Although social isolation and loneliness are different, they can be related. Actual social isolation and perceived social isolation (loneliness) are associated with increased risk for early mortality. Few studies have examined the potential synergistic effects of social isolation and loneliness on health. However, in 2018, a German study explored whether loneliness, social isolation, and their interaction predict mortality.
Using a large, representative sample of German middle-aged and older adults, with a follow-up period up to 20 years, study researchers found that loneliness and social isolation do interact synergistically: the higher the level of social isolation, the larger the effect of loneliness on mortality; and the higher the level of loneliness, the larger the effect of social isolation.
They concluded that both concepts are important in predicting health status. However, more studies are needed that investigate the interactions between loneliness and social isolation. In addition, popular and professional literature could better clarify the differences between social isolation and loneliness and their synergistic effects.