Understanding the associations between the number of close friends and life satisfaction: Considering age differences

Life satisfaction refers to one's subjective evaluation of life, which is the cognitive aspect of subjective well-being. Understanding factors that contribute to life satisfaction has important implications as higher life satisfaction is closely associated with better physical, psychological, and behavioral health outcomes. Close friendship serves as a valuable source of social support across life spans. Although there are some studies regarding the associations between friendship and well-being, much less is known regarding the relationships between the number of close friends and life satisfaction and how this association varies with age. By analyzing data from 29,785 participants with an age range of 16–101 years old from the Understanding Society, the current study found that there is a significant interaction effect of age with the number of close friends (b = −0.003, p < 0.01, 95% C.I. [−0.004, −0.001]) after controlling for demographic covariates. Simple slope regressions showed that the positive association between the number of close friends and life satisfaction is the strongest in young people (b = 0.018, p < 0.001, 95% C.I. [0.012, 0.024]), and less strong in middle-aged (b = 0.008, p < 0.001, 95% C.I. [0.003, 0.013]), and the weakest in older adults (b = 0.004, p < 0.01, 95% C.I. [0.002, 0.007]).