DIMENSIONS Spring 2002

Spotlight on Research: The Role of Neuropsychological Testing in AD

by Cheryl Dawes

photo of Memory Research Center personnel

For people with Alzheimer's disease (AD), walking to the grocery store can be a difficult task that could even lead to getting lost. Taking a walk and navigating from home to the grocery store calls upon a variety of mental processes that take place in different parts of the brain.

Neuropsychological testing allows psychologists with specialized training to determine whether a person has problems with any of the processes that take place in the brain. This type of assessment is an important part of diagnosing Alzheimer's disease (AD) and a valuable tool for researchers seeking to find ways to prevent or slow the progression of the disease.

Undergoing a neuropsychological assessment involves answering a series of questions especially designed to measure specific mental functions. By evaluating the results of these tests, a neuropsychologist can determine whether a person is functioning within the normal range for his or her age and level of education, explains Dr. Monique Cherrier, acting assistant professor of psychiatry and behavioral science and director of the University of Washington Memory Research Center.

Cherrier, a clinician and researcher, explains that a neuropsychological assessment provides a picture of strengths and weaknesses in a person's cognitive abilities-abilities to solve problems, remember information, express ideas, and process information. It also establishes a baseline against which future performance can be compared. "This is particularly important in distinguishing any normal changes in cognition due to aging from a progressive disease process such as AD," she says. "At the initial assessment, I often recommend that the individual return for a re-evaluation in six months to one year. Sometimes at the re-evaluation, signs of progression to more serious memory and cognitive impairments consistent with AD are evident, and for other individuals their memory remains stable, suggestive of normal changes with aging. This kind of information can be a tremendous relief for the individual and family members."

In addition to determining whether memory changes are associated with normal aging or signs of dementia, neuropsychological assessments are routinely used to distinguish different types of dementia. Knowing which brain disorder is responsible for a person's dementia can help in treatment because some types of dementia are reversible.

Neuropsychological assessment is also an important aspect of research aimed at learning more about treating AD, such as the effectiveness of new drug or behavioral interventions. In a study of healthy older men, Cherrier used neuro-psychological assessments to examine the relationship between testosterone supplementation and cognitive function. Cherrier and her colleagues found that participants who had received supplements had significant improvement in spatial and verbal memory, compared with pre-supplementation and compared with the control group who had not received supplements. The results of the study in healthy older men suggest that men with AD may also benefit from hormone supplementation, says Cherrier. She has begun a new study designed to determine whether testosterone supplementation improves memory in men with AD.

Cherrier's research also involves developing new neuropsychological tests to measure different kinds of memory more closely. Her major focus is to develop a sensitive method for measuring spatial memory, which is one of the cognitive abilities used in navigating from one place to another.

"One of the earliest symptoms in AD is environmental disorientation or episodes of getting lost," notes Cherrier. "Despite the frequency of this symptom, we do not have a good method for measuring spatial memory." She points out that a reliable and sensitive measure would aid in the development of effective interventions to improve spatial memory.

To investigate spatial memory, Cherrier and her colleagues have designed a new test that measures the ability to learn and recall a route to a particular destination and specific landmarks along the way. In a study comparing performance on the new test between patients with AD and healthy controls, the researchers found that patients with AD performed significantly worse than controls. Their poor performance was characteristic of poor spatial orientation or spatial reasoning. These results suggest episodes of environmental disorientation with AD are more closely related to a poor ability for remembering spatial layout than to an inability to recognize landmarks. More research is needed to investigate the relationship between the level of dementia and performance on the test and to evaluate other cognitive abilities that may be involved.

Cherrier's research also addresses methods for early diagnosis of AD. She is currently developing memory tests to be used with functional magnetic resonance imaging (fMRI) studies. With fMRI, a noninvasive imaging technique, it is possible to identify areas of the brain that become active when a person performs a task, such as recognizing a word. "Recent studies have shown that changes in cognitive functioning as measured by fMRI are detectable in individuals at risk for developing AD even before changes are evident on neuropsychological tests," she notes. "This technique may represent how our evaluation techniques will evolve in the future."

The University of Washington Memory Research Center is conducting several studies aimed understanding effective ways to treat memory problems. The Center offers free memory evaluations for individuals 65 and older who have concerns about their memory. For more information, call 206-221-5698 or 866-866-0187 (toll free) or email wellness@u.washington.edu.

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