I was diagnosed with ADHD in 2014 and took Methylphenidate for 3 years (40mg XR once daily). It worked for the ADHD, but also increased my anxiety significantly. I then was switched to Adderall IR, 10mg once a day, because of this side effect. I took this dose for 6 months, but it didn't really help me - I felt like it was "half-working".
My dose was increased to 20mg IR once a day 2 weeks ago and, not only do I notice better concentration ability compared to Methylphenidate, I also notice a new cognitive thing I haven't on Methylphenidate.
I have the subjective feeling that now, I understand certain concepts about my life, much better than I did before.
Whereas before life was a mess full of complex geometric shapes (metaphor), now everything feels symmetric and understandable. I notice patterns I haven't seemed to have noticed before, especially when it comes to social behavior.
Everything is so clear and easy to understand. It's like there's another dimension in social relationships that was hidden from me for years, and now I see through it. This has also come next to enhanced creativity.
It's a very interesting effect which I never noticed during 3 years of taking Methylphenidate daily.