June 7, 1999 "When I was younger, I could remember anything, whether it had happened or not; but my faculties are decaying now and soon I shall be so I cannot remember any but the things that never happened. It is sad to go to pieces like this but we all have to do it."
-- Mark Twain
Mark Twain was not the first person to recognize the propensity of old folks to clearly recall things that never happened, but new research from Washington University in St. Louis is providing still more evidence that Twain based his satire on a keen understanding of the human condition.
"Our study reaffirms what Mark Twain said years ago -- older adults do appear more likely to remember things that never happened," said David Balota, Ph.D., lead author of the study and a professor of psychology in Arts and Sciences at Washington University.
"It is sad, as Twain said, when our memories 'go to pieces,' but Twain may have been wrong when he said that we all have to do it," Balota said. "Our studies and other ongoing research in the field are beginning to provide important clues about the processes that lead to memory loss in both normal aging and in Alzheimer's, and about which specific aspects of memory are prone to breakdowns and which seem to remain intact."
In an invited address June 5, 1999, at the American Psychological Society meeting in Denver, Balota will argue that this study provides further compelling evidence in support of a relatively novel approach to understanding how Alzheimer's cripples the human mind.
"These findings suggest that the cognitive problems associated with Alzheimer's might be better conceptualized as a breakdown in attention rather than primarily a breakdown in memory in the classical sense," Balota said.
"Our results are quite consistent with recent neuropathological evidence linking Alzheimer's disease to physical breakdowns in the frontal lobes, where much of the mind's strategic information processing, including attention functions, are believed to be in part coordinated. Taken together, these studies provide evidence for an attention-based model of Alzheimer's disease."
The study, which is supported by a grant from the National Institute on Aging, is in press for publication in a forthcoming issue of the journal Cognitive Neuropsychology. Other authors on the study are Michael J. Cortese, Janet M. Duchek, David Adams, Henry L. Roediger III, Kathleen B. McDermott and Benjamin E. Yerys, all of Washington University in St. Louis.
It's no secret that older adults often express frustration at their increasing inability to recall seemingly simple things, but this study suggests that older people -- and to a much greater extent those individuals struggling with Alzheimer's -- should also be somewhat skeptical about the accuracy of even those things that they think they remember quite well.
"Our findings, along with other studies, demonstrate that older people are very susceptible to the creation of false memories," Balota said, "which is interesting because it suggests that memory problems associated with aging are not the result of a broad general decline in all memory-related functions, but are due to sharp declines in some cognitive areas, specifically portions of the brain that control the strategic processing of information once it is recalled from memory."
Balota's study is based on an analysis of false recall and recognition rates among 159 individuals who were divided into five groups: healthy college students, healthy older adults about age 70, healthy old-old adults about age 85; and two groups of older adults with either very mild or mild symptoms of Alzheimer's related dementia, who volunteered to participate in studies at Washington University's Alzheimer's Disease Research Center.
Subjects were read a list of 12 associated words that strongly suggest another non-presented critical target word, and later asked to recall words on the list. Imagine being read a list of words, such as Bed, Rest, Awake, Tired, Dream, Wake, Snooze, Blanket, Doze, Slumber, Snore, Nap. Although the word Sleep was never presented, research demonstrates that many people will later recall the word and appear to believe incorrectly that it was indeed presented as part of the list.
Such lists of semantically associated words, first developed in 1959 by James Deese, have recently become a popular and powerful paradigm for the study of memory function. By applying the simple word recall tests to various groups of individuals under various constraints and conditions, researchers are slowly unravelling important details about human memory function.
Balota's studies indicated that young adults recalled the presented words about 70 percent of the time, but mistakenly recalled the non-presented word in about 30 percent of the trials. Whereas, healthy older adults recalled the presented words about 55 percent of the time, and the non-presented words about 37 percent of the time. And people with mild Alzheimer's related dementia actually recalled the item that was not presented slightly more often (35 percent) than they recalled words that were actually presented (only 32 percent).
Results from the study are shedding light on one of the most salient problems in Alzheimer's research -- how the disease influences a person's ability to acquire and retrieve new memories. A key to understanding the memory process is knowing that memories are never generated as 100 percent accurate, vivid snapshots of past events and experiences, rather they are constructed from various tidbits of related information that the mind is able to retrieve and assimilate.
Memories of events, experiences and other knowledge-based information are stored in intricate webs linked by logical, semantic associations; a thought or other stimulus can spark a reaction along these networks and cause a flood of information to be activated. Higher strategic processing skills are then required to sort through these jumbled recollections and associations, discarding those that seem out of touch with reality and focusing on those that most meet the needs of the current task at hand.
Current models in experimental psychology emphasize the importance of a particular strategic information processing function -- attentional control systems -- in both the encoding and retrieval of information in memory. These attentional systems, Balota explains, allow a person to keep focused on a particular topic (the understanding of this text, for example) while inhibiting irrelevant information that is also impinging on the senses (the way in which your third toe feels on your left foot, which is also providing a signal to the brain but is not consciously apprehended until you select that pathway).
The ability to maintain attention to the mental task at hand is critical to the memory retrieval process because the mind must constantly weigh and choose among various streams of potentially relevant information that flood into the conscious mind from the memory network. For instance, the ability to retrieve useful information about "organs" during the following sentence "The musician was pleased to hear about the sale of pianos and organs at the music store" requires that the mind be able to quickly recognize and discard tangentially related information, such as information about "organs" of the human body.
The notion now being put forth by Balota and other Alzheimer's researchers is that the underlying structure of the knowledge-based memory system remains relatively intact, at least during early stages of Alzheimer's, while critical strategic information processing systems in the brain's frontal lobe begin to break down. The loss of these strategic information processing skills, such as the ability to maintain attention on the memory task at hand, makes it increasingly difficult for the brain to accurately processs and assimilate the information it initially set out to retrieve.
The increase in false memory susceptibility among healthy older adults and individuals with Alzheimer's seems to indicate that the mind is somehow overwhelmed by the flood of jumbled recollections still pouring in from an active network of knowledge-based associations. False memories result not from a lack of information, but from the mind's diminished ability to process the information and reach sound conclusions.
"Recent studies in our laboratory indicate that attentional control breakdowns can indeed provide a coherent famework to interpret both the attention breakdowns and the memory breakdowns that occur in Alzheimer's disease," Balota said. "It is quite possible that the apparent memory loss in Alzheimer's disease is in fact a breakdown in attention, as opposed to a breakdown in memory, as one finds in classic cases of amnesia.
"If indeed at least some of the breakdowns may be due to strategic failures," Balota continued, "then it is possible that more appropriate strategies may be trained in these individuals and this may help reduce some of the cognitive declines that occur in both healthy older adults and in early stage Alzheimer's disease. For example, if there is a better understanding of the manner in which such false memories are produced, maybe these individuals could be trained to avoid such distortions of memory. The critical first step is to determine which systems breakdown and which systems are relatively preserved in these populations."
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