Scientists have several theories about what's behind this deterioration, from actual brain shrinkage, the hippocampus  loses 5% of its neurons every decade for a total loss of 20% by the time  you're 80 years old to the drop in the production  of neurotransmitters, like acetylcholine, which is vital to learning and memory.
Znanstvenici imaju nekoliko teorija o tome što se nalazi iza tog propadanja, od stvarnog skupljanja mozga, hipokampus gubi 5 % svojih neurona svakog desetljeća ukupno 20% do 80 godina starosti do pada proizvodnje neurotransmitora, kao naprimjer acetilkolina, od vitalnog značaja za učenje i pamćenje .