The more library books per capita, the fewer residents require nursing care: Japan study

The Mainichi

24-06-2025

TOKYO -- Researchers in Japan have found that the more public library books a municipality has, the fewer residents require long-term nursing care. Why is this? The Mainichi Shimbun spoke with one of the authors of the research paper titled " Public libraries and functional disability: A cohort study of Japanese older adults."
The research was led by Koryu Sato, a lecturer at Keio University's Faculty of Policy Management, and Saeko Otani, a Kyoto University Faculty of Medicine graduate currently in training, using the results of a survey tracking more than 70,000 elderly individuals over seven years, and their study was published in the March issue of the medical journal SSM - Population Health.
'So, what is it about libraries?'
Sato, who studied data analysis at the University of Tokyo's Faculty of Economics, holds a master's degree in public health from Harvard University and a doctorate in economics from Waseda University. His specialties are medical economics and social epidemiology.
The research began after Otani, then an aspiring doctor and avid reader, expressed a desire to study the relationship between reading and health.
However, many previous studies have already explored the connection between reading habits and health. For instance, a lifespan study released by Yale University in 2016 followed 3,635 people aged 50 and above for 12 years, finding that those with reading habits had a 20% lower mortality rate over 12 years compared to nonreaders. Additionally, readers had a 23-month longer period before their survival rate dropped to 80%. Other studies have shown that reading helps prevent cognitive decline.
"Reading alone lacks novelty," Sato thought, prompting Otani to suggest, "So, what is it about libraries?" Thus began their unique study on libraries and health.
An unexpected correlation
They utilized data from the Japan Gerontological Evaluation Study, one of the largest surveys of elderly individuals in Japan. The study analyzed data from 73,138 people aged 65 and older who were healthy in 2013 and lived in 19 cities and towns across the country, tracking them until 2021. During this period, 16,336 individuals, or 22.3%, were certified as needing long-term nursing care.
Sato and Otani examined the number of books in public libraries in these 19 municipalities and analyzed their relationship with the number of certifications showing people required long-term care. "In fact, we didn't expect a correlation between libraries and health," Sato admitted. The results were therefore surprising.
More books, fewer nursing care certifications?
The data analysis revealed a correlation: municipalities with one more book per capita had 4% fewer care certifications, and those with 10 more books per capita had 34% fewer certifications. The national average is about 3.7 books per person, according to the 2024 public library tallies, but in Tokyo's 23 special wards alone, the number ranges from roughly two to eight books, with Chiyoda Ward having the most.
Some might question whether municipalities with many library books are wealthier, offering more services, and whether residents are richer and more health-conscious in the first place. However, Sato explained that the results account for demographic and socioeconomic factors.
Specifically, they adjusted for factors such as age, gender, years of education, household income, marital status, employment status, social participation, municipal financial strength and population density to ensure these did not influence the results.
"What we found is merely a correlation, not a strict causal relationship, so we can't definitively say 'increasing library books will reduce long-term care certifications,'" Sato said. "However, even after removing the influence of various factors, the correlation with the long-term care risk was clear."
Health benefits even for nonreaders?
Their study also found that while there was a significant correlation between the number of library books and long-term care risks among those with established reading habits, it still existed for nonreaders. This suggests that living in a municipality with many library books may extend healthy life expectancy, even for those who don't read.
Why do library books benefit the elderly's health?
Sato suggested, "I think that the number of books indicates the library's richness. Having an excellent library nearby is thought to offer physical, cognitive and social participation benefits."
He added, "One is the physical effect. Going to the library instead of reading at home contributes to health. Preceding studies show that prolonged sitting is harmful for health, and even without physical exercise, just light walking is beneficial for health."
Libraries offer more than just reading
The second benefit is cognitive function. Sato explained, "Reading itself is brain training, and unlike regular reading, going to a library offers unexpected book encounters, broadening knowledge. Library events can also stimulate intellectual curiosity."
The third benefit is social participation. Sato noted, "Participating in regular activities like hobbies helps maintain cognitive function and reduce mortality, according to previous studies. The Ministry of Health, Labor and Welfare also focuses on 'community places' where elderly people can conduct activities to prevent care and frailty. A large collection of books indicates that the library is large, and it may serve as a hub for community activities. Libraries also have heating and cooling. This potentially bridges economic and living environment gaps for the elderly, such as those with or without air conditioners."
Indeed, libraries offer benefits beyond just reading, such as physical and social participation advantages.
The key is 'social participation'
On weekdays, libraries are filled with elderly men who are "regular library-goers." Previously, they were often negatively viewed in Japan as "people who can't enjoy retirement" or "those without a place in the family." However, knowing that regular library visits reduce long-term care risk might change perceptions of people around them.
Interestingly, however, the correlation between the number of library books and health was stronger for women than men in this study. Despite the perception that elderly men dominate library visits, why is this the case?
Sato speculated, "It may be due to the degree of 'social participation.'" He added, "While men benefit physically and cognitively from library visits, women overwhelmingly excel in social participation. In terms of this, I think that women likely gain more from library events and group activities."
Indeed, "social participation" might be the key to further improving the health of elderly men who frequent libraries.
(Japanese original by Ayako Oguni, Opinion Editorial Department)