I think you misunderstand me. Somebody halfway through life isn't just sitting around waiting to die. But if there are ADHD indications and no obvious suffering or underperformance, it is clearly a condition that has been lived with. How valuable is the treatment at that point? There's quite a range between "meh, if it hasn't been a problem then it's probably not going to move the needle" and "it is lifechanging, you don't know what you're missing.". Sibling reply suggested the latter certainly _can_ happen. It seems like a number of posters in this thread have personal experience/wisdom to share.