If only you could stop talking long enough to actually listen to others, you might learn things a little faster. As it is, your mind is constantly spinning and your lips move just as fast. Give yourself some leeway, though.
The truth is that your brain isn't wired up to any of your other parts (like your heart, or ego, or physical self), so there's not much to tie it down or keep it in line. So off it goes on yet another tangent. Your mind moves so fast that no one -- not even you! -- can keep up with it. Which makes relationships fairly difficult; if no one can match your mental pace, you're going to end up feeling misunderstood or misconstrued more often than not. And who wants a relationship in which they feel misunderstood? Is there a remedy? Well, the mind is malleable. Even if mental connections to other parts of yourself are lacking, you can develop them yourself. When that happens, you'll feel less nervous and more able to connect successfully with others.