In a study of 44 AD patients treated with AChE inhibitors (donepezil, rivastigmine or galantamine), 26 untreated AD patients and a control group (n = 35), it was found that the serum levels of 25(OH)D2 and 25(OH)D3 were the lowest in untreated AD patients and the highest in the treated AD group [131]. This evidence concerns the gene ACHE and Alzheimer disease.