According to research by a professor at the University of Chicago, extreme loneliness can increase an older person's risk of premature death by 14%.
This makes extreme loneliness a risk factor for premature death that is nearly as potent as disadvantaged socioeconomic status. Disadvantaged socioeconomic status is known to cause an increase of 19% in risk of early death.
The researcher notes that a 2010 study even found that loneliness has twice the impact on early death as obesity does.