and assist the aging mind, it is necessary to consider changes in neural health and in behavioral context that occur in later life, as well as to understand inter-and intraindividual differences in cognitive function both cross-sectionally and over time.
We examined recent advances in the relevant science and identified three major areas in which scientific developments are creating significant opportunities for breakthroughs. The committee recommends that the NIA undertake major research initiatives in these three areas.
1. Neural Health. The NIA should undertake a major research initiative to build the scientific basis for promoting neural health in the aging brain.
Recent research shows that, contrary to a conventional belief, neural cell loss may not be the primary cause of cognitive decline in older people who are not suffering from Alzheimer's disease or related dementias. It suggests that aside from neural cell loss, changes in the health of neurons and neural networks play a major role in cognitive function. A new research focus on neural health in aging can improve basic understanding of the aging mind and lead to new health-maintaining interventions. A research initiative on neural health should consist of elements addressed to each of four major goals: developing quantitative functional and performance indicators, including behavioral tests, for neuronal health and neuronal dysfunction; identifying factors that affect neural health during the aging process, especially including imbalances in homeostatic processes, such as apoptosis, inflammation, and oxidative activity; devising interventions for the maintenance of healthy neu-
rons and the rescue and repair of neural networks; and assessing the efficacy of intervention strategies.
2. Cognition in Context. The NIA should undertake a major research initiative to understand the effects of behavioral, social, cultural, and technological context on the cognitive functioning and life performance of aging individuals and to build the knowledge needed to intervene effectively in these contexts to assist individuals' functioning and performance.
Current research indicates that aging impairs cognition in some tasks but spares it in others. Until recently, the impairments were thought impossible to prevent or change. However, growing bodies of evidence show that the most impressive feature of the human mind across the life span may be its adaptability. Life experience can bring about lasting changes in the brain that shape the aging mind. In other words, biology and culture codetermine cognitive structure and functioning. Individuals adapt, sometimes with great success, so as to maintain cognitive functioning and task performance in the face of changes in the brain and in their social contexts. Systematically different life experiences yield systematically different cognitive contents and processes. And technology can modify the context of cognition to greatly improve functioning for older people. Much can be learned from increased research attention to the aging mind in its context: to factors such as cultural expectations and differences, changes in living situations and motives in late life, and emerging technologies. A new research initiative on cognition in context would seek to understand such factors and to identify ways to maintain and improve cognitive functioning of older people, taking these factors into account. Research under the initiative would pursue three major goals: understanding adaptive processes that affect cognitive functioning and performance during aging; understanding how differences in sociocultural context bring about systematic variation in cognitive functioning and performance; and developing the knowledge needed to design effective technologies, based on advances in the technology of sensing and information processing, to support adaptivity in older people.
3. Structure of the Aging Mind. The NIA should undertake a major research initiative to improve understanding of the structure of the aging mind, including the identification of mechanisms at the behavioral and neural levels that contribute to age-related change in cognitive functioning.
As already noted, research has established that aging affects cognitive functioning and performance of life tasks differently depending on the cogni-
tive operation and the individual. Although the patterns of variation are not yet well understood, some of the differences have been linked to life experience factors, including physical exercise, diet, cognitive training, expertise, and the provision of environmental support; others have been linked to changes in sensory-motor functioning and to chronic diseases. A new research initiative on the structure of the aging mind would aim to specify the patterns of variation in cognitive functioning during the aging process and to identify the mechanisms, at levels of analysis from the molecular to the cultural, that contribute to age-linked stability and change. The research would include stability and change in knowledge and cognitive content that is specific to cognitive aging in humans. Research under the initiative would contribute to the search for effective interventions to assist older people in maintaining cognitive functioning and performance. The initiative should include studies of the full variety of phenomena that have been linked to cognitive aging and should emphasize the use of promising methods of measurement and analysis that are either new or underutilized in cognitive aging research. Research under the initiative should emphasize three method-based research strategies for understanding the aging mind: relating high-resolution measures of neural functioning to measures of cognitive functioning; elaborating theory-based and mathematical models; and conducting and analyzing large-scale, multivariate studies.
Achieving the goals of these research initiatives will require, in addition to financial support for research, special efforts to meet the needs for interdisciplinary research, provide specific infrastructure, and increase collaboration between the NIA and other agencies.
Interdisciplinary research. The study of the aging mind is highly interdisciplinary and becoming more so. Life scientists, behavioral scientists, and social scientists are challenged to seek new levels and forms of collaboration. To achieve the needed collaborations, the NIA should consider new funding mechanisms, including asking scientists from very different fields to work together in selected areas and establishing new research programs, program offices, and special emphasis review panels. In addition:
4. The NIA should support postdoctoral fellowships, conferences, workshops, and summer institutes to encourage individual scientists to broaden their knowledge and technical capability to address interdisciplinary issues that are central to the new research initiatives. It should organize a special competition that would provide multiyear support of a few small multidisciplinary research centers or teams focused on analytical problems that require the simultaneous application of multiple perspectives.
Research infrastructure. Infrastructure is needed in the form of access to aged animals for research; a large longitudinal database on human cognitive aging; and improved capacity for using brain imaging to study the aging mind.
The NIA should support the infrastructure for research on cognitive aging in the following ways:
5a. The NIA should help support the maintenance of colonies of pathogen-free aged animals (including primates, rats, and mice) in regional centers.
5b. The NIA should undertake a major effort to expand or develop large-scale longitudinal studies of cognitive aging. The studies should cover the range of variation in the population and should support research aimed at understanding the relationships among neural, cognitive, behavioral, sensory-motor, health, and life experience variables as they affect cognitive aging. Other institutes of the National Institutes of Health should be invited to cooperate in this effort, as they may benefit from the type of comprehensive longitudinal research being developed.
The NIA and cooperating institutes should engage in structured discussions with the research community, perhaps through a series of workshops, to address the problems involved in using resources effectively to create a broadly useful base of longitudinal data on cognitive function and its neural, behavioral, and experiential correlates.
5c. The NIA should support the capacity for using brain imaging data in the following ways:
supporting a consensus conference to develop standard procedures for collecting and reporting human brain imaging data, specifically including MRI data, on brain-behavior relationships in aging; and
working with other institutes at the National Institutes of Health to establish a monkey brain imaging facility with fMRI capability at the National Institutes of Health and to support a few similar centers elsewhere.
Collaboration between the NIA and other agencies. Several of the above recommendations are best advanced through collaborations involving the NIA and other agencies. For example, investments in animal colonies, improved MRI capabilities, and longitudinal research will be widely beneficial, and research on adaptive technology for aging will also help nonaged disabled populations.
6. The NIA should seek additional opportunities to participate with other institutes such as the National Institute of Mental Health, the National Institute of Neurological Disorders and Stroke, and the National Eye Institute to develop initiatives in neuroscience and cognitive aging as a way to increase the power of its research investments.