CHAT and Alzheimer disease: Second, porphyran significantly improved cognitive dysfunction in Aβ1-40-induced AD model animals, where the mechanism of action was determined as bidirectional regulation of the cholinergic system: both enhancing choline acetyltransferase (ChAT) activity to promote acetylcholine synthesis, as well as inhibiting acetylcholinesterase (AChE) activity to reduce its degradation, thus effectively elevating the level of acetylcholine in the brain and providing a new potential intervention strategy for the treatment of AD [60].