No, I'm pretty sure being "hyper-focused" is the opposite of ADHD, considering that "focus" and "attention" are synonyms and "deficit" and "hyper" are opposites,

And the effect of amphetamines is improved focus (as well as slight euphoria and wakefulness) BUT one possible problem is that people lose control of what they focus on and tend to get lost in the details. I. e. you start out writing a letter and end up reading about 18th century calligraphy.