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Selective Memory May Point to Early Memory Loss in Older Adults

July 21, 2016

Findings from a recent study by California researchers suggest that discriminating remembrance—selectively recalling positive information over neutral and negative information—may be a marker for early stages of memory loss in the elderly. The results are to be published in Learning & Memory in August (2016. 23:415-421).

Michael Yassa, PhD, University of California (Irvine) and colleagues designed and employed a test that uses participants’ recall of stories with differing emotional content to identify memory deficits and decline, particularly in the context of aging and Alzheimer’s disease. Thirty-two older adults (21 females, 11 males; mean age, 74.8 years) took part in the study.

After each story was read aloud, participants were asked to recite all of the details they could remember. The task was repeated after 20 minutes and 1 week later. This allowed the neurobiologists to observe how story recall varied as time passed.

Study subjects also took a verbal learning exam to gauge general memory performance. This served to distinguish between individuals who were high performers and those who were low performers (ie, showing subtle memory deficits). Importantly, none of them suffered from overt memory problems severe enough for a clinical diagnosis.

Analyzing the results, researchers found that low-performing older adults exhibited a large “positivity effect,” or propensity to remember positive information. However, this came at the expense of retaining neutral material. On the other hand, high-performing older adults could recall more from neutral stories at the expense of retaining positive details.

“This bias toward positive retention may be a compensatory mechanism that masks the effects of memory loss in the elderly,” Dr Yassa said. “It is possible that selectively remembering positive information may be related to changes in the brain networks supporting memory, emotional valence and reward value.”

Because all study participants at the time of testing had no memory complaints, researchers believe that the exam they created, called the Emotional Logical Memory Test, may tap into subtle changes in emotional memory abilities prior to obvious symptoms of cognitive decline.

Further work will be necessary to establish whether subjects expressing the positivity effect are more likely to develop Alzheimer’s disease. If so, the test could prove to be a valuable tool in the early detection of Alzheimer’s susceptibility. —Amanda Del Signore

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