From the abstract:
Both social isolation and loneliness are associated with increased mortality, but it is uncertain whether their effects are independent or whether loneliness represents the emotional pathway through which social isolation impairs health. We therefore assessed the extent to which the association between social isolation and mortality is mediated by loneliness.
Aging & Longevity > Health: Brain & Mental
Aging & Longevity > Social Interaction & Isolation
National Academy of Sciences