Remembering what to remember and what to forget

June 25, 2009

People in very early stages of Alzheimer's disease already have trouble focusing on what is important to remember, a UCLA psychologist and colleagues report.

"One of the first telltale signs of Alzheimer's disease may be not memory problems, but failure to control attention," said Alan Castel, UCLA assistant professor of psychology and lead author of the study.

The study consisted of three groups: 109 healthy older adults (68 of them female), with an average age of just under 75; 54 older adults (22 of them female) with very mild Alzheimer's disease, who were functioning fine in their daily lives, with an average age of just under 76; and 35 young adults, with an average age of 19.

They were presented with eight lists of 12 words, one word at a time, each paired with a point value from 1 to 12. A new word with its value was presented on a screen every second. The words were common, like "table," "wallet" and "apple." They were given 30 seconds to recall the words, and were told to maximize their scores, by focusing on remembering the high-value words.

The young adults were selective, remembering more of the high-value words than the low-value words. They recalled an average of 5.7 words out of 12. The healthy older adults remembered fewer words, an average of 3.5, but were equally selective in recalling the high-value words.

"It's not surprising that the older adults recalled fewer words," Castel said. "Memory capacity declines with age. However, the older adults were just as selective as the younger adults."

The people with very mild Alzheimer's disease recalled an average of just 2.8 words and had some trouble in focusing on just the high-value words, recalling some lower-value words.

"They recall fewer words and their ability to be selective is worse," Castel said. "They understand that they should attend to the high-value words, but they can't do it as well."

What are the implications of this study?

"Memory can be a limited resource," Castel said. "If we can recall only so much information, we need to be selective in old age. A trick for successful aging is to know what the important things are and to remember those things. Many older adults learn to be more selective because they know they can't remember everything. The ability to be selective might decline when our attention is divided and in the early stages of Alzheimer's disease."

Castel, who conducts research on human memory and aging, including how memory changes as we get older, suggests that older adults focus on fewer, important things.

"If you can remember only a few things before you travel, for example, you might want to remember to take your wallet, your plane ticket and your passport," he said. "If you forget your handkerchief and your comb, those aren't so important."

Castel has conducted similar studies in which some words have negative point values; if you recall them, your score will decrease.

"Healthy older adults are good at not recalling them," he said. (He has not done that study with people in early stages of Alzheimer's disease.)

If you don't want to remember something, he said, the best thing to do is not to pay attention to it.

The research was published in the May issue of the journal Neuropsychology. It was federally funded by the National Institute on Aging, part of the National Institutes of Health. Co-authors are David Balota, professor of psychology and neurology at Washington University in St. Louis; and David McCabe, assistant professor of psychology at Colorado State University.

Castel, 33, follows his own advice.

"I can't remember everything," he said. "I'm learning to be more strategic. I ask myself, what are the three most important things I need to do today. It's about prioritizing."

Source: University of California - Los Angeles