The study included 11,194 people aged between 65 and 84 who cooperated in an epidemiological survey conducted by the Tokyo Metropolitan Government, and the team of researchers examined the percentage of people who developed dementia between 2016 and 2020. The "odds ratio," which indicates the risk of developing the disease, was calculated as 0.6 for dog owners and 0.98 for cat owners, compared to 1 for those who did not own dogs or cats.