Neuroscience and Cognitive Aging

LEARNING OBJECTIVES

• What are the basic structural changes in the brain as we age?

• What cognitive functions are associated with volume shrinkage in the aging brain?

• How do decreases in the dopaminergic system relate to changes in cognitive functioning as we grow older?

• What happens to brain activation as we age?

• What are the cultural implications of neuroimaging?

• How does bilateral activation serve a functional role in older adults’ cognitive functioning?

• What are the major differences between the HAROLD and STAC models of brain activation and aging?

amuel is 73 and he is worried about contract­ing Alzheimer’s disease. He remembers that his father became disoriented at this age and had trouble remembering things that he was just told. How can Samuel find out if his brain is aging normally or pathologically? Psychological tests are somewhat, but not completely, predictive of disease. This is a dilemma older adults are facing in our society today.

A major thrust of adult development and aging research has focused on cognitive aging, both normal and pathological. The development of classic theories of cognitive aging has been pri­marily based on behavioral data (see Chapter 6; Salthouse, 1996; Schaie, 1996). More recently the availability of neuroscientific methods such as those described earlier has stimulated research that allows us to study cognitive processes—and changes in these processes—in the living brain using noninvasive brain imaging techniques, such as the magnetic resonance imaging (MRI) and functional magnetic resonance imaging (fMRI) techniques discussed earlier. For example, Stephen Rao and his colleagues found a means to identify Alzheimer’s disease as much as 10-15 years before memory problems and other symptoms occured (Leveroni, Seidenbert, Mayer, Mead, Binder, &

Rao, 2000). By focusing on the brain’s ability to recognize famous faces, they discovered that images of famous faces activate those areas of the brain that are first assaulted by Alzheimer’s disease. They suggested that a lack of activity in these regions may signal the onset of the disease. This is exactly the type of information in which Samuel would be interested. In order to make these types of discoveries, we must first have a strong knowledge base of how the brain ages nor­mally. Let’s examine what the field of neuroscience and aging has contributed to our knowledge of the aging brain.