Why older people can’t multitask as well

April 12, 2011

Scientists at the University of California, San Francisco (UCSF) have pinpointed a reason older adults have a harder time multitasking than younger adults: they have more difficulty switching between brain networks.

UCSF scientists compared the working memory of healthy young men and women (mean age 24.5) and older men and women (mean age 69.1) in a visual memory test involving multitasking. Using fMRI, the researchers tracked blood flow in the participants’ brains to identify the activity of neural circuits and networks.

Participants were asked to view a natural scene and maintain it in mind for 14.4 seconds. Then, in the middle of the maintenance period, an interruption occurred: an image of a face popped up and participants were asked to determine its sex and age. They were then asked to recall the original scene.

Older adults had more difficulty maintaining the memory of the original image. The fMRI analysis showed that when both the young and older adults were interrupted, their brains disengaged from a memory maintenance network and reallocated neural resources toward processing the interruption.

The younger adults re-established connection with the memory maintenance network following the interruption and disengaged from the interrupting image. The older adults failed both to disengage from the interruption and to reestablish the neural network associated with the disrupted memory.

“These results indicate that deficits in switching between functional brain networks underlie the impact of multitasking on working memory in older adults,” said Wesley C. Clapp, PhD.

Ref.: Wesley C. Clapp et al., Deficit in switching between functional brain networks underlies the impact of multitasking on working memory in older adults, April 11 online edition, PNAS