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Why multitasking gets harder as we get older

Scientists have discovered why it becomes harder and harder to multitask as we age. Just as our bodies become stiffer, our brains become less maneuverable as we get older, a new study shows. 

Older brains, researchers found, have trouble refocusing after they’re interrupted or distracted.

While nobody’s particularly good at multitasking, we do get worse as we age,  says Dr. Adam Gazzaley, study co-author, associate professor of neurology, physiology and psychiatry and director of the neuroscience imaging center at the University of California, San Francisco.

Gazzaley looked at the impact of interruptions and distractions on “working” memory. This type of memory is like the screen on a computer. Just as we can edit and manipulate words on the screen before we save them to the hard drive, with working memory we can take in information and mull it over in our brains without committing it to permanent memory. That's why we can do simple calculations and compose short works in our heads.

Gazzaley and his team suspected that interruptions and distractions might interfere more with the working memories of older people and explain the occurrence of “senior moments,” like forgetting what you wanted from the fridge after you’re interrupted by a phone call. 

To test this, the researchers ran a simple experiment with the help of 22 young people (average age 25) and 20 seniors (average age 69). While in a functional MRI machine, each study volunteer was shown a nature scene and asked to remember it for about 15 seconds. While they were thinking about the scene, the volunteers were briefly shown a picture of a face and then asked to determine its age and gender.

When the 15 seconds were up, they were shown another nature scene and asked whether it was the scene they’d been asked to remember or a new one.

As the researchers expected, the older people had more trouble than their younger counterparts remembering whether the second picture was the same as the original one. When the researchers looked at the fMRI scans, they could see what was happening during the experiment as some parts of the brain lit up while others dimmed.

When people were interrupted from thinking about the scene, the part of the brain responsible for memory maintenance went offline, while the parts of the brain needed to make a decision about age and gender fired up. After the decision was made, the memory maintenance network came back online, while the decision-making regions turned off. 

The switching process went smoothly for the younger people. But the brains of the older people had trouble turning off the decision-making regions and firing the memory maintenance network back up.

What this means, Gazzaley says, is that the older you get, the more trouble you’ll have switching back and forth between tasks. So, if you have an important deadline to meet, you might want to silence your cell phone ringer and mute your computer so you don’t know when new emails come shooting through. 

What are some tricks you've developed to keep yourself focused?

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