Distraction underlies memory problems with aging

• Brain • Sep 16, 05

The memory impairment that often accompanies aging may be related to an inability to ignore background information while focusing on the task at hand, investigators report in Nature Neuroscience.

“We were interested in how memory and attention change with aging, to see if changes in (nerve) activity might be associated with changes in performance,” said lead investigator Dr. Adam Gazzaley.

To that end, Gazzaley and his colleagues at the University of California, Berkeley performed specialized MRI scans on the brains of healthy subjects as they participated in tests of memory and attention. Included were 17 subjects ages 19 to 30 years and 16 subjects ages 60 to 77.

The subjects were shown three series of human faces and scenic landscapes, and told to remember faces and ignore scenes, to remember scenes and ignore faces, or to passively view both types of picture without attempting to remember them. After a 9-second delay, they were tested on their ability to recognize the selected picture.

The MRIs showed that both groups exhibited enhanced activity in a brain region called the posterior cortex when asked to remember scenes, compared with when they were asked to ignore scenes. However, only 44 percent of older subjects, compared with 88 percent of younger subjects, were able to block activity in this region when asked to suppress information that was irrelevant to the task at hand.

Older individuals were also impaired in the working memory tasks, having reduced accuracy and slower reaction time, compared with younger subjects.

“Attention is a two-sided coin,” added Gazzaley, “which involves both the need to focus on relevant information as well as suppressing information that is irrelevant or distracting.”

“We found that focusing on relevant information is not enough,” he continued. “In aging there seems to be preserved ability to focus on information that is relevant for the task but a deficit in suppressing information that is distracting.”

Alzheimer’s disease is a common, progressive, degenerative disease of the brain. It is characterized by loss of memory and other cognitive functions. Among people aged 65 or older, it is the most common cause of dementia. Dementia is a group of symptoms marked by the gradual loss of mental function.

A subpopulation of older subjects who performed as well as younger subjects was also identified, which “is a cause for optimism, encouraging us to look for clues for successful aging,” the researcher added.

Based on this, he said, the team now plans to evaluate drugs used to treat Alzheimer’s disease, such as Aricept (donepezil), and different rehabilitation programs “to see if we can correct the suppression deficit and if that leads to improved short term memory.”

SOURCE: Nature Neuroscience, September 11th online issue, 2005.

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