Cognitive vitality is essential to quality of life and survival in old age. With normal aging, cognitive changes such as slowed speed of processing are common, but there is substantial interindividual variability, and cognitive decline is clearly not inevitable. In this review, we focus on recent research investigating the association of various lifestyle factors and medical comorbidities with cognitive aging. Most of these factors are potentially modifiable or manageable, and some are protective. For example, animal and human studies suggest that lifelong learning, mental and physical exercise, continuing social engagement, stress reduction, and proper nutrition may be important factors in promoting cognitive vitality in aging. Manageable medical comorbidities, such as diabetes, hypertension, and hyperlipidemia, also contribute to cognitive decline in older persons. Other comorbidities such as smoking and excess alcohol intake may contribute to cognitive decline, and avoiding these activities may promote cognitive vitality in aging. Various therapeutics, including cognitive enhancers and protective agents such as antioxidants and anti-inflammatories, may eventually prove useful as adjuncts for the prevention and treatment of cognitive decline with aging. The data presented in this review should interest physicians who provide preventive care management to middle-aged and older individuals who seek to maintain cognitive vitality with aging.

In the matrix of relations between the physiology, anatomy, and behavior of the older nervous system, a particular vantage point is research on the-slowness of behavior with age. A review of the evidence indicates that the slowing of behavior with age not only appears in motor responses and sensory processes but becomes more obvious with increasing complexity of behavior. For this reason the expression "slowness of behavior with age" is preferred to the more limited phrase "changes in reaction time with age." While there are probably both general and specific factors in behavioral slowing with age, the organization of a general factor of slowness raises some fundamental questions. Behavioral factors are apparently involved, but more recent emphasis has been placed on the role of neurobiological changes in the central nervous system.

This article states some principles and gives a perspective on research findings on aging that lie behind some of the daily life circumstances of growing old. Usually a science and real-life dialogue such as this is caught in a division between a humanistic orientation and the empirical scientific traditions or what one might call the mechanistic traditions. My proposition is simply that laboratory research on the psychology of aging is a potential friend of the aging adult and that we ought to utilize the findings of the laboratory for the benefit of an aging population.Much of my own research and that of several of my colleagues has been devoted to the study of the differences that occur with advancing age in speed of response (Birren, 1963, 196S). The issue is, How is such research relevant to the circumstances of older persons? I believe it has several points of relevance. For one thing, older people are strikingly affected by accidents. Accidents occur to older people whether they are pedestrians, drivers of cars, or in their own homes utilizing the normal appliances in everyday life. In particular, older people hurt themselves through falls, often fatally. Sometimes it would appear that the older person lacks the speed and agility to execute an evasive action in the face of an impending accident. Sometimes the accident-avoiding action has a limiting physical quality about it; that is, the younger person would or could move or jump out of the way more quickly and thus avoid an impact. Sometimes the action also has to do with time taken to scan

Over 100 years of observations have established that slowness of behavior is a characteristic of becoming old, although it is now recognized that health, use of medications, and physical activity may modify the extent of the slowing. Early research indicated that there is a limited contribution to slowing by peripheral sensory-motor factors. Substantial evidence has pointed to the central nervous system as the locus of the slowing. Recent investigators have expressed divided opinions about whether there is a pervasive general slowing of behavior by the central nervous system or whether there are specific localized mechanisms. This is not unlike early disputed views of the brain as having localized or global behavioral functions: Both principles appear to be simultaneously true. Sufficient research has been conducted to indicate that there are specific factors as well as a general process associated with the slowing of behavior with advancing age. Whether such slowing is a primary or secondary cause of age differences in cognitive processes is a significant scientific issue. A marked broadening of research on aging has been accompanied by an interest in identifying both the neurophysiological correlates of slowing as well as its role in specific cognitive processes. Yet another aspect of the changing research picture is the trend to move beyond the mere use of chronological age as the sole basis for comparing performance differences. Measurement of more independent variables is suggested as part of clusters or causal complexes that will indicate sources of the changes in speed and other aspects of behavior. These causal complexes include biological indicators such as disease, physiological capacity for work, and length of life, as well as causal complexes of social factors involving such variables as education, occupation, and ethnicity. There has been considerable discussion of markers of aging. In this approach, factors found to be closely associated with advancing age are used as measures of the effectiveness of attempts to modify the course of aging, e.g. by diet, exercise, new learning, and drugs. Along with other biomarkers of aging, speed of behavior may prove to be a criterion for assessing the impact of interventions on the rate and processes of aging. As a marker of aging, speed needs further exploration that will compare the slowness observed in different subgroups of adults with a wide range of outcomes in their productivity, capacity for adaptation to life's demands, and health. The present status of information about slowness of behavior with advancing age indicates that it is one of the most reliable features of human life.(ABSTRACT TRUNCATED AT 400 WORDS)

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