After the first week of headaches, Darius Leonard figured maybe this is just how concussions work. By the second week, he began to grow impatient. Once the symptoms persisted into their third week, his mind really started to wander.



The Colts welcomed their All-Pro linebacker back to practice on Monday, fresh off their bye week. Then, Leonard revealed for the first time what he went through on his journey back to the field after missing the past three games.



“The third week,” Leonard said, “that’s when I really started thinking, ‘Wait a minute. Now I have a wife and kid. I’ve had a headache for three weeks. Will I ever be the same? Do I keep playing? You have those thoughts in the back of your head.”



Leonard’s revelations offered a glimpse into the complex nature of dealing with concussions in football, from the diagnosis stage (he wasn’t diagnosed until after a game) to the subsequent treatment of the...