It’s unavoidable. I hate to admit it, but we are going to get older and our minds will too. The important question is: What can we do to slow this process? This was the topic of discussion at yesterday’s Café Science led by neurologist Scott Small.

Cognitive aging is a functional disorder of the brain (unlike a structural disorder such as stroke or tumor) that occurs in a subregion of the hippocampus called the dentate gyrus. Because there are no serological or histological markers for hippocampal pathologies, cognitive aging is particularly difficult to diagnose. In order to study a functional disorder such as cognitive aging, an imaging technique that meets three basic criteria is needed:

1. It should be sensitive to functional changes in the brain.

2. The spatial resolution of the imaging technique should be able to capture the affected area of the brain, even if it is only a few millimeters. It should also be able to capture multiple affected areas as the disorder spreads.

3. It must have cross species capabilities (for research and development purposes, of course).

Small and his colleagues have spent years developing a functional magnetic resonance imaging (fMRI) analysis technique that meets the criteria necessary to study a functional brain disorder like cognitive aging. Basically, a contrast agent, which relies on the paramagnetic properties of deoxyhemoglobin, is injected into the subject. As the contrast agent moves though the brain, areas that are less metabolically active (i.e. dysfunctional regions) will have a higher concentration of deoxyhemoglobin and transmit a different signal than a healthy region of the brain. Small has used this technique to image normal hippocampal function across the human lifespan.

What did he find? I am afraid to say that 60% of elderly people exhibit hippocampal decline. But there is still hope. Small also discussed some of his more recent work, which found exercise can increase blood flow though the dentate gyrus, the only subregion of the brain where new neurons can form in adults. Small believed that this phenomenon was due to the remodeling of muscles as one exercises. More glucose transporters are built into muscles, allowing for quicker glucose uptake after a meal, a factor which he found was critical to the prevention of cognitive aging.

So as the weather gets nicer, go out and get some exercise. Your body and your mind will thank you for it.