A good way to find out how to think clearly would be to look for some of the rare people who are effective despite serious neurological or mental disorders and find out how they cope.
I remember in one of Oliver Sacks' books, he described a surgeon with Tourette's, which involves tics and involuntary outbursts, but somehow he managed to be perfectly steady in the operating room, and he also was a private pilot.
Perhaps tangential, but the 2015 world champion of public speaking Mohammed Qahtani actually has a really severe stutter. I got the chance to work with him, and he stuttered since he was a child, and still does, severely, during normal chat and workshops and so on, but as soon as he's on stage and he's "on" it disappears.
I remember in one of Oliver Sacks' books, he described a surgeon with Tourette's, which involves tics and involuntary outbursts, but somehow he managed to be perfectly steady in the operating room, and he also was a private pilot.