Sustained treatment with effective doses of cholinesterase inhibitors or memantine is crucial to transfer treatment effects in dementia. Numerous studies, with often small samples sizes, describe low adherence rates. The purpose of current study was to examine the medical adherence of antidementia therapy in Austria. We analyzed the data of 10 Austrian Health Insurance Funds, including treatment-naive dementia patients. Study outcome measures were discontinuation, switching, number of days on therapy, Medication-Possession-Ratio, and compliance. A total of 15,809 patients (mean age: 79.9 y, female: 67.3%) met the study’s inclusion criteria. After stratification by index medication there were 40.3% on donepezil (n=6371); 26.6% on rivastigmine (n=4206); 15.3% on galantamine (n=2424); and 17.8% on memantine (n=2808). After 6 and 12 months on therapy, 5376 (34.0%) and 9243 (58.5%)…