I have been taking 100 mg Amantadine every morning for the last six months.
You are lucky to have found a doctor who understands what living with a brain injury incurs.

It has increased my alertness, spacial awareness and cognitive functions better than any other drug I have taken over the last eighteen years.

My advice is, try it at a low dose, 100mg is the lowest, and you will know within five days if it works for you.

After eighteen years of avoiding noisy stimulating environments, I can now sit back in a relaxed state taking it all in with no indications of confusion and fatigue. It works for a few hours of exposure and if necessary I would take another 100mg. I find I would rather leave than to take anymore tablets if it is possible, because of the perceived long term side effects.

After six months, I have no side effects and 100mg is just as effective as when I started but the thought of doing more, by taking more, is tempting but I have avoided the challenge.

It does not do much for your memory, you are not going to be back to you once were, it will not repair damage, it just allows you to live a better life in the present.