Background The existence of social withdrawal (Hikikomori), which meets the conditions “not attending school”, “not working”, and “isolated at home for more than 6 months”, is gradually being discovered by the world, and their mental health and healing is being highlighted. However, there are very few Hikikomori-related surveys searching their physical health, as it is generally believed that most Hikikomori are adolescents. Middle-aged Hikikomori are also found outside Japan, and their physical health is more important, because Hikikomori have difficulty managing their health due to the socially isolated circumstances and lack of sociability. Although “isolated at home for more than 6 months” could not be used, we extracted a group with low social independence with reference to Hikikomori-related surveys. We estimate that people with low social independence have similar characteristics and problems to Hikikomori, because they share many causes for the problem of difficulty in managing their own health. People with low social independence were identified, and their physical health, such as smoking and drinking status, consultation rates of various diseases, and how often they attend cancer screenings, was analyzed. Methods We extracted middle-aged people with low social independence and a control group from the national survey in Japan and stratified them by sex and age. Their health risks were assessed by univariate analysis. Criteria for the experimental group were set with reference to Hikikomori-related surveys. Criteria for the control group included “aged 40–69”, “living with parents”, “not receiving care for disabilities”, and ”working”. Results Low-social-independent men had higher consultation rates for diabetes, stroke or cerebral hemorrhage, myocardial infarction or angina, gastric and duodenum diseases, kidney disease, anemia, and depression, while lower consultation rates for dyslipidemia and hypertension. The tendency of non-smoking and non-drinking was found among them. They seldom attended cancer screenings. Low-social-independent women had higher consultation rates for liver and gallbladder diseases, other digestive diseases, kidney diseases, anemia, osteoporosis, and depression. The tendency of non-drinking was the same as men. More heavy smokers were found among those aged 40–49 years, with no significant differences in other age groups. They seldom attended cancer screenings, as well as men. Conclusions In terms of current physical health, low-social-independent men have more fatal diseases. Both sexes with low social independence seldom attend cancer screenings and have an increased risk of developing progressive cancer in the future. At least in terms of non-smoking and non-drinking, they live healthier lives than the control group, and what makes low-social-independent men have various fatal diseases is still unclear.

Background There is no global consensus on whether pandemic-related factors are related to child abuse. How the pandemic reinforces the risk factors of child abuse might depend largely on individuals’ current and past lifestyles in each country. Some changes of lifestyles continue after the pandemic, and it is important to understand which factors are strongly associated with child abuse. We analyzed the pandemic-related characteristics of offenders and non-offenders of self-reported child physical abuse from Internet survey data in Japan and discussed how the pandemic affected physical child abuse and what caused the difference by gender. Methods We conducted a cross-sectional study on physical child abuse by caregivers based on the Internet survey conducted from September to October 2021. We divided the participants who were living with their child aged less than 14 years into offenders and non-offenders based on the answer to the question about physical child abuse. The population distribution of the sample was compared to that of caregivers under the same conditions in a large Japanese dataset. The association between their characteristics and physical child abuse was analyzed by univariable and multivariable analysis. Results The caregivers analyzed in the cohort had similar population distributions to those in the large Japanese dataset. As risk factors of male offenders, “work from home 4–7 days/week,” “decreased work,” “normal relationships with household members (compared to good relationships),” “COVID-19 infected, both themselves and household members, within a year,” “unwillingness to receive COVID-19 vaccination because the license process of the vaccine is doubtful,” “high levels of benevolent sexism,” and “history of child abuse” were observed. As risk factors of female offenders, “bad relationships with household members (compared to good relationships),” “fear of COVID-19,” “COVID-19 infected, both themselves and household members, within a year,” “feelings of discrimination related to COVID-19 in the past two months,” and “history of child verbal abuse” were observed. Conclusions Among male offenders, a significant relationship was observed regarding work-related changes, which may have been reinforced by the pandemic. Furthermore, the extent of the influence and fear of losing jobs caused by these changes may have varied according to the strength of gender roles and financial support in each country. Among female offenders, a significant relationship was observed regarding fear of infection itself, which is consistent with the findings of other studies. In terms of factors related to dissatisfaction with families, in some countries with prominent stereotyped gender roles, men are thought to experience difficulties adapting to work-related changes induced by crises, while women are thought to experience intense fear of the infection itself.