We've long known that motor activity and cognition are married together. They are both heavily dependent on the frontal lobe. Also, we know that motor activity is often used to help us think. For example, there has been research that shows that gesturing while speaking facilitates our thoughts. While we once thought that it allowed us to communicate more clearly with a person across from us, we know that it goes deeper and revs up or cognitive engine.
In this article, we see yet another example of the marriage between motor activity, in this case gait, and cognition. We see that the studies, "provide striking evidence that when a person’s walk gets slower or becomes more variable or less controlled, his cognitive function is also suffering."
While this research is fascinating, in some ways, it shouldn't come as a surprise. There is lots of research that shows that physical exercise improves cognitive function and can slow the progression of degenerative conditions. In other words, the mind and motor marriage has been speculated upon and elucidated over the past 2 decades.
Even so, this article gives non-physicians a clear symptom to watch for in their loved ones. When the gait begins to change, there may be degenerative changes beginning in the brain.