Based on the reduction of cholinergic function, this hypothesis arose in the 1970 ́s, after post-mortem observation of human brain tissues of people with AD.(29) Some studies have shown that AD patients reduce choline acetyltransferase rates, especially in cortical and hippocampal regions, which are punctual neurodegeneration sites of the disease.(30) A study prior to that by Bowen et al., also pointed out reduced levels of the enzyme in individuals with cognitive dementia.(29). Here, CHAT is linked to Alzheimer disease.