A study by Japan's National Institute for Environmental Studies, conducted jointly with the Tokyo Metropolitan Institute of Gerontology and the University of Tokyo, has shown that elderly people who keep dogs have a 48% lower risk of developing dementia requiring care. The work was published in July 2026 in the International Journal of Environmental Research and Public Health and is based on data on 11 224 Tokyo residents aged 65–84 who were followed for 7,5 years from 2016 to 2023.
The participants were divided into three groups: current dog owners (8,6%), those who had kept a dog in the past (22,6%), and those who had never kept one (68,8%). During the observation period, 1989 people (17,7%) developed dementia requiring care. An analysis using instrumental variables revealed that current dog owners had a 48% lower risk compared with those who had never kept dogs (odds ratio 0,52). Among those who had kept a dog previously, the risk was reduced by approximately 25%.
The researchers attribute the effect to three main mechanisms. Daily walks with a dog increase physical activity and help maintain a regular daily routine. Chatting with neighbours during walks reduces social isolation. In addition, interaction with the animal, including eye contact, stimulates the release of oxytocin, which has a positive effect on brain function and emotional state.
If the share of elderly dog owners in Japan rises from 8,6% to 13,4%, public spending on medical care and nursing over 4 years will fall by approximately 592 billion yen. At the same time, additional household spending on food and veterinary care will amount to about 4,63 trillion yen, but the net savings for the budget will remain significant.
The results highlight the potential of simple everyday habits in preventing cognitive impairment in the elderly. The study was the first to assess not only the medical but also the economic effect of dog ownership in the context of an ageing society.
