I have been clean for 10 years,and have asked my primary care dr, psychologist, and psychiatrist, to no avail. No one can answer me. I am hoping you can. Using methamphetamine causes your brain to produce dopamine. Does a persons brain only produce a certain amount in their lifetime, and once gone it produces no more? I have no energy, I do NOTHING. I go nowhere but work and back, I have no desire to do anything. Have I used it all up?