CANADA: Researchers have discovered that middle-aged people are more readily driven to distraction by interruptions, due to age-related changes in how their brains work.
In research made public yesterday, scientists at the University of Toronto and the Rotman Research Institute documented for the first time how age alters the brain's ability to ignore irrelevant intrusions.
"I have certainly found that as I have gotten older it is harder to deal with distractions," said lead author Dr Cheryl Grady (52), who studies the cognitive effects of ageing. "This experiment tells me why that is. This is happening in my brain."
By scanning the brains of healthy young people, the middle-aged and the elderly, Dr Grady and colleagues detected a gradual breakdown in the brain circuits that maintain the normal balance of the attention span.
Two key regions of the brain that allow the mind to focus on a single task - tuning out the mental static of unwanted thoughts - get out of kilter much earlier in life than previously suspected.
Normally, special neural circuits in the prefrontal cortex become more active when the mind pays strict attention. At the same time, related brain areas in the medial frontal lobe - thought to monitor more general background activity - simultaneously slack off. When the mind is at rest, the level of brain activity in those regions is then supposed to reverse. The researchers discovered, however, that starting in 40-year-olds or more, this see-saw pattern began to break down during memory tasks.
"It's known that older adults are more easily distracted. We think we've found a mechanism in the brain to explain this," said Dr Grady. "The functional changes are detectable by middle age." The research is published in the Journal of Cognitive Neuroscience.
As a practical matter, many researchers are trying to learn whether multi-tasking techniques meant to improve communication and productivity could instead make people scatterbrained, leaving them lethargic and forgetful.
Scientists from King's College at London University, for example, recently determined that people trying to juggle phone calls, e-mail, and other routine office distractions suffered a greater loss of IQ than someone smoking marijuana.
However, Dr Grady suggested that people in their 20s today - their brains moulded by instant messaging and all the other high technology of the short attention span - may be better able to manage unwarranted interruptions when they reach old age. - (LA Times-Washington Post service)