OBJECTIVES: With population aging across European countries, Alzheimer's disease (AD) represents an increasing burden for societies and health care payers. The present study assessed the health-economic potential benefits of hypothetical interventions in preventing AD across 9 European countries. METHODS: A 3-state dynamic Markov model was developed in a population of 65+ year old patients. Age-specific conversion rates from No AD to AD were retrieved from a European study. On top of the non-specific mortality rates, an adjustment factor was applied to patients with AD. Annual costs data for AD were retrieved for 9 major European countries including France, Germany and the UK. These costs (societal perspective) ranged from €9,856 in Ireland to €36,885 in the UK. Two preventing AD interventions were simulated, based on relative risk reductions (RRR) of 0.8 and 0.5. RESULTS: In order to be break-even, annual costs of interventions ranged from €90 in Denmark, Ireland and Sweden to €335 in the UK and from €230 up to €831 in the same countries, respectively for interventions with RRR 0.8 and 0.5. For a given willingness to pay of €50,000, interventions were cost-effective in France at €380 and €970, in Germany at €290 and €770, respectively for RRR of 0.8 and 0.5. For these 2 interventions, average per patients expected savings ranged from €1,859 and €4,829, respectively for RRR 0.8 and 0.5, in Belgium. The demographic projections led in France to a reduction of AD prevalent patients of 25,295 (0.8) and 66,334 (0.5) cases. This translated into annual savings in France of €559 million and €1.465 billion, respectively for RRR of 0.8 and 0.5. CONCLUSIONS: These analyses demonstrate the large potential health-economic benefits of AD preventing interventions. The results are robust across 9 major European countries and should encourage intervention development and financing.