[The relationship between intra- and inter-generational exchange and mental health among young and older adults]

Objective　The purpose of this study was to examine the relationship between intra- and inter-generational exchange and mental health among young adults aged 25-49 years and older adults aged 65-84 years.Methods　In 2016, a community-based, cross-sectional survey was conducted. A total of 3,334 young adults (valid response rate: 24.6%), and 3,116 older adults (valid response rate: 46.0%) completed the survey and were included in the analysis. Their mental health was evaluated using the World Health Organization-Five Well-Being Index (WHO-5), and those who scored under 13 or scored less than one on any item were considered to have poor mental health. To evaluate the intra- or inter-generational exchange, participants were asked about their frequency of interaction with people aged 20-49 years or aged ≥70, excluding family and co-workers. Young adults who interacted with people aged 20-49 years or older adults who interacted with people ≥70 were classified as "having intra-generational exchange," while young adults who interacted with people ≥70 years or older adults who interacted with people aged 20-49 years were classified as "having intergenerational exchange." Therefore, individuals who interacted with both generations were classified as "having multi-generational exchange," and those who did not interact with any generation were categorized as "no exchange." We conducted a logistic regression analysis that included mental health as a dependent variable, intra- and inter-generational exchange as independent variables, and gender, age, educational attainment, marital status, living situation, subjective economic status, social participation, employment, self-rated health, and Instrumental Activity of Daily Living as covariates.Results　Of the 3,334 young adults, 61.5% were mentally healthy, 51.3% had intra-generational exchange, 21.9% had inter-generational exchange, 16.5% had multi-generational exchange, and 42.7% did not have any exchange. Of the 3,116 older adults, 65.8% were mentally healthy, 67.9% had intra-generational exchange, 34.3% had inter-generational exchange, 29.9% had multi-generational exchange, and 21.1% did not have any exchange. A logistic regression analysis revealed that "having intra-generational exchange" and "having intergenerational exchange" were significantly related to better mental health in both young adults (intra-generational; Odds ratios (OR) 1.19, 95% confidence intervals (CI) 1.10-1.30: inter-generational; OR 1.13, 95% CI 1.03-1.25) and older adults (intra-generational; OR 1.15, 95% CI 1.02-1.29: inter-generational; OR 1.46, 95% CI 1.30-1.65). Therefore, "having multi-generational exchange" was more strongly related to better mental health compared with "only having intra-generational exchange."Conclusion　Among young and older adults, intra- and inter-generational exchange were related to better mental health, and multi-generational exchange showed the strongest relationship with better mental health.