Fifty-four carefully selected subjects (37 females) satisfying criteria for mild (n = 25) or moderate (n = 29) AD were included in the study. Rivastigmine was prescribed at the initial dose of 3 mg/day b.i.d.; the dose was escalated to the maximum tolerated one in at least 4-week intervals. The response to treatment was assessed using the ADAS-Cog and CDR scales. Whole blood samples were collected twice: before the first rivastigmine dose and at the 2nd week on active treatment