I’m 41 and I was diagnosed in August at NYU’s Adult ADHD center. They do research on ADHD in adults there, including medication trials, so I trust them to be up to date in their understanding of proper treatment of the disorder. They’ve been working with me to find the right medication, and never said anything about age being a barrier to taking meds, and never mentioned anything about stopping medications in the future. They did want me to get signed off by an internist for some heart issues I’ve had in the past before prescribing — but it was clear it was just that I had a preexisting condition, nothing to do with my age.
Here’s a quote from my psychiatrist that might apply in your situation:
“Several years ago, we surveyed 400 primary care physicians who treated mental health disorders, anxiety disorders, and depressive disorders, and asked them about their understanding and training regarding ADHD. We found they were twice as comfortable treating depression and anxiety disorders as they were treating ADHD. And, in fact, they had received much less training in the management of adult ADHD than for the other mental health disorders. So there is a knowledge gap here, in part.”
I would definitely get a second opinion. Best of luck.