"i feel like the character in the movie &quot;limitless&quot; because i have been responding extremely well with this medicine!  it is known that medicine works different for everyone, but for me it&#039;s a god send and i only take 20 mg. i have always had a tough time comprehending everything even talking.  i have to focus on what i&#039;m saying to make less grammar mistakes and sometimes i do sound slow. vyvanse has enhanced my comprehension: i can now do math quicker, enjoy reading and listening, and actually talk like a normal person. i feel happy and energetic.  sounds too good to be true, but i consider myself lucky. no adverse side effects yet.  "