Non-stimulant medications may need to be tried, such as Wellbutrin or Effexor or a tricyclic antidepressant. However, often the person doesn't focus well enough and a combination may be indicated. I'll often combine whichever stimulant seemed to work the best with whichever nonstimulant worked the best, such as Adderall and Wellbutrin. No one can focus without adequate sleep, and the brain needs proper nutrition. Too much caffeine decrease focus.
Smoking pot decreases focus.
I wish you the best, Dr. Richard Sogn.