BIOTEST Fast-Acting Liquid Alpha-GPC contains the most potent, highest quality, and most pure form of L-alpha-glycerylphosphorylcholine available. Alpha-GPC is a precursor to the neurotransmitter acetylcholine. Clinically, it's been used both orally and intramuscularly to treat Alzheimer's disease, vascular dementia, stroke, transient ischemic attack (TIA), as well as to improve memory, cognitive function, and learning. Clearly, you don't have to be a physician to see that it has profound effects on the nervous system. However, prior to Dr. Ziegenfuss, not many researchers thought to test alpha-GPC on advanced athletes. On the other hand, choline, which is a precursor to alpha-GPC, has been tested on athletes and shown to improve athletic performance and endurance.