I used Alpha GPC in school as a natural alternative to Adderall. The stuff is pretty amazing as far as focus and material retention is concerned. Performs on the same level as Adderall, IMO, and carries no stimulant sides. After Muscle and Fitness published an expo on Alpha GPC for "explosive strength" I took it for a while pre-workout. I could not tell any difference in strength, however, focus was greatly improved. The brand I used was Jarrow Formulas, Alpha GPC 300. It runs about $30 for a 60ct bottle of 300mg pills. For those curious, the following is taken from the Jarrow label:
"Alpha GPC (L-alphaglycerylphosphorylcholine, also known as choline alfoscerate) is a phospholid metabolite found concentrated in neuronal membranes. Made from lecithin. Alpha GPC is extremely well absorbed and crosses the blood brain barrier. In the brain, Alpha GPC supports brain function and learning processes by directly increasing the synthesis and secretion of acetylcholine. Alpha GPC protects neurons and improves signal transmission by serving as a precursor to membrane phospholipids."
Hope this helps..........MAYO