Slowed Reflexes in Aging Could Be Due to Brain Changes

Breakdowns in brain connections may be the reason why your physical response times slow as you age, a new study has found. The decline occurs in an area of the brain called the corpus callosum, which helps regulate "cross-talk" between the two sides of the brain, said lead author Rachael Seidler, an associate professor in the School of Kinesiology and psychology department at the University of Michigan. Normally, one side of the brain controls movement on the opposite side of the body. For example, the left side of the brain controls movement on the right side of the body.

But when regulation of cross-talk between the two sides of the brain starts to break down with age, both sides of the brain talk simultaneously while one side of the body tries to move, resulting in slower response times, the researchers explained. Seidler and colleagues studied the response times and brain activity of adults aged 65 to 75 as they used computer joysticks, and compared them to a group of 20-25 year olds. They also used a functional MRI to image the blood oxygen levels in different parts of the brain, as a measurement of brain activity in the older group. "The more they recruited the other side of the brain, the slower they responded," Seidler said in a University of Michigan news release.