“Age does not depend upon years, but upon temperament and health. Some men are born old, and some never grow so.”
“A man is as old as his arteries.”
The dogma that aging brings inevitable cognitive decline is being challenged by studies of the rapidly expanding oldest segment of our society, adults older than 60 years. Although some aspects of cognition are affected by aging, many changes in cognition previously considered the unavoidable consequence of brain senescence may instead result from incremental insults on brain function associated with aging-related medical conditions. The detection of such changes, which may stabilize or even reverse with appropriate intervention, and their differentiation from the cognitive changes associated with neurodegenerative disease or other neurological disorders is a critical task. The primary goal of this chapter is to describe changes in various cognitive abilities that occur with normal aging and with common age-related medical and neurological conditions.
General Intellectual Functioning
Intelligence is generally measured by summing the scores on a variety of verbal and performance subtests. Studies of aging have consistently shown that subtests measuring verbal abilities remain stable with normal aging. In contrast, subtests that require nonverbal creative thinking and new problem solving strategies show a slow decline with age. Crystallized abilities (information and skills gained from experience) remain relatively intact with aging, while fluid intelligence, which involves flexible reasoning and problem solving approaches, declines. Numerous studies have documented this general pattern in both cross-sectional and longitudinal research designs. Below, we review the literature on the effects of normal aging on specific cognitive functions (Table 62-1).
Table 62-1 Cognitive Effects of Normal Aging ||Download (.pdf)
Table 62-1 Cognitive Effects of Normal Aging
PRESERVED COGNITIVE FUNCTIONS
COGNITIVE FUNCTIONS SHOWING DECLINE
General intellectual functioning
Crystallized, verbal intelligence
Fluid, nonverbal intelligence, speed of information processing
Sustained attention, primary attention span
Divided attention (possibly)
“Real world” executive functions
Novel executive tasks
Remote memory, procedural memory, semantic recall
Learning and recall of new information
Comprehension, vocabulary, syntactic abilities
Spontaneous word finding, verbal fluency
Construction, simple copy
Mental rotation, complex copy, mental assembly
Attention involves the ability to focus on one or more pieces of information (auditory or visual) long enough to register and make meaningful use of the data. Attention requires both simple and complex immediate processing and provides a foundation for working memory and other cognitive functions. Sustained attention, or vigilance, entails attending to one type of information over a period of time. After controlling for reaction time and sensory changes, sustained attention and strategies for maintaining vigilance do not appear to change significantly with age. Divided attention, or the ability to concentrate on more than ...