This study compared the incidence of vertebral fractures in the 2 groups of elderly female patients with AD who were administered risedronate or a placebo, combined with ergocalciferol and calcium supplementation. We recruited 500 ambulatory women from consecutive patients in our outpatient clinic who were 70 years or older, living in the community and cared for by their family caregivers, and who met criteria for dementia and probable AD according to the Diagnostic and Statistical Manual of Mental Disorders, Revised Third Edition.18 Patients were recruited from March 2003 to April 2003, and each patient was followed up for 18 months. Patients younger than 70 years were excluded from the study. Patients with impairment of hepatic, renal, cardiac, or thyroid function or those who had known causes of osteoporosis, such as primary hyperparathyroidism, renal osteodystrophy, or familial osteoporosis, were excluded from this study. Also, patients were excluded if they had received any drug known to alter bone metabolism, such as corticosteroids, anticonvulsants, estrogens, calcitonin, bisphosphonate, calcium, or vitamins D and K (all forms), for 3 months or longer during the 12 months preceding the study. The study neurologist (Y.S.), who remained blind to the results of biochemical assays of bone metabolism, diagnosed AD.