Aside from caffeine and L-theanine, other compounds are crucial in making nootropics work for you. One such substance is L-deprenyl, also used to treat Parkinson’s disease. Another is the amino acid tyrosine, which functions to help one work under stressful conditions. Sometimes, manufacturers add in the muscle-building supplement creatine, which can act as your brain’s energy buffer. For the most part, creatine monohydrate is used, unlike all other forms of creatine.