June 10, 2004
The ability to retain rote memory skills may remain more intact than other kinds of memory in persons with early Alzheimer's disease, a new study reports. The findings could lead to improved strategies for tending to and caring for a loved one with the debilitating memory-robbing illness, report researchers from the Howard Hughes Medical Institute.
"From this and other studies we have done, it appears that a number of brain systems are more intact in Alzheimer's than we had anticipated," said co-author Randy L. Buckner, Ph.D. "The findings suggest that if we can help people use these brain systems optimally by providing the right kinds of cues or task instructions, we may be able to improve their function."
The scientists found that so-called "implicit" memory, the kind of unconscious memory that allows you to perform routine, long-remembered skills like tying a shoe or punching keys on a keyboard, remained fairly well preserved in those in the earlier stages of Alzheimer's. At the same time, "explicit" or conscious memory, like remembering an event from the past or recalling a loved one's name, progressively fails in those afflicted with Alzheimer's disease.
The results in no way point to a cure for Alzheimer's. But they could help with training or rehab programs as well as day-to-day care for those with the memory-robbing disease, the researchers suggest. For example, if someone must get a daily injection or take a pill, it may be easier to have them do that at the same time and place each day with the same caregiver. Under such familiar and structured circumstances, their "implicit" memory may kick in, and they may be more inclined to roll up their sleeve or open their mouth and take their medicines without a fight.
Mapping the Brain
The researchers studied three groups of individuals: 34 healthy young adults, 33 seniors with intact memory, and 24 older adults in the early stages of Alzheimer's memory loss. All were given a series of words and told to classify them as living objects (such as "dog" or "horse") or inanimate ones (such as "cloud" or "house").
"For this task, we found that all three groups showed a significant reduction with practice in the time required to decide on a word, which is the hallmark of implicit learning," said Buckner. While the younger adults were faster in performing the tasks, all three groups showed a robust reduction in time with practice, he said.
The researchers next asked participants to repeat the task as their brains were studied using a high-tech brain scan called functional magnetic resonance imaging (fMRI). "What was surprising and novel in this study," said Buckner, "is that the brain region with the greatest activity during the task was the high-level region of the frontal cortex," a region of the brain involved with complex memory function that often becomes damaged by Alzheimer's. "These results suggest that despite the damage to these areas in Alzheimer's, certain memory processes that seem to depend on them remain fundamentally intact."
Although the findings are preliminary, Buckner believes the studies point to a promising approach for training and rehabilitation. "Our hope is that by demonstrating the availability of these systems, this knowledge will be translated to cognitive training programs for the healthy elderly and those with forms of dementia, which we just had not anticipated when we began this work," Buckner said.
"Our earlier work had shown that if you leave older adults to form their own approach to a task spontaneously, that's perhaps the least helpful situation," he said. "Whereas, if you constrain the task and give very directed goals, it helps older adults recruit those remaining neural areas. In this study, we've shown that it is possible to tap into high-level cognitive areas that show preserved memory function."
The study appeared in the June 10, 2004 issue of Neuron, a journal of brain research. For more on the latest research on caregiving and Alzheimer's disease, visit www.ALZinfo.org.
Cindy Lustig, Randy L. Buckner: "Preserved Neural Correlates of Priming in Old Age and Dementia." Neuron, Vol 42, 865-875, 10 June 2004.