The 2018 Japan Floods Increased Prescriptions of Antidementia Drugs Among Disaster Victims

Natural disasters can impair the cognitive function of older victims. However, it is unknown whether such natural disasters affect drug treatment for dementia. The aim of this study was to evaluate the effect of the 2018 Japan Floods, the second largest water-related disaster in Japan, on the prescriptions of antidementia drugs (ADD) for older people (≥65 years of age). Retrospective cohort study. Prescription data in Hiroshima, Okayama, and Ehime prefectures for 1 year before and after the disaster were extracted from the National Database of Health Insurance Claims. From the database, we selected 1,710,119 people age 65 years or over as the study participants. In logistic regression models, sex- and age-adjusted odds ratios (ORs) of victims for new ADD prescriptions were calculated. Trends for the ORs before and after the disaster were evaluated using difference-in-difference models. Whether or not there was an increase in the trend for ADD prescriptions (daily dose or number of drug types) was also evaluated among continuous ADD users. Among 1,710,119 participants, 15,994 (0.9%) were recorded as a disaster-victims, and 112,289 (6.6%) were prescribed ADD. Among original nonusers, after the disaster, victims were more likely to start using ADD than nonvictims who had not been affected [adjusted OR = 1.33 (95% CI 1.16–1.52)]. Among continuous users, an increasing trend for ADD prescriptions was more often observed for victims than nonvictims [1.61 (1.13–2.31)]. This effect was robust even after the predisaster trend of ADD use was taken into consideration. The disaster increased the number of users of antidementia medications. The findings suggest the need for evidence-based recommendations to address cognitive impairment among disaster victims, which is lacking in current clinical and disaster guidelines worldwide.