It is often said that aging is not for the faint of heart. Today, we can also add that aging is not for the faint of mind.
As we get older our ability to perform a whole range of cognitive tasks decreases. Those tasks, which begin to decline in our 30s, include information retrieval, reaction time, and inhibitory functioning. Yet, there are many older adults whose cognitive abilities remain as sharp as younger adults. So, why do some of us stay mentally sharp while others falter? The answer? It's all in your brain.
In a recent study, College of Liberal Arts & Sciences psychology professor Art Kramer and other colleagues from U. of I. found that older adults who performed a simple cognitive task at the same high level as younger subjects had more white matter in their brains than those older adults who tested poorly.
"We found that both performance and brain-activation differences of older good performers and the older poor performers are predicted by changes in brain structure, specifically by the volume of white matter connecting the right and left hemispheres of the frontal lobe," Kramer says.
White matter contains the essential wiring that allows the brain's two frontal lobes to communicate with each other and carry out executive functions. When the volume of white matter decreases, a "dirty connection" can occur between the two lobes impairing brain function. Less white matter also will affect the brain's ability to tune out irrelevant information.
Kramer's team tested 40 older adults between the ages of 52 and 87, and 20 younger adults between the ages of 19 and 28, at the U. of I.'s Beckman Institute's Biomedical Imaging Center. While lying in a functional magnetic resonance imaging (fMRI) machine for 15 minutes, subjects were asked to focus and perform tasks located in the center of their vision while distracting and irrelevant information appeared in the periphery of their vision. Results of the older adults were compared with those of the younger adults.
While the subjects were in the fMRI, the team took brain scans every two seconds to track blood flow changes to the brain. Changes in blood flow are used to infer changes in neural activity.
While some older adults showed the same mental acuity as their younger counterparts, poorer performing older adults tended to do twice as bad as the younger subjects.
Another member of the team and first author, research scientist Stan Colcombe, explains: "When we looked at the differences in brain structure, what we found was that there were differences in the frontal white matter-the areas of the brain that allow the frontal lobes of the brain to communicate with one another were less intact, had less volume in the poor performers than in the good performers."
Results of this study solve just one small piece of a larger puzzle of aging and brain function, Colcombe says.
"There are all kinds of hypotheses about what might be causing age-related declines in cognition and this is how we sort out from the virtual infinite number of possibilities what seems to be one important player. Also, we'll have to develop different strategies for intervention: cognitive or cardiovascular or, at some point, pharmaceutical."
