A dear friend of mine had an onset of brain damage because of a toxic batch of vitamins / amino acids (synthetic) that got into this country and caused a run of bizarre symptoms, known as eosiniphelia myalgia syndrome. She suffered from cognitive lapses, language skill loss, and sometimes complete switch-offs. After many trials of various things, her neuropsych told her to learn new things, and she set about doing so with determination. She swears she could feel the brain pathways clicking when she finally managed to retain the new data she was forcing herself to go over nad over until it lodged. Gradually she recovered her old competencies by exercising herself in the pursuit of new knowledge. The condition is in complete remission. She was one of the lucky ones, though. Some died, and some lived in severely reduced cognitive states.