Purpose: Some studies have suggested that the use of benzodiazepines in the elderly is associated with an increased risk of dementia. However, this association might be due to confounding by indication and reverse causation. To examine the association between benzodiazepine anxiolytic drug use and the risk of dementia, we conducted data mining of a spontaneous reporting database and a large organized database of prescriptions. Methods: Data from the US Food and Drug Administration Adverse Event Reporting System (FAERS) from the first quarter of 2004 through the end of 2013 and data from the Canada Vigilance Adverse Reaction Online Database from the first quarter of 1965 through the end of 2013 were used for the analyses. The reporting odds ratio (ROR) and information component (IC) were calculated. In addition, prescription sequence symmetry analysis (PSSA) was performed to identify the risk of dementia after using benzodiazepine anxiolytic drugs over the period of January 2006 to May 2014. Results: Benzodiazepine use was found to be associated with dementia in analyses using the FAERS database (ROR: 1.63, 95% CI: 1.61-1.64; IC: 0.66, 95% CI: 0.65-0.67) and the Canada Vigilance Adverse Reaction Online Database (ROR: 1.88, 95% CI: 1.83-1.94; IC: 0.85, 95% CI: 0.80-0.89). ROR and IC values increased with the duration of action of benzodiazepines. In the PSSA, a significant association was found, with adjusted sequence ratios of 1.24 (1.05-1.45), 1.20 (1.06-1.37), 1.23 (1.11-1.37), 1.34 (1.23-1.47), 1.41 (1.29-1.53), and 1.44 (1.33-1.56) at intervals of 3, 6, 12, 24, 36, and 48 months, respectively. Furthermore, the additional PSSA, in which patients who initiated a new treatment with benzodiazepines and anti-dementia drugs within 12- and 24-month periods were excluded from the analysis, demonstrated significant associations of benzodiazepine use with dementia risk. Conclusion: Multi-methodological approaches using different methods, algorithms, and databases suggest that long-term use of benzodiazepines and long-acting benzodiazepines are strongly associated with an increased risk of dementia.