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Memory Loss Patterns Help in
Diagnosis of Alzheimer’s

Lead Researcher: Scott A. Small resources

Through a novel use of functional magnetic resonance imaging (fMRI), P&S researchers have provided evidence of two distinct patterns of memory decline in the elderly. Clinicians hope to use this technique someday to diagnose patients in the very early stages of Alzheimer’s disease so they can implement early interventions to slow the condition’s progression. Scott A. Small, assistant professor of neurology, published his findings in the April 1999 issue of Annals of Neurology.

Memory decline with age is common, with some reports suggesting that more than 40 percent of people over age 60 have some memory impairment. But not all age-related memory decline inevitably leads to the development of Alzheimer’s disease. "Both Alzheimer’s disease and other age-dependent physiologic changes probably contribute to memory decline in the elderly. A key question for researchers is, ‘How do we distinguish between these processes?’ A test that could do so would be helpful in identifying individuals in the early stages, when the main focus of treatment is halting progression," says Dr. Small.

Dr. Small and his colleagues used fMRI, a non-invasive modification of traditional MRI, to analyze changes in the hippocampus region of the brain during memory tests. It’s been known for decades that the hippocampus is integral to the brain’s memory function. Other functional imaging techniques, such as positron emission tomography (PET), have been used to study brain changes related to memory function, but these techniques have been unable to selectively assess different regions within the hippocampus and thus cannot show how specific areas of the brain alter as memory declines. The study led by Dr. Small is the first to document functional changes in various areas in the hippocampal formation.

"The hippocampus is the first brain structure to be targeted by Alzheimer’s disease; therefore, detection of changes in this area would provide early diagnosis of the condition. Through the use of fMRI, we were able to show two distinct patterns of age-related memory decline in the healthy, non-demented elderly. We believe that those individuals with dysfunction in the entorhinal region of the hippocampus have early Alzheimer’s disease, while those with dysfunction in other regions of the hippocampus do not," says Dr. Small.

The study first evaluated memory function in three groups of individuals over age 64: four patients with normal memory, 13 with isolated memory decline, and four with mild Alzheimer’s disease. All of the study participants viewed photographic portraits for four minutes while undergoing a brain MRI. Study participants were selected from the Washington Heights Inwood Aging Project, a long-term, community-based random aging project. They were followed for at least three years. The research was funded by the National Institute on Aging.

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