Age makes it harder to focus, ignore distractions

Thursday, November 27, 2008

WASHINGTON -- The older we get, the less able we are to filter out distractions while performing mental tasks, a study published Tuesday in the Journal of Cognitive Neuroscience showed.

“Older adults are vulnerable to distraction due to an inability to suppress processing of irrelevant environmental stimuli,” the authors of the study conducted at the Toronto-based Rotman Research Institute at the Baycrest Center for Geriatric Care wrote.

The study asked 12 adults whose average age was 26, and 12 older adults, average age 70, to “encode” several faces while having their brains scanned with a functional magnetic resonance imaging (fMRI) scanner — an instrument which makes a noise like a jack hammer.

Both younger and older adults who experienced difficulty “encoding” a memory, or laying down a new face in the brain, showed lower activity in cerebral regions used for such tasks.

But the brains of older people showed greater activity in other regions, which was not seen in the younger brains, the study showed.

“The older brains showed increased activation in certain regions that normally should be quieter or tuned down,” said Dale Stevens, leader of the study.

“The auditory cortex and prefrontal cortex, which are associated with external environmental monitoring, were idling too high,” Stevens said.

“The older brains were processing too much irrelevant information from their external environment — basically the scanner noise,” said Stevens.

“Not only are we reporting new brain evidence of the well known problem of distraction in aging, but we show that the fMRI might inherently make older adults’ cognitive performance worse than it would be in the real world, outside the scanner,” said Cheryl Grady, a scientist who worked on the study.

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