A cholinergic is any compound that increases the level of choline or acetylcholine in the brain. They may do this by either increasing the level of choline in the body directly, or indirectly by inhibiting the break-down of acetylcholine. Choline is a water-soluble nutrient that usually gets grouped with the B-vitamins. It is a precursor to the neurotransmitter, acetylcholine. Acetylcholine is a neurotransmitter that has a number of essential functions in the brain and body. It is known to play an important role in memory, learning, muscle activation, REM sleep, attention, motivation, and several other aspects of functioning. Taking Cholinergics by themselves can, over time, lead to mild improvements in learning, memory, and overall cognitive performance. However, Cholinergics are usually taken to increase the effectiveness of other nootropics, and to reduce side effects. For example, the cholinergic compound Alpha-GPC is commonly taken with Racetamic nootropics, like Piracetam and Aniracetam. Users report that this increases the effectiveness of both drugs while also reducing certain side-effects, like headache and brain-fog. While more research is needed to support these claims, some early studies show that taking a choline source with certain Racetams will increase their effectiveness.