I've actually met a few adults 50's or early 60's that take adderall or another stimulant. The rules don't really change with age. If your 50 and have heart or other problems that a stimulant might intensify the doctors might not want to prescribe. Of course if you're 10 and have heart/other problems they would take the same precausion.
If your really curious and don't feel like going the doctor route you can always try one of your daughters pills and see how you feel. Of course taking meds that aren't prescribed to you is very risky so I wouldn't recommend it.
Just wondered are there any ADHD on board that are in their 50's and take adderall? I see my daughter responds well to it but she is only 23, I am 50. It says in the med description it amphetime like and I am thinking my Dr might not prescribe them to a older patient. what do you think. Any feedback is welcome Ladybug